The Perfect Paper Safe

My darkroom paper safe has, for decades, been a small DIY wood cabinet with some shelves inside. I have never trusted it to be light tight, so I kept all the paper and test strips stored inside in black plastic envelopes like the ones paper and film are packaged in. The hinged door was held closed with a window latch. Although it’s large enough for 11″ x 14″ paper, I never put any paper larger than 8″ x 10″ in it. In fact, I practically never use 11″ x 14″ paper. This was no one’s idea of a perfect paper safe and I wanted something better.

My Old Paper Safe

The Research Phase

I wanted something that made access to the paper and test strips as easy as pulling it out of a drawer. As with all such projects, I started with research on the internet.

There is a nice drawer based design by Kenneth Wells in a 1971 issue f Popular Science.

A very attractive and practical DIY based design by Reinhold Schable can be found on FADU. In fact, if you haven’t visited Reinhold’s website, re-inventedphotoequip.com, you should definitely drop by.

Page 133 of the Darkroom Cookbook (2nd Edition) has a drawer based design that is both simple and close to what I wanted.

From Page 133 of Stephen Anchell’s Darkroom Cookbook

Construction Materials Considerations

On top of the designs by others, there is a lot of discussion on the photo forums about which materials are good for building a paper safe and which are problematic. The TL;DR of it is that you should stay away from materials that contain formaldehyde. From that discussion and my own research I learned that “engineered wood” like plywood, particle board, and MDF contain adhesives that can produce chemical vapors harmful to photographic emulsions, although there is some argument that, because of new regulations, modern versions of those manufactured products have less of the harmful chemicals. It is also plausibly reasoned that water based paints are less likely to emit emulsion-unfriendly vapors than oil based coatings.

Another possible solution is to apply shellac over engineered wood and painted surfaces to block the chemical outgassing. As an experiment, I covered one half of a painted surface with shellac to see if there was any discernable difference.

Masonite primed and painted with flat black latex paint. Left (darker) side sealed with Shellac.

After the allowing several hours to dry, I held each side right up under my nose to see if I could smell any difference. I expected the shellac to smell like shellac and the latex to smell like latex, but the shellac side had no detectable smell while the latex side smelled as you would expect freshly pained latex to smell. Not a very scientific test, but it certainly dampened my skepticism. A downside to the Shellac is that it leaves a glossy finish (making it look darker in the picture above). I prefer a flat finish for light proofing in order to minimize reflections.

In any case, I condensed that research down to a decision to avoid those products altogether and stick with ordinary wood and Masonite (hard board) which, I was surprised to learn, is made with pressure and water, rather than adhesive chemicals. I also decided to stick with water based paint and glue and allow at least a couple months of outgassing of any acrylic or latex binders before trusting it to safely store photographic paper.

Pictures of the Project

For anyone interested in seeing the actual construction of the paper safe, I took many snapshots during the six weeks it took me to complete the construction, painting, and installation in my darkroom. You can view those pictures on my CityShadows.org website here.

Features and Design

The design requirements were as follows:

  • Drawer based operation.
  • No cover to lift up or slide back to access the paper.
  • Must fit the space I had planned for it.
  • Sized to hold 8″ x 10″ and 16″ x 20″ paper.
  • Drawers should open fully, so the interior is fully accessible from above.
  • Must close and stay closed reliably without a latch.
  • Extracting individual sheets of paper must be fumble free.
  • The project had to be something I had the skills and tools to build.

Basically, I was envisioning a drawer with a stair step front that would mate with a stair step cabinet, thereby creating a light trap. There would be two equal size drawers with dividers as necessary to create compartments for 8×10, 16x20s, and the associated test strips. I use 2″ x 5″ test strips for everything. I began the design as a LibreOffice Drawing which was fine to render the simpler aspects such as the divider layout.

LibreOffice rendering of interior dividers for 8×10 version of drawer.

For the more complex light trap features, I quickly realized that the complexity was going to need the 3D features of a CAD program, so I switched to FreeCAD which I’d used on another project. Personally, I really struggled with the learning curve for FreeCAD and am far from adept at using it, but once you’re done, you can view and rotate every piece and how they fit together. You can also see immediately if the component parts can be practically crafted with the available tools and materials.

Cabinet frame showing the stair step design where the drawer front will mate to create the light trap.
Drawer frame showing the stair step design of the front panel that mates with the cabinet.

