Is there interest in a New Rapid Rectilinear lens?

[Nodda Duma]

Electronic shutters are not uncommon in my industry. The question wouldn't be having to design them from scratch, but adopting existing electronic shutters for the timing. Then also adopting to something like Bluetooth for interfacing with a smart phone.... Which without looking I think off the shelf electronic shutters are comparable in cost to the copal shutters....

Bluetooth circuits themselves are not a significant cost driver.




Another approach would just to have a simple trigger circuit that runs off Bluetooth. that I think is trivial

 

[Dan Fromm]

There are Dagors that fit that description. I have an 8.25" f:6.8 in an Ilex 3 shutter, and I've seen a 180mm.

David, apropos of 180/6.8 Dagors that cover 8x10, please review: http://www.largeformatphotography.info/forum/showthread.php?13109-Lousy-Dagor

 

[Dan Fromm]

I'd quite like a new multicoated lens that doesn't have the dagor tax on it...

Lachlan, Dagors and Aldis Unos are the two anastigmats that would benefit least from multicoating. Each has only four air-glass interfaces.

If you want Dagor types that don't have the Dagor cachet and price, look into Boyer Beryls and f/6.8 Berthiot Eurygraphes.

 

[Dan Fromm]

Shutters are an interesting problem. AFAIK no one is making mechanically timed leaf shutters. All we have in that line is new old stock, if any remain, and used. But Melles Griot is still making Ilex electric shutters and there are very pricey ones from, e.g., Rollei or Schneider. Schneider still offers lenses in Copals but AFAIK Copal has stopped shutter production.

 

[Nodda Duma]

Approximate layout (maybe two optimization runs back) for an f/6.3 system. Total mass of glass is at 205 grams. Note the (not quite) symmetry corrects odd aberrations (distortion, coma, lateral color) perfectly.

Sorry about image of computer screen. Was working it on a computer w/o Internet access.

 

[Lachlan Young]

Lachlan, Dagors and Aldis Unos are the two anastigmats that would benefit least from multicoating. Each has only four air-glass interfaces.

If you want Dagor types that don't have the Dagor cachet and price, look into Boyer Beryls and f/6.8 Berthiot Eurygraphes.

Dan,

The simple answer is that I'd like a new lens that simply works - I could get a 190mm WF Ektar, but they're getting on a bit and the shutter is massive with a top speed of 1/50. I've been aware of both the Eurygraph and the Beryl for a while - your article on galerie-photo about Boyer is very useful. However, I'm not desperate to take a gamble on a Beryl that may be of indeterminate age/ QC/ coating/ shutter threading - further to this, I've never been lucky enough to find one in an FL that I wanted & in a shutter - a case of either/ or!

Cheers,

Lachlan

 

[Dan Fromm]

Front mounting, Lachlan. If the shutter is close to the rear of the lens mechanical vignetting won't be quite as terrible as you fear.

The only cure for fear of buying a really crappy old lens is to buy only when pictures of the lens are very promising. As you probably know I've bought a heap of Boyer lenses. Only one in poor condition so far. The picture of it in the listing on Marktplaats wasn't good. Shame on me.

Cheers,

Dan

 

[TheToadMen]

I saw this info about an interesting lens today:Wollensak Velostigmat Series II f/4.5

[TD="colspan: 1"]Along with the Verito in 1911, Wollensak introduced the Velostigmat Series II lens with a speed of f/4.5. This lens was marketed as a "high speed Anastigmat." It was produced in sizes with coverages ranging from 3.25x4.25 inch to 11x14 inch, with a diffusion feature on the three largest sized lenses (6.5x8.5, 8x10, 11x14). The user was able to twist the front part of the barrel causing the front element to move out of position to add diffusion. There is a scale marked with 5 settings on the front barrel edge to denote the various diffusion amounts. This feature allowed Wollensak to market this lens as a sharp general purpose lens that also allowed diffusion to be added at any f stop. This differed from the Verito where the aperture selected determined the amount of diffusion. The August 1911 issue of Camera Craft Magazine wrote, "The Wollensak Optical Company had a most complete exhibit of photographic lenses and shutters in their booth at the St. Paul Convention. The line included several new and interesting lenses and shutters. The Series II Velostigmat, F-4.5, recently perfected, is a remarkable lens, having all the good qualities of an Anastigmat. The three larger sizes are equipped with an ingenious device whereby the operator is enabled to obtain any degree of softness or diffusion he may desire. As this lens has a field that is absolutely flat, any diffusion introduced by means of the diffusing device will result in an equal diffusion or softness over the entire plate. This diffusion is by no means what is termed "fuzzy" and no ghosts, or double outlines result, as is the case with some lenses intended for soft focus." By 1911, Wollensak was able to offer photographers the Vitax, Verito, and Velostigmat Series II lenses, all with distinct purposes and with various types of diffusion methods, and as such, the three lenses were frequently advertised together.[/TD]

