Petzvals Completely Backwards?

[DanK]

Is there a reason for petzval lenses to be oriented this way?

The last three petzval type lenses I have come across have been backwards?....Each lens had the cemented pair in the rear, and the two singles with the air space mounted up front with the hood...

All three were in rough condition, 'stored for years' lenses....all from different locations...and did not appear to be handled beyond packing and shipping....certainly not used in quite some time...

Why is this so? Is there a reason or just a fluke?

Thanks again,
Dan King

[Paul Fitzgerald]

It's just easier that way, petzvals are convertible. Just remove the 'rear' 2 lenses and the cemented cell is a nice meniscus, about 1.5x the combined FL. Try it out if you have the bellows to reach, if not just put the cemented cell back in front for the extra extension.

have fun with it.

[goamules]

Do these three you've found happen to be brass tube types, from multi cameras? If so, remember that the outside threaded part of the barrel (for mounting) is the front, not the rear. So a cemented pair in the mounting thread part of the barrel is correct.

Otherwise, you must be finding Petzvals where people have accidentally reversed them in the past. The proper config is cemented in front.

[DanK]

Garrett,

Yes all three brass Rack and Pinion type - Two were B&L and One Darlot - two were magic lantern types and one appeared to be a portrait type....

On each lens.....the cemented doublet was in the rear (retaining ring side of the rack)....and the two single air-spaced elements were in the front with the hood....knob side of the rack....

The elements all appeared to be oriented correctly....just backwards front to rear....

Anyone ever shot one in this configuration?

Thanks,
Dan

[DanK]

Also, Thanks Paul...Appreciate the reply

Dan

[Fotoguy20d]

The ones Garrett is referring to (Garrett, pls corretc me if I'm wrong) is the type from a CDV camera, which is usually just a brass tube. In those, the lenses were internal to the camera body and the external threaded end is actually the front. If they have rack/pinion, they would be external to the camera (or lantern body) so you could focus, so the thread would be at the back.

Try shooting with your petzvals in both directions and see what sort of behavior you get from them. I've noticed some differences depending on the lens. And, definitely try using them as a meniscus - I got some really interesting effects with a fast Gundlach projection lens that way.

Dan

[Tim Deming]

I've received numerous lenses with elements reversed back to front, or in inverted order. Sounds like in your case, someone took the pinions off and put the lens tube in backwards, I've received lenses like this as well. Lots of people seem to like to take old lenses apart if it's easy to do, and not be too careful about how they put them back together.

cheers

Tim

[Fotoguy20d]

I just looked at two of my magic lantern lenses with rack/pinion and hood - a Darlot and a no-name brass lens - both have the cemented pair up front.

Dan

[Ty G]

I had a B&L set up just as you say, backwards. I am totally guessing here, but what I am kinda thinking is that they were made that way. Here is why. A petzval on a camera is designed to give optimum view on the rear (ground glass). While the lantern is wanting the best image to be out front (on the wall). I have always wondered if some of the later companies set lantern lenses up that way. I may be wrong and well accept that.

[DanK]

Thanks all...

Interesting Ty....sounds reasonable....since the projection is rear to front...but..

The two triplets from magic lanterns I have are both oriented with the single up front and air spaced doublet in the rear...so I'd think the petzval types would be oriented similarly...

(And one of my 'backwards' lenses was a portrait lens for camera use)

I'm leaning towards the lenses just being put together wrong over time....especially since the petzval test post in the forum didn't show much of an advantage to them being arranged backwards....

Dan