Construction

A major part of the reason for taking on this project now was because I had recently purchased a table saw which permitted more precise cuts than I was able to do previously. The CAD program spelled out the exact dimensions I needed to achieve a gap of no greater than 1/16th of an inch between the drawer front panel and the cabinet stair step geometry. I used a caliper and test cuts to achieve that level of precision. At first, I tried cutting the stair step on a DIY router table, but it was slow going and not exact enough, so I coughed up the money for a set of dado blades for the saw. That made it about 3000% easier and more precise.

I used poplar for the main framework, but used much more rigid red oak strips as supports under the Masonite floor of the 16×20 drawer. Masonite is susceptible to sagging. The poplar dividers for the 8×10 drawer are glued and screwed to the sides of the drawer and, using screws from below, act as supports for the floor of the drawer. Since the 16×20 drawer has a large area with no support from above, I raised the floor enough to place the support strips under it. This made sense because I don’t use as much 16×20 paper, so the drawer doesn’t need to be as deep as the 8×10 drawer.

In addition to the drawer floor panels, the cabinet was entirely enclosed in Masonite panels and, because the drawer front receded into the font of the Masonite enclosure, it formed part of the stair step light trap configuration.

The “Soft-Close” drawer slides I used allowed for full extension of the entire drawer and have a feature that pulls the drawer closed the rest of the way when the drawer is pushed within a couple inches of closed. That feature actually holds the drawer closed quite securely, making inadvertent opening nearly impossible. In the quiet of my darkroom, I can tell from the “thump” that that it closed completely. I also chose rounded drawer handles that could not snag on clothing and pull the drawer open.by accident.

In order to make extraction of individual sheets fumble free, I placed a wedge behind the paper, opposite from the finder access gap. The wedge is the full length of the paper and pushes the paper out toward the top of the stack. This clever self fanning feature was copied from the Reinhold design. In addition, I placed a sheet of Masonite under the paper, but slightly smaller than the size of the paper so the paper overhangs it on the finder access side. This elevates the paper by 1/8th inch off the main floor of the drawer making it easy to get my finder under the last sheet to lift it out. I should note that, since Masonite is a dark brown, I didn’t paint the floor of the drawers. Less paint means less outgassing to worry about.

One of the last construction steps was the mounting of the front panel of each drawer. The front panels were already matched to the cabinets to fit without any rubbing that would result in the black paint being worn off. The drawer front mounts to the main drawer frame with two machine screws. I glued small pieces of sand paper, to the drawer frame, rough side out, so that the front panel would not move once the screws were tightened. Using shims in the gaps around the edges, I centered the front panel and tightened the screws. There is no rubbing of the stair step surfaces against each other. The gaps aren’t perfect, but they are at least as good as I hoped hey would be.

Installation in My Darkroom

My enlarger table is home built and I designed the paper safe to fit into a space below the counter top next to my D5 Chromega. Basically, it would reside just below the table top where my old paper safe had been setting. A fair amount of customization of the table was required. My paper safe not only had two drawers, but each drawer had its own cabinet. To mount it, I installed two shelves, appropriately spaced, and used aluminum brackets to secure the cabinets to the table legs. Because each drawer is a complete unit, I can remove either one for modification or repair without disturbing the other.

The upper drawer holds two type of 8″ x 10″ paper and associated 2″ x 5″ test strips
The lower drawer holds 16″ x 20″ paper and associated 2″ x 5″ test strips

Final Thoughts

After finishing the installation, I left the drawers open for 2 months to dissipate any residual vapors. After that, I placed sheets of paper, face up, in the the drawers and developed them after several weeks to make sure there was no fogging. In actual use, I decided to place the paper face down to minimize exposure to the safelights from repeatedly opening the drawer to extract paper during printing sessions. My safelight are very safe, but reducing exposure to them is never a bad thing. In fact, I develop RC prints face down for the same reason.

Since I use Ilford Cooltone and MGIV RC 8×10 paper and Cooltone FB 16×20 paper almost exclusively, this will cover 99.9% of all my printing needs. Any other photo papers I use are stored in a cabinet in their original boxes.

Conclusion

So far, the new paper safe drawers have been working perfectly. No fogging and accessing paper is now much more convenient. Is it “The Perfect Paper Safe”? Well, maybe not, but given what I had been using, I had nowhere to go but up.

Orange “OC” Safelights Are As Rare as Unicorns

The Availability of High Quality Affordable OC Safelights is Dwindling

If you’ve done any safelight shopping these days, you’ve probably noticed that new OC colored darkroom safelights aren’t as plentiful as they once were. Lights with red filters seem to be much more common, but the orange ones are easier on the eyes and make darkrooms seem brighter.

