Performance Between Apo Symmar and Apo Symmar-L?

[neil poulsen]

Is there really that much of a performance difference between Apo-Symmar and an Apo-Symmar-L lenses?

I heard that the former used some sort of radioactive component that was eliminated in the latter. So I've always assumed that if either was sharper, it would be the Apo-Symmar, since there were fewer constraints in the choice of materials for that lens.

Yet recently, someone suggested to me that the Apo-Symmar-L is much sharper than the Apo Symmar. Is this correct?

[Oren Grad]

The story when the Apo-Symmar L series was introduced was that some glass types required by the Apo-Symmar design had been phased out because of environmental regulations.

The main functional difference between Apo-Symmar and Apo-Symmar L is that coverage of the 120, 150, 180 and 210mm focal lengths was increased to 75 degrees compared to 72 degrees for the corresponding lenses in the Apo-Symmar series. Comparing MTFs doesn't show any differences that would justify a claim of "much sharper" for the L series. Rather, it looks as though what Schneider achieved was to switch to the new glass and also increase the coverage of the shorter focal lengths, without losing performance compared to the Apo-Symmar series. So if you need the extra coverage in one of those focal lengths, I certainly wouldn't hesitate to consider an Apo-Symmar L.

[Sal Santamaura]

I doubt (but am not certain) that radioactive constituents were still used during Apo Symmar manufacture. It seems more likely that lead was what new environmental rules banned and forced Schnieder -- as well as other manufacturers -- to redesign.

With respect to sharpness, since the 210mm Apo Symmar was reputed to be unusually sharp, and my copy certainly is, attached are Schneider's technical data for it.

Here are comparable data for the 210mm Apo Symmar L:


https://web.archive.org/web/20091229041554/http://www.schneideroptics.com/pdfs/photo/datasheets/ApoSymmarL/ApoSymmarL_56_210_2.pdf

I've never used an Apo Symmar L, so can't add personal opinion, but the graphs do characterize how those two lenses differ in coverage and designed MTF.

[Oren Grad]

Here are the MTFs for 150:

[EdSawyer]

Actually if you extract the images and overlay them (from the 150mm) you see that the original APo Symmar is better nearly everywhere than the L verison, ironically particularly in the corners, at all apertures.

[Oren Grad]

Actually if you extract the images and overlay them (from the 150mm) you see that the original APo Symmar is better nearly everywhere than the L verison, ironically particularly in the corners, at all apertures.

You cannot directly overlay the charts to compare them: the percentages on the x-axis refer to different absolute distances from the center of the field because they are defined relative to the image circles for the respective lenses, which are larger for the L series.

EDIT: I should also add that the differences that are there are more pronounced at wider apertures than at f/22, and with the exception of some stuff going on with field curvature at f/11, which moves the point of maximum modulation around a bit, the differences aren't that large even at the wider apertures. If someone is sensitive to differences at that level, and they're important for the pictures being made, there's isn't really an alternative to testing individual samples, no matter what brand and model, to confirm suitability for purpose.

[Pere Casals]

Yet recently, someone suggested to me that the Apo-Symmar-L is much sharper than the Apo Symmar. Is this correct?


IMO both the APO Symmar L, the APO Symmar and the older Symmar-S MC all perform the same. Sample to sample variations are greater than any average improvement in the different models.

Search "symmar" in the Arne Croell and C.Perez tests. http://www.arnecroell.com/lenstests.pdf , http://www.hevanet.com/cperez/testing.html

Obviously those tests have technical limitations, but they show what practical results can be.

Probably it can be said if a sample worked a bit better or worse in a resolving power test, but IMHO it would be crazy challenging to say if a shot comes from an old Symmar-S or from a Symmar L

Of course if one stops f/22 for DOF then no difference can be seen, because diffraction is limiting performance to the point that no practical difference can be seriously noticed.

