built up lens board to increase extension

[Mike Anderson]

I have a Calumet wide (12" rail) camera and have a 150mm lens on the way. I understand 150mm might pushing the length limits of that camera, so I'm thinking of building up a lensboard to push the lens out 1/2 inch or maybe more (like a recessed board in reverse).

Anyone see any problems with this concept? I'm surprised that there aren't any lensboards already made like this.

This camera holds the lens board about an inch behind the pivot points, so I'm thinking it might be a good idea in general to get medium focal length lenses pushed out closer to those pivot points.

Any suggestions or warnings appreciated.

...Mike

[jmcd]

If you have 12" of bellows (do you?) you can go 1:1 with a 150mm lens.

I believe they call the board you describe a top hat.

[Gem Singer]

A reversed Calumet recessed board will work just fine when used as an extension lens board.

However, I believe that your 12" monorail should be adequate for a 150, unless you are planning on using it for extreme close-ups.

I have a 10'' monorail on my Toyo, and I am able to use lenses as long as 210mm for general photography.

[Mike Anderson]

If you have 12" of bellows (do you?) you can go 1:1 with a 150mm lens.

12" of rail. About 7" max from lens board to GG.

...Mike

[Mike Anderson]

A reversed Calumet recessed board will work just fine when used as an extension lens board.

I have one, and when reversed it feels a little loose (rattles), and maybe leaks light, but I can address this.

However, I believe that your 12" monorail should be adequate for a 150, unless you are planning to use it for close-ups less than 1:1.

Well I need to do some lens board tinkering to accommodate the new lens, so I'm thinking while I'm at it I might as well push the lens forward a little, assuming there's no negative consequences in doing so.

Thanks for the info,

...Mike

[Ron Marshall]

Anyone see any problems with this concept? I'm surprised that there aren't any lensboards already made like this.

There are! Top Hat or extender boards. Scroll-down in the following link for an example:

http://www.thalmann.com/largeformat/toho.htm

[ic-racer]

The Horseman top hat board systems frequently show up on fleabay. http://cgi.ebay.com/Extended-Lens-bo...ht_1914wt_1167

It would certainly be possible to make an 8x8cm Horseman to Calumet adapter board (though likely to cost more than that Chinese top hat board system ).

I can't speak for that Chinese board system, but I have a few 'standard' 8x8 boards from China and they seem fine.

[Mike Anderson]

There are! Top Hat or extender boards. Scroll-down in the following link for an example:

http://www.thalmann.com/largeformat/toho.htm

So there are. I would have thought these type of things would be more common, that most camera manufacturers would offer these just as they offer recessed lens boards.

...Mike

[Mike Anderson]

The Horseman top hat board systems frequently show up on fleabay. http://cgi.ebay.com/Extended-Lens-bo...ht_1914wt_1167

It would certainly be possible to make an 8x8cm Horseman to Calumet adapter board (though likely to cost more than that Chinese top hat board system ).

I'm keeping this operation low budget. I have a lens board with too-big-a hole, and I'll build a prototype extension out of stacked/glued black matte board and screw it to the factory board. Push the lens out 1/2" and see how that works. If it works, I can do a production version with hardwood plywood.

...Mike

[Keith Pitman]

I always liked this one. I'm sure other types of fruit would work also.