APO Sironar S lenses in 300mm + in today's market

[StuartR]

Can you enlighten us, Bob (or at least me!)? I know the basics of MTF charts, but I am not an expert. I see that there are some differences in contrast, and the S seems a bit better in the MTF, but to my untrained eye it does not look particularly dramatic as Pere says. At the working aperture of 22, it seems as though the Sironar S has about 5% more contrast at the 20lpm level, but otherwise it looks pretty comparable to me. What is your interpretation?

[Bob Salomon]

Can you enlighten us, Bob (or at least me!)? I know the basics of MTF charts, but I am not an expert. I see that there are some differences in contrast, and the S seems a bit better in the MTF, but to my untrained eye it does not look particularly dramatic as Pere says. At the working aperture of 22, it seems as though the Sironar S has about 5% more contrast at the 20lpm level, but otherwise it looks pretty comparable to me. What is your interpretation?

You should be able to go to the Rodenstock Precision Optical Page at the Qioptiq web site and download the Rodenstock paper on reading the curves. If not, Dan should have it on his site.

[Leigh]

You should be able to go to the Rodenstock Precision Optical Page at the Qioptiq web site and download the Rodenstock paper on reading the curves.

Nope. Not there.

- Leigh

[Bob Salomon]

Nope. Not there.

- Leigh

Then this may help, but note, they talk about LINES PER MM, RODENSTOCK CURVES ARE FOR LINE PAIRS PER MM!

[Oren Grad]

I have posted a new sticky thread at the top of the Lenses subforum with documents from Zeiss and Schneider that talk about how to understand MTF.

http://www.largeformatphotography.in...understand-MTF

[Pere Casals]

read the curves! They are different!

Bob, Rodenstock provided excellent and accurate technical information about their glasses, but as they were serious they could not provide reliable MTF graphs at 40 or 60 cycles/mm for Sironar 300 versions, this is because the sample to sample variation or the ultimate performance at extintion variability.

IMHO a significative difference is not seen at 20cycles/mm, and contrast at 2.5 cycles/mm proves that "general" contrast is the same.

But the S has luxurious ED in it, that's not a joke, allowing the design working perfect from 1:10, and probably having better sample average at 40 cycles/mm graphs, but at 40 c/mm then we enter in the sample variation realm, so a serious manufacturer was not to deliver those graphs in what perhaps we would see a difference.

The N vs S debate has been seen a lot of times, any newcomer (like me) asks or searchs that at one point.

Sadly those threads lacked a single side by side sample, and also little was said about the role of ED glass in the S.


Brochures: https://onedrive.live.com/?id=8D71BC...71BC33C77D1008

[Bob Salomon]

Bob, Rodenstock provided excellent and accurate technical information about their glasses, but as they were serious they could not provide reliable MTF graphs at 40 or 60 cycles/mm for Sironar 300 versions, this is because the sample to sample variation or the ultimate performance at extintion variability.

IMHO a significative difference is not seen at 20cycles/mm, and contrast at 2.5 cycles/mm proves that "general" contrast is the same.

But the S has luxurious ED in it, that's not a joke, allowing the design working perfect from 1:10, and probably having better sample average at 40 cycles/mm graphs, but at 40 c/mm then we enter in the sample variation realm, so a serious manufacturer was not to deliver those graphs in what perhaps we would see a difference.

The N vs S debate has been seen a lot of times, any newcomer (like me) asks or searchs that at one point.

Sadly those threads lacked a single side by side sample, and also little was said about the role of ED glass in the S.


Brochures: https://onedrive.live.com/?id=8D71BC...71BC33C77D1008

Search for the Rodenstock brochure that introduced the S and there you will find side by side comparisons of the S and the N.

[Pere Casals]

Search for the Rodenstock brochure that introduced the S and there you will find side by side comparisons of the S and the N.

Thanks Bob, I cannot find that brochure... is there any link to it ?

[Ken Lee]

Here's a diagram which shows the difference between the 3 different 150mm Sironars, the N, the S, and the W. I don't remember who made it.

Performance varies as we move away from the center of coverage. The S and N compete for best sharpness until we approach the extremes of coverage. The N drops off first while the W drops off last.

As Bernice pointed out, this may be a theoretical plot, not based on empirical testing. I presume we can extrapolate a similar result for the 300mm series.

[Ari]

Sturart, as "asf" pointed out, much of the results you're seeking depends on technique and good supporting equipment, and if you make a living from this, the right gear is crucial.
I've seen significant differences by switching over to Toyo film holders, which are harder to find and more expensive, but they're much more consistent than Fidelity or Lisco holders.
Same goes for tripod and head, I look for repeatable, trustworthy gear that works day in and day out.
Finding the lens appropriate to your work is another step, and there's some good advice here.
My "forever" lens is a Cooke XVa; after a lot of testing and shooting, I found the XVa to have superior contrast, a special sharpness/smoothness, which give it a very unique look. This applies to colour and B&W.
It costs about the same as a new 300mm Apo Sironar-S, maybe a bit less, but a significant advantage is that it's a convertible lens, so you can use 300mm, 460mm and 646mm focal lengths, and they're all excellent performers.