Plan for a 8x10 springback, anyone ?

[Yourix]

Hi there

I'm planing to build a reducing back for a old 10x12 wooden camera.
I know what are the critical measures to respect for the film to be in the plan of focus but before drawing the whole thing I wonder if anyone has plans for a 8x10 wooden springback ? Such backs are manufactured since at least a century and I'm sure there is no need to re-do the whole thing.
Plans in metric would be super-cool but imperial could do the job as well. I'll be very grateful for any help. Old drawings, sketchup 3d...anything ;-)

Thank you

[lassethomas]

I designed and 3d printed a back for my 8x10 Szabad. If you are interested in the Fusion 360 file pm me

[domaz]

Why not just find an 8x10 back, possibly from an old donor camera and mount it up on a board that fits your 10x12 camera?

[Tim Meisburger]

I made an 8x10 back for my Kodak 2d, which came with a 5x7 back. All I did was use a 4x5 back as a model and scaled it up. The only critical dimension is that the film plane in the holder and the back of the ground glass are in the same plane.

Modifying a donor back would be much easier, but I was never able to find one at a reasonable cost, and I enjoyed making the back.

[Greg]

8x10 wooden Burke & James (B & J) backs are very solidly built and usually go for little money.

[Jim Jones]

Check this out: https://jongrepstad.com/building-a-large-format-camera/. For the 8x10 film holder, the critical dimensions are .260 +/- 0.016 inches from the face of the holder to the back of the film, 9.322 maximum width, and 10.850 maximum from the bottom of the holder to the face of the locking ridge.

[Yourix]

Thank you for your feedbacks.
I'm sticking to my project of building one because in my place (France) old 8x10 back are rare and expensive... Plus this will be a rehearsal before building a modern 10x12 back later...
Scaling up the 4x5 back I have and make it fit the 8x10 holder is probably the best option...
Thank you

[John Layton]

I do believe that some of the standard measurements were modified/changed many years ago...so my advice would be to procure film holders of similar age/vintage and, once you've ascertained that they are all equal...use one of these as a basis for measurements.

For a basic (but effective) film plane measurement, lay a straight edge across the width of a film holder with its dark slide removed, and a "waste" sheet of film, and measure down from the bottom edge of the straightedge to the surface of the film. This is the measurement that you want to duplicate...from the bottom surface of your ground glass frame to the surface upon which the ground glass will rest (assuming you'll be using a "simple" ground glass with the "ground" surface facing towards the front of the camera).

If you want to go a bit crazy...you can take several measurements from straightedge to film surface as outlined above - but based on the point of "very first contact" with the film's surface. In other words, if you watch very closely as your measuring device contacts the film's surface...that you can (often) push the film down very slightly before the film's base makes contact with the septum below it. If this is indeed the case, it will also be likely that measurements taken this way will be different between the center and near the edges of the film...in which case you can take an average reading and use this for your ground glass frame measurement.

But if you do decide to measure in this "point of first contact" way...just be careful not to breathe on the film as you do this, as the moisture from your breath can cause the film's surface to shift slightly as the moisture is absorbed.

If you want to go even more crazy...do the above measurements at different temperatures and humidity conditions - and maybe even with a film holder at different orientations - particularly at whatever orientation it would most likely be placed in as you make photographs...like perpendicular to the ground. Make sense?

Edit: My apologies for going into way too much detail above...but when I designed my L-45A camera I got really obsessive about this!

[Jim Jones]

[QUOTE=John Layton;1704807]I do believe that some of the standard measurements were modified/changed many years ago...so my advice would be to procure film holders of similar age/vintage and, once you've ascertained that they are all equal...use one of these as a basis for measurements. . .

I neglected to say in post #6 above that the .260 inch dimension from the film holder face to the back of the film is from the American National Standards Institution publication ANSI/PIMA IT3.108-1998 of 1998. Actually, the original dimension given was 6.60 +/- 0.406mm, and the 0.260 inch conversion is from Annex A included in that publication. That measurement has long been discussed (or argued) on photo forums, so years ago purchasing the cited publication from ANSI seemed worthwhile. I'm obsessive, too!

[Tin Can]

Glad you spoke up.

ANSI Spec which I will not supply has differences in 'T' for different size film

Meaning 2x3, 4X5 'T' will vary from 11X14 'T' and larger


and very few will measure correctly as the septem may flex

We always argue about this

Richard Ritter has set his and published them on his website

He does not make 8X10 holders

We have plenty