Last of the 35mm format

Grandpa Ron · Nov 5, 2018

Here are three of my latest pinhole camera shots. They are taken with an .014" pinhole for an f 155 aperture.
They are as shot with no enhancements. My objective is to get as good a picture as possible with the pinhole, not the computer processing.

I believe this is as good a resolution as I can get with the 35 mm format, as the image is enlarged many times for viewing.

My next attempt will be with a 4x5 view cameras which will allow a large format and a smaller aperture with the pinholes I can make. But first I have to restore the camera.

The three photos are; the field next door, a bend in the Tippecanoe River and an old pond viewing deck.

REAndy · Nov 5, 2018

What was the ASA/ISO of the film used, and the exposure time please. Thanks.

Grandpa Ron · Nov 5, 2018

REAndy,

The camera is and old Praktica SLR. with the lens removed the shortest cover plate I could fabricate was 55 mm from the film plane. With a .356 mm pine hole (.014") the f value is 155.

To answer your question , The film was Fuji color 200 ASA. The difference between the light meter reading at f 22 and f 155 is a time multiplier of approximately 60. Plus reciprocity.

The field shot was 3 seconds. Bright grass and sky dark trees. The light meter said 1/25 sec. at f 22 so I rounded to it to an even 3 seconds
The river bend was 12 seconds. Bright grass and sky but mostly shaded river. The light meter said 1/15 sec. at f 22 but I wanted a bit more shade detail so I increase the exposure to 12 seconds.
The pier was shaded with a sunny highlight and bright back ground. The light meter was 1/25 at f 22 so again I rounded up to 3 seconds.

I was surprised that in many cases doubling or tripling the exposer time did not make as great an impact on the negative as one might expect. I attribute this to the greater latitude of modern film and to the non-linier properties of reciprocity.

My best results with this film have been between 3 and 6 seconds in normal sunshine. I hope this helps.

Theo Sulphate · Nov 5, 2018

Strange as it may sound, I really like the softness of the images. The river photo is especially pleasing.

Jim Jones · Nov 5, 2018

A 0.01 or 0.011" pinhole might give slightly sharper images at a 55mm focal length. When image sharpness is graphed against pinhole diameter there is a slight peak in sharpness in the center of the image as the pinhole approaches optimum diameter. In my experience with panchromatic film, this occurs when the diameter is calculated with Pinhole Designer with a user constant of 1.4 or 1.5. Your 0.014" pinhole might do well at a focal length of 4" on the 4x5.

Grandpa Ron · Nov 5, 2018

I have to agree, there is a certain charm to soft focus scenes, especially tranquil nature scenes.

I certainly do not want to discount the 35 mm format potential, but I was at a cross roads. I could buy a laser cut pinhole or I could finally restore my Uncles 1910 Seneca camera.

Well, bringing the old camera back to life won out. Not just for pin hole work but also for some old fashion "under the hood" photography.

As an alternate I have an old 120 film box camera which would give me a 2 1/4 x 2 1/4 negative. Never a dull moment in this hobby.

REAndy · Nov 6, 2018

to the OP: Thanks for the information on the exposure time and film ASA. I'm not that familiar with the various variety of pin-hole cameras and am curious about exposure time. Reading some other posts and they have said that they need several minutes of exposure. So, I suppose the wide range of exposure time has to do with the particular camera (pin-hole diameter)(effective F stop). Thanks again.

Grandpa Ron · Nov 6, 2018

The easy way to look at it is if you take the pinhole and project the light a short distance to the film the light image is small and bright. If you move the film plane farther back, the projected light image gets larger and dimmer, so it takes more time to expose the film.

So you end up adjusting several variables.

The amount of light. Usually the sun decides that.
The size of the pinhole.
The focal length from pinhole to the film.

I have found that as you approach an f number of 250 reciprocity become a significant factor and the amount of time goes up sharply.

Good luck

TonyB65 · Nov 8, 2018

REAndy said:
to the OP: Thanks for the information on the exposure time and film ASA. I'm not that familiar with the various variety of pin-hole cameras and am curious about exposure time. Reading some other posts and they have said that they need several minutes of exposure. So, I suppose the wide range of exposure time has to do with the particular camera (pin-hole diameter)(effective F stop). Thanks again.

I tried my Noon pinhole camera out for the first time recently, shooting with Acros 100. It has an aperture of F222 and the difference between a 2 minute exposure and 5-7 minutes was absolutely minimal, this was shooting 6x12 (It has the option of 6x6, 6x9 and 6x12).

Grandpa Ron · Nov 8, 2018

Tony

You are quite correct. Even without allowing for film reciprocity most negatives are usable plus or minus one f stop from perfect exposer. This is a time variable of 4X.

If your best exposure was 2 minutes, a 4 minute exposure is at best a one stop difference plus the effects of reciprocity. That is what makes time estimating so difficult.

Also, I have gone from 3 second to 12 seconds exposure and the photo disc images showed some differences. The negatives were noticeably different, the automatic transfer equipment from negative to disc compensated for the exposure.

TonyB65 · Nov 9, 2018

Grandpa Ron said:
Tony

You are quite correct. Even without allowing for film reciprocity most negatives are usable plus or minus one f stop from perfect exposer. This is a time variable of 4X.

If your best exposure was 2 minutes, a 4 minute exposure is at best a one stop difference plus the effects of reciprocity. That is what makes time estimating so difficult.

Also, I have gone from 3 second to 12 seconds exposure and the photo disc images showed some differences. The negatives were noticeably different, the automatic transfer equipment from negative to disc compensated for the exposure.

Indeed Ron, but I quite like the fact you don't have to be so precise, and I tend to bracket and see which shot I like the best, there's an element of serendipity with pinhole photography that appeals to me.

Deleted member 88956 · Mar 15, 2019

Grandpa Ron said:
REAndy,

The camera is and old Praktica SLR. with the lens removed the shortest cover plate I could fabricate was 55 mm from the film plane. With a .356 mm pine hole (.014") the f value is 155.

...

I would try with same pinhole but increased focal length to about 75 mm. perhaps you can make a spacer ring to extend FL for a test. Optimal pinhole for 75mm is about 0.32mm (by Airy) and 0.39mm (by Rayleigh). I throw out all other theories into these kind of calculations. At the end of the day, calculators are to get into the ball park, live tests can only confirm performance, so much more in a case of trying to get the best resolving qualities.

Also, since we're clearly talking getting as high a resolution as possible, and I'd guess this probably goes without saying here, pinhole quality plays a huge part in how image is rendered, far more than a small difference in pinhole size. it is worth of a microscopic evaluation to see how good the pinhole actually is (roughness of its edges). Of course thickness of the walls at pinhole edges falls into the same considerations. Here again, while it should be as thin as feasible, it cannot be so thin it goes into flexing state, which will also degrade rendering quality. So the material hole is made in also matters.

Last of the 35mm format

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