Being Adventurous (Buying Cheap)

When I recently decided to add a couple small safelights to my darkroom, I settled on the Yankee bullet-shaped Circular Safelight available at B&H Photo for $32.95. After reading the reviews, it was clear that whoever took over Yankee photo products manufacturing had probably never stepped foot inside a darkroom. This safelight is made from white plastic that is not opaque and by no means “safe”, so I knew it would require some modification.

When I received them, I tested them out and, sure enough, the enclosure glowed with unfiltered light. Furthermore, the “amber” filter was more rad than amber. I lightly sanded the housing, taped over the threads on the housing and lock ring, masked the screw-in metal base, and spray painted the entire exterior with several coats of flat black paint. I covered the label with black electrical tape. No white light was going to escape it after that.

Yankee Safelight Before and After Painting

My experimentation showed that, with a 15 watt bulb, the supplied filter would easily and noticeably fog Ilford Cooltone RC paper at a distance of 4 feet. But, testing a safelight involves more than just exposing a piece of paper to the safelight and then developing it to see if it has turned gray. Photo paper characteristics can be altered by exposure to light that is not strong enough, by itself, to cause a visible gray tone upon development.

What Constitutes a Truly Safe Safe Light

Pre-flashing, a common technique used to pre-sensitize paper so that, when exposed in the enlarger, very dense areas of a negative will show texture where it might otherwise have been completely washed out. But, pre-flashing is something you want to control and do only as needed. You certainly don’t want your safelights doing it for you.

If you want to be confident that your darkroom safelights are safe, there are methods for doing so. Recommendations for testing are available from Ilford and Kodak. The secret is to make sure that your safelight will not noticeably darken very light image tones on the paper you use when exposed to that safelight for the worst case time and distance for your working habits and environment.

I’m a bit obsessive with regard to safelights because I use the pre-flashing technique routinely and I don’t want to worry about rushing my work in order to minimize exposure of printing paper to the safelights. The “amber” filter supplied with the Yankee safelight wasn’t going to cut it, so I began experimenting using Rosco theatrical lighting filters.

How I Made a Terrible Safe Light Into a Very Good Safe Light

When my testing was complete, I settled on a stack of Rosco filters and used a 7 watt bulb instead of the recommended 15 watt bulb. Using the original plastic filter as a template, I cut the Rosco filters to fit inside the locking ring, taped the filter stack with small pieces of Scotch tape, and then secured them to the front of the Yankee safelight housing with the locking ring. After much experimentation I decided on the following stackup of filters:

Modified Yankee Safelight Ready to Assemble
When Taped, the Filters Fit Like a Drum

I tested the this stack up by placing a pre-flashed test strip under the safelight at a distance of 42″ with all my other safelights turned on as well for ten minutes. The bulb I used was a General Electric 7 watt S11 medium base “night light” bulb. Based on my experimentation, I assume it would be safe for longer, but 10 minutes was already beyond what I expected the paper to ever be subjected to based on my workflow.

A few additional Observations

The brightness can be adjusted by changing the strength of the neutral density filter. I found through experimentation that stacking Rosco ND filters is not the same as using a single stronger ND filter. Their filtration is not uniform over the entire spectrum and stacking them will exaggerate that variance. While you may not see a difference in color with the naked eye, a digital camera will reveal a stark difference (at least it did for me). In lieu of an ND filter, you can reduce the light output by partially covering the front of the safelight with a piece of opaque material to reduce the total light output. Covering half the area, reduces the light output by half.

I don’t think the diffusion material is necessary, but removing it will probably increase the light output.

A Cheap Lamp Holder and Cannibalized Extension Cord Completed the Installation

For one of the safelights, I used a handy socket extender that rotates and bends to direct the light where you want it.

Articulated Lamp Socket Extender is a Handy Addition

Finally, yes, this was more work than I anticipated, but I already had the filter material on hand and the the safelights now suit my needs perfectly. My 10′ x 12′ darkroom uses three of the old box style Premier Safelights, but I wanted a couple of small safelights to brighten the dark corners. I couldn’t find any of the 5″ x 7″ or 10″ x 12″ OC lights that used to be so common, so these were the lowest cost option. I didn’t want to have different colored safelights in my darkroom. I wanted them all to be orange. By the way, I considered the Brightlab OC safelight, but some of the reviews indicate that it too is far more red than amber.

Never Ending Enlarger Re-Alignment

Most articles that talk about enlarger alignment tell you how to do it, but don’t explain how it can be a never ending battle.  For me and my two Omega D5s, the mechanisms that throw my enlarger out of alignment are drop-away baseboard tabletops and different negative carriers.

