Looking for Mojo --

[Jack Flesher]

Looking for Mojo -- What are your favorite lenses and why?

Background: A few shooting buddies and I were discussing our preferred lenses and realized that our tastes have migrated from always wanting to use lenses that deliver ultra-crisp resolution to finding some that render the image in a bit more singular fashion. The problem is how to describe a specific lens' signature look -- or its "Mojo" -- without seeing it first-hand.

What I mean by Mojo is some distinct look that belongs to a lens or series of lenses -- in other words, a lens that can deliver a sharp image but also maintains a unique look or signature. Maybe it has great Bokeh or smoother color or delivers better shadow detail than others in its class. One example would be the Cooke 945 "portrait" or soft-focus lens. It is definitely soft-focus wide open, but becomes quite sharp stopped down -- and yet maintains a smoothness throughout that range that is unique. Obviously there are other lenses with their own unique qualities out there too, so hopefully you get the idea.

By contrast, Kerry Thalmann has his excellent list of "classics" and most of these lenses will deliver stunningly detailed images but don't necessarily have any unique character trait. A prime example of one of these ultra-crisp lenses is my Rodenstock 150 APO Sironar S -- it delivers images so sharp you feel like your eyeballs are getting cuts on them when you view a transparency made with it, yet IMO it lacks any specific character trait other than that extreme resolution. Not that ultra-sharp and accurate color is a bad thing, just that it isn't necessarily distinctive...

So whether it is old, new, classic or not, if you have a favorite lens or lenses you feel are distinctive, can you please share what they are and include a brief description of what each unique look is? Also, please be sure to state whether you primarily use it with color, B&W or both.

Thanks in advance!

[Oren Grad]

my Rodenstock 150 APO Sironar S -- it delivers images so sharp you feel like your eyeballs are getting cuts on them when you view a transparency made with it, yet IMO it lacks any specific character trait other than that extreme resolution

The current plasmats do have distinctive characters compared not just to so-called classic lenses but also to each other. The distinction is most readily seen in the OOF rendering, which is quite different among the different brands. Photograph a stand of trees from nearby with the lens set for a middling aperture with each of the current plasmats; the way the trees fuzz out with distance will provide a distinctive "signature" for each one.

[Joseph O'Neil]

Fujinon 105mm CMW. Razor sharp, fairly lieghtwieght, not bad on movements, but I think because there are so few 105mm lenses out there, and because 90mm is a defacto standard in 4x5 use, the 105 fives you a slightly different "look" than the norm.

Byt that I mean, it "feels" like a 90mm when shooting with it, or when doing prints - the print has the "feel" of a 90mm, but not quite, and it's something you cannot exactly put your finger on if you don't know it was a 105mm it was shot with.

Also, i have a very good, used 90mm Angulon, and another bigger 90mm that covers 5x7, but the 105 gives me a much better range of movements than my 90mm Angulon, and is easier to work with, and a lto lighter than my big 90mm I still carry my 90mm Angulon when backpacking, but my 105 gets used the majority of the time when I want something wide angle now.

There's something else i cannot quite put my finger on, but there's a subtle difference between Japanese and German lenses/glass I think. I only shoot B&W, so maybe it shows up more in colour, I dunno. My 105mm I bought used, but frankly it was pretty much brand new when I bought it from Badger. It even "smelled new", so i don't think it was very old, looked like somebody opened the box once, and said "nope".

By comparison, my 135mm Sironar-N I bought new too - i think the last year the made them as a matter of fact (they only sell the 135mm Sironar - S ), is the closest thing I can comapre it too in brand new lenses.

As a very general, broad, and ill-defined statement, comparing these two lenses, all I can say is that the German lenses seem to be "sharper" while the Japanese lenses seem to be "deeper". Does that make any sense, or do I just sound like a guy who been snifffing too much fix in the darkroom lately? :)

so there you go, my "future mojo classic"

Oh yeah, as new lenses go, the 105mm is fairly inexpensive. Never hurts, eh?

joe

[Ralph Barker]

FWIW, Jack, I'm still mostly a "crispy critter" - preferring relatively modern lens designs that provide as much sharpness and coverage as my budget will take. When I'm in a soft mood, I'll use diffusion filters or other things to give the type of softness I want for the specific image. That might be a Zeiss Softar, white net, black net, or even 1/4" bubble wrap rubber-banded over the (otherwise sharp) lens. The results are certainly different than those produced by the old classic soft-focus lenses, but my mojo is on the thrifty side. ;-)

[William Mortensen]

I've actually found myself wishing for uncoated modern lenses; for b/w work, the contrast of a multicoated lense can be a bit harsh compared to the "yumminess" of an uncoated lens where the flare takes a bit of the hard edge off. I recently bought a Caltar II-N 300mm, and found that while it was ultra-mega-turbo-sharp, the tones just don't seem to flow as smoothly. Mind you, I'm used to older optics, and perhaps just haven't adjusted my processing yet...

Personally, I've really enjoyed the old Wollensak Velostigmats, and think they're one of the sleepers in terms of price and, if not raw sharpness, at least having a nice look and feel to them.

[Ben Calwell]

My old Schneider 180mm convertible Symmar has a softness that I like for some images. I call it my N-1 lens. It seems to automatically cut the contrast on some scenes, which is good sometimes.

[Capocheny]

Jack,

You must be talking about "bokeh..."

It's a term that gets used a LOT over on the P.net Leica forum (and generates a LOT of hot and heavy discussions/arguments there! :)] For example, people go on and on about a 35 Summicron version 4 giving the most beautiful bokeh in the world! And, others talk about older Leica lenses giving better bokeh than the newer models. LOL... they really get into a feeding frenzie over there!

So, I'm surmising that you're talking about a lens which gives you sharpness where you want sharpness but gives pleasing softness in those OOF areas? For example, shooting a portrait with a longer lens gives you a nice sharp image of the subject but the background area is out of focus... people on that particular forum argue over whether the OOF areas are a nice, soft rounded shape or that it gives an octagonal, harder shaped OOF area (from the shutter blades of their lenses.) This is what they refer to as the "bokeh" characteristic of a particular lens. Is this what you're talking about? :)

I can't say that I've noticed any specific "soft and pleasing OOF areas" in the lenses I've used... mostly just nice sharp, crispy images from shooting at f16, 22, or smaller. However, it might be interesting to try some shots at f5.6 to see what happens with those OOF areas.