(source: Dead Link Removed)

I would like a lens like this as well. A 12" lens did cover 8x10" and a 15 1/2" lens did cover 11x14".
See also: Dead Link Removed

 

[Dan Fromm]

I saw this info about an interesting lens today:Wollensak Velostigmat Series II f/4.5


(source: Dead Link Removed)

I would like a lens like this as well. A 12" lens did cover 8x10" and a 15 1/2" lens did cover 11x14".
See also: Dead Link Removed

Bert, can you spell Tessar? That's what it is.

 

[TheToadMen]

Bert, can you spell Tessar? That's what it is.

T - E - S - S - A - R ?

And does a Tessar also this?
"The user was able to twist the front part of the barrel causing the front element to move out of position to add diffusion. "

 

[Nodda Duma]

Moving the front element of a Tessar by a small amount will have an impact on spherical aberration... Which I am assuming "diffusion" = soft focus = spherical aberration.

 

[Dan Fromm]

Bert, please see http://www.largeformatphotography.i...p?57385-Velostigmat-Series-II-Info-and-Images

 

[LJH]

Moving the front element of a Tessar by a small amount will have an impact on spherical aberration... Which I am assuming "diffusion" = soft focus = spherical aberration.

That's my (limited) understanding.

 

[AgX]

Moving the front element of a Tessar by a small amount will have an impact on spherical aberration... Which I am assuming "diffusion" = soft focus = spherical aberration.

In first instance it would change focus. Thus to employ front lens movement for introducing aberrations one has to re-focus the whole assembly to keep the focusing range.

(Though for many application the focus range is fixed. One thus could design a front-element-only focusing lens that way that for best focus the front lens is in a otherwise undesirable position.)

 

[Nodda Duma]

Yes it would change focus. If you (as the barrel designer) were ambitious, you could characterize the focus shift and compensate with a cam.... Sort of like is done with the compensator group of a zoom lens.

 

[Dr Croubie]

Or, given that this is LF we're talking about, move the front element in/out to your desired level of softness, then focus by moving the standards as per normal (as long as you don't make it so soft that you can't see well enough to focus it).

 

[LJH]

Or, given that this is LF we're talking about, move the front element in/out to your desired level of softness, then focus by moving the standards as per normal (as long as you don't make it so soft that you can't see well enough to focus it).

That's how I roll with my 2 Veritos.

 

[TheToadMen]

Bert, please see http://www.largeformatphotography.i...p?57385-Velostigmat-Series-II-Info-and-Images

This article, that Dan mentioned, explains how the diffusion ring works:

The adjustable diffusion is one of the more interesting features of the Velostigmat Series II, and one that sets it apart from the many other Tessar lenses available. The adjustment was a rotating front ring that allowed the front element to be unscrewed one rotation, giving it slightly more distance from the other elements. There is some confusion as to how it should be used, but the 1916 Wollensak Lenses and Shutters Catalog explains:

“The amount of diffusion is variable at will and so places in the hands of anyone artistically inclined, a powerful means of expressing their individuality. It is by no means difficult to manipulate this attachment, by turning the front mount around to the marks 1, 2, 3, 4, or 5, as desired, then focus. When the indicator is set at 0, the lens is ready for general work, producing negatives with snap and life; set at 1, you have a slight diffusion, at 2, a greater degree of diffusion, and so on, the higher the number, the greater the diffusion.”

