I'm a lens designer

[adelorenzo]

I've also been following the thread on APUG but hadn't chimed in. All I have to say is that I'm really interested in the design you have going and would back a kickstarter as long as the price was right.

[Toyon]

I've noticed that soft-focus designs (excepting perhaps the Imagon style lenses) are very popular and hold their value. There is a need for an affordable soft-focus lens in the a 6"-8" range for 4x5 that would offer reasonably wide coverage.

[Toyon]

I've noticed that soft-focus designs (excepting perhaps the Imagon style lenses) are very popular and hold their value. There is a need for an affordable soft-focus lens in the a 6"-8" range for 4x5 that would offer reasonably wide coverage. Please note: the Petzval is not a soft focus lens.

[Will Frostmill]

I saw the thread over on APUG, and I'm delighted you came here.

I have a special interest in a certain kind of lens that is at odds with the traditional 'make everything sharp at the hyper focal distance' theme. I like to do full and half length portraits, fairly wide open in order to render areas behind the plane of focus with low contrast, while simultaneously giving the plane of focus as much acutance as I can. My goal is to provide a clear outline of the high-local-contrast subject, unbroken by blur caused by too-shallow depth of field, against a backdrop of low-local contrast, at normal to mildly wide focal lengths.
For my purposes, dramatic field curvature can be an asset, rather than a liability, provided that I can figure out its three dimensional shape.

There are a bunch of ways to do this, with a bunch of trade offs - high acutance designs seem to get double-line bokeh, late 'soft' lenses seem to make everything glow which makes the contrast between foreground subject and background bokeh blur, high acutance developers sharpen everything which can make light-dark transitions in the bokeh weird, and sometimes I just run out of depth of field before I get the background knocked down to where I want it.

I guess what I'm saying is that I want something 'better' than a late model Tessar?

A pair of lenses for moderate wide (127mm on 4x5) and normal (150mm on 4x5) would be really neat. I also like small formats, and I do think a design that could be scaled down might be really popular with the "let's mount this on a mirrorless and see what we get" crowd.

If you are interested in a challenge, I think a redesign of the Aero-Ektar would be fantastic. They are big, heavy, radioactive, a little long for a normal lens, and seem to transmit light at f/3.5 or slower despite being designed for f2.8. Oh, and they are optimized for near-infinity and IR, so not as sharp as they could be at the plane of focus, while simultaneously blocking a bunch of useful UV for the wet plate folks hoping for a fast normal. Oh, and we love them. Pretty much any lens that dramatically improved on at least two of these characteristics would be really popular. Or, at least exciting to talk about. If you check out the November Portraits thread, I think there is a fine example from within the last few days.

[Mark Sawyer]

I've noticed that soft-focus designs (excepting perhaps the Imagon style lenses) are very popular and hold their value. There is a need for an affordable soft-focus lens in the a 6"-8" range for 4x5 that would offer reasonably wide coverage. Please note: the Petzval is not a soft focus lens.

Petzvals can be a soft focus lens if the element spacing is varied, as with the Dallmeyer Patent Portrait and the Wollensak Vitax. Similarly, the Tessar can be soft focus, as can the Cooke Triplet or Heliar.

Imagons are a classic soft achromatic doublet that don't go for quite as much as other soft lenses simply because they are so common, and perhaps because people are confused by the h-discs, which aren't necessary anyways...

[richardman]

Hi Jason, assuming you want the widest reach of audience, then a 4x5 lens is your best bet - there are just many more 4x5 users than other LF format.

So what's missing in the 4x5 segment? Not sharp lens, we have plenty of that. Not soft focus, we have plenty of that too. Petzval? Lots of choices too. Super-fast? Got that in the 150/2.8 Xenotar and Aero-Ektar, among others.

A modern triple convertible, OTOH, is solely missing. Cooke on their Convertible page says they may consider it but I have emailed them and they do not plan to make one.

Make it in something like 120-180-240, or 150-210-280, or 90-150-240 and I bet you will have a lot of buyers.


So there

[Corran]

Super-fast? Got that in the 150/2.8 Xenotar and Aero-Ektar, among others.

The Xenotar is really rare and expensive, and the Aero Ektar is big, heavy, kind of expensive now, usually isn't in shutter, and has the staining/transmission problem. So I think that area has room for another lens, maybe at f/3.5 or f/4 instead if costs are exorbitant. I wouldn't mind a lens that covers 4x5, that's ~100mm, but that fast.

The other thing about the Xenotar is the large size and Compur #2 shutter. At best, it gets up to 1/125 (that's what mine hits set to 1/200 after a fresh CLA), so if possible, a smaller design that gets in a #1 shutter and can get up to those faster speeds would be quite nice.

[Nodda Duma]

What's great for me is when I get the opportunity to learn something new. I also find differences in jargon between the user world and the designer world amusing but educational. I try to avoid optical engineering jargon for everyone's sake and I will try to warn the reader when I cannot resist and lapse into engineering-speak.

So it's great to learn what's important to photographers. For my photography I love a very sharp very fast lens...it appeals to the design perfectionist in me. My favorite goal is very sharp, very easy to make/assemble, and very cheap. But that's not necessarily important to everyone else.

Bokeh, for instance, is a characteristic that I've never had to consider before but is obviously important in photography. So, as I've looked at these designs I've taught myself how to "tune" when I can the bokeh.

Soft focus = spherical aberration, which is easy enough to adjust in a design (basically I shift each lens and evaluate the resulting spherical...and then when I make a real lens I'll say "move the second group back 2 3/4 turns for great soft focus").

Btw the 165 f/6.3 would be beautiful in and of itself for 4x5.



Please keep the ideas coming...I am making a list.

[Jmarmck]

As and Arkansas native and a lifetime Razorback fan, what is with the Running Razorback?

[Nodda Duma]

As and Arkansas native and a lifetime Razorback fan, what is with the Running Razorback?

Better looking logo than a Razorback standing there with its snout rooting in rotting veggies