Cheers

[Christopher Perez]

I too have been looking for a bit of "mojo" in various lenses. It's led me to consider ancient vs merely old vs brand new. I feel as if I have uncovered a few potentially "heretical" facts.

This past weekend I took a small stack of 150mm lenses, including a modern multi-coatedplasmat APO wonderoptic, a 30 year old plasmat, and a 70 year old tessar formula lens out of a wee-walk through my neighborhood.

<ul>
<li>For resolution, with the sun over my shoulder, I have to say there is absolutely no difference between the lenses.
<li>For contrast, there's not a whole lot of difference. In fact, the uncoated 70 year old lens is simply awesome in terms of contrast. But then, the Arca Swiss I have has 171mm standards and a very nice "roomy" bellows for light to not bounce around in. And I feel that if there was a broader contrast range, the single and multi-coated lenses would be demonstrably different than the uncoated lens.
<li>For out of focus area rendering there is a difference. The 70 year old and 30 year old lenses are wonderful in the way they treat the out of focus areas. There's a lack of "harshness" that the APOwonderoptic exhibited.
<li>As an experiment, I remounted the APOwonderoptic into an old shutter and Voila!, the out of focus rendering matched the older lenses. The difference? The old shutters have 10 or more aperture blades and the new shutter has only 5.
</ul>

I also hauled out my incredibly contrasty, extremely sharp Schneider 210mm Xenar f/6.1 and a really nice old 21cm Voightlander Heliar f/4.5. Both lenses are single coated.

<ul>
<li>At f/8 and f/11, the Schneider is a visibly better lens when the negatives are viewed at 160x magnification. At 10x, the Schneider looks sharper and contrastier. But the Heliar has this really "sweet" overlay of uncorrected aberrations (at least that's how it appears to me).
<li>For contrast, the Schneider is visibly better than the Heliar at f/8 and f/11. And I know from previous comparisons that my single coated Xenar matches the contrast performance of my multi-coated Nikkor 200 M f/8.
<li>For out of focus area rendering, both lenses are equal at f/8 and f/11. There is a smoothness to both lenses that is just thrilling to look at. However, by f/16 and f/22, the Schneider becomes "harsh". The reason? The aperture shape of the Copal 1 that the Xenar is mounted to is quite round at wider apertures, and becomes rather sharp sided as it stops down.
<li>I remounted the Xenar into a round aperture shutter and, again, Voila!, the Xenar and Heliar match in terms of out of focus renderings all the way down to f/22. Yes, the Heliar comes mounted in a multi-blade apertured shutter that looks nearly perfectly round all the way down through the range of apertures.
</ul>

My heretical conclusions are:

<ul>
<li>The sharpest lens you will ever own is a tripod.
<li>Having a lens is better than not having a lens. That is, lenses are largely equal within their specified image circle.

<li>I have empiric evidence that shows modern lenses mounted in round aperture shutters change the characterists of the out of focus areas to match earlier lenses (both single and uncoated) that typically came mounted in round aperture shutters. There is no "magic" in lens design that changes this fact.
<li>Contrast differences between single and multi-coated optics are not as great as some marketing literature would lead us to believe. In fact, under typical 6 to 1 contrast ratio scenes, I can't tell the difference between them.
<li>With the sun over the shoulder, uncoated lenses can match coated optics contrast. What appears to be more important than lens age and coating (or the lack thereof) is that lens surfaces are clean.
<li>Uncoated lens resolution performance can match coated optics. [see the following exception]
<li>Of all the gear I have ever owned, tested, and used, only the Heliar, Fuji SF, and Rodenstock Imagon or poorly assembled lenses give visibly different images.
</ul>

So where is the "mojo"? I think it's in the shape of the aperture. It can also be in how a lens behaves beyond it's specified field of coverage (see Kerik's wonderful samples of this effect).

[Bill_1856]

Goerz Dagors, 120mm, 150mm, and 210mm, all coated and in post-WW2 shutters.

[darter]

Mr. Perez, I know about the effects of the Fuji and Imagon products, but am very curious what sort of an effect you have gotten with the Heliar design? Thanks.

[Jack Flesher]

Some great comments -- Thanks!

Joseph: I have noticed differences between manufacturers too, but not just specifically between German and Japanese -- even differences from Japanese to Japanese and German to German -- so no, I don't think you're too far into your fix ;)

Mark: "Yumminess" would indeed describe the kind of look I am after! I too have noticed that some older lenses drive more detail into the shadows and these lenses often also generate a light haloing around highlights, especially with B&W. Perhaps it is just a simple matter of less coatings and more residual flare per Ben's comment?

Ben: Thanks!

Henry: I am aware of Bokeh and definitely think it is a factor, but what I am referring to goes beyond how the oof areas get rendered.

Christopher: Interesting observations on aperture shape -- I have heard this reported from others with respects to Bokeh, but not with respect to the less tangible imaging qualities.

Bill: Can you try and describe the "look" those Dagors generate?

[paulr]

"For resolution, with the sun over my shoulder, I have to say there is absolutely no difference between the lenses."

Christopher, I assume you're talking about on-axis performance. Which shouldn't surprise anyone. If you're talking about performance significantly off-axis, I just don't believe you. I realize that what's significantly off-axis for a modern lens often correleates to the edge of the image circle (or beyond) on the old lens ... but this is part of what the newer technology buys you.

At any rate, I wish you'd make it a a habit of making this distinction ... the issue seems to come up every time you report on your tests.

[Christopher Perez]

I know about the effects of the Fuji and Imagon products, but am very curious what sort of an effect you have gotten with the Heliar design?

Between f/4.5 and f/11, my 21cm Heliar isn't as sharp as my other 210mm lenses. The in focus objects are ever so slightly less sharp compared to 210 Xenar images at equivalent apertures. It's not unpleasing, just obvious under 160x magnification. Overlay the Heliar image with something that appears to either be general lower contrast (the quick and easy answer) or uncorrected aberrations of some kind (probably closer to the truth) and you end up with a combined effect of "creaminess", even in the infocus transitions between dark and light.

The Heliar is sharper than either the Imagon or Fuji SF lenses at equivalent apertures. Comparing against Jim Collum's images over on Omniblog, the Heliar looks a little like the Cooke PS optic, except for the fact that the highlights don't "glow" quite like the Cooke. I would be cautious in calling a Heliar the Cheap Man's Cooke, but the effect has certain similarities, up to a point.

