Under exposed results

bryans_tx · May 13, 2023

Scenario:
Portrait.
Strobe.
Exposure found using canon 5D mk Iv manual mode. Same iso as film.
Setting found: F16, 1/125

Film setup:
4x5
Fuji 250mm lens
Same setting as canon on lens.
Develop:
D23 6 minutes, stearman tank
A few washes in water
Fix.
Results underexposed by what looks like several stops.

I’m quite sad of course lol!
Dang!

I had not yet checked shutters speed so I also made two shots at f22… omg thry almost blank!

After you finish laughing, any opinion?
The D23 only a few weeks old and had many more developments on it to do.
Stock solution

bryans_tx · May 13, 2023

Film Ilford fp4+

Alex Benjamin · May 13, 2023

Bellows extension factor. Did you compensate?

bryans_tx · May 13, 2023

Looking at them again perhaps the best two of the four, are probably one stop underexposed.
Making fresh D23 now!

Alex Benjamin · May 13, 2023

bryans_tx said:
Looking at them again perhaps the best two of the four, are probably one stop underexposed.
Making fresh D23 now!

I'll ask again: did you compensate for bellows extension ? Depending on how close you are to the subject, if you don't compensate, that will account for the under-exposure. Not the D23.

Bill Burk · May 13, 2023

Did you use the right strobe sync?

bryans_tx · May 13, 2023

Alex Benjamin said:
Bellows extension factor. Did you compensate?

Awwww dang it. ok I totally forgot.
I actually wrote this down in a notebook a week ago.. it’s off by .85
Check math please:
Bellows 304.8mm
Lens 250mm

Thanks a kick in the pants helps !!

bryans_tx · May 13, 2023

Bill Burk said:
Did you use the right strobe sync?

Synch not issue with 4x5 lense, but can be with the stinky digital test camera haha
Well it should not be. It was 1/125 on both
It was the bellows factor

bryans_tx · May 13, 2023

I will be able to triple check the bellows mistake as I also took same pics with two more film cameras lol. You can never shoot enough film/ cameras

Vaughn · May 13, 2023

Shutter speed would not matter in this case -- as long as the lens is actually open for the very short duration of the flash itself.
Exposure will be controlled by aperture alone -- thus the reduced exposure at f/22.

bryans_tx · May 13, 2023

Yes sir, I did make a no strobe test to see how much ambient light was present… very little considering light from a window

koraks · May 14, 2023

bryans_tx said:
Synch not issue with 4x5 lense

Assumed, or verified?
Under the dark cloth, observe the ground glass screen while releasing the shutter. You should be able to clearly see the flash image. If not, you've got a sync problem.

I generally use a much slower shutter speed with large format and strobes. Working apertures are pretty small most of the time so available light is not much of an issue for a shutter speed of say 1/30.
Yes, sure, leaf shutters should sync perfectly anyway. Unless they don't due to age etc!

Show an example of one of the negatives to receive more focused/appropriate advice. Qualifications like "looks underexposed by several stops" are an interpretation; it generally works better to share as objective information as possible.

Ian C · May 14, 2023

Per the numbers given in post #1, the image distance (second nodal point to the image plane) of 304.8 mm and lens of focal length f = 250 mm, the required exposure compensation is 0.57 stops, or somewhat less than 2/3 of an f-stop. An underexposure of slightly less than 2/3 stop, though undesirable, isn’t a big deal on B&W negative film (though it would be a problem with color transparency film). You should still have a decent recording of the scene.

Regarding your comment,

“Results underexposed by what looks like several stops.”

If the negative looks far too thin (like “several stops”), then you likely have more problems than can be accounted for by a 0.57-stop bellows compensation error alone.

The test for correct flash synchronization given in post #12 is easy to do and will verify whether you have correct flash synchronization. Also check that you’re using fresh film developer, an accurate processing thermometer, and recheck the temperature/time chart for the film and developer combination in use.

BrianShaw · May 14, 2023

After you finish laughing, any opinion?

No laughter from me. Learning to use strobe flash is a challenge! I'm not too sure about using digital camera for exposure determination, though... not because it's wrong but because I have no experience with that method. My suggestion is to try again but use either a flashmeter or GN calculation to determine exposure. A GN calculation might be worth doing even if it is just to verify what the digital camera is telling you.

