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Thursday, 08 July 2010


Hi Ctein,

Thanks for a great article which is incredibly informative and practical. I'm still learning darkroom technique, but you've opened my eyes up to a couple of potential problems that I may have to rectify... Or perhaps "optimise" -- given that my work space (and wife) dictates: bathroom first, darkroom second.

I'm not sure if anyone reading this will think you're paranoid or OTT, but certainly from what I can imagine these measures are appropriately sound. I only wish that I had the time and space to dedicate to a room like you have. I suspect there is a lot more tinkering that you've done in that photo to optimise the end result and I for one hope you will share it here.

Cheers, Pak

Just curious, but I've always found keeping my eyes open for five minutes is the way to detect stray light. I might be odd though...

No, it's much more effective to keep your eyes shut for five minutes. (Of course you do have to open them AFTER that time. Duh.) It's an effective shortcut. It will take a considerably longer time to see and identify small, faint light leaks if you sit there with your eyes open. Close your eyes for a while and the light leaks will pop out at you once you open your eyes again.


In grad school there was a guy who had something like a compendium lens hood on his color enlarger. The enlarger belonged to the school and they weren't keen on him rebuilding it's stage and bellows or repainting the darkroom.

A bit off topic, and just out of curiosity, but whenever I see glossy plastic blackout sheeting, I wonder whether specular reflections off glossy walls are a cause for concern in a darkroom. (I assume not, if it's good enough for Ctein).


Let's hear it for black plastic sheeting! Years ago I built a 'darktent' in a garage with the stuff. Simply quartered the garage with 2 lengths of iron clothesline wire tightened with turnbuckles. Stapled black plastic sheeting to 2 walls and draped and taped it over the top and sides to form the 'room.' Simple, took less than a day, and cheap. Lasted as long as I lived in that house.

Well if you get tired of printing in that area you could always make a grow-op out of it LOL.

That is one frightening looking room Ctein - an architectural gimp mask - though it looks like you can really set to your developing in there.

The room looks quite scifi actually - that sort of seem appropriate

Great info Ctein, even though you've sworn off film for the future!


I also have gone to some lengths to reduce enlarging flare in my darkroom: http://www.philipmorgan.net/2009/01/05/reducing-enlarging-flare/

I believe my prints have improved as a result.

Re eyes-wide-shut-or-open. Thanks for the advice MIke. I suppose I was talking about ambient light which, rightly or wrongly I tend to worry about more - but then I only use the "darkroom" for film loading/unloading - and it takes me hours to load sheet film.

For the wall part, I just bought a small apartment to be my Dark Apartment as my dear think that my 3 Jobos have outgrown the toilet by a lot . As I am doing my planning, I wonder it would be better to get the Nova Darkroom tent (which will fill up nearly the whole living room, that is a very small apartment) or I should go to the darkroom "painting" like Ctein. Cleaning and later small insert would be an issue I think. I am not comfortable with that darkness :-). Like white wall.

For the enlarger, I have done the first issue of enlarger light leak, but never thought of the second or third issue. How to fix the paper backscattering and enlarger lens issue? For 4x5, I enlarge and for 8x10, I contact print. Any difference of the strategy of fixing these two issues.

I don't know whether this pertains to you at all, so please forgive me if this is useless information.

With some students I found that they actually do better in pitch dark doing dexterity tasks such as loading film if they do shut their eyes. Some people seem to have a hard time "relaxing" their eyes in the dark, and continue to strain to see even if they can't. Anxiety about light leaks might be making things worse. Try closing your eyes and purposely relaxing, and concentrate on visualizing what your hands are doing.

Again, no idea if this pertains--just throwing it out there in case it might be helpful.


Dear Robert,

Actually, less of a concern than flat black. Flat black scatters a small amount of light in all directions. Shiny black reflects most of the light at the complementary angle to the angle of incidence. Unless you had everything in your darkroom are arranged just so (wrong), light emanating from the enlarger just bounces around the room several times until it's fully absorbed; very little of it gets scattered back in the direction of the print easel.

