Poor Petzval simulator lens

[goamules]

http://www.bhphotovideo.com/explora/photography/hands-review/video-portraits-lensbaby-twist-60-optic

This lens is marketed to "replicate the famous Petzval." It's funny how the worst problem of the Petzval, swirl, has been turned into a feature to be replicated and enhanced.

[Steven Tribe]

I have posted ny comments there! No-one seems positive!

[jnantz]

they have an imagon-type lens and now a petzval-type lens, and lenses that
allow the user to tilt-shift .. lensbaby makes fun stuff.

[mdarnton]

Regardless of your personal opinion on it, to many people, including on this board, swirl is the reason to have a Petzval. Me, I look at the results of any Petzval and wonder why anyone has one, swirl or not. . . but that's MY opinion. A couple of the other Lensbaby lenses are quite nice, IMO.

[goamules]

Yeah, i'm not too bent out of shape about it. I know why people like the swirl - because it's not "cell phone perfect." And that's rare.

But the center section of a good Petzval was what was used for 100 years. They cropped off the swirl, if any. The center is sharper and faster than any other lens, of the times.

[Rael]

Regardless of your personal opinion on it, to many people, including on this board, swirl is the reason to have a Petzval. Me, I look at the results of any Petzval and wonder why anyone has one, swirl or not. . . but that's MY opinion. A couple of the other Lensbaby lenses are quite nice, IMO.

There's always this one (http://microsites.lomography.com/petzval-lens/). I wonder if in their redesign, the accentuated the swirl.

[Tin Can]

Just way ahead of current scientific thought.

Light has a twist.

http://advances.sciencemag.org/content/2/4/e1501748.full

[Mark Sawyer]

Only by replicating the Petzval swirls for the digital masses can we ensure it will become so commonplace as to be universally nauseating. Why should only the large format artistés suffer, when everyone can? :p

[Rael]

Only by replicating the Petzval swirls for the digital masses can we ensure it will become so commonplace as to be universally nauseating. Why should only the large format artistés suffer, when everyone can? :p

Ha! The first time I saw it, I thought, "Oh Cool! How can I do that?" and the 10th time I saw it I thought, "That makes me motion sick."

[goamules]

Those that don't know, there is another petzval clone just being made that is for large format. Supposedly the lens company analyzed a Dallmeyer 3B. They just shipped some prototypes to testers this week.

[Steven Tribe]

In an old discussion, this was one of the few lenses that was thought economically suitable for a new production line. Perhaps they should have gone for a 4B which is probably more suited for formats which are currently being used? Extra expense would have been marginal and the 3B has already been acquired by the present generation of "players". This cannot be said of the 4B due to very restricted production!

I still think that the RVP would have been a better choice - more useful on lighter built cameras.

[Steven Tribe]

And here, I think, is the "item" mentioned by garrett:

http://eckop.com/historical-reproduction/

I'll post in a more appropriate place later.

[Mark Sawyer]

...Perhaps they should have gone for a 4B which is probably more suited for formats which are currently being used? Extra expense would have been marginal and the 3B has already been acquired by the present generation of "players". This cannot be said of the 4B due to very restricted production!

I still think that the RVP would have been a better choice - more useful on lighter built cameras.

I agree completely about the 4B, or even a 5B, being more appropriate to the larger plates we're doing today. The 3B was really a cabinet card size, and though they draw $2000 today, they're fairly common. (Personally, I'd like a 27B...)

The RVP was just an achromatic doublet, like many, many others. Though each may have had its own signature, whether one particular signature could be faithfully replicated in a reproduction is (I think) dubious. Of course, it remains to be seen how closely the new 3B recreates the signature of the old ones...