I need to use the Heliars more to see how the lenses behave under different lighting conditions. The "mojo" effects might be what I'm looking for. But my Xenar in a nice round aperture'd shutter may, in the end, give me the kind of "mojo" I'm looking for, and give brilliant resolution and contrast.

Ah... these nuances... it's enough to drive a person to Madness. :-)

[Christopher Perez]

I assume you're talking about on-axis performance. Which shouldn't surprise anyone. If you're talking about performance significantly off-axis, I just don't believe you. I realize that what's significantly off-axis for a modern lens often correleates to the edge of the image circle (or beyond) on the old lens ... but this is part of what the newer technology buys you.

I'm talking performance across the company specified field of coverage. Not even just slightly off-axis. I mean all the way to the edge of the 4x5 neg for anything within the specified field of coverage.

I'm sorry, I'm having a really difficult time seeing what "new" technology buys me. I'm not being glib in saying this. And I'm not being a "Luddite" just because it's "cool" or "counter marketing".

Here is a short example. In practical terms, straight on (no rise/fall), a 90 Angulon can be (and in my case is) as sharp at the edge of a 4x5 frame at f/22 as a 110SuperSymmar XL at the same aperture. Of course the SS-XL has much much greater coverage (covers 8x10). Perhaps greater coverage is what you mean by "...what the newer technology buys you..."? Because in terms of resolution and contrast, I just don't see much difference.

If you'd like to come by and personally inspect the images toward the edge of the frame under 160x magnification, I'll even buy you a beer.

I feel the need to add that Rodenstock's Geronar series (three element three group designs) are less than stellar until you reach f/16. My 21cm Heliar at f/5.6 is sharper than the 210Geronar is at f/6.8. So here is an example of "modern" lenses which give less performance than old stuff, even on-axis.

[Frank Petronio]

Jack, just go ahead and buy the (new) Cooke and be done with it. Of course with a scan back you can use all those brass barrel lenses too. It's time to talk to Jim Galli and search the APUG forum for bokeh. Just don't mention that you're using digital anything (not even your fingers) and that you're viewing the website on an analog computer.

[Henry Ambrose]

Christopher,

The important distinction is that for cameras with movements sharpness over the usable area of the image circle is important. So comparing a 90 Angulon straight on and the 110XL straight on is valid only for people who won't use movements. Put two inches of rise on the front standard and the 110 will make a sharp image where the little 90 cuts off. Measuring resolution and contrast over the specified image circles of very different lenses really does tell only part of the story for use on cameras with movements. Of course you know all this already but it is an important distinction to make.

Your tests and reports are valuable and appreciated (really appreciated!) Nothing I wrote above should indicate otherwise.

[paulr]

"Measuring resolution and contrast over the specified image circles of very different lenses really does tell only part of the story for use on cameras with movements."

exactly. same with measuring at one aperture, or at one magnification.

if you do all your work under a close, ideal range of conditions ... say, no movement, f22, subject at infinity, then it's relatively easy to do meaningful tests like this ... for you. but as soon as you start throwing in some real world variables, and variations in working styles, it becomes a lot more complex.

what optical designers have learned over the last 50 years is to get better performance over a larger image circle, a larger range of apertures, and a larger range of magnifications. and the manufacturers have learned to make the things with better consistency, and with better flare resistance.

for an easy example, look online and compare the curves of that Schneider Xenar of yours (sharp, yes, but still a dated design) and compare it to the same focal length Apo Symmar. You'll see that in many situations, the Xenar is just as good. But that in many it isn't.

it's quite possible that none of these improvements are relevent to your work. that doesn't make them irrelevent to everyone.

[Jack Flesher]

Frank: LMAO! Yes, the folks over at APUG can be a bit Draconian at the simple mention of anything digital :)

Re the Cooke and the Betterlight...

I knew I wanted a LF digital solution because I knew I wanted the movements and unique look that LF can deliver. Then having had the opportunity to shoot with Jim Collum and Mike Collette's Cooke, I fell in immediate lust with the look from that lens...

I am not exactly sure which drove the purchase of the other, but shortly thereafter, the stars aligned somewhat and a local BL photographer was making a switch from studio and landscape to people, so he sold me his Super 6K HS to help fund his move to a high-res digital MF back. Then two days later I found a Cooke PS 945 with shutter in stock, thought about it for three days and decided WTH and bought it. That happened just last week and it is scheduled to arrive tomorrow; I may not sleep very well tonight ;)

[John Kasaian]

Just take whatever lens you've got and smear vaseline on it---that'll give 'er mucho mojo ;-)

[Mark Woods]

John,
As much as I like your posts, you're a little off base here. Vaseline is opaque. KY jelly OTH is not. Use the KY and get the full benefits of an out of the box diffusion ;-) (Try it, you'll like it!)

MW

[Frank Petronio]

Not that I know from experience, but isn't there an entire smorgasboard of personal lubricants available? Not to mention the natural alternatives, mucus, spit, and nose oil?

I am not sure, but it seems like the new Cooke would do better with rendering color than most of the older lenses that work so well for B&W. But I am not a lens geek -- I just know that looking at a digital capture at 100% really exposes a lenses flaws so much more than traditional. And what Jack needs for the scan back is an APO that still has that old and beautiful bokeh.

[Henry Ambrose]

hmmm..........

Based on Christopher's ideas it seems like its time for Jack to buy an old shutter for a new lens. Best of both worlds.

[Jack Flesher]

Folks, thanks for the ideas, but FTR:

Over the years I have tried all manor of techniques to try and replicate the singular look of certain old lenses. These involved virtually every available filter from Softars, to diffusion to soft contrast. I tried applying Vaseline, clear nail polish, hair spray, various inks and compounds to UV filters. I sampled various thicknesses and colors of cellophane, gel filter material, white netting, black netting flesh-colored netting, all without and with holes of varying sizes in them.

The end result was that the Softar was the best effect of all of them IMO. BUT it still does NOT match the look from a classic lens. Moreover, as soon as I became proficient with Photoshop, I could quite easily replicate the Softar effect. All modesty aside, I am pretty darn good with Photoshop and cannot accurately replicate the look I see in some older LF lenses.

I even have tried removing cells and changing cell spacing in a variety of lens all to no avail. The Rodenstock Imagon does have a singular look, though it is somewhat harsh relative to the Cooke. Yet both of these lenses produce a generally softer effect than the "mojo" I am referring to above, though the Cooke stopped down to f16 and further is on the money. I think the best word so far has been "Yumminess" -- sharp yet buttery smooth -- that is what I'm looking for ;)

As far as the shape of the aperture, that may in fact have a lot to do with it, but the Cooke and the Rodagon are in the same shutter and they generate very different looks.

