View Full Version : Ektrachrome Reciprocity for Pinhole purposes
03-19-2010, 06:15 PM
I recently bought a box of Ektrachrome 100G in 4x5 and specifically looked for reciprocity information before shooting $35 worth of film in 10 easy shots.
As per instructions found inside the box of film I set about last weekend to shoot all 10 shots with a little feather in my cap. I intuited that the information you can read like on this page here: KODAK Reciprocity Info (http://www.kodak.com/global/en/professional/products/films/e100vs/features.jhtml) is information not for pinholers but for normal photography. So without so much as a good realistic guide for reciprocity I do what I normally do and that is examine all the reciprocity figures for all the films I have information on, and apply a best average using whatever information I can shoot from the hip. So basically I treated Ektachrome like it was an average of TMAX 100 and FP4 reciprocity exposure figures.
After using my shoot from the hip reciprocity exposure information, if anything the shots should have come out overexposed, but instead they came out underexposed. This is the third time (using three different eras of Ektrachrome) for this mistake for me. Everything is underexposed. Not by much but by enough that makes it difficult to render anything with the scans. And I spent $10 a scan on these so that's $108 down the drain almost. Again. I've repeated this enough times to know that the reciprocity figures supplied by Kodak are just plain wrong for pinholers. I think there's got to be a different way to calculate things for pinhole versus normal lens-photography where you have a lot of light to work with. Anyone with some hints or advice based on experience?
03-19-2010, 07:41 PM
Dunno, the only color transparency film I've shot with pinhole was Fujichrome T64 with an 85B filter taped over the front. An equivalent exposure only about 20% longer than a test shot with a lens (same scene, same camera) produced a good exposure match. The info available seems to be a little sketchy, and the tungsten films are apparently optimized for longer exposures, which worked in my favor. With multiple failures, I'm inclined to wonder if your calculated f-stop might be off -- it wouldn't take much of an error in that pinhole diameter measurement to throw things off quite a bit. In the instance I described, I bracketed several exposures about a stop either way. I fear testing is about the only reliable way. My approach would be to run a roll with some bracketed test shots and skip any expensive scanning until you see what you get.
The other hazard with color, of course, is that the different layers may respond differently as you get far away from the optimized useful range. I notice that Kodak sheet said something about a small color compensation filter at long exposures.
03-19-2010, 07:49 PM
First, don't have your film scanned until you have seen it, unless you enjoy potentially throwing a lot of money down the toilet.
Ektachrome is nowhere near as good at maintaining reciprocity during long exposures as is Fujichrome.
Of course the shots are underexposed. That is what reciprocity failure does, so you would expect that, not overexposure. You did not adjust enough. You need longer exposures.....and/or Fujichrome. No film is designed to be optimized at the effective f stops and exposure times used with pinholes. It is especially hard to get it to work in night shots, as film will not be exposed at all below a certain amount of light, no matter how long the exposure is. You simply need to experiment more. Make sure your effective f stop is properly calculated, first of all.
03-20-2010, 12:50 AM
Now that I got home, I am seeing that these are not as bad as I initially thought. I think perhaps the monitor I have at work is darker than this one at home. Plus I think that there has to be a video card capability difference because they look better than I thought. Having said that, they are clearly slightly underexposed. I did not intend for navy blue skies... haha. Vivid color. gotta love it? I dunno... anyway...
Ektachrome is nowhere near as good at maintaining reciprocity during long exposures as is Fujichrome.
Dude, I am in total agreement with you on this. I thought at first in my mind I did not want to touch Fujicolor anything as I am not fond of the negative film at all. But I had a box here, and shot it and had a problem with overexposure on darn near most of the shots because most of the shots were full daylight and thus the reciprocity effect is minimized. Clearly I have to tidy up all my allowances. But at this point I am close to labeling where the real reciprocity should be on Astia. I love Astia. Love it all the way. It is probably the best 4x5 film on the market if you are going to scan. Anyway, Astia is only slightly skewed on the higher speeds (I estimate 1.25x to 1.5x) and gets closer to the curve of TMax 100 figures when f22 is slower than 1/15 second but not quite as slow as TMax 100. I have not tested for any scenario where f22 is slower than 1/4 second as far as I can remember.
Make sure your effective f stop is properly calculated, first of all.
Yes, that is under wraps. Got the accurate figures from Zero Image and used software program to plug in the parameters of the camera to derive my list of exposure variants.
03-20-2010, 01:05 AM
Dunno, the only color transparency film I've shot with pinhole was Fujichrome T64 with an 85B filter taped over the front. An equivalent exposure only about 20% longer than a test shot with a lens (same scene, same camera) produced a good exposure match.
Okay, this lines up pretty much with my experience too. To a degree though, because it does get slower exponentially the dimmer the light.
The info available seems to be a little sketchy, and the tungsten films are apparently optimized for longer exposures, which worked in my favor.
Very good, then I will expose these 20 I have in the freezer in readyloads next and save the daylight film for my Cambo this next time around. I'm really thinking of ending the affair with Ektachrome soon as I am out of my stock which is only 30 sheets. I'm going back to Astia.
With multiple failures, I'm inclined to wonder if your calculated f-stop might be off -- it wouldn't take much of an error in that pinhole diameter measurement to throw things off quite a bit.
Well, I used the specifications provided by Zero Image on this camera. I shot all my past Ektachrome on another pinhole camera that I found out to be really umm.. sub-par. I am confident that my calculations are correct because I am getting better results now than ever before. However, understanding the incremental nature of adjusting for exposure variations can become a rather expensive proposition these days which is why I am asking for someone to share what worked for them so I can cut down on my loss of $'s at a time when I am ramping up to quit the day job and go travel nonstop for photographic purposes. Anyway, I am inclined at this point to believe that Ektachrome is slightly unpredictable in general from one emulsion to another perhaps, and, that the curve may be more of a set of stairs rather than an incline.
