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View Full Version : Which 300mm Dagor for 12x20?



coriana6jp
01-17-2010, 07:22 PM
Inspired by the dagor thread, I remember reading somewhere(probably the LF forum) that some 300mm dagors will cover 12x20. The only problem is I have no clue as to which ones are up to the task. If anybody has any hints that would be great!

Thanks.

Gary

Oren Grad
01-17-2010, 08:03 PM
While we wait for the Dagor experts to arrive, here's a hint: older. Much older.

JLP
01-17-2010, 08:41 PM
As Oren said, i have a 300mm Gold Ring Dagor which will not even be close to cover 12x20. My favorite for 8x10

coriana6jp
01-17-2010, 09:28 PM
Oren & Jan,

Thanks, I had suspected it would be the older dagors that covered. I had read the Gold Ring/Dot Dagors had alot less coverage than their older counter parts. That is a shame really, my favorite 8x10 lens is my 14 inch Gold Dot Kern Dagor.....I really wish it would cover 12x20.

Gary

sanking
01-17-2010, 09:29 PM
While we wait for the Dagor experts to arrive, here's a hint: older. Much older.

Depending on when and how they were manufactured Dagors of the same focal length vary quite a bit in coverage. I have seen 14" and 16.5" Dagors that would not cover 12X20, but I once owned a very old one that threw a circle of illumination large enough for 12X20, but of course I had to stop down to f/64 to get decent performance on the corners, and even that was not all that good. The serial number of the 12" Dagor that I had that covered 12X20 suggested that it was made in the 1920s so Oren is right in that you should think older rather than newer.



Sandy King

Brickbird
01-21-2010, 01:35 PM
Gary....You might want to get one of my Fuji 300 lenses that I finally got mounted in a Copal 3 by Grimes. It does not quite cover the corners wide open but the coverage is mighty. You would end up with about a contact 11x19 which is still nice. They are all in barrel. Just mount in a board and use the cap. It is a fixed f8 so you could go from there with exposure. Let me know if you are interested........................Tav

Michael Kadillak
02-05-2010, 11:27 PM
At one point or another we all have a tendency to get inspired by Mr. Dagor.

When we finally locate one and put it to use we quickly find an excuse to sell it to someone that is a bit behind us in the "dagor mystique" curve. I have seen the cycle repeat itself regularly.

When I was recently working on a lens project with an optical physicist and mentioned the Dagor he looked back at me like he had just bitten into a lemon. "Surely we can do much better than that," he commented. He showed me the curves and pointed out the deficiencies of the design and we moved on. The project was doomed when we got to the materials cost but I got a real taste about what technological advancements in optical glass and computerized design programs have done to dramatically improve the process of lens design. Bottom line from my point of view - there are many other alternatives that are much less costly and perform much better.

Cheers!

sanking
02-06-2010, 07:24 AM
Michael,

I have sold off most of my Dagor type lenses so mostly agree with your comments. Modern plasmat type lenses are sharper at large apertures than Dagors, and probably have better coating.

However, the design itself did not reach the end of the line in the 1970s with the multi-coated Kern dagors, which are some of the most contrasty lenses ever made. The fairly recent Schneider 550mm XXL Fine Art lens is in fact a true Dagor design which takes advantage of new glasses and computer design. So with all the background of lens design Schneider chose a Dagor type design as the one that best delivered the specific image qualities they thought important in a lens of this type.

Sandy King

Greg Davis
02-06-2010, 08:01 AM
Sandy, does this make the XXL Fine Art lenses convertible?

sanking
02-06-2010, 08:44 AM
Sandy, does this make the XXL Fine Art lenses convertible?

It is convertible of course, but how good it is converted I really don't know. In the early days all Dagors were sold as convertible lenses even though the single elements were not fully corrected. They were ok for portrait use but did not produce sharp landscapes. I once had an old 19" Dagor and use it in convertible mode. It had a lot of chromatic aberrations and was not really useful unless you use amn orange filter to block most of the red light.

Sandy King

Michael Kadillak
02-07-2010, 10:50 AM
Michael,

I have sold off most of my Dagor type lenses so mostly agree with your comments. Modern plasmat type lenses are sharper at large apertures than Dagors, and probably have better coating.

However, the design itself did not reach the end of the line in the 1970s with the multi-coated Kern dagors, which are some of the most contrasty lenses ever made. The fairly recent Schneider 550mm XXL Fine Art lens is in fact a true Dagor design which takes advantage of new glasses and computer design. So with all the background of lens design Schneider chose a Dagor type design as the one that best delivered the specific image qualities they thought important in a lens of this type.