[Christopher Perez]

As far as the shape of the aperture, that may in fact have a lot to do with it, but the Cooke and the Rodagon are in the same shutter and they generate very different looks.

I believe this is attributable to lens design. While both lenses (Cooke and Rodenstock) are deliberately designed for "softness" at certain apertures, I think they attempt to achieve it in different ways.

For lenses that are designed to be sharp, aperture appears to provide one of the most influential controls over rendition of out of focus areas. This seems to hold true independent of optical design.

For lenses designed to be soft, it appears to me that optical design overrides, to a larger extent, aperture shape at wide apertures. But even here, there are examples on-web that show the out of focus effects of the shape of the pasta strainer disks that the Imagon uses.

[Christopher Perez]

... look online and compare the curves of that Schneider Xenar of yours (sharp, yes, but still a dated design) and compare it to the same focal length Apo Symmar. You'll see that in many situations, the Xenar is just as good. But that in many it isn't...

Tessars are patent date 1902. Plasmats are patent date 1925 (from http://www.panix.com/~zone/photo/czlens.htm). To me, this means both designs are quite old. This leaves room for improvements in the implementations of both designs.

I am well aware of the MTF charts for tessars and plasmats. In addition, I consider two things:

1) Will I use the vast coverage of a 210mm plasmat on 4x5 (my current format of choice)? My answer is no. The tessar coverage is more than enough for the kinds of work that I do. But if I worked in 5x7 and needed rise/fall image controls, a plasmat would be a better choice.

2) In the real world, many of the design effects we are talking about here are masked by other factors. Film, processing, lighting, and focusing accuracy of a camera system have large influences on the outcome of an image.

Years back when I lived in LA and worked as a B&W print tech on Sunset Blvd (as part of Samy's Camera), I had the opportunity to study St. Ansel's early photograph of Half Dome. We all know the image. It's the one he took with a red filter. Anyone recall the lens he used? Anyone taken a critical look at the edges of St. Ansel's prints of this image? Yes, you see some "pulling" due to being at the edge of the field for the lens he used. But the resolution and contrast is incredible.

So it comes down to: Are we as photographers capable of utilizing our equipment to the fullest design extent possible? Only you can decide.

In the mean time, I'm off to play some more with a few Heliars, old Symmar Convertibles, and modern tessars. The old stuff may give a few hints at that illusive "mojo"... :-)

[robert_4927]

One word answer....Verito.....Three word question.....What is photoshop?....lol....Mojo? Wasn't he a man that thought he was a woman?... oh wait, that was JoJo.

[Jack Flesher]

Christopher: In the mean time, I'm off to play some more with a few Heliars, old Symmar Convertibles, and modern tessars

I'd be really curious to hear more specifics on how the look of the Heliars differ from the convertable Symmars ;)

[paulr]

"Tessars are patent date 1902. Plasmats are patent date 1925"

Christopher, are you suggesting the Apo Symmar is a 1925 design? These are the dates of the first designs that used the Tessar and Plasmat topology. They are not the dates of the current designs implemented in these lenses. As far as I know the Xenar hasn't changed much since 1919 (if it has, it probably hasn't changed in the last several decades). But the current Apo Symmar is a redesign from just a couple of years ago, and the latest in a process of evolution that's been going on every decade or so for a long time. It's a 21st century design that's the descendant of a 1925 design.

If you don't think you can see the difference between a Xenar and an Apo Symmar in the real world, try taking a picture of a building, with plenty of front rise, and then compare the upper corners. The difference won't likely be subtle--assuming the Xenar has the coverage you need at all.

[paulr]

I'm also a bit skeptical of the aperture blades as the only factor in determining bokeh (or character, or mojo ...)

i've just seen too many well-researched and well-illustrated examples of the role of aberrations.

like this one:

http://www.vanwalree.com/optics/bokeh.html

and this one (which demonstrates the effect of aperture shape, along with the effects of aberrations):

http://www.luminous-landscape.com/essays/bokeh.shtml

[Christopher Perez]

Christopher, are you suggesting the Apo Symmar is a 1925 design? These are the dates of the first designs that used the Tessar and Plasmat topology. They are not the dates of the current designs implemented in these lenses. As far as I know the Xenar hasn't changed much since 1919 (if it has, it probably hasn't changed in the last several decades). But the current Apo Symmar is a redesign from just a couple of years ago, and the latest in a process of evolution that's been going on every decade or so for a long time.

I'm arguing this the other way around. Plasmats have been improved over time. So too have Tessars. What I have also tried to point out is that an old lens used within it's coverage area will be a very very usable optic and that there are few reasons to avoid them.

If you don't think you can see the difference between a Xenar and an Apo Symmar in the real world, try taking a picture of a building, with plenty of front rise, and then compare the upper corners. The difference won't likely be subtle--assuming the Xenar has the coverage you need at all.

Wherein lay the nub of your argument vs mine. I have looked at how tessars and plasmats fall off toward the edges of their fields of coverage. They are similar. Of course a tessar has less coverage and it can't be used with as much rise as a plasmat can under identical conditions. There's really no arguing this and I believe we are in agreement.

You need rise that gets your 210mm to the limits of what a plasmat gives. I don't, because it's a heck of a LONG ways up there to reach those limits. In shorter focal lengths, I either accept the limits of what a lens will cover, or I buy a wider coverage optic.

I'm also a bit skeptical of the aperture blades as the only factor in determining bokeh (or character, or mojo ...) i've just seen too many well-researched and well-illustrated examples of the role of aberrations.

I have been talking with a lens designer over dinner. It has been, how shall I say, illuminating.

Aberrations are curious things. In LF lenses we take certain properties for granted. Many of the more popular designs are easy to build and control aberrations fairly well (all things considered). Smaller format lenses (which much of the "bokeh" whoohaa has revolved around and most of the on-line investigations have been devoted to) make certain tradeoffs that make aberration control more difficult. Hence you see more variability that leads to these kinds of discussions.

Within LF work, I believe my comments hold true. Aperture shape controls the rendering of out of focus areas. The exceptions being lenses specifically designed to retain a certain amount of controlled aberration. Of course there will be lenses from any manufacturer that are of poor construction or alignment, and these can pick up undesirable qualities on their way to market.