[goamules]

I also want to see side by side comparison tests with an authentic 3B. The guy that put the project together has constantly hawked that this new lens "will be the same as a Dallmeyer 3B except the cost!" To me, if it wasn't made by the original manufacturer, (Dallmeyer, or Ferrari, or Rolex, etc.) it's NOT one of those. Just as Darlot and many others in the 1800s made Petzvals, and advertised them "every bit as good as a Dallmeyer", they were not that brand. The new lens is an "Eckhardt Optics" and all the name dropping will not change that. Now, the important thing is how does it perform? Is it as sharp and aberration-free as Dallmeyer? I hope so, because a lot of the current popularity with Petzvals, thanks to Lomo, is the horrible swirl if they are used wrong, or built wrong. Swirl is a serious problem that lens designers always tried to overcome. If you want swirl, you can get a poor lens. If you want sharp, low field curvature, and nice falloff, you get a Dallmeyer, Voigtlander, etc....

[goamules]

On promising sign is that the optical company supposedly reverse engineered a genuine 3B. I would hope that means every part of the glass, from the refractive indices, to the curves, and all. There are other optical companies that have brought back older lens designs. Zenit in Russia has started making the Jupiter 3 35mm lens again, after about 40 year hiatus. http://www.dpreview.com/articles/3384038008/lomography-introduces-jupiter-3-lens

[Steven Tribe]

I am sure that EO is up to the job. The formula is available at:

http://www.dioptrique.info/OBJECTIFS4/00177/00177.HTM

which has corresponding analyses for dozens of classic designs. So he can check his measurements!
The advantage with the early 1866 design is that few types of glass were available from Chance Brothers in England. Just 2 different types of glass were used.

[Tin Can]

I am sure that EO is up to the job. The formula is available at:

http://www.dioptrique.info/OBJECTIFS4/00177/00177.HTM

which has corresponding analyses for dozens of classic designs. So he can check his measurements!
The advantage with the early 1866 desigm is that few types of glass were available from Chance Brothers in England. Just 2 different types of glass were used.

Steven,

Can we assume the early Petzval were hand ground, perhaps using methods like this http://gotgrit.com/coarse1.php/osCsid/20dc67c6a3fb6ef119678b87cb43a949 ?

Your link is very interesting with 'tuning' images and much more.

Some could replicate by hand, just as they make their own telescope lenses and mirrors.

I found it revelatory to watch a video of a man who a Viking Ulfberht (http://www.pbs.org/wgbh/nova/ancient/secrets-viking-sword.html) A lot of work, but he did it and proved it.

[Steven Tribe]

There are photo series around which show production shops at various makers. The basic equipment was a vertical Lathe, like a potter's wheel. Diamond tipped tools were also used for cutting the glass blocks and very experienced staff used tools like old files to do fine roughing through controled "chipping". Fine work was done with fixed glass held with pitch and tools which matched the exact radius required. There was a lot of spitting to keep the abrasive damp!

[Tin Can]

Steven, seems I forgot they had potter wheels, waterwheels and other ways of running machinery.

The DIY telescope grit supplier I linked to, has a lot of advice on making large optical glass, his smallest blanks are 8".

I may never make a lens by hand, but I am starting to know how.

Thank you

[Dan Fromm]

I am sure that EO is up to the job. The formula is available at:

http://www.dioptrique.info/OBJECTIFS4/00177/00177.HTM

which has corresponding analyses for dozens of classic designs. So he can check his measurements!
The advantage with the early 1866 design is that few types of glass were available from Chance Brothers in England. Just 2 different types of glass were used.

Steven, I've never done it but I know several people who've tried to have lenses made from some of the prescriptions that Eric collected. They were all told that the glasses specified in the prescriptions are no longer made and that there are no good substitutes.

[Steven Tribe]

The two glasses used were described by Monckhoven ( 1867, quoted in Lens VM) as:


Crown no. 2 refractive index 1.52; dispersive power 0.04 and
Light Flint no.1 refractiveindex 1.57; dispersive power 0.0473.

These match with the Dioptrique figures.

These were standard products from Chance Brothers, for decades, so perhaps discarded glass could be used as a source?