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View Full Version : Are Chamonix WP Holders Compatible With Seneca Back?



Scott Sharp
1-Dec-2009, 19:22
I have a Seneca Whole Plate (6 1/2 x 8 1/2) format view camera. An Improved Seneca View, circa late teens to early 1920s. Vintage Whole Plate film holders are nearly impossible to find as most WP camera owners know.

The Chamonix WP holders look like a good option. Any idea if they are compatible with the Seneca GG back or if Chamomix can make holders that are?

Thanks, Scott

Oren Grad
1-Dec-2009, 21:06
If you can provide measurements of your back, I can check for you. I need the width of the opening for the holder and the distance from the far stop to the beginning of the locking groove.

Roger Thoms
2-Dec-2009, 20:39
Scott asked me to post the measurements since his camera is in the shop. My WP Seneca is a City View Camera, should be the same as Scotts Improved Seneca View.

The width of the opening is 7 7/8" and the distance from the far stop to the beginning of the locking groove is 9 1/8"

Roger

Steve Hamley
2-Dec-2009, 20:55
My Chamonix WP holders are 7-13/16 wide, and 9-3/16 to the start of the rib. They're also made to the Eastman standard, so if an Eastman holder fits, so will the Chamonix.

Another option is AWB holders, but they're pricier. I'd rather have the standard dark slides and pulls on the AWB. And if you send your back (or measure it), Alan will ensure the T-distance is correct.

Cheers, Steve

Oren Grad
3-Dec-2009, 09:44
I get 7 13/16" wide and 9 1/4" to the start of the rib on my Chamonix holders.

However, the Chamonix holders are not designed to exactly match the Eastman holders. The Eastman holders are a bit smaller - the one I have in hand at the moment is 7 3/4" wide and 9 3/16" to the start of the rib.

This seems like a small difference, but it can be enough to matter. For example, my Eastman holders will fit my Rittreck WP back, but my Chamonix holders won't - they're just a hair too wide.

Richard K.
3-Dec-2009, 11:49
I'm curious about how the T-distances compare. Has anyone measured this for the holders and also for the back(s)? I once bought an 8x20 Korona and included holder (couldn't tell the brand) off by 1/4" ! :eek:

Scott Sharp
3-Dec-2009, 12:28
Measuring my two WP size Eastman Glass Plate holders, they match Oren's Eastman holders. Eastman measurements: 7 3/4 " wide and 9 3/16" to the start of the rib. The Eastman WP holders do fit the Seneca back.

Looks like the Chamonix WP are slightly larger though not by much (1/16th) and could probably be modified to fit the Seneca back. Does anyone actually have a Chamonix WP holder they are using with a WP Seneca camera?

Good question on the T-distance comparison. Anyone checked that?

Oren Grad
3-Dec-2009, 12:49
Looks like the Chamonix WP are slightly larger though not by much (1/16th) and could probably be modified to fit the Seneca back. Does anyone actually have a Chamonix WP holder they are using with a WP Seneca camera?

It might not be necessary to modify anything. My Chamonix holders fit fine in my Eastman backs because there's a fair amount of wiggle room between the Eastman backs and holders.

Roger Thoms
3-Dec-2009, 15:40
The Grove on my Seneca back is 7/32" wide, how does that compare to the width of the rib on the Chamonix holder?

I also measured the T distance on my back and it is 7/32", if someone could compare that to Chamonix holder.

Roger

Roger

Scott Sharp
5-Dec-2009, 15:11
Oren,

Would you measure the T-distance on your Chamonix holder?

Thanks, Scott

Oren Grad
5-Dec-2009, 16:02
Scott -

Afraid my Chamonix WP holders are all loaded with film at the moment.

My recollection is that the specification for the Chamonix holders is 0.260". The number may be buried in one of the earlier WP holder threads here. I also don't know how faithfully their manufacturing adheres to the specification.

Do not expect to be able to match the T distance - the old camera backs and holders were all over the map. My Eastman holders don't even quite match my Eastman backs. You could get lucky, but if you must have it exactly right, odds are you'll either need to have your back shimmed or trimmed, or holders custom-built.

Before you worry too much, do some depth-of-focus calculations for the focus distances and aperture settings you expect to use with the camera, and think about the kinds of subjects you like to photograph, whether they sit still, how much depth they have, and how important it is to get the plane of focus *exactly* correct.

Sal Santamaura
5-Dec-2009, 16:08
...My recollection is that the specification for the Chamonix holders is 0.260"...That is correct. Chamonix modeled its holders after my Lotus WP holders. Lotus and I decided to base them on Lotus 8x10 holders, simply shortening the length and width. Therefore, Lotus and Chamonix WP film holders share their T dimension with the ANSI 8x10 T dimension.

Oren Grad
5-Dec-2009, 16:10
I'm curious about how the T-distances compare. Has anyone measured this for the holders and also for the back(s)? I once bought an 8x20 Korona and included holder (couldn't tell the brand) off by 1/4" ! :eek:

Richard, a while back when we were in discussions with Fotoman about the possibility of having WP holders made, I measured a bunch of holders and backs I had on hand. The holder depths to septum - not accounting for the thickness of the film - ranged from 0.254" to 0.332", while the back depths from bearing surface to GG surface ranged from 0.243" to 0.257". This doesn't include the Chamonix camera or holders - I didn't have them yet. Sandy King has seen a wider range of WP equipment than I have, and in another thread here recently he reported an even wider range of T-distances than that.

Roger Thoms
6-Dec-2009, 00:02
Richard, a while back when we were in discussions with Fotoman about the possibility of having WP holders made, I measured a bunch of holders and backs I had on hand. The holder depths to septum - not accounting for the thickness of the film - ranged from 0.254" to 0.332", while the back depths from bearing surface to GG surface ranged from 0.243" to 0.257". This doesn't include the Chamonix camera or holders - I didn't have them yet. Sandy King has seen a wider range of WP equipment than I have, and in another thread here recently he reported an even wider range of T-distances than that.

As I posted earlier, my Seneca "Camera City View" WP's measurement from the bearing surface to the ground glass is 7/32" or 0.219". It's not looking good for Chamonix holders fitting the Seneca's.

Roger

Richard K.
6-Dec-2009, 08:44
As I posted earlier, my Seneca "Camera City View" WP's measurement from the bearing surface to the ground glass is 7/32" or 0.219". It's not looking good for Chamonix holders fitting the Seneca's.

Roger

Actually if the holder width and rib distance work, the T-distance issue can be solved by shimming the GG by 0.041" - a lot easier than routing/shaving the frame down!