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View Full Version : Why am I getting unexposed area on 4x5 sheet film?



Hao
24-Jul-2015, 19:51
First and foremost, greetings to all the friends here in the LFP forum!

Recently I've gotten negs with unexposed area at the top side of the image when shooting vertically.
The camera is Wista Rittreck View with 4x5 back. I also use the original extension hood to block out the unwanted light.
I employ some movements as well, front tilt and back tilt/swing.

I've been going back to do some test shots, trying to figure out what went wrong in the workflow.
The result seems to be consistent. The negs from the same location/setup would show the same amount of unexposed area at the top.
I paid attention when viewing the ground glass if the bottom is blocked (the top of the neg), however cannot be 100% certain when I reviewed the negatives...

I remember that "what you see is what you'll get" rule in large format view camera. If that's the case, could people tell me what else I might have missed in the process?

I will post some example below for the reference.

Thank you very much!


137499137500137501137502

Randy
24-Jul-2015, 20:18
Has me baffled.
Do you pull the dark all the way out?...no, that would be showing at the bottom of the image.
Not having the film holder inserted all the way in?
Lens rise / fall beyond lens coverage?
The only other I can think of is the lens hood.

Michael Clark
24-Jul-2015, 20:26
Could be the lens shade blocking the view when using front movements, like tilt, rise, fall etc.

Doremus Scudder
24-Jul-2015, 21:28
It's probably bellows or your lens hood blocking a bit of the image. Unfortunately, what you see wide open focusing is often NOT what you get. Whatever is blocking the image is likely not really noticeable when viewing wide open for focusing, but comes "into focus" when you stop down. Set up your camera for a similar shot and then stop down to your taking aperture and check again. I'll bet you'll find the culprit in no time.

Best,

Doremus

Vaughn
24-Jul-2015, 21:43
I vote for sagging bellows. If you GG had cut corners, you should be able to see whatever is blocking the light. If you do not have cut corners: After setting up the camera and before you put the film holder in (also no dark cloth), try looking in from the lens and making sure you can see all of the GG.

The image is pretty dark around the edges -- easy to miss seeing something like this.

richardman
24-Jul-2015, 22:13
Sagging bellow would make the BOTTOM area unexposed, not top.

LabRat
24-Jul-2015, 22:15
So if the top is being cut-off, that means something is shading at the bottom of the camera... (Or a hood, as suggested...)

How much front rise are you using??? Any excessive movements will cause the bellows to flex, and sometimes end up in the optical path...

Also, the inner lining of the bellows might be loose inside, and when using movements, might pop a little away, getting into the optical path...

Take the rear focusing panel off the rear, and extend the bellows to your shooting extension... Have a lens on the front... Then look through the camera (without GG), put your eye or ruler at the bottom corner of the rear cut-out and line it up with the edge of the lens, and the center (where the stopped-down iris would be) and check that there is nothing that might be sticking out that would cross that line... Repeat while using you movements...

Also, if you are using a reduction back, some of them are a little thick, and one of the edges might be getting into the optical path on extreme movements... Check that, too...

Steve K

ic-racer
25-Jul-2015, 05:01
I also use the original extension hood to block out the unwanted light.

This has all the components of a frequent beginner's mistake.
You need to stop down your lens to check the compendium shade. A lens 'Sees Around' any object smaller than the aperture diameter. Wide apertures don't show the shade (or finger held in front of the lens etc.) Aperture has no effect on the angle of view on the film, so don't think you want a wide aperture to see the shade at the bottom edge of the frame.

Paul Metcalf
25-Jul-2015, 07:05
Sagging bellow would make the BOTTOM area unexposed, not top.

The bottom is the top (of image) with a view camera

Jac@stafford.net
25-Jul-2015, 07:38
I have done accidentally that exactly as ic-racer described with a messed up (improvised) compendium.


The bottom is the top (of image) with a view camera

To clarify: the image is inverted in the lens. An object intruding in front of the lens is a different matter, but I'm sure you know that.

Old-N-Feeble
25-Jul-2015, 11:11
I vote it's the compendium lens shade. With the lens wide open for composing you may not see it because it's far more out of focus than when you stop down. With the shade, in FRONT of the lens, creeping into the image at the top, the dark area will be at the top. If the bellows, being BEHIND the lens where the image is inverted and reversed, was impeding light transmission, it would necessarily have to be rising upward into the light path. Unless you're putting something under the bellows to prevent sagging that's highly uinlikely.

dsphotog
25-Jul-2015, 13:02
Are you removing the dark slide completely from the holder during exposure?

richardman
25-Jul-2015, 13:10
The bottom is the top (of image) with a view camera

Exactly my point: the images show darkening at the top, a bellow sag (from the top) would affect the bottom of the images.

