What is a Beseler extended lensboard for?

My lenseboards are flat with a slight recessed area but I recently saw a Beseler lensboard that was called an "extended" lensboard and Im curious what it is for?

Thanks
Gary

Could that "extention" actually be intended as recess to hold lenses of short focal lenght?

Extended AKA "top hat" just an easy way to permit use of a longer length limited by bellows length.

John Koehrer has it correct.

The practical usage of something like this is when you wish to make a really small full frame print, sometimes smaller than the format you are printing from. Another common use for this set-up is if you are duplicating film stock.

If, for arguments sake, you have a 120 negative, say a 6x6cm one and you need to do a print that comes out at 6x6cm. Then you need either a very long set of bellows on the negative carrier, or you attach what was called a top hat underneath with the lens of choice attached to that to give you the extension you require.

One such set-up we had was with an extension of about 200mm and at the end we placed an Apo Rodagon 90mm f/4 with this in place and a 35mm neg in the carrier, we could make duplicate transparencies using Kodak color print film, which gave us a duplicate colour corrected 35mm transparency developing the film in standard C41 colour negative chemistry.

This set-up was dedicated to an old Besler 4x5 enlarger. Using variations of that and using a Durst 8x10 enlarger, we sometimes made colour corrected 35mm slides from 8x10” film stock. We used to call it, “unlarging”

Mick.

I also noticed that on regular beseler lensboards that there is a slight recess around the hole. What is that for? I have some odd lenses that dont fit my lensboard and have considered making one of aluminum plate but Im curious what that recessed area is for. Are lenses always mounted from the recessed side? Are they ever mounted from the flat side?

The recess in Beseler 4” x 4” x 1/8” lens boards is there to make the board thin enough so that the threaded shank of the lens barrel fits thorough the board with enough male thread on the other side to install the retaining ring to hold the lens to the board.

Beseler made its lens boards two ways:

1. Counter bored on the lens side.

2. Counter bored on the retaining-ring side.

Lenses whose barrel is smaller than the counter bore could fit into the counter bore. These could use a lens-side counter bore. Lenses whose barrels are too large to fit into the counter bore required a counter bore on the retaining-ring side. Many lenses can fit either style.

The proper lens board for a 105mm lens is a slightly extended board. I have one at home (at work now) but don't know what the actual part number is off the top of my head.

The actual use for the extended lens board is to accommodate an enlarging lens with an extended back element. I have a 60mm WA Companon and the rear element sticks out from the flat lens board. I needed this lens board to clear the filter slider on my 45 MCRX. This board is not needed on my newer 45 MXT. These boards are fairly rare and should be worth more than a standard board


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