[robert_4927]

You can go to cameraeccentric.com and read the wollensak catalogs . They refer to their soft focus effect being obtained with lens abberations. I don't recall if they mentioned anything about aperture shape. But it is worth a look just to see the older company catalogs.

[paulr]

"You need rise that gets your 210mm to the limits of what a plasmat gives. I don't"

That's not really the point. I'm talking about what happens when you get anywhere near the image circle of the Xenar.

If you look its MTF chart at f11 and infinity, you'll see that by the time you 80% of the way to the edge of the circle, which is not much displacement of a 4x5 neg, performance is already abysmal. MTF-20 is already at zero; MTF10 tangential lines are at zero, and MTF10 radial lines are at 25% ... barely there. At that same distance from the axis on the apo symmar, you're only 60% of the way to the image circle, and you're still in the flat-response area. Meaning, performance is practically as good as it is on-axis.

This is just one example. If you compare closely you'll find many more. Obviously, if you don't use movements, only photograph at infinity, and at f22, etc. etc. ... none of this will matter. The modern design is for people who want more flexibility than that.

Your conclusions about bokeh in LF lenses still seems to be based mostly on conjecture. It contradict a lot of annecdotal experience as well as the more serious investigations i've seen. You could be right, but I'd want to see some evidence beyond a casual comparison of two lenses to be convinced.

By the way, what are these tradeoffs you see in the small format lenses? LF lenses make huge design tradeoffs to get their big image circles. This is why the new crop of digital lenses is so good. In general, the best small and medium format lenses are better corrected than LF lenses, for this reason.

[paulr]

I just did some math: at f22 at infinity, the top corners of your neg will hit 80% of the image circle ... and the resulting terrible performance ... with less than one inch of front standard rise. at f11 things are much worse.

With the apo symmar, you don't hit the zone of that kind of poor performance until you've raised the lens over three inches.

Not everyone needs all three inches of rise ... but a lot of people would be happy to have more than one inch. especially in any kind of urban situation, where there's going to be more than sky in those top corners.

[Christopher Perez]

That's not really the point. I'm talking about what happens when you get anywhere near the image circle of the Xenar.

As I have already explained, the tessar lenses perform very similarly toward the edges of their fields of coverage as plasmats do.

If you look its MTF chart at f11 and infinity, you'll see that by the time you 80% of the way to the edge of the circle, which is not much displacement of a 4x5 neg, performance is already abysmal.

A 210mm tessar at wide apertures covers between 52 and 57 degrees (depending on who made it and what marketing literature you find). This is at least 230mm's of coverage. This is more than enough room for movement in 4x5 work (which, BTW, only requires 155mm of coverage straight on). Drop off at the edges of the field in some tessars is pretty fierce. But it's not this way in all tessars. Some drop off more gradually. Same holds true for plasmats. It all depends on how the lens was designed and implemented.

The modern design is for people who want more flexibility than [just straight on shooting].

Both Rodenstock and Schneider have recently (over the past two decades) introduced certain implementations of plasmats that increase their coverage. This much is true. The old Symmar Convertibles cover 70 degrees, while the new APO-S or Symmar-L cover 75 degrees. I see this as a potentially useful, but not huge, improvement over earlier implementations. For some reason you don't seem to want to recognize that old lenses can provide more than enough movement that achieves a similar level of flexibility as modern lenses. Perhaps I'm mis-reading you?

Your conclusions about bokeh in LF lenses still seems to be based mostly on conjecture. It contradict a lot of annecdotal experience as well as the more serious investigations i've seen. You could be right, but I'd want to see some evidence beyond a casual comparison of two lenses to be convinced.

For my own education, research, and understanding I am in the process of swapping modern lenses into round apertured shutters. Thus far my results have been absolutely consistant with my statements. This surprises me. I would have thought that out of focus area rendition would be more influenced by optical design or some other factor (such as coatings). But thus far in my investigations it is not.

The lenses I have swapped between shutters include an ever increasing list of fun things. Thus far I have swapped a 150mm Symmar Convertible, 150mm Germinar W f/9, a 150mm Fuji W/EBC, a 300mm APO Germinar f/9, a 300mm Nikkor M f/9, a 210mm Symmar Convertible f/5.6, a 240mm Germinar W f/9, and a 200mm Nikkor M f/8.

Control lenses (ie: those already mounted in round aperture shutters) have thus far included 15cm Kodak Anastigmat f/4.5, 150mm Symmar Convertible, 21cm Voightlander Heliar, 210mm Symmar Convertible.

As I said, thus far my results are absolutely consistent. Frankly, I remain shocked. It seems too easy. It seems like a too simple explanation for something we as humans might want to make more "artistic" or "complex" just because we believe a certain way.

If anyone is interested in this, all they have to do is take their new WonderLens and mount it up in a round apertured shutter. This is quick, easy, and completely verifiable as you can readily inspect the results from the comfort of your own home or business.

By the way, what are these tradeoffs you see in the small format lenses?

Any lens that needs to wrap itself around a flapping mirror runs the risk of being nothing more than a well thought out set of compromises. Many 35mm and 120 format lenses fit this catagory. Though the "best of class" Mamiya 7 lenses have been designed along the lines of the more symmetrical LF designs (plasmat, biogon).

LF lenses make huge design tradeoffs to get their big image circles.

There is nothing inherent in lens design or physics that support this claim.

[William Mortensen]

Regarding the coverage of tessar designs, bear in mind that some tessarscover better than others. The Nikkor 450-M tessar, for example, has rather generous actual coverage, even by plasmat standards.

[paulr]

Christopher, i feel like you're muddying the waters by bringing up all these other tessar designs, etc... i'm just talking about your own example of the 210 xenar and apo symmar. My point is a simple and verifyable one ... you're limited to under an inch of front rise at infinity and f22 with that xenar, before you start seeing dramatic image degradation.

"I see this as a potentially useful, but not huge, improvement over earlier implementations. For some reason you don't seem to want to recognize that old lenses can provide more than enough movement that achieves a similar level of flexibility as modern lenses. Perhaps I'm mis-reading you?"

The old lenses do not offer comparable performance off axis to the new ones. I'm not looking at the size of image circle; I'm looking at the size of the circle that represents excelent performance. Fifty year old tessars and plasmats do not come very close to what modern designs can do.