Perhaps the particular Symmar-S 150 in the C Perez tests shows worse corners wide open, but it shines in the center/mid (76/85 lp/mm, way better than the APO), my guess: if the front cell of that old S was unscreewed a bit then those corners would have improved and center would have worsened.


To me it's about the photographer, some LF photographers are sharper than others, and if this is important or not... ymmv.

[interneg]

It seems more likely that lead was what new environmental rules banned and forced Schnieder -- as well as other manufacturers -- to redesign.

I recall Zeiss saying words to that effect when they redesigned the 38mm Biogon too. Though I can't remember if it was an outright ban, or that new regulations would make it uneconomic to manufacture using lead content glass at consumer (as opposed to government/ industrial/ scientific) price points.

Edit: Arne beat me to it, couldn't remember if it was RoHS or not that was behind the change.

[Arne Croell]

Sal is correct, it was the phasing out of lead compounds (here: oxide) as part of the RoHS (Reduction of Hazardous Substances) regulations of the EU, that triggered the Apo-Symmar redesign. Radioactive thorium oxide was phased out much earlier, in the early 1970's. The last radioactive Schneider lenses I am aware of are Repro-Clarons and some Xenotars. If you're wondering, the "hazardous" part of RoHS is not about the user of the lens in this case, but the production process and the waste management of the grinding/polishing slurries.

[Arne Croell]

I recall Zeiss saying words to that effect when they redesigned the 38mm Biogon too. Though I can't remember if it was an outright ban, or that new regulations would make it uneconomic to manufacture using lead content glass at consumer (as opposed to government/ industrial/ scientific) price points.

Edit: Arne beat me to it, couldn't remember if it was RoHS or not that was behind the change.

It is initially an outright ban - another example is lead-free solder. I think you can apply for exceptions if there are no real alternatives (e.g. lead car batteries) and a near 100% recycling rate is guaranteed. I am sure there are others such as national security. It was probably easier to redesign then try to make the case for an exception for a few thousand lenses in Brussels, and how do you guarantee the recycling for these lenses?

[Pere Casals]

if it was an outright ban, or that new regulations would make....

Regulations are becoming painful.

"With arsenic oxide, lead oxide, and boron oxide forbidden, optical glasses will be almost eliminated. Of 120 glass types in the SCHOTT catalog, only five would be permitted under REACH in the near future."

https://spie.org/news/spie-professional-magazine/2014-april/euro-regulations?SSO=1

https://web.archive.org/save/https://spie.org/news/spie-professional-magazine/2014-april/euro-regulations?SSO=1

[neil poulsen]

Thanks everyone for the responses.

Peres' post not withstanding, the person to whom I referred may have been thinking of a Symmar-S lens.

In a 150mm focal length, if the -L lens has greater coverage, it may be worth swapping the non-L for an L.

All be it, I was told by a Schneider technician that only under magnification could one tell the difference in a photograph between a Symmar-S and an Apo Symmar.

Yes, I think it was the lead component I'd heard about; not whether a lens had radioactive components.

[Pere Casals]

In a 150mm focal length, if the -L lens has greater coverage, it may be worth swapping the non-L for an L.

If one shots 5x7 then perhaps those 3º may make some difference, for 4x5 it's not that clear. Anyway the "coverage" is a bit "elastic", because manufacturer's criterion to say if a lens has one degree more or less is not disclosed and it has some commercial input.




All be it, I was told by a Schneider technician that only under magnification could one tell the difference in a photograph between a Symmar-S and an Apo Symmar.

... and it can happen that a particular Symmar-S is well sharper than a particular APO Symmar, that technician should have also mentioned that. My Symmar-S 135mm resolves Element 2.1 at 1:20 magnification f/16 in the mid, which is 80 lp/mm.

by f/22 we can find ancient convertible symmars that are slightly sharper than most Symmar-S, APOs and L, it would be difficult to find a single dog between those that are Technika stamped.

https://www.kenrockwell.com/schneider/150.htm