Baseboard Alignment Error

My enlarger is bolted to the wall and the table is mounted below it.  To make larger prints or for more extreme cropping, I can remove the upper tabletop and project down to a lower table top.  I can also remove the lower tabletop and project all the way to the floor.

Removable Tabletops (projection surfaces)

Both of my enlargers are configured similarly.  The tabletops are 3/4″ plywood supported on three or four sides and they are not perfectly parallel, although they are close.  For most routine printing, they don’t introduce enough error to worry about, but when I am being very critical and exposing at wide apertures to avoid diffraction issues, I will align the enlarger for the specific configuration in use.

Negative Carrier Alignment Error

Omega has two main types of negative carrier.  First is the two-piece sandwich and second is the spring loaded Raid Shift carrier.

Rapid Shift (top row) and sandwich style (bottom row)

Each of these carriers can be further divided into glass and glassless.  I use glass carriers exclusively.  In theory, when the Omega lamp house is lowered onto these carriers, they are compressed perfectly flat eliminating any chance of injecting alignment error.  The reality is different. I align my enlargers using a laser alignment tool.  Once I have the enlarger aligned for one carrier, I would expect all my other carriers to behave the same.  They do not.  The rivets in these carriers warp the metal slightly.  The spring tabs at the rear of the Rapid Shift carriers are also cable of preventing the two haves from lying perfectly flat.

Finally, the glass thickness may not be precisely correct for the film thickness, causing a slight bowing of the carrier when the lamphouse is lowered onto it.  My carriers have a mix of original equipment clear and anti-Newton glass from Omega, Focal Point, and some that came installed in carriers purchased from ebay.

What I have found is that my laser alignment tool shows that aligning with one carrier, does not always mean all carriers will be in alignment.  Furthermore, lowering the lamphouse onto the carrier may also also alter the alignment.  Granted, the shift is not great, but it is enough to shake my confidence that I will get corner-to-corner sharpness in a large print at wide apertures.  Large, for me, is 16″ x 20″ or 20″ x 24″.

While there is no easy fix to this dilemma, anyone who uses a view camera knows that lens adjustments (swings and tilts) can be used to match a plane of focus to a non-parallel film plane using the Scheimpflug Principle.  Stated another way, the lens plane can be adjusted to accommodate any errors in alignment between the enlarger film plane and the easel.  Besseler did exactly that when they offered a lens board called a Bes-Align.  It has three adjustment screws to allow an enlarger lens position to be adjusted in a way that can be used to accommodate a misalignment between film and easel.

Bes-Align

The adjustable lens board can be used in conjunction with a Micromega or Peak grain focuser to tweak the lens plane as required to ensure the corners the image projected onto the easel are in focus.  It provides a quick way to fine tune enlarger alignment to compensate for errors introduced by different negative holders or baseboard (table top) configurations.

I made a version of the Bes-Align to fit an Omega D5 years ago.  I simply attached a lens mounting plate to an Omega lens board using three machine screws with an 3/16 inch layer of black foam between the plate and the lens board.  The foam serves as a light seal and as a spring to act against the three adjustment screws.

My copy of the Besseler Bes-Align adjustable lens board to fit an Omega D5 enlarger.

My copy of the Be-Align was functional, but I wanted something deeper that would accommodate the rear extension of my El-Nikkor lenses, so I decided to add a spacer and make it more rigid with actual springs rather than relying on the resilience of the foam rubber spacer.

Improvements included springs and a 1/4″ spacer.

I drilled out the threaded holes in the original design lens board in favor of threading new holes in the much thicker spacer.

The adjustment range of the new design will permit perspective control on architectural pictures.

I found cheap springs at the local home improvement store and cut them to length with a Dremel tool.

The springs are fairly stiff and the adjustment screws go most of the way through the 1/4″ space making the assembly quite rigid.

 

The hole in the stock Omega lens board is considerably larger than the lens mounting hole.

The rear of the lens extends up into the gap between the lens mounting plate and the Omega lens board.

I used soft black foam shelf liner material to seal against leaks. I cut the strips, roughed up the glue surfaces with sand paper, and then epoxied them to the edges of the 1/4″ spacer.

Fitting the light seal strips before actually gluing them.

I sanded, primed, and painted the pieces to further reduce light leakage and reflections. I did not paint the surfaces that were to be glued.

Spring placement and final assembly of the pieces.

As you can see, I ultimately settled on using Phillips head adjustment screws. I tested the 40 mm lens first to make sure the lens wasn’t too far away from the film plane to focus.

This shows how far back the lens extends toward the rear, but I will easily be able to slide the lens board out of the enlarger without having to unscrew the lens.

