Frankenstein Polaroid

From Dallas Makerspace
Jump to: navigation, search

Frankenstein Polaroid is a camera that will take Polaroid Packfilm Instant Film but have the fun and ease of use of modern 35mm cameras.

The goal is to take an existing Polaroid camera and remove the automatic exposure shutter system and replace it with a more versatile manual/aperture priority/time priority shutter. Most cheap Polaroid cameras have lame "guess focus" lenses or middling coupled rangefinders. These would be replaced with a through lens system with focus screen or a high quality coupled rangefinder.

To facilitate the particulars of using packfilm, a microcontroller will automatically measure ambient (or film?) temperature. It will allow selection of known film types so a timer can be preset with the correct development time.

polaroid pack film info

  • image size: 73mm x 95mm ( 119.8mm diagonal )
  • sensitivity: ISO 100 and ISO 3000 are available from FujiFilm

Any replacement lens will have to have a coverage circle large enough cover the film, otherwise there will be vignetting. Some vignetting might be cool, but a tiny circular image in the middle of the print would simply be wasting film.

polaroid camera lens info

  • 114mm plastic, glass, 1 to 4 elements ( most everything, from the Automatics to the cheapo fixed bodies )
  • 127mm glass ( just the international version of the Model 185 )
  • 220mm plastic single element ( the "BigShot" portrait camera )

The 114mm lenses ( by far the most common focal length ) had maximum apertures ranging from F3.8 to F9.2. A replacement lens could really have any aperture or focal length within reason. The information we need is the image circle size. Unfortunately this site says you can't find the image circle size without the angle of coverage. The angle of coverage varies between lenses.

I would think that the maximum aperture and focal length would allow you to calculate this some how.

polaroid pack film camera info

It is all here.

usage patterns (what's it good for?)

So why make what is essentially a Polaroid 600 (which was just a modified Mamiya Press camera)? Well first off, those are very rare and expensive. It would probably be easier to get a "normal" 120 roll film medium format camera with a Polaroid film back. Actually, it'd be way easier... Detail below. Ok sorry side tracked.

It might be neat to have a Polaroid set up to do Extreme macro shots.

It would also be neat to have a nice portrait camera that you could take to parties or events and take people's pictures. The novelty of instant portraits never wore off from those old enough to remember its hey-day and simply astounds those younger who never experienced it.

You could also build really strange cameras, such as cameras with four lenses that took instant pop art. Or two lenses, one which is a telephoto and one which is a wide angle, for strange instant collages.

The real kicker here is getting something you can't get (easily and affordably) any other way: An SLR interchangable-lens Polaroid. I'm not even sure such a camera was made at any price.

Another thing to point out is that most of the Polaroid cameras have very "slow" lenses. The maximum aperture is usually something like F/8.8. Interior shots at night have a scene exposure value of about 5. If you use an exposure table you can see that even with the high ISO Fuji Film, which is about ISO 3000, you can't get a good shutter speed until you have an aperture of about F/4. A Frankenroid would be able to have lenses this fast if designed properly.

Just get a conventional medium format camera with a polaroid back

list of polaroid backs Possible cameras:

  • Bronica ETRS
    • a complete setup costs between $200 and $400
  • Bronica GS-1
  • Mamiya 645 (Pro, Super ) (?)
    • manual focus camera outfit $250 - $500
    • (that link might be bad)
  • Hasselblad ( haha yeah right )
    • a zillion dollars
  • Pentax 6x7
    • didn't find any examples of camera outfits
    • body - $200 - $250
    • lenses - vary widely. $200 will get you one
    • view finders
    • what else?
  • Mamiya RZ
    • I didn't find any bodies or outfits for sale
  • Bronica SQ
    • bodies $100 - $400
    • lenses $50 and up. $200 typical
    • polaroid back $30
    • viewfinder/prism $100
    • total: $280 - $730+

not sure about:

  • Mamiya RB67

So as you can see, the "polaroid back on a medium format camera" can be pretty expensive. $250 will get you in the door, and there are plenty of lenses available for for all of these.

The cheap way to get something along these lines is to get a shutter and lens combination from an old camera and build a box around a cut up junk-o non-folding Polaroid (like the Colorpack III).

You'd spend $5 for an old crap 620 film camera and $5 for the Colorpack. But you'd not have an SLR or anywhere near the quality lenses as what you'd get above. It might surprise you, but a $5 lens from the 40s isn't as good as a $300 lens from the 70s. ;)

Using a 35mm Camera Teleconverter to increase the image circle of a 35mm Camera lens

Another idea I found on the web talks about moving the rear element of a teleconverter to increase the image circle of a standard SLR lens. I have a stack of Minolta lenses and I've already futzed with a cheapo teleconverter to make it a macro tube. That means someplace I have all the guts of a teleconverter waiting to be used.

Using the teleconverter also gets you a "standard" lens mount for whatever lens system you're using.


about shutters

There are two main types:

Most Polaroid cameras have focal point shutters, or at least something close to a focal point shutter. Most 35mm cameras have focal plain shutters. It will probably be easiest to implement a focal point shutter because the focal plain (the entire piece of Polaroid film) is very large.

achieving an SLR

The SX-70 is now ridiculously overpriced on the used market, but it would actually satisfy many of the requirements of this project. Here is a presentation about its design. It used non-symmetic molded optics. If you thought Polaroid made junk, you should read this. Those guys were brilliant.

amazing presentation on non-symmetric lenses (I should make a PDF of this in case it disappears. It documents part of the Polaroid company's engineering and is a real eye-popper. Those guys were amazing!)

and here is the PDF for the presentation!

explanation of the SX-70

Going the Other Way

So after a splurge of garage sales and asking around, I now have an unhealthy amount of Polaroid cameras. Some use the easy to find roll film, but many others use the discontinued 600 and SX-70 films. The Impossible Project is making new batches of film for those formats, but they're right now about $22 for 8 prints ($2.75/shot) while the pull apart film from Fuji is still under $1 per shot.

So then I stumbled across this Instructable to use traditional cut film in a Spectra camera. Cut film is also called sheet film, and its just a big piece of film that you expose one at a time. You use a cut film holder to hold a single exposure, and slide each film holder into the camera one at a time to take the photo. There is a dark slide that you slide over the film to keep it light tight so you can switch to the next film holder. It is pretty zany stuff if you've never seen it.

Another idea is to convert a Polaroid camera to a pinhole camera and use it with positive photo paper.