Newbie Question: Neg vs. Transparency Exposure...greenspun.com : LUSENET : Large format photography : One Thread
I've been doing the LF thing for a little while now with an ancient 4x5 and I'm having a blast. I've gottoen to the point where I am pretty confident when shooting color print or B&W but for some reason I'm missing the exposure big time when it comes to chromes. Sometimes as much as 4 stops. I'm really confused as I think that I'm doing things pretty much the same way. With the negative film I am not requiring any special processing. It comes out pretty good on the first pass even though I take duplicates just in case. My chromes on the other hand are awfulllllll..... Any advice would be greatly appreciated.
-- Cleeo W. Wright (email@example.com), August 15, 2001
Expose for the highlights (by using an incident meter in the brightest area of the scene).
In which direction are you off by "as much as 4 stops," underexposure or overexposure? Most people, when moving from b&w or color neg to chromes, are in the habit of giving more exposure "when in doubt," which usually results in disastrous overexposure with chromes.
-- John (WhitmanDesign@aol.com), August 15, 2001.
Sorry... I should have mentioned that they were all underexposed. I should also mention that I've been doing 35mm for quite a while and I understand exposure pretty well. At least I thought I did. That is why I am so confused. I'm really looking for any ideas on what I might be missing or forgetting when it comes to the all manual process. I'm using a Sekonic L508 for my meter. It is usually set on incident mode.
-- Cleeo W. Wright (firstname.lastname@example.org), August 15, 2001.
If your exposure times are greater than 1 second, this could be due to a greater amount of reciprocity failure with chromes vs negs.
-- Steve Baggett (email@example.com), August 15, 2001.
Have you perhaps not calculated for bellows extension when making your exposure determinations?
-- (firstname.lastname@example.org), August 15, 2001.
You mention you're using an ancient 4X5. Are the lenses ancient as well? To be off by 4 stops with the experience you have (I've seen your work on the critique forum and it's quite good) I wonder if it isn't an equipment problem rather than you personally. Is the exposure problem occuring with all your lenses or just one in particular? If it's only lens one you might want to have the shutter speeds tested particularly if it's an old lens. A shutter speed problem would certainly be much more noticeable with transparency film vs. neg film due to the decreased exposure lattitude.
Another suggestion would be to try a different metering method. I occassionally use a spot meter but for most of my work I use the meter in my 35mm. It's one more item to add weight to the backpack but the results have always been very reliable.
-- Mark Windom (email@example.com), August 15, 2001.
Just to be sure, please describe in excruciating detail what the transparencies look like that makes you think that there is an exposure problem.
-- Michael Feldman (firstname.lastname@example.org), August 15, 2001.
Yes, please describe in detail what you were taking a picture of, how far away the subject was, time of day, type of slide film, etc. It will help us help you =)
-- Edward Kang (email@example.com), August 16, 2001.
If you really are off by 4 stops with the chromes I doubt your exposure is right with negative film. You are probably getting by with the 'wrong exposure' and the ability of your printer to get at least something out of the negative. Even following the 'sunny 16 rule' and printed exposure charts for indoor use you should be closer than what you say. Check more carefully the negatives with a good pro lab to see just where your exposure really lies and I bet it is close to the same as your chromes... unless you are forgetting to change the film speed setting on your light meter.
-- Dan Smith (firstname.lastname@example.org), August 16, 2001.
If you are shooting Tri X (ASA 400) and then change to fuji Velvia (ASA 50)that is about 3 stop difference, I vote for Dan's comment, are you sure you are not forgetting to change the setting on your light meter?
-- Jorge Gasteazoro (email@example.com), August 16, 2001.
"Expose for the highlights (by using an incident meter in the brightest area of the scene). " - What?
An incident reading is a measurement of the light falling (incident) on the subject. The brightest area of the scene has nothing to do with it.
The subject is assumed to be 'average' with the highlights falling 3 stops above, and the shadows 4 stops below the nominal exposure point.
I'm not disagreeing that an incident reading gives good results, especially with transparency film, but the accepted method of use is to stand at the subject position and take a reading with the meter cone or dome pointed back at the camera. If the main subject is completely in the shade, then so be it. You shouldn't go out of your way to find the brightest patch of light to stand in to take an incident reading.