In actual use, very little diffusion is evident, even at setting 5. This has led some to try focusing at the 0 (sharp) setting, then dialing in the softness. The rotation, however, causes the focal length to shorten slightly, so the focus-then-adjust method results in an out-of-focus rather than soft-focus image. But the Wollensak catalog makes it clear, set the diffusion, then focus. So what is the “artistically inclined” photographer to do?

There is a “cheat” possible that allows one to adjust the diffusion far past the factory limited setting of 5, to a setting that would be (by counting the rotations) of 40 or so. At that setting, the Velostigmat Series II has an obvious and (at least in my eyes) lovely soft-focus signature. (...)

 

[Nodda Duma]

Update:

I'm exploring the design space just a little. It is 165mm f/6.3 corrected for an 8" x 10" film format. It can be used with a Copal 1 shutter. I am now sitting at 200g of glass in a 8 lens / 6 group configuration. It has settled into a variant of the Super Angulon configuration (not surprisingly), but not a true Angulon. Basically 4 singlets and 2 doublets where the S.A. includes cemented triplets (in your jargon, a 3 element cemented group...I've always avoided these due to cost). Size? The OD will be about 65 mm diameter, or roughly 2 1/2" and the total length when assembled onto the Copal 1 will be perhaps 3". Back focus is 134 mm, or about 5 1/4".

The performance is very good. Even wide open you can focus so that the central maybe 5-10 degrees is very sharp....although I would focus at about 50% out. This will provide a subtly soft focus. Corner softens just a bit more but (hopefully) not displeasingly so. This is due to residual field curvature. Light rolls off as you'd expect for such steep incident angles at the film plane. I had to vignette just a bit to get it in the Copal 1. So wide open you'll see about a 2 1/3 stop loss at the corners. Stop down the lens one click and it is no longer vignetted, and you lose only about 1 1/3 stop at the corner (check my math... illumination is 40% at the corner what it is at center). The roll-off is gradual even wide-open.

Stop down the lens to f/8 or even better f/16 and it really sharpens up. At f/22 it is just about diffraction-limited over 75% of the film area. At f/32 it is diffraction-limited in all but the very corners. There is very little focus shift (at least where I set focus for optimization)...maybe 10 microns from f/6.3 to f/32?

I have not corrected out beyond about 80 degrees, but it should illuminate far enough out to accommodate some reasonable amount of the lens shifting that you large format guys like to do. Perhaps I will leave that unexplored and just let you find out with the real lens

I'll use multi-layer coatings to avoid ghosting and keep the throughput up. I'll be looking at ghosting since there's a couple of elements where the ray angles off the glass surface are close to perpendicular. That's usually the surfaces I have to watch. I'm not too concerned...just one of the many details to look at in a lens design.

Cost? I used cost as a constraint on glass type selection during optimization, so the actual glass-cost is lower than it would have been if I used high-index, low-dispersion glasses. Honestly I didn't really need them. Without having yet quoted parts, it'll be lower definitely than, say, a new Schneider S.A. even if the total quantity sold were to be only 100. Should be significantly so.... but I do not want to speculate further. I am generating drawings to send out for quotes so that I can look at the cost curve (per unit cost vs. production run quantity).



I saw an opportunity to replace the doublets with singlets and sacrifice just a bit of performance to reduce cost / weight further. That variant sits at 165g of glass and lags the performance of the lens described above by about a stop (ie how it sharpens as you reduce the aperture). Even wide open it is pretty good.


The next step will be tolerance analysis (to verify that production run lenses can be assembled inexpensively and maintain performance). I expect tolerances to be loose but we'll see. I also need to generate a solid model of the lenses and send to my mechanical engineer friend for him to design the barrel. He has worked in the industry as long as I have...this will be a simple problem for him.

Zemax has the ability to simulate how the lens actually images. It uses an image file as the subject (typically some kind of pattern meaningful to an optical engineer or a very well-corrected test photo) and generates the image as you'd see at the film plane at whatever resolution I care to set. I'm trying to find a high enough resolution picture as the "subject" so that I can provide a good demonstration of what the lens will be able to do. But... the kids are awake now so that will have to wait until tonight.

