Swirl effect and Petzval lenses

**Neil Purling** · 10-Feb-2007, 03:08

Am I correct in thinking that the characteristic 'swirl' effect in out of focus areas away from the frame centre is due to particularly strong coma?
I saw a Petzval type lens on UK ebay,8.75" with its flange.
However to mount the flange on a Linhof panel would mean taking away the interior lip when the 3 1/16 hole is cut. Is the lip a light trap?
Does any other lens exhibit this effect without emptying my bank account?

I have two old Rapid Rectilinears, one being a Beck No3 6" focus Biplanat and also a old B&L lens in kodak Ball Bearing shutter that came off a 116 size Autographic.
I have not shot with either lens. Both need lens panels cutting and the Beck is at S K Grimes for this to be done and a retaining ring made.

**C. D. Keth** · 10-Feb-2007, 10:55

Yes, you are right. The Petzval swirl is uncorrected coma. Even minor coma left uncorrected will create that effect noticeably. The brownie lens definately won't. I have a lens off of the same type of camera and it's just a simple meniscus lens. You can't open up enough to get the coma because the whole frame goes frightfully soft.

I have no clue about the others, but someone here will know. Probably Jim will chime in. I hear he is psychically drawn the threads with "petzval" in the title.

**Neil Purling** · 10-Feb-2007, 11:54

The Kodak lens is a R.R type of f8 aperture, focal length being unknown. I would guess at around 135mm maybe? If I get a lens plate drilled for it I will try it along with the Beck 6" f5.8. Are Rapid rectilinears not prone to coma? The title suggests they are not.

I liked the Petzval swirl. The effect is usually quite strong, because some Petzvals have no diaphragm or slot for Waterhouse stops. Can you get Petzvals shorter than 8" focus? It is a matter of what will mount to a Technika or Graflex lens panel with its flange.

Any other lens that exhibits such massive uncorrected coma?
In another forum someone suggested it would be possible to use a +4 diopter filter on a Copal shutter via adapter ring.
Would such a simple lens exhibit this effect too?

**erie patsellis** · 10-Feb-2007, 13:02

for those of you that like the look, and love to experiment, find an old CRT projector lens, ideally a higher quality 6" diameter or larger, on the Delta HD-6 lenses, there is an aspheric fromt element that is adjustable, in the original useage, for corner focus. By removing it and reversing the lens, the back focus is about 5-6", lots of uncorrected coma and did I mention f1 or f1.1? (I have several here, including a HD-10 (8" diameter) and I'm in the process of disassembling one to mill a waterhouse slot in one) Just imagine a fully coated, fast portrait lens, for less than a tank of gas....(or a 4x5 full field f1 astro camera with the lens right way around, back focus is about 3/4")

erie

**Neil Purling** · 10-Feb-2007, 15:08

Sounds interesting. However, I bet they are heavy bastards, even without a added shutter on the back of the lens.
Perhaps a genuine Petzval type, even a magic lantern lens would be better?

**erie patsellis** · 10-Feb-2007, 16:14

Very, though I can hang one off of my C1, I'm making a lensboard that recesses the lens about 2 or 3 inches, and I'll attempt a studio/packard type shutter on the front, still a work in progress.

**C. D. Keth** · 11-Feb-2007, 09:52

Originally Posted by Neil Purling

The Kodak lens is a R.R type of f8 aperture, focal length being unknown. I would guess at around 135mm maybe?

The lens from mine (a model 2a autographic folding brownie) was 105mm.

About the diopter on a shutter: yes, it will have huge amounts of coma. The problem is that i will also ahve so many other problems that you would have to stop down to 11 at least to not be bothered by those too much. By then, the coma problem would be greaty reduced as well.

**chachahavana** · 8-Jun-2009, 09:39

Hi erie

How is the result and that would be wonderful if you could share some images.

Thanks in advance and cheers

ChaCha

**urs0polar** · 5-Aug-2009, 20:37

I am also interested in cheap Petzval type swirly lenses... I have a question, however: without a Speed graphic w/ focal plane shutter, is it worth it? I have Technika V, and I'm not sure the boss would let me swing a speed graphic in these trying times.... unless the lens + speed graphic would be cheaper than monkeying with barrel lenses on technika lensboards.

are there any petzvals that come with shutters, or is adding a shutter to a petzval always a DIY thing?

**Ernest Purdum** · 6-Aug-2009, 09:43

Petzvals in shutters exist, but are super rare. I have never that I recall seen one listed in a dealer's catalogue. Of course roller-blind shutters, Luc and similar shutters could be used.