Anyone know anything about 12x20 holder varieties?

[walter23]

What are the different varieties?

It looks like Chamonix builds theirs to fit Lotus.

What about the old Korona banquet holders? Are they compatible with any modern cameras?

I would like to get a feel for the different families out there. I'm working on a 12x20 build and would like to base the holder dimensions on a design that is in fairly common use (if such can be said for these formats).

 

[scootermm]

Walter, I have a 12x20 Folmer & Schwing camera and presently shoot only with it.

From what I've heard, the common belief is that most modern cameras - Lotus, canham, etc - are built to the common Korona style, that there is a groove cut into the camera back and a rib built into the film holder to lock. The F&S being the reverse of this (rib on the camera back, groove cut into the film holder). S&S holders are built to roughly this standard from what Sandy King has mentioned to me and on the forums etc.
Aside from the need to necesitate removing a rib on the Korona style holders (the common S&S holders available) and routing a groove in, the Korona/S&S holders work wonderfully in my F&S camera. The holders are of reasonably identical dimensions as original F&S holders.
I have shot extensively with both a 7x17 and 12x20 F&S. The 7x17 camera back required a strip of wood to be used to center the S&S/Korona holders in the back of an F&S camera. But aside from the groove/rib mod needed the holders worked well.

Likely would be ideal to buy a set of holders and build your camera to work with them.
I know the critical dimension that is referenced is the T-Dimension (distance from lens to film plane/groundglass) but honestly I have never measured whether my Korona/S&S holders have an identical T Dim as the original F&S holder. Just havent felt the need to, nor has the need arisen.

hope that helps. There are many others here that likely can give alot more technical information, that could even go counter to my experience, But I am no technician, this has merely been my experience.

 

[BarryWilkinson]

Walter,

AWB publish a few film holder dimensions on their website...

http://www.filmholders.com/filmho1.html

If that's any help?

Barry

 

[jgjbowen]

When Richard Ritter was building my ULF camera, his advice was to obtain the holders first, then have the camera back built/modified to fit the holders.

That being said, I have 3 sets of 7x17 holders, the first are standard S&S 7x17 holders. The 2nd set are S&S 7x17 holders that were Sandy King's personal holders, these are 1/4" shorter than the standard S&S holders, but work fine. The 3rd set are AWB 7x17 holders. All three sets of holders are of the "Korona" design and work fine in my Ritter ULF camera.

 

[CRhymer]

Hello Walter,

The best advice, already stated by others, is get/make your holders first. I can highly recommend Sandy King's (although others are also good). I have some 7x17, 11x14, 12x20 and 20x24's of his and they all work well. The climate here is very dry, so swelling and warping of dark-slides is not an issue. He will also tell you how he has made slight modifications in dimensions over time and tell you what you need to know to get it all right. You don't mention whether you plan on making your own holders. I considered it, and have a well equipped shop, but I found that it wasn't worth the bother. I have also bought some used holders on eBay, but they cost almost as much as new ones after I had to repair them and do slight modifications. Sometimes Sandy has some new or slightly used old stock for a very reasonable price - can't hurt to ask.

Of course, as Scooterman says, you want all your holders to have the same T dimension. Interestingly, I gave my father in law an 8x10 Korona that has the rib groove design that Scooterman describes for Folmer & Schwing, but my Korona 7x17 uses the opposite system. There must be some historical info on this somewhere.

I see you are in Calgary. That is practically next door.

Cheers,
Clarence

 

[walter23]

Thanks Clarence.

I'm wondering if anyone has the time or inclination (and some vernier calipers) to go over a 12x20 holder and make a sketch, plus information on the width & height of their holders? For the chamonix/lotus/korona style...

There is a small handful of us working on this project and we'd like to build them from scratch rather than buy the 8 or so we'd want (if we buy holders we're already over budget for our prototype camera!). Obviously the first holder will be built before we build the back. We could probably work out a deal to get a cheap holder for you if you could give us really good dimensional information and test the thing once it's constructed.

 

[garysamson]

Walter,
Besides the historical F&S and Korona holders, and Sandy King's contemporary holders, Ron Wisner makes 12x20 holders which he claims are derived from Burke & James dimensions. Non of these holders are interchangeable with out modification of the back or holder with the exception of Sandy's holders and the Korona holders. Richard Ritter knows the most about this issue as he has done many modifications to adapt camera backs to accept holders of different dimensions.

 

[sanking]

We are making a new batch of 12X20 holders right now and they will have the same dimensions as AWB. Chamonix holders are also made to AWB specs. Lotus holders are not. You can get the dimensions from the AWB site noted earlier. However, I think it will be very difficult to build a holder without having a model to work from.

At this point we (S&S) have on hand a few older generation 11X14 and 12X20 holders that I will sell at significant discount over current retail. If anyone is interested contact me by pm.