As far as bokeh, I'm not convinced by your tests is largely because I don't know how you're evaluating your results. There's a lot of subjectivity involved in evaluating bokeh; there are also a lot of objective parameters that influence it, including subject contrast, magnification range, distance in front of/behind plane of focus, and aperture. I don't know what your standards are, or what conditions where used to make the testt images. The sites I've seen that demonstrate spherical aberration analyze the conditions, and they show the results ... in pictures.

"Any lens that needs to wrap itself around a flapping mirror runs the risk of being nothing more than a well thought out set of compromises"

true for wide angle lenses, but not most normal lenses and longer.

""LF lenses make huge design tradeoffs to get their big image circles."

There is nothing inherent in lens design or physics that support this claim.""

the researchers at Schneider would be astonished to hear this. According to them, image circle is the single biggest design compromise in any LF lens design. It's specifically why all the small camera lenses have dramatically higher MTF performance, why the Schneider and Rodenstock digital lenses have dramatically higher MTF performance, and why it's impressive that modern plasmats have been able to get wider without getting softer.

I'm not an optical engineer, but I'd be happy to put you in touch with one of the engineers who educated me on the topic.

[Christopher Perez]

... i'm just talking about your own example of the 210 xenar and apo symmar. My point is a simple and verifyable one ... you're limited to under an inch of front rise at infinity and f22 with that xenar, before you start seeing dramatic image degradation.

Wow! Really? Not in my experience. Not with the 210 Xenar I own. It's not a super lens or a Linhof select or a unique design or anything special. It's just an off the shelf Schneider Xenar f/6.1. That's it.

The old lenses do not offer comparable performance off axis to the new ones. I'm not looking at the size of image circle; I'm looking at the size of the circle that represents excelent performance. Fifty year old tessars and plasmats do not come very close to what modern designs can do.

I have evidence to the contrary. You're free to review my VOE any time you like.

As far as bokeh, I'm not convinced by your tests is largely because I don't know how you're evaluating your results.

I know nothing from "bokeh". I assume, until someone shows me otherwise, that many people equate "bokeh" with what others of us phrase as the rendition of the out of focus areas.

I have read where Cosina/Voightlander thinks that multi-coatings/single coatings influence "bokeh". I have read where other people put other parameters on their definition of "bokeh". I'm sure there are as many definitions and interpretations as there are photographers with brains.

For the record, my test setup and criteria remain simple. My criteria is how lenses render out of focus areas. My references are old lenses that are claimed to be examples of the kinds of effects people describe. My test setup subject matter is around 5 feet away. My VOE are the negs I create as part of the process of comparing lenses.

When I can take a modern multi-coated optic and drop it into a different shutter and get a different result that, in fact, matches the out of focus rendering of reference lenses, well I think I've uncovered something relevent. To confirm what I think I'm seeing, I'm taking the effort entirely at my own expense to try as many different lenses as I can afford. I have nothing to loose, right? Perhaps I have something to gain; a little knowledge.


""LF lenses make huge design tradeoffs to get their big image circles."

There is nothing inherent in lens design or physics that support this claim.""

the researchers at Schneider would be astonished to hear this. According to them, image circle is the single biggest design compromise in any LF lens design.

What tradeoffs did Schneider tell you they needed to make to achieve the coverage they designed to? For the people I have spoken to, it's more along the line of ease of manufacturing traded-off against glass availability traded-off against projected ROI. Nothing really about the physics involved. That's been understood and solved a long time ago. The parameters are well known.

I'm not an optical engineer, but I'd be happy to put you in touch with one of the engineers who educated me on the topic.

Yes. Please do!

I too have been talking with lens designers. It will be very very interesting to compare notes.

[Christopher Perez]

... and all the original poster was enquiring about was where to find a little mojo... :-)

[Jack Flesher]

and all the original poster was enquiring about was where to find a little mojo... :-)

Amen! And BTW, Jim Galli just posted some images with major mojo up a few threads ;)

[paulr]

"When I can take a modern multi-coated optic and drop it into a different shutter and get a different result that, in fact, matches the out of focus rendering of reference lenses, well I think I've uncovered something relevent."

i think that's a fair thing to conclude from your methods.

on the other hand, what you said earlier ... "I have empiric evidence that shows modern lenses mounted in round aperture shutters change the characterists of the out of focus areas to match earlier lenses (both single and uncoated) that typically came mounted in round aperture shutters. There is no "magic" in lens design that changes this fact."

strikes me as overreaching--a broader, more sweeping generalization than i think you can make from the information at hand.

same with this earlier statement: "For resolution, with the sun over my shoulder, I have to say there is absolutely no difference between the lenses."

that one would need a paragraph full of qualifiers to be of general use to people. because there a lot of differences between the lenses in question. you've just found specific circumstances that don't reveal the differences. someone working under other circumstances would have a very different experience.

i'm not trying to give you a hard time, Christopher. But I tend to jump when I see conclusions that fly in the face of both my own experience and established research. especially when they aren't even supported by the evidence cited. for one example, i know (from experience as well as mtf data) that a tessar derrived lens wouldn't work for me doing urban landscapes, but it would probably work fine in the plains or the desert. likewise, my current plasmat might not be enough for someone who specializes in architecture. these qualifications are important.

i'll be happy to put you in touch with one of the technicians i've spoken with. in the mean time, take a look at some typical mtf charts for 35mm lenses, and compare them to the best large format lenses. you'll see that the best of the small camera lenses have an amazing combination of higher speed, lower price, and better optical performance. It's such a glaring set of differences that some people have formed conspiracy theories around it. but the answer is a lot simpler: unconstrained by the need for large image circles, the designers can easily make much sharper lenses. the schneider digitars are a perfect example of this. take a look at the mtf charts, and make sure you notice how much higher the resolutions are that they're graphing. the schneider lenses for rollei 2-1/4 cameras provide another direct comparison.

At photo new york last fall, a technician showed me pictures from a special purpose schneider lens that could resolve over 200 lp/mm at 50% mtf--absolutely unheard of in all previous camera optics. the catch? it was designed to cover, without movements, a digital sensor the size of the fingernail on your pinky. at the other end of the spectrum. lenses that cover ULF measure much worse than ones that cover 4x5. i've heard it posited that with bigger film sizes, the designers don't try as hard ... but this is silly. their constraints are rooted in optics, and to a lesser degree, in economics.

[William Mortensen]

While not completely convinced (or unconvinced) of the full impact of aperture shape, I'd note that, according to Christopher's theory, all lenses would have that lovely bokeh when shot wide open (an inherently circular aperture), which is where many of us would be looking to capture that effect.

