Thursday, December 29, 2016

Effects of Exposure and Development Times on Wet Plate Collodion

   Recently I have been seeing a lot of people having problems identifying the signs of their plates being either overdeveloped or overexposed, so I decided to do the following simple exercise that should make it easier for folks with a discerning eye to see if one of these troubles may be possibly plaguing them at the moment.

  I might have mentioned before that when working with wet plate collodion it is possible to overexpose and underdevelop a plate and still achieve a tolerably good plate.  It is also possible to SLIGHTLY underexpose and overdevelop, but only very slightly so before serious ugliness sets in.
For absolute best results of course there's really nothing like nailing the exposure within 1/4 of a stop and having development run the length of time which you have previously determined to be the best based on your collodion and developer formula.  We all know however that bullseye is sometimes hard to hit, so here's what we can do to fudge it a tad.

  I have always develop by inspection.  I use slow developer and use it cold.  I know that with that I can usually go to about 50sec without any ill affects.  With a perfect exposure I see the highlights start to appear at about 7-8 seconds, mid-tones come in at about 15-20 and then the shadows start building.  Sometimes though I don't nail my exposure (especially with the very first plate of the day) and I see the highlights pop up after only 4-5 seconds.  That's when I know I'll have to stop development early ('pull' is the film term for that).  Sometimes I slightly underexpose and don't see the highlights come up only after 10 seconds - that's when I know I may be in trouble, but I still 'push' development longer just a bit hoping that even at 60-65sec mark the fog of overdevelopment won't show....  I find that if anything it's better to expose a little more and cut development a bit short than ti underexpose and try pushing it.

  When plates are OVEREXPOSED and underdeveloped they still have nice and clear shadows, but the highlights are not as bight and mid-tones are also a bit flatter and muddier.  They aren't all that bad looking.
  When plate are UNDEREXPOESD and overdeveloped it's a different story though.  Just a slight overdevelopment my cause only a barely visible problem, but it will get worse very quickly as you keep pushing development.  There are MANY different types of 'fog' that are possible with wet plate, but the one that comes from overdevelopment is probably the ugliest.  Luckily it's also one that is the easiest to identify.  It looks as if there are tiny golden crystals lodged in the dark areas of your image.  They shimmer slightly in the light.  it tends to happen first in the parts of the plate where the collodion is thickest, so a lot of times, when you just barely overdeveloped, you'll see those crystals outlining the area of your plate where the collodion was first poured on.

  So to demonstrate the theory I made 5 plates today.  I shot in a place right by the darkroom where I shoot a lot, so I know that my ideal exposure there is about 3 seconds (Dallmayer 2B lens did have a Waterhouse stop in and at the given bellows extension the effective aperture was f6.5).  The 5 plates were thus given the following exposure/development times in seconds:

1) 3/50 - normal
2) 6/30 - one stop overexposed and 40% less development
3) 12/20 - two stops overexposed and 60% less development
4) 2/75 - about 2/3 stop underexposed and 50% overdeveloped 
5) 1/115 - about 1.5 stops underexposed and 130% overdeveloped 

  Here are the 5 plates.  Center one is normal #1, top left is #2, bottom left is #3, top right #4, bottom right #5


  Oh, just for reference - here's the setup I shot in color.  As you may know yellow of the brass photographs really dark, but I chose that on purpose so that there would be big empty area where the first signs on overdevelopment would show on plate #4.


 So here are the plates individually.  I shot all these on a copy stand with Canon 5DII, nothing was done in photoshop to clean them up or change brightness or contrast.

Normal

Overexposed by 1 stop - underdeveloped by 40%
  
Overexposed by 2 stop - underdeveloped by 60%

Underexposed by 2/3 of a stop and 50% more development than normal

Underexposed by 1.5 of a stop and 115% more development than normal

  As you can see the last plate is just terrible.  Crystallization galore! However in the slightly underexposed and only a bit overdeveloped one the crystallization is only really evident in the lower part of the lens barrel.  But under magnification it's there for sure.  That's probably where the edge of my puddle stopped initially when pouring and so the thickest collodion deposit is right there in that crescent-shaped area.  Here's a closeup of that spot.  There's more crystals that you can see in the full plate image, but in real life there are slightly less apparent than in the image below.  Still, best not to let that happen to you!



  Oh, and some of you may wonder about the chemistry I use for this test so here it is.

  Fresh UVP#3 Collodion mixed from A/B stock about 5 days ago (available from http://uvphotographics.com/ - excellent and super fast collodion, but I still can't get rid of those darn lighter areas you see on top of each plate...  very weird, but that's a topic for more experimentation and possibly another future blog entry)

  Developer at about 45-50°F as follows:
  Water 350ml
  Iron Sulfate - 7.5g
  Glacial Acetic Acid - 10ml
  95% Grain Alcohol - 15ml
  
  I sincerely hope this was at least somewhat helpful to at least some of you.

EDIT:  Someone asked if overdevelopment fog wipes off.  NO WAY - this stuff is deep there.  It really does look totally different from all the other types of fog possible...

EDIT 2:   Here's a good exercise that you may want to do to determine what is the absolute MAXIMUM amount of development time that your developer will allow.  It'll take only an hour or less and it'll be helpful - believe me.
  Coat and sensitize a plate and then develop it for just a little longer than you normally do. Keep careful track of time in developer.  Look for the signs of golden-looking crystals.  Don't see them?  Do another plate for just a little longer.   Do a few plates until you start seeing those crystals.  Again - they usually appear first in the center of the plate where collodion first came in contact with the plate during your pour.
  So say you start seeing then at 25sec (most people use more concentrated developer than I do their usual development times are 15-20sec).  That means you can PUSH development to about say 22-23sec without ill effects.
  Make sure to note the temperature of your developer - hotter developer will work fast, colder will be slower, kinda obvious, but I thought I'd mention that.

Anton

5 comments:

  1. Thank you sooo much for doing this! As a novice, I am constantly plagued my the exposure/development balance. This is really instructive.

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    Replies
    1. Glad you found it helpful.
      I do recommend doing the test I described at the very bottom. Waste 3-4 plates, but you'll know how long you can go for with your developer. Then try to not go ALL the way, but maybe 10% less time - that will give you brightest highlights.

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  2. Anton, I love that I don't have to pick your brain. You just put it out there on the table for us. Thanks.

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