I'm also going to see what just the front or back groups will do by themselves.

Oh... and of course there is no distortion (corrected by symmetry), and no uncorrected color. It is a good lens. The layout looks really good.

And yeah.. pretty soon I will cross-post to the large format forum.

-Jason

 

[StoneNYC]

So I've read this entire thread every single post, and although this does sound like a neat idea I'm going to throw my hat in and my own perspective.

There are tons of heavier lenses available in 8 x 10 for almost all focal lengths.

What there aren't a lot of is light weight lenses that cover 8x10 with the generous movement in this focal lengths.

My kit consist of the Fujinon 300 C, Fujinon 450 C, and hopefully someday, a fujinon 600 C.

I've always said that I wished that Fuji had also made a 200 C lens, and a 720 C and 900 C

I don't really like 210, I prefer 200, I know it seems like such a small difference but that extra little bit of coverage really seems to make a difference in my images, with 4x5 I love the 90 mm, and as far as I understand it 200 is much closer to that four 8x10.

Anyway, people often say to me that it's not possible to do for some reason, I'm not sure exactly because I don't design elements and I don't understand, all I know is that having more availability for ultra lightweight very sharp lenses that have large coverage areas is where it's at for me, I hike everywhere and I'm not wanting to take along heavy lenses.

I did recently pick up a particularly interesting lens called a Graphic-Kowa 210 f/9, what's interesting about it is that I'm told that this is an "earlier design" which had a coverage for 11x14 with a tiny bit of wiggle room, whereas the later generations of this same lens were all only 8x10 coverage.

If this is true, the design already exists for a 210mm that covers 11x14 with movements, that could possibly be improved with modern technology.

Now I have purchased the lens and have it in my kit, and have shot a few 8x10 images with it, but I do not have access yet to an 11x14 camera to truly test the theory of the seller that it should cover 11x14 because of some kind of lens element reflection number.

I'm sort of off on a tangent but basically what I'm saying is that it would be really lovely if something like this design which certainly is light, it's almost lighter than my fujinon 300 C, could be made.

And again on the longer end of things, for one there aren't that many 600 C lenses available these days, and not cheap, and anything longer and it seems they are mostly telephoto designs that are heavy and bulky...

I feel that 720 is probably a much better focal length than 600 but probably harder to design which is why fuji stuck to 600, and also 900 would be grand in a "compact" design.

On the point of shutters, I agree that having many more aperture blades it would be a lot more pleasing, I've grown very frustrated with the choppy background light blur that I get with modern aperture blades, however unfortunately I also prefer a modern shutter that is reliable and doesn't break if you do the procedure in the wrong order, so I stick to copal.

The problem is that copal stopped making their shutters except for the copal-0 so new copal 1's and copal 3's aren't really attainable in large scale.

finally besides the fact that I would really love to see the new shutter that is accurate, but also has many more blades to give a perfectly round aperture hole, I disagree entirely that it should be electronic, one of the reasons that I started shooting large-format in the first place was to get away from battery reliance, I was constantly having issues where I was shooting long exposures at night in cold weather and the battery would suddenly die. I don't want an electronic shutter I want to manual mechanical shutter. I would not mind however an attachment that would trigger the mechanical shutter by way of a Bluetooth interface with my phone, however someone is actually already working on this and it might behove you to partner up with that person, I'm sure someone here can add a link to that post as I believe they are on the large-format forum.

Also would you please give us a link to your thread there so we can follow it there as well?

So what do you think? Is it possible to make ultra light but wide coverage contact lenses that are also ultra sharp in those extreme formats?

 

[Nodda Duma]

I'm sure it's entirely possible. I'll add it to the list.


One thing I have to ask is that you define "lightweight".


For me at work, that means a few ounces. For the 165 mm It's looking to be less than a pound total. For someone else it may be 5 lbs. So feed the designer numbers . Realistic numbers of course.


And yes I will cross-link. Hoping to start that thread tonight.

 

[Dan Fromm]

So what do you think? Is it possible to make ultra light but wide coverage contact lenses that are also ultra sharp in those extreme formats?

