Re: 35mm pinhole - questions & observations

Rick, that makes sense. I'll resize it. I have never really understood
defraction very well, but I just re-read the online articles by Guillermo
and Richard Koolish a few times and it makes much better sense. I still
don't quite understand how it works for zone plates though...

As for the lines, I don't know if the film has been through an X-ray
machine. I got it for christmas in one of those student paper/film combo
packs. I noticed they were on sale. Maybe something happened to it before
I got it. I have never used this film this fast before. Does one need to
handle it differently from regular film? I did open the camera and take the
film out when I was done shooting in sunlight. It then went into my pocket
and I processed it that night.

I would like to try infrared pinhole like what you do with your exa. Maybe
when it stops raining :P. I was going to do some before the rain started,
but I didn't have any on hand like I thought. Looking at the pictures, it
could be anytown usa. I guess the real-estate flags and bike path are the
only things specific to los osos.

David, I made the pinhole out of .005" brass shim from the hardware store.
I used a regular needle to make a small dimple, then used my dremel
moto-tool to flatten the dimple. I repeated that until I had a hole.
Normally I would keep going until I had the size I wanted but I just stopped
as soon as it was there. I then cleaned the hole up by lightly putting the
needle into it and rotating, as well as sanding it with 600 grit sandpaper.
I inspected it with a microscope and measured it with an enlarger.

My camera does not have aperture-priority metering, so I just did it by eye
based on sunny-16 (As i said earlier, I didn't calculate it correctly). The
slowest i can possibly hand hold and get a useable image is 1/4 (not
perfect, useable). In those situations when I need to do so and am without
a tripod, I opt to underexpose because it can be corrected somewhat in the
darkroom, but camera shake isn't fixable.

Guillermo,
I will make an 8x10 tomorrow and post it. Any requests on which one?

John

----- Original Message -----
From: "Richard Heather" <rheather@slonet.org>
To: <pinhole-discussion@pinhole.com>
Sent: Thursday, January 11, 2001 4:49 PM
Subject: Re: [pinhole-discussion] 35mm pinhole - questions & observations

> John,
> If the pinhole is too small diffraction will overtake the circle of
> confusion. Diffraction will add to sun flare. The lines in the frames
> seem to extend to the border. Has the film gone through an Xray scanner?
> I should have recognized my own town on the pictures but had to look
> twice.
> Richard Heather
>
> john yeo wrote:
>
> > A few days ago I made a pinhole body cap for my canon AE-1. I made
> > the pinhole as small as I could, it ended up .0065 +/- .0005" f/270.
> > Would using one of the formulas to determine the optimal size work
> > better for such a small focal length? Or does that only apply to
> > longer focal lengths. Larry's site gives .011" as the optimal size.
> > That would be better for handheld exposure and looking through the
> > veiwfinder but I want the sharpest image possible since it's such a
> > small negative. After looking through the viewfinder for a few
> > seconds, it's pretty easy to see the image. I have a rubber eye-cup
> > that really helps block out excess light. For my first roll I used
> > delta 3200. Using the sunny 16 rule, I figured out exposure to be
> > about 1/15 sec. I have since made a dial calculator, and it says it
> > would be between 1/11 and 1/8 sec. Looking at the negatives, they
> > could have used the extra stop. Flare didn't seem too bad through the
> > viewfinder, but it is awful on the negatives. I don't know what the
> > vertical line is on some of the frames (17,18,28,29) Maybe some of you
> > can provide an answer to that. I walked to the post office and took
> > the camera with me. Just took pictures of whatever. I even shot some
> > cars moving at 45mph!!! All exposures except for the first few were
> > hand held. I bracketed a bit, and the exposures range from 1/4 to
> > 1/30. They are actually sharper than what the contact sheet looks
> > like... my scanner isn't very good. here's a scan of the contact
> > sheet:low res 64kb
> > http://holgamods.blinkk.net/images/ph35cs-lowres.jpghigh(er) res 192kb
> > http://holgamods.blinkk.net/images/ph35cs-hires.jpg John
>
>
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Received on Fri Jan 12 01:03:46 2001