If you ever need to make any REALLY black target, take a sheet of shiny black material, roll it into a cone and curve it a little bit so it's more like a horn shape. Put a card over the opening with hole in it about about half the diameter of the cone. Light goes in but it won't come out!


Dear Steve,

As I've mentioned in comments previously, this darkroom was thrown up as a temporary measure when I moved into this house, in a matter of days, using black plastic stapled to both sides of a 2 x 4 frame, adding a door purchased at the local hardware store. The temporary measure has lasted 25 years now; I am certain it's going to last me until I tear down the darkroom.


Dear Patrick,

You're being fooled by the distortions caused by a wraparound panorama made standing in the middle of the room, combined with an absence of scale. Those trays sitting on the tables on the opposite side of the room? They are 17" x 21" trays; it's a large darkroom!

Mike has been in it; he can confirm that it is spacious and well laid out.

~ pax \ Ctein
[ Please excuse any word-salad. MacSpeech in training! ]
-- Ctein's Online Gallery http://ctein.com 
-- Digital Restorations http://photo-repair.com 

Dear Ctein,
Interesting article. I doubt I will ever had room for a set up like this, but it does look enticing--a world for yourself.

How do you handle ventilation? And do you keep the black bags up all the time? I some climates, one will get yicky mold build up between the bags and the wall.


I don't care what color anybody's darkroom is - I'm just happy to see Mike and Ctein talking about darkrooms. Again.

Has Ctein thrown down the gauntlet?

Ahhh, plastic sheeting. I once had an attic apartment. I wanted to do some printing but the bathroom just wasn't going to accommodate my Omega 4x5 enlarger. So I put it in the next room and used the bathroom for the wet stuff. I had a total of 4 windows, so I just blacked out the whole place, my entire apartment was my darkroom! It worked fine as a darkroom, but I had a few other issues. First off, I did a little too good a job with sealing the windows, I noticed a distinct lack of ventilation. Secondly, it was rather disconcerting to wake up and have zero clue as to what time it was. When I looked at my alarm clock, I had no idea if the time was AM or PM...

I once worked in a slide duping lab (try to find one of those now!) and made myself a little space to do some enlarging on the side. The boss liked what he saw and started to offer slide enlargements. I learned a hard lesson in controlling light spilling from the enlargers. E-6 took about 45 minutes to process and dry. It was absolute torture to make a test only to find that light leaks made the enlargement worthless. We ended up making black baffles that dropped down past the negative stage and of course painting the walls near the enlarger a matte black. Luckily, duping film was pretty slow, so we didn't have to go to the lengths that some others might have had to...


"With some students I found that they actually do better in pitch dark doing dexterity tasks such as loading film if they do shut their eyes."

Now that is rather interesting. When I think about it there is an element of "trying to see in the dark". The brain is a funny thing. I'm going to give it a try.


Ctein - "Dave's right for Dave..."

Are you sure about that?

What I liked most of all the discussion is the DIY black body suggested by Ctein in one of his comments.


Let's hear it for black plastic! I too am using a dedicated room for a darkroom; I made timber frames and stapled plastic to them. I can easily remove the frames when we move (since we are currently renting).

I hadn't considered stray light from the enlarger - I have a Beseler 45 somthing or other (not near me right now) - and there is light escaping from the top half. I hadn't thought to try and contain that since it didn't seem to reach the easel. Although now that you mention the X trick, I'm thinking I should make sure everything is ok...

I don't want to be around when fire breaks out, with all that plastic, and tape and other flamable stuff. Not to mention the dust and smell .. I worked in darkrooms for years, pure horror is that Ctein stuff ..

Mike and Ctein! (and David Vestal, Gordon Lewis, Anchell, Fuller, Dr. Chapman, Weese and others....) I've a debt of gratitude to all of you.
In the times before Internet (and living in the Amazon) your writings, texts and advices were the only source for serious photography, all written with a touch of class.

