How to put Bokeh/Character into a vintage brass lens?

[Greg]

I have a Emil Busch Portrait Aplanat 11" No 3 f/6 brass lens that I had mounted in a Copal shutter. Problem is that the optics have proved out to be too sharp and emulate a modern lens. Is there any way to simply modify the lens to give it some vintage character? I've read in a few places that unscrewing the front or rear elements adds vintage character to the lens. Anyone have any experience with that? Or is it worth it to try to substitute either the front or back group of elements from another lens? Would appreciate a direction to go in.

thanks

[IanG]

Interesting question because lens designers from early on were trying to eliminate aberrations

A fast triplet would be an idea fairly wide open, I have 4 or 5 Cooke II triplets the same design as the IIa soft focus lens but without the adjustment which increases the separation. Increasing the separation with a lens like this would have far more effect than with an Rapid Rectilinear. It may be similar with a Tessar.

Ian

[Paul Metcalf]

panty hose.

But what's "vintage character?"

[Steven Tribe]

Your lens was a very succesful aplanat made well into the 20th century. It is known to be very sharp when stopped down.

Perhaps the best solution is use it fully open and adjust the speed using ND filters.
Or you could experiment with the diffusion discs made by Eastman, but later called Kodak discs. A series gives slight effect and the B series is more extreme.

[IanG]

Earlier today I was testing some lenses after my new 1911/12 Dagor arrived a CP Goerx (Berlin) Dopp. Anastigmat Serie III Dagor f6.8 120mm. The tests, just rough and ready using a DSLR are here in a thread about Dogmars. I later did a test shot with a 6" RR and it was similar to the Tessar perhaps a fraction more contrast.

Now my point is that Dagors are or were cult lenses yet here's a lens (uncoated) that performs more like a modern coated/multi coated lens - so it's not really a Vintage lens look. However a Tessar can, have a look at Ken Lee's page on his website, I'd add however that a coated Tessar stopped well down (f22) is not really any different to a modern Plasmat at the same aperture, or a modern Cooke Triplet.

I've seen a lot of original contemporary prints by Kertesz, Brassai, early Doisneau made with uncoated pre-WWII lenses and the images (prints) are fairly small and exquisite but the negatives don't print any where near as well on modern papers because the films were exposed and processed to a much higher contrast and density to counteract the lower contrast lenses but the papers were matched to that.

You say that the Aplamat emulates a modern lens, but the reality is it's of course the other way around historically. When I look at large family photos shot with 12x10 or 15x12 cameras around 1910 I just see quality images. There's nothing to indicate the quality of the lens.

Ian

[Nodda Duma]

Ahhh..a lens design question!

"Character" comprises on-axis effects such as spherical aberration, veiling glare, sphero-chromatism, and coatings. Of these, the simplest to adjust post-design is adjusting the spacing between lenses. So try shimming up one of the outer lenses.

"Bokeh" is what out of focus imagery looks like of course, and I think the type you're talking about has an off-axis component likely due to astigmatism. You can adjust the amount of astigmatism in a lens design (correction of off-axis aberrations) by shifting the stop position. That might not be as easy to do in an assembled lens, but technically move the front lens group closer to the stop and the rear group further or vice versa to adjust correction of astigmatism.

Odd aberrations are also corrected by the (roughly) symmetrical layout of the front and rear groups. So you can remove one or the other to reintroduce the aberrations. Of course the focal length doubles and the f/# halves.

[Mark Sawyer]

But what's "vintage character?"

I think most of us on this forum would qualify as "vintage characters"...

[Greg]

Thanks for all the feedback.

Think I should have been more specific than using the phrase "vintage character".

Let me explain, for me the "vintage" look is the image I get on my 4x5 when I use my brass Darlot Opticien Paris B. F. & Co.lens. Approximately a 7 inch f/3.1 optic with a full set of waterhouse stops. Covers 4x5 but unfortunately by no means my Whole Plate. Have seen a few longer Darlot brass lenses on EBay, but their 4 figure starting bids are too much for my wallet.

Now at least I understand that the Aplanat, being a 4 element symmetrical lens, doesn't lend itself to the simple act of screwing out its front or rear elements. I have used the Aplanat wide open, but the image it produced was just no wheres near that of my Darlot.

Greg

[IanG]

There's plenty of other Petzval lenses around and not all go for high prices, you're paying for a brand name with a Daorlot etc, you need to keep a patient eye on Ebay and other sources.

Ian

[lecarp]

panty hose.

But what's "vintage character?"

Your right, if he wears those while using the lens he will most definitely look like a character.