I suppose one can have bellow push-up too far from the bottom, but that would take active work.

Jerry Bodine
25-Jul-2015, 13:33
This has all the components of a frequent beginner's mistake.
You need to stop down your lens to check the compendium shade.

Now I feel much better knowing that it's a common beginner's mistake. I did this very same thing a loooooong time ago using my first box of 8x10 Ektachrome film and brand new SINAR Norma. The film was expensive but affordable then, though still painful enough that the mistake was understood very quickly and never has been repeated. A few weeks after that more and different lessons were learned with the first box of Tri-X. So much LF to learn, so little time.

Tracy Storer
25-Jul-2015, 16:08
It is VERY possible for the bellows to intrude on the image path at the back of the camera. I have experienced it with a ULF Wisner, and even with a 5x7 Deardorff.
If you tilted the lens forward, without applying any rise, that would have the additional effect of lowering the lens, relative to the center of the film, and may have dropped it below the "horizon" of the bottom of the bellows near the rear of the camera. If there was swing in play as well, this could have contorted the bellows into the "perfect storm" and caused exactly the effect shown in your examples. Check your ground glass edges stopped down, as others have suggested, and sometimes, with certain cameras, you will see this problem, you can often pull the bellows forward a bit so the large pleats at the back will clear the cone of light coming from the lens.

Old-N-Feeble
25-Jul-2015, 17:02
I imagine the OP would have seen light blockage caused by the bellows as he was composing because that type of interference in the light path to the GG isn't affected by f-stop.

Hao
25-Jul-2015, 19:30
First of all, I have to say thank you to all of you who share you valuable experience in this discussion!
I am pretty sure it must have been some beginner's mistake which caused the problem. Today I am going to take the camera to the market and do some more tests there and will report soon!


All the comments are well appreciated.
Hao

Paul Metcalf
26-Jul-2015, 07:34
Good luck with this. I'm suspecting it's something fairly straightforward. If it is bellows sag, I will often put my balled up dark cloth or even a balled up light coat under the bellows to support it. This is only an issue for me when using a lot of extension (long lens).

richardman, the attached image is what you see under the dark cloth with a large format camera. Bellows sag could cause the blockage at the bottom of the image (which because of image inversion - actually rotation - is the top of the developed image), and the slight twisting is not uncommon for a lot a bellows (resulting in the slanted line).

Tracy Storer
26-Jul-2015, 07:43
I imagine the OP would have seen light blockage caused by the bellows as he was composing because that type of interference in the light path to the GG isn't affected by f-stop.

I beg to differ. I think it's very possible this is what happened. Also bellows vignetting DOES change with f-stop.

Old-N-Feeble
26-Jul-2015, 10:09
I beg to differ. I think it's very possible this is what happened. Also bellows vignetting DOES change with f-stop.

I understand but the vignetting is at the top of the image so the bellows would have had to rise up into the light path. What I meant about the OP noticing bellows vignetting even if the lens aperture is wide open is that this type of light obstruction is caused by a 'shadow' that doesn't significantly lessen when the lens is wide open... at least not like it does when the physical impedance is immediately in front of the lens.

Doremus Scudder
26-Jul-2015, 10:30
There are a lot of possible scenarios for the bellows to impinge on the image area. Bellows sag usually happens in the middle of the camera when using lots of extension. It causes an unexposed area at the top of the projected image, i.e., the bottom of the scene when viewing the image right-side-up. However, when using lots of rise and shorter lenses, the bellows on many cameras will creep up near the back at the bottom of the ground glass, causing a blockage at the bottom of the ground glass/top of the image when viewed right-side-up. This is a distinct possibility for the OP's problem, as is possible vignetting from the compendium shade. Both of these phenomena are difficult to see when focusing wide open, hence the advice to check at taking aperture, either observing the ground glass or looking back through the lens at the ground glass.

Doremus

ShannonG
26-Jul-2015, 12:03
Yup,,what everyone else said... Do a proper test session..
--Same subject like a brick wall to see the movements
--with and without movements (big movements so you know the capability of your set up)
--with and without the lens hood
--long bellows and short bellows
--wide open and closed down
-- if you put a grey card on the wall and meeter that ,you can also practice your zone placement at the same time
--TAKE A LOT OF NOTES

its just beginner stuff but by shooting a hand full of test negs now will save your images in the long run and you will know your set up and method better.

