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View Full Version : 300mm Rodenstock Sironar-S vs. Sironar-N



Ralph
22-Sep-2005, 16:42
Forgive my ignorance, but I know nothing about lens design, 6 elements, 8 elements, plasmats, hazmats, and so on. My question is whether there is any sharpness difference between the Rodenstock Sironar-S vs. the "N." I am responsible for doing some super-high-resolution copywork of large illustrations (the glass on my old Caltar 300mm is beat to hell, but it's the right focal length). My shooting distance is about 7-10 feet (which I don't think moves it into the macro range). The client's goal is making huge Lightjet enlargements of the resulting 8x10 sheets scanned to digital.

I know the "S" has a larger image circle, but I don't need a lot of movement. The "N" would thus be a logical choice if the two series are equally sharp (there are two 300mm "Ns" -- I think -- on Ebay right now, although because the language in the two ads is almost identical despite sellers on different continents I'm suspicious of both, and one doesn't say "N"). But while searching the archives to see if this has been addressed, I saw Chris Jordan's post saying that he had found the answer to his sharpness quest in the Apo "S" series, so maybe there is a difference? And what about the "APO" designation? Are all Rodenstock Sironars going to be APO, or are there older "S" and "N" models that aren't? Should I care? (The illustrations to be copied are in color fwiw.)

For this current job, at least, "sharpness" is my biggest priority -- not weight, or filter size, or maximum aperture, or even cost (I'm not paying, just doing, and can sell the lens after the job is done if I don't think I'll use it again.) Any lens gurus able to comment?

Bob Salomon
22-Sep-2005, 16:55
The S is corrected for image ratios of 1:5 to infinity. The discontinued N is corrected for image ratios of 1:10 to infinity. For your type of work copying flat objects a 300mm Apo Ronar would be best. For table top studio work to infinity the S would be best.

Ralph
22-Sep-2005, 17:04
So the "N" is no more? OK.

By the way, I was going to add that I know the Schneider 305 G-Claron is highly-regarded. I didn't mention it only because a friend and I did multiple high-res tests of a Nikkor 360 vs. a G-Claron 355 and in every case the 355 was noticeably less sharp than the Nikkor, so I've always been wary about the words "G-Claron" when big enlargements are involved. But if the 305 version is likely to be sharper than anything else in the 300 class I'll consider that . . . or anything else likely to be "sharpest in class."

And if the consensus is that most modern lenses in this category are unlikely to differ much even under huge enlargement (I'm talking feet, not inches), I'll accept that too. (I've mostly done contact printing so I've never thought much about lens sharpness before.)

David Karp
22-Sep-2005, 18:11
A Caltar II-N from Calumet is the same as a Rodenstock Sironar-N. If you can find a used one, they typically cost less than the Rodenstock version of the same lens. They still show the 300mm f/5.6 on their website, but it is out of stock. Maybe it will never be re-stocked, unless Rodenstock is willing to do a production run for Calumet.

Craig Wactor
22-Sep-2005, 18:29
As I understand it, the "S" uses low-dispersion glass, which would give you more local contrast and therefore a sharper looking image. I do not think the resolution is actually higher, though. I also believe the S has 3 degrees more coverage than the N.

Both the Sironar-S and -N have been apochromatically corrected lenses all along. It was a marketing decision to add "APO" to the name. Both lenses have been updated through the years without changing the name, apparently. But I think any Sironar-S or -N is an APO lens.

I have used both the -N and -S version of the 150mm. They are both incredibly sharp, hard to tell the difference. My use has been mainly close to infinity, though.

If money is no issue, I would buy the Sironar-S, then ship it to me when you are finished with it ;o)

paulr
22-Sep-2005, 22:00
I just recently saw Schneider's own MTF charts for the 305 g-claron. It's just not a sharp lens. It's adequate for the 1:5 through 5:1 magnification it's designed for, but not much better than that. Terrible at infinity (at least compared to a modern plasmat). My guess is it's main design goal was affordability, unless there's something involved in process lenses that I just don't understand. The distortion numbers are nothing to get excited about either.

Oren Grad
22-Sep-2005, 22:16
Yes, the G-Claron MTF curves look OK until you read the fine print and realize that they represent 3/6/12 lp/mm, while the corresponding curves for the Apo-Symmar and Apo-Symmar-L represent 5/10/20 lp/mm.

Ken Lee
23-Sep-2005, 09:47
The tests performed here (http://www.hevanet.com/cperez/testing.html#300mm_and_longer" target="_blank) by Perez and Thalmann suggest that their sample 305 was as good, or better, than other lenses in the same category.



Do you consider this a fluke, or am I missing out on a little technical joke about lp/mm ?

Oren Grad
23-Sep-2005, 10:32
The tests performed here by Perez and Thalmann suggest that their sample 305 was as good, or better, than other lenses in the same category.

It's impossible to draw that conclusion based on a single poorly-controlled test at a single magnification that uses an inadequate performance metric. I don't think the Perez/Thalmann test results are useful, except to underline how hard it is to rigorously and quantitatively test optical performance in an amateur setup. At least on the basis of the information they provide, there's no way to disentangle the causes of the variation in results that they report for a given lens type, let alone use the data to compare different lenses in any meaningful way.

