5/8" extension on Beseler lensboard?

[eric]

Why is there a product with a 5/8" extension on a Beseler lensboard? It says its for a 105 and 135mm. I have a 105mm and it seems fine. I just got a 135mm lens and was wondering if I need a regular lensboard or a 5/8" extension lensboard.

 

[Nick Zentena]

For reductions? You got a model number for that board?

 

[eric]

For reductions? You got a model number for that board?

This one

http://www.bhphotovideo.com/bnh/con...ils&Q=&sku=4525&is=REG&addedTroughType=search

It says its for 105-135mm lenses.

 

[Nick Zentena]

I bet it's mostly aimed at the 23 model more then the 4x5s.

 

[eric]

I bet it's mostly aimed at the 23 model more then the 4x5s.

I sort of found something on the innernet (so it must be true right? ) that the extension is used for some lenses that have a large rear element. So I'm guessing, that some o fthe bigger lenses with 39mm thread, have that feature. I think you are right though, on the 23c, the focus rail stops short.
So let say that I won this on the auction site cheap, I put my 135mm on it, and use it for 4x5 negs, perfectly okay right? I just need to raise the enlarger 5/8" inch more I guess.

 

[Nick Zentena]

Only problem would be when you want to make a max size enlargement. You'll be giving up some size at the top end. But if you aren't making 24x24 [or whatever the top size is] I doubt you'll notice.

 

[Nick Zentena]

Actually I take that back. Considering you can focus a 50mm with a flat board the extension won't matter even with a max enlargement.

 

[eric]

But if you aren't making 24x24 [or whatever the top size is] I doubt you'll notice.

Doesn't everyone make 24x24?
I can barely make a nice 8x10

 

[Papa Tango]

You will find one also that is recessed...