Paul Metcalf
26-Jul-2015, 16:38
I understand but the vignetting is at the top of the image so the bellows would have had to rise up into the light path.No the top of the image shown by the op is at the bottom of the film holder which is on the downside of the camera in the back, so this is actually possibly the bellows sagging into the image area from the top of the camera, which shows at the top of the image because it's flipped (or rather rotated) to the bottom. Is it not common knowledge what happens to an image when it's projected through a lens? The reason you see the image upright in a 35mm or maybe some medium format cameras is because there is a mirror that's inverting the image before it appears in the viewfinder.

richardman
26-Jul-2015, 17:13
richardman, the attached image is what you see under the dark cloth with a large format camera. Bellows sag could cause the blockage at the bottom of the image (which because of image inversion - actually rotation - is the top of the developed image), and the slight twisting is not uncommon for a lot a bellows (resulting in the slanted line).

I never have bellow sag that affects the bottom of the image path, only the top. I will keep that in mind.

Tracy Storer
26-Jul-2015, 18:58
By the time the image exits the lens, to pass through the bellows, it is already upside down. The problem is either the inside top of the compendium shade, or the inside bottom of the bellows. The water is getting very muddy here, needlessly.


No the top of the image shown by the op is at the bottom of the film holder which is on the downside of the camera in the back, so this is actually possibly the bellows sagging into the image area from the top of the camera, which shows at the top of the image because it's flipped (or rather rotated) to the bottom. Is it not common knowledge what happens to an image when it's projected through a lens? The reason you see the image upright in a 35mm or maybe some medium format cameras is because there is a mirror that's inverting the image before it appears in the viewfinder.

Jim Andrada
26-Jul-2015, 23:40
I've had something like this when the lining of the bellows was getting old and popped up a bit at the bottom of the camera and I just plain missed it because I was being hassled by the property owner just as I was about to make the exposure. - I was on the edge of the street outside his fence and I'd already poked my head into the office and been told it was OK to photograph there, but the guy who was yelling at me had just driven up. Anyhow he calmed down, I took the picture and then went in and had a nice chat with him and his partner for a half hour. I took them a nice print but they'd gone bust and left.

Anyhow, a bellows or compendium issue seems like the most reasonable explanation.

richardman
26-Jul-2015, 23:50
Everyone who uses a view camera probably knows the image is UPSIDE down. It's on the ground glass. The only confusion really is that a bellow sag can affect the top of the bellow (the bottom of the image) which has been my only experience, or I suppose if the front standard is lowered, then the bellow sag can affect the bottom of the bellow (the top of the image) which I have not experienced myself and didn't realize it could happen and I am glad to learn that. Things only get muddled because assumption was made about view camera users not knowing the image is upside down.

Hao
27-Jul-2015, 01:21
Hello everyone~

Once again, all the comments are very appreciated and you people have been a great help.

So I went out and did some tests mentioned above as well as paid attention to the details in my workflow. The verdict is out: All of which mentioned are true to my circumstance.
First, the ground glass on my Wista Rittreck in particular is rather bright and clear in the centre according to my angle of view, on the second examination I realised that it was me who neglect the bottom of the ground glass.

The shaded area was caused by both the sun shade and the front tilt movement (upward). Occasionally I only looked through the ground glass using the built-in pop-out hood, and that spelled the trouble since the little hood didn't provide
the healthiest viewing experience.

The compendium sun shade, on the other hand, was another cause of the matter. As people have pointed out, when viewing with wide open aperture at f5.6, the situation was barely recognisable until stopped down few stops. It has also
come to my attention that after changing composition, whether that includes tilt, swing, shift, etc...I need to check the sun shade again and adjust accordingly should it gets in the way.

All in all, it's a valuable lesson to learn. Most importantly, it's great to know the class is supported by so many people here on the forum. Thank you!


Hao

Regular Rod
27-Jul-2015, 04:24
A while ago I eschewed the loupe in favour of a pair of powerful +5.5 reading glasses that cost only 8.95 including P&P on eBay (item # 271669873654). These make it easy to check all the composition and corners and edges simply by wearing the glasses and using a dark cloth. They are so effective that even at f64 it is possible to check every part of the image. That lens shade encroachment would be spotted immediately with this method, it has saved me from deploying just a tad too much rise on more than one occasion.

RR

Hao
27-Jul-2015, 20:06
A while ago I eschewed the loupe in favour of a pair of powerful +5.5 reading glasses that cost only 8.95 including P&P on eBay (item # 271669873654). These make it easy to check all the composition and corners and edges simply by wearing the glasses and using a dark cloth. They are so effective that even at f64 it is possible to check every part of the image. That lens shade encroachment would be spotted immediately with this method, it has saved me from deploying just a tad too much rise on more than one occasion.

RR

Sounds good in your situation!
I am already a spectacle wearer myself, not sure how the two should stack up though...

Thanks~