[MF3D.FORUM:1373] Re: build your own medium format stereo camera, cheap and easy

["Don Lopp" <dlopp@xxxxxxxxxxxxxxx>]

I looked up my old notes on pinhole photo experiments of 10 years ago showe
that the  sharpest 4x5 and 8x10  photoswere obtained on (4x5) at 5 sec at f
320 on T Max 100 and for 8x10 T Max 100 film the best was at f/450 about 15
seconds- under sunny 16.0 conditions, the best pictures were obtained with a
G filter after increasing the exposure by a factor of about 5 fold.AT their
best I never considered these photos as being very sharp when compared with
standard B+W photos. I suppose that in this day  of video and digital
photography many have forgotten what a sharp photo should look like? DON
P>S> I forgot to saythat f/320 was .0180 inch  and that f/450 was about .025
inch.
----- Original Message -----
From: "Brian Reynolds" <reynolds@xxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Wednesday, November 29, 2000 4:57 AM
Subject: [MF3D.FORUM:1371] Re: build your own medium format stereo camera,
cheap and easy


> Paul Talbot wrote:
> > L wrote:
> > > There is a 6X9 medfrm cardboard pinhole camera kit
> > > that you can get for around $30.  It is made by
> > > Besller.  IT is a fun camera, and if you strap it into
> > > a tripod, it can take sharp pictures from about 2
> > > inches to infinity.
> >
> > How sharp?  I've not seen many pinhole photos, but
> > what I've seen, though it had a large DOF range,
> > was not at all sharp.  A friend I showed it to
> > said that was typical of all pinhole shots he'd
> > seen: very soft, but consistently so over a wide
> > depth range.  Maybe it's just that neither of us
> > have seen the best of pinhole photography, but until
> > I see something dramatically sharper I'll remain
> > skeptical of how well it would work for MF stereo.
> >
>
> Pinhole pictures can be very sharp.  On page 16 of the first edition
> of Eric Renner's "Pinhole Photography: Rediscovering a Historic
> Technique" there is a pinhole picture of the Old State House in
> downtown Boston by Roy Hines that looks like it was taken with a lens.
> It was taken with a pinhole on 8x10 film.
>
> There are several things that lead to sharp pinhole pictures.
> Probably the two most important are that the pinhole must be on very
> thin material and the hole must be round and burr free.  A popular
> material is brass or steel shim stock (0.001-0.003 inch thick) from an
> automotive supply store.  Examining the hole with a high power
> magnifier (or a slide projector or enlarger) will let you determine
> its quality.
>
> The larger the film format the easier it is to get sharp pinhole
> pictures.  Personally I don't think you can get sharp pictures on 35mm
> film because you have to enlarge them too much to view them.  I'm
> happy with enlargements from 4x5 negatives and I have also done 6x9
> (including using the camera that Lincoln wrote about).
>
> There are several formulas for optimizing pinhole size vs. film to
> hole distance to get sharp images.  If you go to
> <URL:http://www.pinhole.com/> you'll find a paper by Matt Young in the
> "Resources" section that includes the derivation of a formula to
> optimize pinhole size based on diffraction and resolution limits.  You
> can also find the pinhole mailing list at that site.
>
> I think the biggest reason that many people have never seen a sharp
> pinhole picture is that most people taking pinhole pictures are not
> trying to get sharp pictures.
>
> > Also, what about exposure times?  Aren't they very long
> > with pinhole photography?  Seems like you'll be restricted
> > high speed film (not good for stereo) or to static subjects.
> > At least until that Provia 400F comes out.
> >
>
> My exposure times run from under a minute (perhaps as quickly as a few
> seconds in bright sunlight) to tens of minutes.  I generally don't
> have enough patience for exposures longer than about 30-45 minutes.  I
> tend to use ISO 100 films (T-Max 100 and Ektachrome 100 Plus),
> although I occassionally use faster film (T-Max 400, E200, and E200
> pushed to two stops to EI 640).
>
> Depending on subject, long exposure times can be an advantage.  I like
> architecture without people.  The long exposure times of pinhole (and
> large format stopped way down) can remove the people if they are in
> motion throughout the exposure.
>
> There is a pinhole photography section on my home page.  Included is a
> series of comparison pictures of the same scenes shot with a 150mm
> f/5.6 lens and an pinhole optimized for 150mm.  Unfortunately the
> scans are not the best.
>
> I would strongly recommend that anyone who wants to work with pinholes
> read Eric Renner's book.  It has all sorts of information on history,
> technique, and examples from many different photographers.
>
> --
> Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
> reynolds@xxxxxxxxx              | "Oooh!"
> http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
> NAR# 54438                      |       "Dexter's Laboratory"
>
>