And an observation that, especially under the subject line of this thread, many of us work in lf as much for the "mojo" of the large negative or contact print as for the pure numerically-defined resolution.

[William Mortensen]

"Mark: "Yumminess" would indeed describe the kind of look I am after! I too have noticed that some older lenses drive more detail into the shadows and these lenses often also generate a light haloing around highlights, especially with B&W. Perhaps it is just a simple matter of less coatings and more residual flare per Ben's comment?" - Jack Flesher

Jack- I think the flare in uncoated optics just soften the grey tones (not the resolution) so the tones just "flow" from one to another. Modern multicoated optics seem a little choppy in the transitions, though it may just be my processing is a bit harsh. But (btw), my single-coated Acuton/Caltar-S 215mm behaves contrast-wise and mojo-wise almost exactly like my uncoated 210mm Dagor, and has substantially better resolution at the corners of an 8x10, so it ends up being my preferred lens in that focal length.

The halos around the highlights are more likely aberations, which I sometimes hate and other times am quite fond of.

[Struan Gray]

I think Chris is testing lenses fairly conservatively - well within their intended use limits - and that this is why the aperture shape comes to dominate. If you stick to repro ratios and stops where aberrations are fairly well controlled, aperture shape is the only factor left.

In LF it is hard to find the consumer coke bottles that are everywhere in 35 mm and digital. I have a $100 wide-range zoom for my Pentax 35 mm that goes really funky wide open in 'macro' mode, where it becomes a swirly explosion of coma and aperture vignetting. Regular LF lenses don't get made like that, especially if you stick to normal taking distances, so for real mojo you have to go looking for portrait lenses or bottom feeding with budget projector lenses - just to get enough aberrations to get started.

I am not an optical engineer, but I used to be bombarded with trade rags after I once bought some laser optics in an unguarded moment. My impression was that for most 'normal' lens applications the real technical advances have been in production engineering. Good consistent glass blanks, computer-controlled polishing, CNC machining of lens mounts, more reliable cements and potting compounds. 'Better' can easily mean that a lens reaches a typical design spec at a lower price, rather than simply having more lp/mm.

[paulr]

"'Better' can easily mean that a lens reaches a typical design spec at a lower price, rather than simply having more lp/mm."

i think this is part of what's going on.

when i asked an optical engineer about it, his first question was "better how?" ... pointing out that my idea of better, which was more sharpness across the image circle, was just one of many things their customers wanted. among others were things that matter little to me, like higher speed, better performance at high magnifications, and lighter weight--all of which are major design parameters that require compromises to achieve.

he said that they have the technology to improve any and all of these things, but not often at prices the market will bear. the lenses available today represent a very mature technology, and any improvements are already pushing diminishing returns. to make a lens that's 5% sharper off axis, without compromising anything else, might cost five times as much money--an amount no one is likely to pay.

[Paul Coppin]

[from paulr re: Christopher Perez]...
Your conclusions about bokeh in LF lenses still seems to be based mostly on conjecture.
...

Hmm. So? Please define "bokeh". Technical dueling aside, IMO, "bokeh" is as much a personal response as a technical fact. Everybody's "je ne sais quoi" is arguably different. Until you can quantify bokeh, all you can do is hypothesize how its arrived at, and for each photographer, what it is, and how its achieved, is not a constant. A variety of photogs looking at a series of images would not necessarily come to the same conclusions as which photo exhibited the "best" bokeh, tho many may agree on a tight grouping of them. Within that group, there may very well be a variety of technical reasons why its "optimum". You are trying to quantify an intellectual continuum. As a methodology, conjecture likely has as much validity as rigor.

I think the formula you are looking for goes like this: {SUM(Chutzpah)+!MOJO}=bokeh/(n+1) where n+1 equals the number of lenses in your collection, plus the one you wish you had... :)

[Mark Sampson]

It's early morning and before coffee- but this thread begs the question;

"When does mojo become a magic bullet?"

[Phong]

Re: " Your conclusions about bokeh in LF lenses still seems to be based mostly on conjecture. "
[pault responding to Christpther Perez]

In response to Paul Coppin's response to paulr's response above to Christopher's Perez response to the post: :-)

The claim from Christopher with which I disagree here and elsewhere, is that only the shape of the aperture of a lens contributes to _any_ difference in the out of focus area. While arguing "best" is subjective, I would think "difference" is much more obejctive. I don't think paulr is arguing "best".

My claim thru my own rather limited experience - and I am no optical expert - is that different lenses render the out of focus area differently in terms of resolution, contrast, flare control, color rendition, etc. all of which go into the making of bokeh. Whether such bokeh is pleasing or not is not in question. The question is whether there is _any_ difference.

[paulr]

"The question is whether there is _any_ difference."

exactly. i'm not looking for a formula that i don't understand. and i think it's great that Christopher took the time to do these comparisons, and to share the results with us--i'm not questioning that either.

i'm being critical of sweeping generalization that are stated as fact, even though they're based on one person's subjective look at a few samples under limited conditions.

[Phong]

"I think it's great that Christopher took the time to do these comparisons, and to share the results with us--i'm not questioning that either. "

I hasten to join you and add that I too appreciate Christopher's effort very much. If not for anything else, at least it leads me to pay more attention to certain aspects of my own image making. Thank you Christopher, and please carry on with your research.

[Jim Galli]

As a person who makes a living in the highly technical engineering side of photography (yes Virginia, I am a rocket scientist) my heart is 180 degrees out from there. It's the romantic aspect of unquantifiable fuzziness where I'm at my peak enjoyment. Call it a magic bullet if you like. I hope no one is ever successful at defining the exact qualities. It will spoil the fun for at least one hopeless romantic.

Notice: Ebay is broke for me until I figure out how to change my e-mail password. That means you all have a fighting chance at those petzval's for the next couple of days. I can't place a bid!!

[Rob Hale]

Chris and Paulr, thanks, excellent discussion !

Struan Gray

'Better' can easily mean that a lens reaches a typical design spec at a lower price, rather than simply having more lp/mm.

Paulr

when i asked an optical engineer about it, his first question was "better
how?" ... pointing out that my idea of better, which was more sharpness
across the image circle, was just one of many things their customers
wanted. among others were things that matter little to me, like higher
speed, better performance at high magnifications, and lighter weight--all
of which are major design parameters that require compromises to achieve.