The 150 mm lens is the heaviest of my lenses, but will be held securely enough to keep it from moving when I change aperture settings.

The final product installed on the enlarger with my under-lens filter holder positioned under it.

Laser Enlarger Alignment

If you’ve been involved in darkroom photography very long, you already know that corner-to-corner sharpness of a print made using an enlarger requires a properly aligned enlarger.  That simply means that the negative, lens board, and baseboard are all parallel to each other.  Tools are available to help verify and adjust the alignment of your enlarger.

I’ve tried enlarger alignment using bubble levels and a clumsy, although workable, DIY version of the ZIg-Align.

DIY mirror alignment system based on Zig-Align (although not as good).

In my opinion, laser alignment tools are the easiest to use, easiest to see, and provide ample precision.  “Easy” is important if you intend to make alignment verification part of your routine.  The Versalab Parallel tool looks like a great solution, but it costs $200+.

The laser tool I finally settled on consists of a 3D printed platform to hold a low cost laser sight.  If you have access to a 3D printer, the design created by Larry Gebhardt at Tripping Through the Dark is the best low cost solution for quick and easy enlarger alignment.  Below are pictures of the one I printed from the file supplied at Thingiverse.  I got the laser sight on Amazon for $10.99, but Amazon no longer lists it.  They are, however sold new on ebay for under $10.

CAUTION!  BE CAREFUL NOT TO SHINE THE BEAM IN ANYONE’S EYES!

I added the little square piece of post-it note to the top to make it easier to read when the beam is reflected almost directly back into itself.

Laser Tool Calibration

The laser alignment tool must be calibrated to be sure he beam is perfectly perpendicular to the base.  To do this, you simply set the tool on a horizontal flat surface pointing up at the ceiling, turn on the bean, and adjust the two set screws until the point of light on the ceiling remains stationary when you rotate the tool in place.  I use the center head from a combination square to keep the tool in place as I rotate it, but anything with a L-shape can be used. If the tool is not calibrated when you rotate it, it will trace a circle on the ceiling which means the beam is not perfectly perpendicular to the table.

Calibration of the tool requires you to be able to rotate it on a flat horizontal surface without it moving.

I tacked a 1″ paper target to the ceiling above my darkroom counter top as a reference point.  Once you have it adjusted, it stays put almost forever.

I tacked a paper target 1″ in diameter to the ceiling as a reference point.

Using the Laser Alignment Tool

To use the alignment tool, you simply place it on the baseboard or easel below your enlarger so the beam shines directly up through the lens mounting hole.  You align the negative stage by placing a piece of glass where the negative carrier normally goes and adjust it until the beam reflects off the glass directly hack down into the center of the laser.  A glass type negative carrier can, of course, be used instead of a separate piece of glass.  I put a piece of black paper on top of the glass to prevent any spurious reflections (e.g. from a condenser lens or mixing chamber above the glass).

The lens stage is aligned in a similar manner.  Instead of attaching the glass, you can simply screw a flat filter onto the front of the lens.  I once tried using a 49mm filter with a cheap ebay adapter to fit the 40.5 mm threads on the lens, but the adapter thread was apparently a different pitch because it didn’t screw all the way in and when I rotated the lens (as you can do with El-Nikkors), the reflected beam moved in a circle indicating that the filter was not perpendicular to the lens axis.  When I tried a 52mm filter with a cheap 52 to 40.5 mm ebay adapter, it worked fine.

If you don’t have a filter, you have to find a way to attach the glass to the lens stage or the front of the lens.  I’ve done this using a rubber band to attach a piece of 4″ x 5″ picture frame glass to a lens board with a few lens spacers installed.

To align the lens stage, I attach a 4″ x 5″ piece of glass to a lens board with a rubber band.

Note the lens spacers above the glass to make sure the glass is registered to the same plane as the lens. The tape protects the rubber band from the sharp edges of the glass, but must not come between the glass and the lens board.

Alignment Sequence

Since adjustment of the forward and backwards tilt of the lens stage on the Omaga D5 seems to require adjusting the tilt of the entire carriage, it is best to align the lens stage before the negative stage.   In other words, adjusting the eccentric rods to affect the forwards/backwards tilt of the lens stage will also affect the tilt of the negative carrier.

Rechecking Alignment

Once you have the enlarger aligned, it is a fairly simple matter to check the alignment before a printing session.  It is also easy to verify alignment after setting up the enlarger for an important print that you want to be perfect.  You can very easily experiment to see what factors may affect the alignment.  For example, does the alignment change when you raise or lower the head?  If you use glass carriers, see if different carriers affect the alignment.  Same is true of different easels or if you have an adjustable table.