What strobe are you using and is it being used in automatic or manual mode; straight flash or bounced/modified?

bryans_tx · May 14, 2023

I used a godox SK400 with fairly large softbox. I always use manual setting.
No flash meter currently

I also have wonder about using the Canon for exposure values. I have just the bare understanding that a 4x5 lens, has a larger physical opening than a 35mm camera. Does this still translate directly ? I dont know, and its on my list to learn. Today I will develop two more negatives, wherein I took bellows into account..

PS anytime I post something that is wrong or confused, please let me know. After 2 rounds of Covid, I swear I have the covid brain fog as an additional source of fun...

bryans_tx · May 14, 2023

IanC and Koraks
thanks, I will test that.

The math I used gave me the .85, you have said .57
the math i used was (bellows/lens FL) squared, then Log base 2 of that result.

I know someone selling a Minolta meter, an older version, easily half the price of others like sekonic 308 versions . ($75) Already have a Pentax spot meter for reflected.

bryans_tx · May 14, 2023

with your instructions i can see the flash from 125 to 400
scan coming up

bryans_tx · May 14, 2023

Houston we have more issues.. fun huh? LOL!
The water spots are one thing. thats on me. but the Horizontal streaks.. uh oh.
(no streaks like this on my 35 and 120 scans )

Straight out of Negative lab pro.

bryans_tx · May 14, 2023

awesome detail though !

BrianShaw · May 14, 2023

Awesome detail and a very nice sitter.

So the flash works, and the lens works, and the film works. You are getting somewhere!

Seems like a processing issue. Did you have enough developer in the Stearman tank and did you agitate efficiently? Or are your film holders the older ones. I think I recall that the film holders were re-worked at some time in the past to eliminate problems like this.

EDIT: In case you haven't seen this: https://shop.stearmanpress.com/pages/blotches-of-doom-solved

bryans_tx · May 14, 2023

I see the horizontal streaks on another scanned negative.
Re-washed the one above, crafeulyy wiped with kimtech, waiting to dry.
I always final wash in Distilled water plus kodak photo-flo
looks like I did not wash it enough at the very least. prior to using the distilled i wash under the sink, in the tank and we do in fact have minerals in the water.

bryans_tx · May 14, 2023

BrianShaw said:
Awesome detail and a very nice sitter.

So the flash works, and the lens works, and the film works. You are getting somewhere!

Seems like a processing issue. Did you have enough developer in the Stearman tank and did you agitate efficiently? Or are your film holders the older ones. I think I recall that the film holders were re-worked at some time in the past to eliminate problems like this.

EDIT: In case you haven't seen this: https://shop.stearmanpress.com/pages/blotches-of-doom-solved

checking that out now. They are Rev4

bryans_tx · May 14, 2023

I noted that after the fix, I lifted a holder and saw bubbles/liquid trapped between the film and the Holder.
this is going to be a show-stopper. I think I will ask for a refund. Film $$, time and subjects are not things to waste.

yes, just under or at 475ml

agitation per massive chart for the film and developer.
I do the flip and some rotation at the same time.

Will see. about to go and develop two more negatives.

thanks soo VERY much for the replies.

BrianShaw · May 14, 2023

Very mysterious. Is there a chance that the film was emulsion side toward the holder? Other than that I'm out of ideas. But it sure would be nice for you (and your sitter) to solve this mystery.

The Stearman has worked flawlessly for me. I hope you figure it out because it really is a nice processing system.

Unrelated question: which Fuji 250 are you using. I have used a Fuji 250SF in the past an dthinking of putting htat back in service. The portraits I took with it were really pleasing. I like mild soft focus and that lens easily allows dialing the softness to a minimum, yet still be there.

bryans_tx · May 14, 2023

Still there. this is again, a show stopper. I will try and get my $$ back. so sick of half azzed products Jazzed up on you tube.
choice now is mod 54 or jobo. jobo a pita to load and $$$ Mod 54 I have a tank for. complaints are of course loading. im fine with loading 4 not 6 sheets.
so mad. really.

Under exposed results

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