wolly 159mm in betax 3

[rich caramadre]

I heard there is a set screw on this lens which will allow you to open the diaphram wider than f12 (for composing only of coarse). Is this true? If so where is it?

Rich

[Glenn Thoreson]

Well, I have one of those but I'm not going to take it off the board to see. In any event, it's an f/12 lens no matter what, so you would gain little. Use a dark cloth and a loupe. It's not that dim.

[Maris Rusis]

I just went and had a look at my 159mm Wolly. The aperture control opens way past the maximum aperture mark but the aperture does not get bigger. Why? Taking the lens apart I see that the way front and rear lens groups are mounted imposes a mechanically vignetted aperture. When closing the iris from wide open it only starts to bite into the available aperture at the maximum marked stop.

On my Wolly 159 at least there is no secret wider aperture hidden in there.

[Mark Sawyer]

It can definitely be done; mine opens to about f/6, and I tried it there and found the corners softened a little but the center was quite sharp and it still covered 8x10 fully. No focus shift I could detect when stopping down, either. Mine came with the limiting screw already removed, so I don't know just how to do it, but here's a mention in another thread, post #13:

http://www.largeformatphotography.info/forum/showthread.php?p=79693&highlight=159mm+maximum+screw#post79693