DIY Omega D5 Focus Extension Lever

Have you ever made a big enlargement where the enlarger head was so far above the base board it was impossible or too awkward to reach the enlarger focusing knob while looking through the grain focuser?  I have and decided to find a way to make it easier.

Can’t reach focus knob while looking through grain focuser

There are a few solutions to this problem.  Omega made a flexible focusing shaft (P/N 464-055) which can still be found on line.  Saunders/LPL made a generic flexible focus extension that is apparently no longer available.  KHB Photografix sells a version deigned for use with the Omega Micromega Fine Focus Control and another version that works with the main focus control.

Being a penny pincher, I wondered if there might be a cheaper way that didn’t challenge my lazy lifestyle too much.  What I came up with was a simple lever that extends down from the focusing shaft.  The procedure is to set up the enlarger as I normally would to make a large (or heavily cropped) print, focus as I normally do, but then simply replace the focusing knob for the long lever to do the critical focusing with the grain focuser.

The materials to build the lever are below.  Dimensions should be adjusted to meet your own requirements.

  1. Pine wood strip 3/16″ thick x 1-1/4″ wide x 27″ long.
  2. Aluminum rod 3/8″ in diameter x 7″ long.
  3. #10-24 machine screw and washer.
  4. 3/8″ shaft coupler (available on Amazon)

The wood strip needs to be light, but rigid.  The length of the aluminum rod should be long enough to keep the lever out of the image area.  The shaft is attached to the end of the wood by drilling the appropriate hole in the end of the shaft and tapping the hole to accommodate the machine screw.  I had a #10-24 tap handy, so I drilled a 5/32″ hole and threaded the hole to accommodate the length of the screw.

The ruler is just for scale. Note the small piece of sandpaper at the hole on the left end of the wood.

Painted black and assembled.

Small piece of sandpaper glued to wood ensures the rod won’t rotate.

Allen wrench sizes are 5/64″ for the knob and 3/32″ for the coupling.

I couldn’t reach the focusing knob, but can easily reach the lever for critical focus.

The lever extends down where I can easily reach it.  “Easily” is a relative term. Since I will be on my knees to look through the grain focuser, it is not as comfortable as when I’m standing up.  I don’t think the flexible shaft focuser would be much better.

The secret is to hang the lever on the focusing shaft so it is vertical before tightening the set screw.  The lever is then moved to effect a small rotation of the focusing knob, making it easy to fine tune the focusing.  If you did a reasonable job eye-balling the focus during setup, the fine adjustment is very small.The light weight of the lever is not enough to turn the focusing knob by its own weight, so once you adjust it, it stays put.  I also found it to be a simple matter to remove the coupling from the shaft without corrupting the focus.

The lever is light, so it will not rotate the focusing shift by its own weight.

I did not tighten the friction tension on the focusing shaft for this project, nor do I consider the focus particularly stiff on my two D5s, but even if you have your focus set to be more loose, the lever will likely never be at much of an angle from its initial vertical position, so the torque will be very tiny.

Adding fans to Omega DV Condenser Lamp House

Bcakground

In my last article, I conducted some temperature tests using the 250W PH213 lamp in the Omega DV Condenser lamphouse.  Omega offered a blower for the DV lamphouse that permitted use of 250W bulb. The Omega part number is 412-020.  I’ve never seen one, but it is listed on the KBH Photografix website.

As expected, with no blower, the 250W bulb generated considerably more heat than the 150W bulb, exceeding 200 F between the bulb and heat absorbing glass.  This article describes my adventures in adding a pair of small fans to the lamphouse to try and reduce the heat buildup from the higher wattage bulb.

Construction

The first step was to remove the plastic covers on each side of the lamphouse.  These covers permit air to flow into the sides of the lamphouse and exit through an opening in the top, cooling by convection.  The bulb is completely enclosed within an inner chamber preventing any light leakage through these ventilation openings.  For this project I decided to attach a 12 VDC 60mm low speed computer fan (Noctua NF-A6x25 FLX) available from Amazon to each side of the lamphouse, both blowing air inwards.   The low speed will minimize noise and vibration and the speed can be controlled by simply reducing supply voltage (or adding resistance in series with the power).  The down side is that a small fan running at low speed doesn’t move a lot of air.

Noctua NF-A6x25 FLX 60mm Fan

To attach the fans, I designed a mounting plate that can be attached to the lamphouse using the existing threaded holes previously used to attach the plastic covers.  Since the #6-32 threading in those holes does not extend very deep into the holes, I used the original self-threading screws to deepen the threads.  I simply worked the screws in and out, each time going slightly deeper.  My #6-32 tap has a pretty long taper and I was afraid it would bottom out sooner than the screws.