-- Pete Andrews (firstname.lastname@example.org), August 16, 2001.
1. Have your shutters tested to make sure they are accurate.
2. Make sure you have set the correct ISO speed on the meter.
3. If you are doing closeups make sure you have applied the correct belows factor.
4. Learn to use the spot meter function on the meter and carefully evaluate your scene or subject matter. Transparency film will accomodate 5 stops with detail from the darkest area to the lightest area. Things that fall outside of that range will be rendered as totally black or totally white.
5. Depending upon the transparency film used and how accurate you are with your metering, you may get 6 plus stops instead of 5. Five is safe, 6 is pushing the film in both directions.
6. Depending upon the film you are using, if your exposures are over 1 second, you may be running into reciprocity problems. Check the film data sheet to see at what exposure you have to apply a reciprocity correction factor.
7. When you've done all of the above - get back to use with the results.
-- steve (email@example.com), August 16, 2001.
Cleeo, Start with a known scene, for example: mid-day, bright sun and subject matter with a variety of reflective values. Your exposure for ISO 100 film should be 1/100 sec. @ F16. If your meter gives you approx. this reading, the problem is probably not your meter or technique. If, after shooting a sheet at these settings, you still get 4 stops off, then your problem is lens/camera related....or maybe a little of everything. But in any event this test should, at least, help you zero in.
-- Bruce Wehman (firstname.lastname@example.org), August 16, 2001.
Try this test. Expose a scene familiar to you--one you have shot before. You say you have used 35mm. Ok. Put some Velvia, Ektachrome-- your choice of film--into your 35, same type of film into your 4x5.Set up both cameras on the same scene in same light. Meter the scene the way you would with your 35mm. Expose a few frames in both the 35 and the 4x5 using the slr meter. Now mater with the unit you use for your 4x5. Shoot a few frames in both the 35 and the 4x5.Process all film. If slr and 4x5 meter match exposure or are quite close, then it would seem the problem is mechanical-shutter, aperture. It could be user- not resetting your meter. It could also be chemical. You indicated that your negative film exposures are fine. Others suggested that you migth have forgotten to reset the exposure meter. I would also suggest that when you exposure for negative film-b/w and color, you expose for the shadows. With transparency film you expose for the highlights. That may be a problem.
-- Bob Moulton (email@example.com), August 16, 2001.
Any chance this is an old lens with "US Stops" instead of what most of use are used to?
-- Kevin Crisp (KRCrisp@aol.com), August 16, 2001.
Cleo, I had a similar experience when starting LF. I have two suggestions which may or may not help depending on your problems. Have your shutter speeds checked (as already mentioned). My Ektar 203 was consistently off by one stop or more until it was recalibrated. Cross check your light meter against an in camera light meter from one of your other cameras in reflective mode. Mine was off by a stop or more. I use incident metering when there is even light (Gossen Luna Pro) and have found this method to pretty consistently give good exposures on chromes. I assume you are using your incident meter correctly, but if you have doubts you may want to verify your technique.
-- Roger Rouch (firstname.lastname@example.org), August 16, 2001.
Without seeing the film, it would be hard to judge what is wrong.
An incident meter reads the light falling, not the amount reflected. Very often the two do not coincide; ie the subject is not a nuetral subject, reflecting an "average" amount of light. I learned this the hard way. I was photographing the Javier Mission in Baja in dramatic conditions. I'd been using the incident meter with good results for a couple of weeks, and thought I might have my exposure problems whipped. Turns out, the walls of the mission were so dark, that even in bright sunlight I had underexposures.
You will learn to judge which situations the incident reading will work. In the meantime, get a spotmeter, calibrate it and trust it. The reflected light reading is your bottom line.
-- George Stocking (email@example.com), August 17, 2001.
I really like the Kodak E100 line. its fine up to 10 seconds. with a spotmeter place the brightest area (that you want detail in) in zone VII. the transparency will be open and luminous in zones IV thru VII.
-- phil sweeney (firstname.lastname@example.org), August 25, 2001.