It has been done. Go here: http://cnum.cnam.fr/CGI/redir.cgi?M11121 , click on Exports, click on PDF, go to p. 43. For another example, http://books.google.com/books?id=cnkWAAAAYAAJ&dq=zeiss+unar&source=gbs_navlinks_s Click on the little starry wheel in the upper right corner of the screen to download as a PDF. See pp. 68-9 Page numbers refer to pages in the PDFs, not to page numbers in the documents themselves.

Quite long focal lengths are cataloged. How many of them were made is an interesting question. Used long ones come to market rarely and command high prices.

I'm puzzled by what contact lens means in this context. Did you mean compact?

And what exactly do you mean by ultrasharp? I ask because discussions with ULFers about what coverage means makes it clear that many, not all, of them contact print. Contact printing demands less sharp negatives than enlargement does.

 

[StoneNYC]

It has been done. Go here: http://cnum.cnam.fr/CGI/redir.cgi?M11121 , click on Exports, click on PDF, go to p. 43. For another example, http://books.google.com/books?id=cnkWAAAAYAAJ&dq=zeiss+unar&source=gbs_navlinks_s Click on the little starry wheel in the upper right corner of the screen to download as a PDF. See pp. 68-9 Page numbers refer to pages in the PDFs, not to page numbers in the documents themselves.

Quite long focal lengths are cataloged. How many of them were made is an interesting question. Used long ones come to market rarely and command high prices.

I'm puzzled by what contact lens means in this context. Did you mean compact?

And what exactly do you mean by ultrasharp? I ask because discussions with ULFers about what coverage means makes it clear that many, not all, of them contact print. Contact printing demands less sharp negatives than enlargement does.

Sorry, yes, that means Compact, not contact...

I understand that many of them contact Sprint and sharpness is not as valuable, but still if you're using one lens for multiple formats for example, I may use that "900mm C" lens on my 8x10 with a 4x5 reducing back (as an example only) shooting .... I don't know the moon or Empire State Building from Brooklyn. I might also want to use that to make a 16x20 image on a 16x20 camera of a landscape, or even the entire city skyline, but wall enlarge it for a mural. The edges also need to be sharp, as does the center for the greater enlarging of 4x5.

One such photographer that recently has been looking for something similar to the 550mm (something) hard to find lens that covers 16x20 but wants ultra sharp edges personally for his work is Dan (Kodachrome) and is just one example of a photographer who is unhappy with anything that is actually attainable and available at a reasonable price for ULF images.

 

[StoneNYC]

I'm sure it's entirely possible. I'll add it to the list.


One thing I have to ask is that you define "lightweight".


For me at work, that means a few ounces. For the 165 mm It's looking to be less than a pound total. For someone else it may be 5 lbs. So feed the designer numbers . Realistic numbers of course.


And yes I will cross-link. Hoping to start that thread tonight.

I consider light to be like the stats for the aforementioned 300 C and 450 C

Under a lb for wider FL's and maybe slightly over for the big long FL's but not 5lbs!! Yeeash!

EDIT: please note also that these lenses are APO corrected even though they don't have that in the name, so they are excellent for color transparency photography as well as infrared photography.

 

[E. von Hoegh]

Sorry, yes, that means Compact, not contact...

I understand that many of them contact Sprint and sharpness is not as valuable, but still if you're using one lens for multiple formats for example, I may use that "900mm C" lens on my 8x10 with a 4x5 reducing back (as an example only) shooting .... I don't know the moon or Empire State Building from Brooklyn. I might also want to use that to make a 16x20 image on a 16x20 camera of a landscape, or even the entire city skyline, but wall enlarge it for a mural. The edges also need to be sharp, as does the center for the greater enlarging of 4x5.

One such photographer that recently has been looking for something similar to the 550mm (something) hard to find lens that covers 16x20 but wants ultra sharp edges personally for his work is Dan (Kodachrome) and is just one example of a photographer who is unhappy with anything that is actually attainable and available at a reasonable price for ULF images.

I think your autocomplete/correct needs to be quarantined.

Anyway, small/sharp/wide coverage adds up to... very slow lenses. The reading glasses/no dark cloth crowd don't like this. Slow wides can be a pain, unless you use Fresnel screen the corners get hard to see even with an angled loupe.