Fan Mounting Plate (dimensions approximate)

I cut the plates out of some 0.092″ thick scrap aluminum I had lying around and started marking and drilling.  As you can tell, I am much more inclined toward functionality than prettiness.  Also, I’m kind of lazy and have a short attention span, so I needed to keep the project within the limited range of my mechanical skills.

Cut scrap aluminum to size and started drilling.

To cut the fan hole, I screwed the plate to a piece of wood so I could rotate it around as I cut it with my jig saw (aka sabre saw).

Jig to cut the main hole in the plate. (the 2 holes at the bottom do not need to be countersunk).

As you can see, the hole placement does not lend itself to easy assembly.  I wanted to mount the fan to the plate and then mount the plate to the lamphouse.  Unfortunately, two of the screws that mount the plate to the lamphouse are under the fan.  The problem solved itself, however, because the upper two screw holes were bisected by the fan cutout.  I installed those two screws into the lamphouse and simply slid the fan plate (with the fan installed) down under them.  Then I simply installed the two lower screws.  Note that I countersunk all four holes, but the countersinking is only needed for the top two screws which are trapped under the fan.

Hook the plate under the upper two screws (already installed) and then install the lower two.

Fan plate with fan attached (this is actually the second fan plate).

I got a variable 3- 12 VDC fan power supply from Amazon to power the fans, but left the task of dressing up the wires until after doing the testing.  Ultimately, the fans were wired together and the wire routed along side the main lamphouse power cord so as to be out of the way.

Results

Test setup.  Thermocouple placement was identical before and after fans.

The “Before Fan tests” were conducted with the original plastic covers still in place before work started on the fans.  The thermocouple was then left undisturbed as I added the fans so as to ensure no other variables were introduced in the test results.  I have heat absorbing glass installed in the top slot of the variable condenser housing.  The thermocouple was centered in the middle of the heat glass and suspended 0.500″ above the surface and 0.700″ below the bulb.  I measured this before the fans were added and after the fans were added to make sure nothing changed.  Experiments are worthless if the conditions of the test are inadvertently altered during the test.  The variable speed controller was set to maximum output (12 VDC) for all of the tests with the fans.

The results are tabulated below.  The results with no fans are the same measurement collected for my previous article.  I started each test with the temperature stabilized at room temperature.  I had the lamp turned on for 120 seconds and then turned off for 120 seconds.  Temperature readings were made at 30 second intervals on the ramp up and on the cool down.

Temperature comparison with fans and without fans.

While the fans certainly do reduce the temperatures, I was hoping for better than this.  My goal was to keep the temperature range for the fan cooled 250W bulb more in line with the temperatures generated by the convection cooled 150W bulb.  That was overly optimistic given the fact that the airflow never actually touches the bulb which is enclosed in its own chamber.  On the bright side, the cool down time is definitely accelerated by the fans.  After the 250W lamp has been off for the 2 minute cool-down, the temperature (111.2 F) is very close to that of the 150W bulb with no fans (109.4 F).

For those who are wondering, I did run one test to see if the cooling performance was different if one fan was flipped to blow out instead of inwards.  The performance was measurably worse, so I reverted to having both fans blowing inwards.

Noise

I measured the acoustic noise of the modified condenser lamphouse against the noise generated by the fan in my Chromega with the noise meter 10″ in front of the respective enlarger heads.  As you have probably guessed, the reason for the noise test is to get an idea of whether the fans could induce vibration that diminishes print sharpness.  The heads on these enlargers are massive compared to the mass of the spinning fan blades, so the risk is presumably quite small.

  • Modified Omega DV Condenser Lamphouse:  43.5 – 44.5 dBA
  • Standard Chromega Lamphouse:  46.5 – 47.5 dBA
  • Ambient Noise Floor:  38 – 40 dBA

For the hell of it, I listened to each of them using a stethoscope and the Chromega was noticeably louder.

But What About Temperatures at Negative Plane

Measuring the temperature at the negative plane with the 250W bulb and starting at 23 C (73.4 F) ambient, I got a thermocouple reading of 27 C (80.6 F) after the lamp had been on for 120 seconds.  With the 150W bulb, the reading was 25 C (77 F) after 120 seconds.  While not hot enough to damage the negative, this may be enough to cause the negative to “pop” out of focus.  This is of little concern to me since I use glass carriers.