Sandy King

You are spot on Sandy. The ability of Schneider to access the wide range of optical glass and modern coatings melded well with the known ability of the Dagor to to produce a very large and highly desirable image circle for the class of customers these Fine Art Lenses were targeted for - ULF photographers. Schneider was also able to excise most of the undesirable components of this lens in the design as it sounds based upon your observations, that it is a marvelous optic to have in the field. Clearly the price to accomplish this package is a bit steep compared to the used market for Artars and others, but after I learned how financially challenging it is to bring a simple Artar type optic into the ULF market, the price now seems very reasonable for what is being delivered. Coming up with the money for it is a whole other matter.

One of these days I hope to own a 550 XXL. But in the meantime I need to close some more deals in my business and then find one for sale. Eventually I found my 30" Red Dot and 305 Computar based upon your recommendations and am pleased with their performance.

Cheers!

Steve Hamley
02-07-2010, 03:53 PM
At one point or another we all have a tendency to get inspired by Mr. Dagor.

...

When I was recently working on a lens project with an optical physicist and mentioned the Dagor he looked back at me like he had just bitten into a lemon. "Surely we can do much better than that," he commented. He showed me the curves and pointed out the deficiencies of the design and we moved on. .. - there are many other alternatives that are much less costly and perform much better.

Cheers!

I'd have to add that Michael's optical physicist is ... sort of right. That's the problem when dealing with physicists and engineers, you only get a technical opinion. I feel safe saying that since I do have a degree in physics.

So let's have the optical physicist tackle all the criteria for which the Dagor is desirable, and not just the optimum optical performance. Here's what I'd ask the optical engineer to design:

It has to have the the same, or better, circle of illumination to 5 lpm (coverage) as the Dagor

It has to have the same, or better, circle of sharp coverage as the Dagor

It can't weigh any more than the Dagor

It can't cost any more than the comparable plasmat that replaced it.

I'd be interested if such a lens is possible. And it might very well be possible. I've always maintained that if Schneider made the Super Symmar XL series at f:6.8 to f:11 in more focal lengths (like the Dagor), there wouldn't be any discussion at all about Dagors, they'd all be sold.

Cheers, Steve

Michael Kadillak
02-09-2010, 05:08 PM
I'd have to add that Michael's optical physicist is ... sort of right. That's the problem when dealing with physicists and engineers, you only get a technical opinion. I feel safe saying that since I do have a degree in physics.

So let's have the optical physicist tackle all the criteria for which the Dagor is desirable, and not just the optimum optical performance. Here's what I'd ask the optical engineer to design:

It has to have the the same, or better, circle of illumination to 5 lpm (coverage) as the Dagor

It has to have the same, or better, circle of sharp coverage as the Dagor

It can't weigh any more than the Dagor

It can't cost any more than the comparable plasmat that replaced it.

I'd be interested if such a lens is possible. And it might very well be possible. I've always maintained that if Schneider made the Super Symmar XL series at f:6.8 to f:11 in more focal lengths (like the Dagor), there wouldn't be any discussion at all about Dagors, they'd all be sold.

Cheers, Steve

I asked precisely the same questions that you posed Steve to my lens design expert a while back. You can get to these criteria with a lens design program and then you come full circle to the realities of this situation. Because of fixed set up costs and volume purchasing requirements necessary to obtain decent pricing you need to be able to sell hundreds of these lenses to attain an affordable price point inclusive of your margin for the average LF/ULF photographer. If you get realistic about the number that you can sell (or your project risk tolerance) which is a far lower number you find that the need to make sure that it is truly an exceptional optic that you produce because your sales price needs to increase due to the smaller lot produced. Then at some point you realize that the market for these products is only so big and already seasoned with old Artars. Ronars, Dagors, Protars and a wide range of other repro lenses that find their way to the lensboard of a LF/ULF camera. Add a poor economy to the mix and it becomes even more unlikely that it could be done. I agree with you about the Super Symmar lens series. Lets start a petition for Schneider to do this?

Cheers!

Steve Hamley
02-10-2010, 09:13 AM
Michael,

I'd love to get Schneider's opinion/input. I think they're aware of such issues as evidenced by the 350mm Apo Tele-Xenar, which fills a "hole" in the lightweight 4x5 lens lineup at that focal length.

As you noted, simply producing new Dagors is probably not desirable because they'd be competing against a huge used market and the Goerz brand. And a f:6.8 - f:8 - f:11 SS XL series might not need much in the way of re-engineering or setup, since the basic design would seem to be completed, and glass and shutters could be very much smaller. I can see that as a true replacement for all the features of the Dagor, except probably price - but you can't have everything.

Sign me up.

Cheers, Steve