Polaroid 450 to 6X7

[Paul Howell]

I've been thinking about converting a polaroid 450 to 6X7, the 450 has a 3 element lens, takes a battery that I can get on Amazon, has a setting for ASA 75, 100 and 150, can shoot Tmax or Foma, then 3000 if I want to shoot Delta 3200, build in rangefinder, and the aperture can be adjusted to fine control exposure. Only issue that the batter compartment is on the back of camera, I would need to remove the door so the 6X7 Mamiya back could fit. I assume that the door is not needed for the battery to work. That means it will be a more complex mod, I need a method to attach the 6X7 back so that it could be removed to replace the batteries. I have a Mamiya press that has seen much better days, maybe I could use the Mamiya back on the 450? Still needs to be removeable. Below is an example of the pack, this is a 250 but same body as the 450.

 

[Donald Qualls]

Might consider mounting the battery externally. As I recall, the later Polaroids in this family would run on 3V (vs. the 4.5V of the earlier models like the 100), so a pair of AAA or AA in a small battery holder could be mounted wherever convenient. That also makes it cheaper to replace batteries (and with longer life) than the snap-end ones.

 

[BobD]

I've converted a number of these cameras to use AA/AAA batteries. It's very simple. Just snip the leads going to the old battery clips and solder in a 3-battery holder. The new holder could go anywhere.

I wonder if a Graflex "23" rollfilm holder might not be a better fit than the Mamyia type?

 

[Donald Qualls]

I wonder if a Graflex "23" rollfilm holder might not be a better fit than the Mamyia type?

Both fit a 2x3 Graflok mount in their original form, so you could make it capable of using both.

 

[Paul Howell]

I have a Mamiya 6X7 on hand, seldom use it. Will look into adding a battery compartment maybe just on left side, back facing user, then need to see about having a adaptor plate machined.

 

[Paul Howell]

Got the 420 today, seems that it will fairly simple mod if I use the back from my old press, no need to fuss with the battery compartment as I take either a 6X7 or 6X9 back off if I need to change the battery. Will need to make a baffle of some sort to light proof the end where the old film was pulled out of the pack after exposure. I ordered a battery will take a week or so to arrive, then will test with a sheet of film to see if the auto exposure is still working.

 

[Paul Howell]

Here is a image of the Polaroid with the back open. The current back is held on by 2 small screws, other than making a light baffle, will need to have a machine shop make an adaptor plate with a cut out for 6X9. Polaroid used very durable plastic, the tow small screws hold the current back in place, thinking 4 screws will hold an adaptor plate in place without issue. Biggest concern is the machine shop costs, small job but will be cheap.

 

[Donald Qualls]

Biggest concern is the machine shop costs, small job but will be cheap.

Small jobs are never cheap, because machine shops don't want them.

They don't want them because of setup time -- even with CNC, someone has to model the part, generate the tool path, and then check the tool path before risking cutters and materials (a high speed carbide cutter alone might cost more than your whole project).

Setup time is half the workload for a run of a hundred small parts -- it's virtually all of a one-off. Sure, there are a few shops that do one-off stuff, but they don't work cheap; they have to pay their own overhead, machine time, wages, and maintenance costs.

If you can do the 3D modeling yourself for the part you need, there are alternatives -- there are businesses all over that do bespoke 3D printing, as well as metal 3D printing (for better strength and opacity), casting (from 3D printed investments), etc. And a couple that do one-off CNC machining from your model -- but then the mistakes are yours; if your model has a problem, you'll find out after you've paid for the part and it's in your hands, and then have to pay again for a corrected one.

 

[Paul Howell]

Left off the not before cheap. 3d printing is an option, there are a few rec centers here in the valley that have 3d printers.

 

[Donald Qualls]

You know, I should consider doing this to my 210. Yep, plastic meniscus -- except I long ago removed that and replaced it with a pinhole, and masked the light meter opening to get correct exposure with 669 and FP3000b. Should work okay with Delta 3200. In reasonably clear sunshine, hand held pinhole is real...

 

[Paul Howell]

That's a thought. I paid more for the battery than I did for the camera. If you have the tools to make an adaptor plate, get a trashed 2 1/4 to 3 1/4 for the back, all set at not much cost. I live in Town Home, no room for a workshop, need to job out the adaptor plate. Still a very portable 6X9, or I have 6X7 and 6X9 sheet film backs that will fit the Mamiya back. Need to scrounge about to see what filter holder will fit the lens, S VII? Using the lighten and darken feature knob should be able to use a yellow and green. I think the shutter speed is fixed, the auto exposure changes the aperture, not sure, would need to take apart the shutter to see how it works.

 

[Donald Qualls]

Based on my experience with a 100, 210, and 350, I've understood that all of this family used an "open till exposed" electronic shutter. Shutter opens, meter starts adding up exposure, and when it's had enough, shutter closes. The 210 was the cheapest model of its generation (fixed focus, non-folding viewfinder, settings only for 80-100 and 3000 speed) and has this, so your 180 probably does as well. Easy to check, once you have the battery. Make sure the shutter is opening, then cover the meter window and fire it -- it should stay open for at least several seconds (maximum got longer with each generation, AFAIK; the 350 would hold for close to a minute). My 210 would, IIRC, hold open for at least fifteen seconds.