I use heat absorbing glass (Omega p/n 473-103) in my condenser enlarger and I don’t have any test results without having the glass installed in the uppermost shelf in the variable condenser housing.  Since I never use a 135 mm lens, I never have to install the movable condenser lens in that slot.  For 4x5s, I use 150 mm which eliminates the movable lens completely.

Finally, and this applies to this article as well as the previous one, thermocouples do not react instantly to temperature changes and we are dealing with a short time line for these tests, so the actual temperatures are likely to have been somewhat higher than the numbers recorded during these tests.  Nonetheless, I think the tests do provide useful information for comparison purposes between the three different wattage bulbs tested.  It also satisfied my curiosity about how practical it is to use a 250W bulb in the Omega DV condenser lamphouse.

Having now added the fans, I believe I will be quite comfortable using the 250W lamp when necessary for large magnifications or to shorten exposure times for dense negatives.

Using 250W PH213 Bulb in Omega DV Condenser Lamphouse

Background

If you have an Omega 4×5 variable condenser enlarger, you probably know it is common to use 75W and 150W bulbs in them.  These enlarger bulbs are designated #211 and #212, respectively.  Often they are referred to as the PH211 and PH212.  You may also know there is a brighter alternative that will physically fit.  The #213 is a 250W version of the above and is available online from Freestyle, B&H, and 3rd party sellers on Amazon.  I measured the new bulb at about 1.3 stops brighter than my 150W bulb which already has quite a few miles on it.

Left to right: 250W #213, 150W #212, and 75W #211

In its stock configuration, the Omega variable condenser lamp house is not rated for the 250W bulb.  My particular enlarger is rated at 75W and specifies the #211 bulb.

Lamp enclosure for Omega D variable condenser lamphouse.

Newer versions of the lamphouse are apparently rated at 150W, although I don’t know of any design differences.  I have been using the 150W bulb in my enlarger for years with no problems.  The power cord can certainly handle the load and there are no signs of any heat damage.  But, even with the 150W bulb, my condenser enlarger is not as bright as my Chromega with its 250W reflector bulb. This is a problem when I intentionally enlarge big and crop small to accentuate grain.  I’m not a fan of long exposure times measured in minutes.

Omega made a blower for the condenser lamphouse to specifically allow the use of the 250W bulb.  The Omega part number is 412-020.  I’ve never seen one, but it is listed on the KBH Photografix website.

There have been discussions on web forums on this topic.  Some suggest using an LED head to get more brightness.  In one discussion on the Large Format Photography forum, the highly regarded Bob Carnie of Toronto, posted that he has been using 250W bulbs in his Omega condenser heads for years with the only downside being a shorter lifespan for the bulb.

Anyway, on a recent project, I really wanted to shorten my exposure times, so I ordered one of the 250W #213 bulbs and started experimenting to assess the effects of using such a hot bulb.

Experimentation

I decided to test each of the three bulbs, 75W, 150W, and 250W, under identical conditions and collect some temperature data.  I do not have an IR temperature gun and I was mainly interested in reading internal temps, so I used the thermocouple that came with my multimeter.  I suspect the readings lag actual temps, but it should be sufficient for comparison purposes.

I use heat absorbing glass (Omega P/N 473-103) placed installed in the highest slot  in my condenser head.  I had the variable condenser in the lowest spot (for lenses up to 80mm).  I placed the thermocouple 0.425 inches above the heat absorbing glass which positions it about 0.700 inches below the bulb.  The temperature readings very greatly if the thermocouple is closer or further away from the bulb even by small amounts, so I repeatedly verified that the thermocouple never moved throughout the testing.

Test configuration: Thermocouple just above heat glass

I turned on the lamp and measured the temperature every 30 seconds up to 2 minutes and then turned the lamp off and measured the cool down for another 2 minutes.

Results

Rather than try to learn how to do a table in WordPress, I just used an image file.  The lamp is on for the first 120 seconds and then turned off for the next 120 seconds for a total measurement period of 240 seconds.

Conclusion

It’s pretty easy to see that the 250W bulb creates a lot more heat stress than the lower wattage bulbs.  Temperature build-up really depends on how long your exposures are and how much of the time the lamp is off and cooling down.  Cool down is slow, so I allowed a considerable interval between tests.  I know from my own past experience that the negative stage stays relatively cool regardless of the bulb wattage because there is so much glass separating the bulb from the negative.  But, since I practically never make more than a few exposures from the same negative, the average off time of the enlarger far exceeds the on time.

I have decided to remove the plastic covers and add a small cooling fan to each side of the lamphouse.  I will have pictures and test results from that project in a future article.