03-20-2010, 03:24 AM
Okay, after hours of trying to reduce the size of one of these scans but crashing the editor a bunch of times from running out of memory, I located a utility program to resize them for me in batch mode, and it actually works. I'll be buying this program. Anyway, started with 4800 dpi scans and now used this program to reduce the size down to where Paintshop Pro can handle it. The program puts a stupid watermark on it but at least I get to see what happens when you reduce the size of the image. It actually looks pretty okay. In fact, I think if I were to had shot this in 75mm instead of 50mm I wouldn't have gotten the vignetting which made me have a panic attack when I first viewed these files. So, here I'm uploading a web-sized reduction so it will fit here. What do you think? 1/2 stop underexposed? I think I'm fairly close... but not right on.
03-20-2010, 04:15 AM
You really cant beat Astia when it comes to colour for just about anything :)
03-20-2010, 08:12 AM
The page with the data that my earlier post refers to has been taken down. But here is a post about Ektachrome 100 films in the era of 100G, and some numbers for calculating reciprocity that should get you a lot closer. The numbers (Schwarzschild exponents) were derived from standard astrophotography tests that test for the amount of reciprocity failure at 128 seconds of exposure time, and are typically good within about 1/3 stop. 100G was one of the Ektachromes with the least reciprocity failure, about equivalent to the best of the Fuji E6 films regarding reciprocity failure.
03-20-2010, 11:07 PM
Underexposed or not, that's a neat shot. I'd bet another half stop should do it.
That data sheet on the 100G strikes me as a bit odd. They say no compensation necessary for exposures up to 10 seconds. Then they mention some color correction at 120 seconds, but unless I missed something (it's happened!) there doesn't appear to be any exposure recommendation for the range from 10 to 120 seconds. Surely it would likely need more than color correction.
There have been some discussions on this forum sometime back about reciprocity failure in B&W films that seemed to suggest the makers' indicated numbers were over compensated, and that maybe the manufacturers are running with ancient numbers. That could be another reason to do your own tests. I'm pretty convinced the exposure numbers from Pinhole Designer (http://www.pinhole.cz/en/pinholedesigner) for Delta 100 were overcooked, based on my limited experience.
03-20-2010, 11:10 PM
With my experience, Ektachrome for me is the only film I know sucessfully works at night for me so far. I have gone up to 30 seconds with no exposure compensation or filters and I had very very good results!!
03-20-2010, 11:34 PM
If you need really long exposures, Provia has excellent reciprocity characteristics. I've done multi-minute exposures with no major issues.
(anologuers stop reading now, but this is relevant for posting gallery & example shots to APUG)
Have a look at the gimp (http://www.gimp.org/) and imagemagick (http://www.imagemagick.org/) for free high-quality resizing and other editing without watermarks. They work fine with gigapixel images (enough for 4x5 and 8x10 scans) if you have the memory; if you don't then they just run slowly due to paging stuff to/from disc.
03-26-2010, 07:35 PM
I'm pretty convinced the exposure numbers from Pinhole Designer (http://www.pinhole.cz/en/pinholedesigner) for Delta 100 were overcooked, based on my limited experience.
I've run the numbers on Pinhole Designer, and for many (perhaps most) of the films, the suggested adjustments are in line with the outdated manufacturers' adjustments.
04-21-2010, 12:07 AM
Okay, I'm back again with more long term results, for those interested.
Ektachrome E100-anything does not appear to be well suited for low light pinhole work with the Zero Image in 25 or 50 mm setup. I think it would be difficult to work with this film on those Zero Image 120 Roll film cameras too. The vignetting is highly exaggerated with the Ektachrome to the point you will lose about half your surface area or more due to blackout vignetting. A lot of the kinds of compositions one would use with ultra wide angle pinhole make for naturally darker regions anyway under most lighting conditions. There seems to be an extra curve for Ektachrome, particularly in dark regions of blues and browns, reds, yellows. Greens seem to pop up above the rest, or maybe it's because it's unusually green this year in California. ;)
Second thing to take note of, Ektachrome does in fact have a reciprocity effect and it is mighty steep once it begins. I haven't yet found the sweet spot but I doubt that you can use the approach Kodak supplies on their fact sheet. That, in my opinion, could only apply to lensed environments because I actually attempted to use their figures this past weekend and man they are so off! I have to go reshoot half of these 18 I just developed, if I want those shots. Oh, I probably will too, now that I know what I know, I'm going to treat low light situations like in a Redwood grove with a gushing stream waterfalling all over the place just a wee bit different.
I could rewind the figures and find out what factor was applied to get the figures that Pinhole Designer has for TMax100, but I might blow a circuit with that kind of math. Anyhow, when TMax100 is 5 seconds, Ektachrome seems to be 4 seconds. When TMax100 is 30 seconds, Ektachrome seems to be about 15 seconds. When TMax100 is 1 minute this is where I am failing big time. I know that 1 minute it way too overexposed because I have a few slides that scream loudly because of blocking in the sky and complete lack of blue in that region. The trouble I'm finding is finding the right place to draw this curve. But I will continue to report my findings. Believe me there will be findings because I'm shooting a heck of a lot of film these days. And I have a lot in the freezer still and know where to get a lot more for the same low price (how does $1.75 a sheet sound on Readyload 4x5's? :D)