Sandy King

 

[CRhymer]

Thanks Clarence.

I'm wondering if anyone has the time or inclination (and some vernier calipers) to go over a 12x20 holder and make a sketch, plus information on the width & height of their holders? For the chamonix/lotus/korona style...

There is a small handful of us working on this project and we'd like to build them from scratch rather than buy the 8 or so we'd want (if we buy holders we're already over budget for our prototype camera!). Obviously the first holder will be built before we build the back. We could probably work out a deal to get a cheap holder for you if you could give us really good dimensional information and test the thing once it's constructed.

I am not sure just what specific dimensions you want, besides the ones listed on the AWB site. I have 10, yes ten 12x20 S&S holders. That is a lot of film to load at once. They are an exact fit for my Canham, and are slightly different (correct me if I am wrong Sandy) than the latest ones, although not enough, I believe, to make a great difference. I don't know what stage your group is at, or what skills/equipment/design ideas you have, but a bigger challenge than establishing dimensions is a good design and material source for light traps and dark slides. I don't know if you are planning on using carbon fibre, plastic, or wood for the frames. I have a couple thousand board feet of cherry and walnut in my back shed that I bought seasoned in about 1985 and moved to my present location 12 years ago. I also have a woodworking shop and experience in boat-building and cabinet making. Even so, I found it more cost effective to buy rather than build my film holders.

On the other hand, I am a DIY’er and think it is great that your group is working on this project. It really would be useful for you to settle on a type and buy at least one holder to use as a model, or at least have a long hard look at an existing one. Is there anyone in Calgary that shoots 12x20? Do you have any film? One sheet of film can be very helpful just to test the guides, flaps etc.

Cheers,
Clarence

 

[walter23]

Clarence, thanks for the suggestions. We have a sheet of film, possibly a couple more. We've found some sources for light trap material (though it is kind of expensive). The construction will likely be predominantly wood (we haven't settled on the darkslide material yet though we've had some discussions about that). The other collaborators on this are actually on or near the east coast of the US; I'm the only one up here in Calgary.

The woodworker has some ideas for setting up guides and I think a custom router bit to try to simplify construction of the film holders. You may be right that buying one as a model would be the best approach though.

Regarding the stage of our building; we've settled on an overall design, and have started constructing the base and focusing mechanism.

 

[CRhymer]

Hello Walter,

Well, last time I checked, Sandy King is not too far from the east coast of the United States - maybe 220 miles from Charleston, SC. One of the costs in getting an existing holder would be shipping to Calgary. If it is shipped within the US it would be quite reasonable. That is definitely the way to go. Let your woodworker look at an original. Your group will quickly save in time what you pay for the holder. I have also found that one can spend a lot of time and materials prototyping, which would be saved by seeing a very good functioning unit.

Good luck, and keep us posted with your progress.

Cheers,
Clarence

 

[walter23]

Thanks Clarence, we will. I expect we won't have a prototype camera until well into next year, but we'll see how it goes.

 

[philsweeney]

We are making a new batch of 12X20 holders right now and they will have the same dimensions as AWB. Chamonix holders are also made to AWB specs. Lotus holders are not. You can get the dimensions from the AWB site noted earlier. However, I think it will be very difficult to build a holder without having a model to work from.

At this point we (S&S) have on hand a few older generation 11X14 and 12X20 holders that I will sell at significant discount over current retail. If anyone is interested contact me by pm.

Sandy King

Hi Sandy,

I believe you stated in the future S & S holders will be to AWB specs? If thats true will the newer S & S 7 x 17 holders work interchangeably with the older ones I have that fit my Korona.

thanks

phil

 

[sanking]

Hi Sandy,

I believe you stated in the future S & S holders will be to AWB specs? If thats true will the newer S & S 7 x 17 holders work interchangeably with the older ones I have that fit my Korona.

thanks

phil

Phil,

The change we are making to the 7X17 holder involves only the placement of the rib-lock. Width and t-dimension remain the same. In the past we have made the S&S holders with the rib-lock at different positions in order to fit specific cameras.

As you know the rib lock *must* drop into the groove to form a light baffle. Unfortunately the Korona standard was very loose as most of the camera were made one-off so in real life you find that the position of the groove relative to the opposite side of the back may vary by up to 1/2". For a perfect fit of a holder to Korona camera it is often necessary to adjust either the holder or the position of the groove in the camera back. Both adjustments are fairly easy to make so we don't believe the small change in specification will make much difference in practice for Korona cameras.

Sandy

 

[philsweeney]

Hi Sandy,

Whew good news. thanks. Though the details are not complete, I am having a 8 x 20 with 7 x 17 reducing back made to use S & S holders. I have 3 7 x 17 holders, one 8 x 20 purchased for the camera build and plan to get a couple more.

phil