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Whir-Click
26-Feb-2018, 17:40
I recently acquired a Wollensak Velostigmat Series I (not Ia) 6.3 lens. This lens is triple convertible, but I canít form a sharp image with the cells alone or in combination.

I suspect someone disassembled the cells at one point and flipped a doublet the wrong way round.

Can anyone with a (functioning) Velostigmat Series I please relate the correct lens arrangement? Is it like this: (( )) | (( ))

Thanks for any help!

Dan Fromm
26-Feb-2018, 17:56
Suggestion. Pick a cell. Either cell. Reverse the inner doublet and reassemble. Look to see whether the reassembled cell forms an image.

Whir-Click
26-Feb-2018, 20:24
Thanks for the suggestion; I arrived at the correct arrangement: (( (( | )) )).

Also, it turns out this lens is only a double convertible, not triple.

mdarnton
26-Feb-2018, 20:32
If it's an f/6.3, it should be a triple; the f/6.8 is a double. Check page 12 for an explanation and page 13, where the separate focal lengths for the f/6.3 are listed on the chart: http://www.cameraeccentric.com/html/info/wollensak_13.html

F/6.8 version lenses are here: http://www.cameraeccentric.com/html/info/wollensak_10.html , on page 17.

And yes, you did arrive at the right arrangement. If I remember correctly, there's a bevel on the inside of the inner component which mates with the shape of the retaining ring, where that bevel is not on the "wrong" side of that component.

I'll be interested in your report of how it works. I have two of these and only have used one of them, so recently that I don't have results finished yet. It's supposed to be a pretty good lens, considering that it's from the dawn of double anastigmat time.

Whir-Click
26-Feb-2018, 20:50
I heartily agree it should be a triple- that’s why I bought it! I had devoured the Wollensak brochures beforehand and thought I couldn’t miss with a Series I 12.5” 6.3 Velostigmat.

But at infinity both cells together are 12.5”, front cell only (in front of shutter) is 18”, and rear cell only (in front of shutter) is also 18”. I don’t have to touch the focus knob to keep a distant object in focus when switching between front and rear cells.

The serial number on the front matches that on the back. I’m stumped.

Whir-Click
26-Feb-2018, 20:54
It’s number 21568 in case anyone encounters it in the wild.

mdarnton
26-Feb-2018, 21:12
Edit--OK, I see you are doing it as I suggested... never mind.

The one I have here at home is #224982--probably quite a bit later than yours, then. I don't remember the speed or number of my other one.

I wonder if yours is an earlier one put in a newer, wrong, shutter, given how far away my number is. My other one is, I think, earlier, and is in a more primitive shutter than the one at home. I will check, tomorrow, the speed and number of that one.

Whir-Click
26-Feb-2018, 21:59
Thank you very much, I appreciate the help and insight.

The Wollensak literature describes the 6.8” Royal Anastigmat as a symmetrical convertible lens in the 1906/7 catalog, and in the first appearance of the 13” Velostigmat in the 1912/3 catalog, conversion is not mentioned at all. By 1916 the 12.5” 6.3 is described as triple convertible.

I assume my lens is a transitional product during this period: faster speed, shorter focal length, but still a symmetrical design and not yet triple convertible. Who knew such variations existed?

desertrat
27-Feb-2018, 11:35
I have two series I Wollys, one f6.8, the other f6.3. Like yours, my f6.3 is symmetrical, both cells have the same focal length.

I think the f6.3 lens is completely satisfactory for my needs. The earlier f6.8 lens has some focus shift and curvature of field, but is still not too bad at small apertures. The older lens also has a lot of small cleaning scratches, but doesn't seem to suffer much from loss of contrast from that.

Mark Sampson
27-Feb-2018, 11:39
If you do a search here, you'll find a very long thread from some years back. Trying to establish a database of Wollensak serial numbers by year... not sure how successful that was but there was a lot of Wollensak info there. It may be of help.

mdarnton
27-Feb-2018, 12:42
My second one is f/6.3 in an Auto shutter (the other is in a No 4 Betax), is two different focal lengths, and is #182692. Neither one has anymarkings at all on the back part.