J. P. Mose
23-Sep-2005, 11:26
I asked this question a few months ago:

http://largeformatphotography.info/lfforum/topic/501320.html

paulr
23-Sep-2005, 12:32
"Do you consider this a fluke, or am I missing out on a little technical joke about lp/mm ?"

The latter. Those lp/mm tests are essentially worthless.

Check out http://www.bobatkins.com/photography/technical/resolution.html for some explanations.
Some of what he discusses only applies to examining aerial images, but some of it applies to any subjective resolution test.

Ken Lee
23-Sep-2005, 12:49
Bob Atkins suggests that if you really want to compare lenses, shoot some familiar object (like a stuffed animal) and see for yourself. Perhaps by now, the USAF target is a "familiar object" to Perez/Thalmann - so their tests would meet his criteria, no ?

paulr
23-Sep-2005, 12:53
The Schneider macro symmar has the sharpest test results I've seen for a 1:1 lens. Unfortunately, I don't think they make it in a focal length longer than 180mm.

Bob Salomon
23-Sep-2005, 13:05
"shoot some familiar object (like a stuffed animal) and see for yourself. Perhaps by now, the USAF target"

But one example above is flat - the test chart, and the other is 3 dimensional - the stuffed animal.

In my response to the OP I pointed out that for his purposes a lens designed for copying flat field art would be best - the Apo Ronar at f22.

Not a lens designed for tabletop reproduction at 1:5 or 1:10 to infinity.

If the stuffed animal is the subject at 1:5 to 5:1 an Apo Macro Sironar would far and away give the best results.

Ken Lee
23-Sep-2005, 13:13
"But one example above is flat - the test chart, and the other is 3 dimensional - the stuffed animal".



- True enough -



Please overlook my lame attempt at a joke ;-)

Christopher Perez
23-Sep-2005, 17:30
Read the fine print on the MTF charts you get from the vendors. What's it say? The information is derived from design data. For implementation data, you'd need to visit Hasselblad's lab in Sweden.

Can't afford a trip to Sweden? Hmmm... then what tests might people have access to which are easily repeatable, verifiable (in the sense that anyone with the right magnification can read the results for themselves), and might give a clue to at least one dimension of optical performance? Could it be that the USAF developed resolution test chart might be a starting point? Ah... maybe...

For a properly manufactured optic, there is no way to tell the difference between lenses in practice. Photographing a fuzzy creature is really silly as a scientific exercise. It may, however, prove whether a particular lens in a particular camera system with film and holders might be acceptable, if not down right pleasing, to you.

Regarding the aforementioned Sironar N vs Sironar S - shoot them both side by side if you can. With the exception of minor color rendition differences, if you can readily see differences in resolution between them in the finished image, I'll buy you a beer. No. Wait. I'll buy you a whole evening of beer. OK?

Any differences between them will be slight and may not show up, even in scientific lab experiments, until you've enlarged an image 160 times.

paulr
23-Sep-2005, 19:30
"Regarding the aforementioned Sironar N vs Sironar S - shoot them both side by side if you can. With the exception of minor color rendition differences, if you can readily see differences in resolution between them in the finished image, I'll buy you a beer. No. Wait. I'll buy you a whole evening of beer. OK?"

Whether you'd owe anyone a beer or not might have to do with the kind of photography they're doing. I mostly do landscape type work, so in my case, you'd almost certainly be right. I only sometimes come close to what my lenses are able to do. The rest of the time, depth of field issues and things blowing in the wind (including the camera) act as great lens equalizers.

I have no trouble telling the difference between enlarging lenses, though. This is a situation with the potential for perfect focus, perfect alignment, and perfect repeatability. People doing photography that comes closer to this ideal (copy work, and some kinds of studio work) might be able to see the difference between modern lenses--especially if they start using movements, or wider than typical apertures. On axis, at f22, as you suggest, it will be hard to tell the difference between most general purpose lenses made since the late 70s.

For applications where sharpness is important, it makes sense to notice some basic design qualities that are often overlooked. Schneider's general purpose lenses are optimized at infinity. The Rodenstock apo sironar s lenses are optimized at 1:10. This alone tells you more than any advertising hype about which might be better for a particular use. I use the schneiders, but have often recommended the sironars to friends doing studio work.

paulr
23-Sep-2005, 19:32
figure 5 on this site (and the accompanying photo and text) offer a great example of why resolution limits tell little about lens quality:

http://www.rlg.org/preserv/diginews/diginews21.html#technical

Craig Wactor
25-Sep-2005, 22:02
I've solved the issue once and for all:

This image was taken with a Sironar-S:

http://www.southwestcustomtrucks.com/images/HOTTIE/070704a.jpg

The same image taken with a Sironar-N:

http://www.all-about-puppies.com/image-files/boston_terriers.jpg

Henry Carter
27-Sep-2005, 20:58
The Sironar-S is so sharp that I can read the serial numbers of her breast implants. Perhaps you should look for a lens that does not make objects look larger than life.

don mills
8-Sep-2009, 11:24
Any updated thoughts on this topic?

I can't decide between the 240mm Sironar S vs APO Symmar. An overall smooth look is slightly more important to me than contrast or sharpness.