What is it and how to dismantle?

[brucep]

I've just got this lens but don't know anything about it. Holding it up the image appears to cover a 10x8 ground glass but I don't have a flange so can't test to see how sharp it may be at the edges.

The blades have some oil on them. Does this actually matter?

Can anyone tell me what it may be, it's acceptable coverage and how to dismantle to clean off the oil if I should.

111731 111732 111733

Many thanks
Bruce

[Louis Pacilla]

You have a rapid rectilinear probably around 10-12". They are nice lenses but don't expect glow or anything super unique in the look but still they give a smooth look pretty sharp stopped down a bit and they are pretty inexpensive as far as brass/vintage lenses go if your looking for one to shot with.

No to question about the oil on the blades. If they move freely you can use it. Oil on iris blades matters most on instant return SLR cameras Not so much on large format as long as the iris move freely. That said, I would NEVER suggest putting oil on iris blades but if it's there and your iris is working I suggest you leave it be. Maybe try and clean the iris a bit while in place but not worth disassembling the iris for cleaning on your lens (IMHO).

To clean You simply unscrew the cells and clean both sides of each cell. They are each made of two elements glued together so there is no air gap present so again just clean both sides of each cell and your good to go.
***If The cells have not been removed for a long while you may have to put a little work into freeing the them. Just be patient, use common sense & use a little lube on the threads if really stuck also use rubber pads like the kind used to free jar lids to help get a grip on the cells.

Hope this helps.

[IanG]

It's unlikely to cover 10x8, I just checked my RR's and have a Wray of similar size which is a 12" and is marked 8x5 so will cover half plate but not whole plate.

Ian

[brucep]

Thanks for the info.
Bruce

[brucep]

The lens actually came apart easier than I thought it would, and I've removed the excess oil from the blades. After working the aperture ring for a while, it now seems to move quite freely again.

I'm going to have a go at making a flange, but have never cut an internal thread before so it might be a complete disaster.

I thought in the 1880s the mounting thread was standardised at 24tpi on lens requiring a flange under 3 inches, but having just spent most of the afternoon with some gauges, I'm pretty sure it is 36tpi and 2" diameter. Is this standard a true standard, or did everyone still please themselves?

Bruce

[Jim Galli]

I thought in the 1880s the mounting thread was standardised at 24tpi on lens requiring a flange under 3 inches, but having just spent most of the afternoon with some gauges, I'm pretty sure it is 36tpi and 2" diameter. Is this standard a true standard, or did everyone still please themselves?

Bruce

Nothing was standardized until the 1970's. IN fact it seems manufacturers purposely made theirs different than anyone else's. And you seem to find a lot of 30tpi which is a bear. Most modern lathes skip that size. Then there's the whole metric thing vss american threads. I have a large box of flanges that have accumulated over the years (sorry, not for sale) and it's absolutely amazing that some new lens will make it to my house and I'll stand there and try all the flanges and 9 times out of 10 nothing will fit. Maddening.

[goamules]

There was at least some standardization within some makers! Taylor Hobson, Ross and Dallmeyer and sometimes Darlot used the same thread pitch for years. But like Jim says, mixing one makers flange to another maker's lens seldom works. FYI, a mid 1950s Wollensak flange fits on one of my 1880s Hermagis Petzvals. Stuff like that sometimes is a match, I think I've done it about 3 times, in hundreds of lenses.