Looks like the bat cave! :-)

My formula for light leaks is. Expose photo paper a little, no neg in enlarger, so you get the latent image over the hump.
cut paper up into small sizes--put them in different places in darkroom, with coin in middle. 10 to 15 mins should do it--keep safe lights on. develop--if you can see the coin imprint. you have a problem some where.
Also check light leaks from enlarger.

As my darkroom isn't permanent and I have to put up and take down the lightproofing, electrical tape wouldn't work for me. to cover cracks around doors/windows I use 120 backing paper.

"Actually, less of a concern than flat black. Flat black scatters a small amount of light in all directions. Shiny black reflects most of the light at the complementary angle to the angle of incidence."

Makes you wonder why camera and lens makers went to the bother of making lens hoods and the inside of cameras flat black when they could just have left them shiny...

Dear Sevad,

Heh, thought someone would ask about that. Good question! Here's the good answer:

There are two reasons why shiny black paint would create real problems. The first is that the light coming in is strongly directional, headed towards the film/sensor, and the walls of the camera and lenses and hoods are parallel to that direction. Light that hits them and gets specularly reflected is going to continue on more or less the same path that it had before, towards the film.

The second problem is that specular reflections preserve the pattern of the light hitting the surface. Why, you might even say they "mirror" it [vbg]. The lens is filled with glass elements that create images. This is not a good combination. Think of what happens when you point the camera directly at a bright light source, so that even the very faint reflections from the shiny smooth lens surfaces become visible. All those ghost images! That's what would happen if you painted the interiors shiny black instead of matte black. Shiny may work better for suppressing light but matte produces a diffuse glow that doesn't show up as distracting ghosts.

Now, here's something you may not know. Neither matte nor shiny black paint work very well! That's because a large fraction of the incoming light rays are almost parallel to the surfaces when they hit them, what we call grazing incidence. Every flat surface is very reflective at grazing incidence, whether it's painted shiny or matte. To see that for yourself, find a piece of matte black cardboard or a matte surface inkjet print, hold it up horizontal just below eye level and look at the surface as you orient yourself towards a light source like a window. Look at how bright the reflections are from that matte black paper at grazing incidence. It's not very black when there's parallel light bouncing off of parallel surfaces. the same problem exists in your camera gear.

Here are two tricks that manufacturers use to suppress that light. One is to use aperture stops within the lens. If you've ever taken apart a lens, you may run across designs where there is a flat metal plate with a circular hole in it immediately before or after some lens element. The holes are smaller than the lens elements, so the full diameter of the element isn't being used. You may have even wondered why they didn't save money and weight by making the lens element and the barrel smaller instead of "throwing away" part of the aperture. Well, one reason for doing that is to make sure that there are no light rays at the very edges of the lens elements near the lens barrel, where they could be reflected.

The second trick is far more common. The manufacturers rib those matte black surfaces. Look inside a well-made lens hood, lens, or camera body, and you'll see that the walls aren't flat, they are grooved. Those grooves catch the light. If you're looking through the equipment from the point of view of the film/sensor, the "front" sides of the ribs are the ones facing the incoming light, but you mostly can't see them. The sides of the grooves you see are the back sides, which are shadowed. Light hitting those surfaces tends to get bounced forward, not back. What reflections you see are from the edges of the grooves (which aren't perfectly thin) and from light that gets reflected twice, once from the front surfaces of grooves and then again from the back surfaces of adjacent grooves.

And that is today's expository lump! I hope you found it, umm, enlightening.

~ pax \ Ctein
[ Please excuse any word-salad. MacSpeech in training! ]
-- Ctein's Online Gallery http://ctein.com 
-- Digital Restorations http://photo-repair.com 

Dear Ctein,

Thank you for some very illuminating reflections on reflections. And a big extra thanks for tossing in the Cone of Darkness. What a cool bonus!

robert e

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