OK - I am an optical ignoramus but coming from a Number 8 fence wire mentality where by the assumption is that if some has done it ( build the lens ) it ( the built lens ) can be improved. Some what similar to your road car engine and converting it to a racing engine. The two above statements suggest to me that if I were sufficiently knowledgeable to disassemble, grind, polish or whatever and reassemble a lens with the correct alignments and spacing I could finish up with a lens tailored to my particular needs. Which leads to the question just how difficult would that be ? Does anyone supply a “KIT” of bits - glues – alignment tools – surface shape gauges etc ? OK this might require some time and effort on behalf of the lens owner but if money can’t buy what can be built and you know what you need, then the “ best “ would actually be available ? For the poor like myself, time and work would produce lenses I could not afford. Just how difficult is it to check a lens for correct alignment ?

I hope that this not a completely stupid question ! but it seems to me putting together a kit or kits of different levels of advancement would be far more saleable than putting another camera on the market as suggested in another thread.

Regards

[Jack Flesher]

It's the romantic aspect of unquantifiable fuzziness where I'm at my peak enjoyment. Call it a magic bullet if you like.

That is precisely what I meant by "Mojo" :)

I hope no one is ever successful at defining the exact qualities.

I think many of the comments on this thread are evidence of the fact that is an extremely unlikely event ;)

[Jack Flesher]

PS: I will add that after playing with my new Cooke for only 48 hours, I feel confident in claiming it has some major Mojo ;)

[William Mortensen]

"I hope no one is ever successful at defining the exact qualities. "

flare + (2 x bokeh) / spherical aberation = mojo

I should be a lens designer...

[paulr]

"Which leads to the question just how difficult would that be ? "

Rob, i think it's a great question. but sadly, based on what's been explained to me, it would probably be one of the most dificult things imaginable.

the design part might might not be too bad ... these days, with the software that's available, and with so many specialized lens designs already in existence, it might not be too hard to borrow from some old ones and do a little tweaking. i'd have no idea where to begin, but with some help and some studying you might get somewhere.

fabrication is another story. one of the guys at schneider said that that each surface of each element requires 24 hours of computer-controlled polishing. centering is done on a lathe that's guided by a laser, with everything calibrated to fractions of a micron. all kinds of interferometry is done along the way for quality control, and at the end, final qc is done by specially trained engineers who judge projected test patterns by eye. this is to say nothing of the coating process, and the machining of the barrel and all that. the level of precision is outrageous. all the top lens manufacturers probably do it in more or less the same way.

probably the best bet for a DIY project is to work with a designer and have a lensmaker build it for you. that's what they did at the gigapixel project ... http://www.gigapxl.org/technology-lens.htm (this is an example of someone needing an unusual design ... something with extreme sharpness and coverage, but able to sacrifice speed, size, and weight).

or you could work with someone like schneider who designs custom and semi custom OEM lenses for people all the time ... http://www.schneideroptics.com/oem/custom_solutions/

no matter what, you'd need some deep pockets. i think off the shelf lenses are pricey enough!

or, if you just want to play, you can do what a photographer i knew in rhode island used to do. he'd buy broken lenses and mix and match elements, and see what kinds of trippy results he could get. there was no engineering going on ... just fun. the results looked like toy camera work, but much more out there.

[Don Miller]

I understand the temptation to buy mojo. I'm in the middle of a major lens feeding frenzy. But doesn't killer mojo come from hunting (or stumbling upon) great light?

[Oren Grad]

But doesn't killer mojo come from hunting (or stumbling upon) great light?

Necessary but not sufficient. If the lens ain't simpatico, your epiphany won't survive reduction to silver-on-polyester.

[Rob Hale]

Paulr

Hmmmm. Thanks for your illuminating response. It seems that fine tuning a lens is more Formula 1 than hot rodding a short block Chev.

I can see that the precision required calls for lathes of some substance ( with the attendant costs ) rather than a jig that might be attached to a mono rail camera. It looks like your MTFs curves or Chris and Kerry’s best of breed testing or both are for the present the practical solution.

My optical ignorance retreats one step at a time.

Regards

[Ken Lee]

If it's a Mojo you want, try this link (http://www.luckymojo.com/catalogue.html" target="_blank). They seem to have a fairly good selection.

[William Mortensen]

Regarding aperture shape and a lens' "mojo", apparently, this is not a new theory:

http://www.cameraeccentric.com/html/info/wollensakcata/veritoa.html

[Frank Petronio]

Ha, I'm in Mojo heaven thanks to Galli. The Heliar he sold me is sweet... damn these forums, I used to like Sironars...

[John Kasaian]

Absolutely amazing this thread is still steaming on :-)

First: Vasilene thinly applied is not opaque ---though I can see how water based K-Y would be easier to clean off your lens after you've gotten your fill of mojo.

Second:

Oh well, after meditating on the uses of K-Y I forgot.

[Jon Wilson]

Maybe not "mojo," but an interesting effect with a 12 inch Voightlander & Sohn estimated at f8....Terrick, our "lab/boxer mix," taking it easy again! :)

[Frank Petronio]

Didn't read it all, but my two cents after trying some of the Bokeh kings... Now I simply use a late 150/5.6 Symmar in a modern five-bladed shutter. But I try to use it wide open, with a round aperture, anyime I want to emphasize the out of focus areas of the photo.

Just like I use my 50/1.4 on the dSLR wide open or not at all... at least in flaring situations.

Both lenses are very sharp and I think the intentional sharp parts of my images "pops" more than if I had used some old hazy "portrait" glass.

[russyoung]

Many thanks to Christopher for his detailed and real-world experiments. One of the difficulties of measuring real world lens performance is that unlike most lab testing methodologies, the 'target' is very three dimensional and it matters just how much depth is contained and at what contrast ratio and distance to the target. The possibilities are endless and to be relevant, your tests must reflect your 'typical' application variables.

That said, in slightly diffuse but still directional light (say a 5 stop range) with the light coming from 45 degrees (or less) off axis falling upon a highly dimensional subject, my favorite lenses are:
1. Kodak 305mm Portrait at about f/6 (but this depends on the contrast range)
2. Sigmar 16 inch at about f/5.6

And yes, Dorothy, a fraction of an f/stop can make a tremendous difference when using a lens with noticeable spherical aberration.

I was a beta tester for the Cooke and after roughly 50 sheets of 4x5 and 5x7 B&W under various conditions (studio and landscape) found it fairly unremarkable when compared to most of the c. 1920 soft focus lenses or the regular Heliars.

Russ