Found a dealer for the SK Micro-Symmar 2.8/50mm !

Davids · Post by **Davids** » Mon Oct 07, 2019 6:45 pm

The Schneider-Kreuznach Micro-Symmar 2.8/50mm is no longer listed on the SK website and as far as I knew the lens was discontinued. I contacted a dealer of line scan lenses about pricing for the Xenon-Sapphire line and to my surprise they told me that they can in fact still get the Micro-Symmar! They are charging $2195.
What intrigues me most about the lens is that it's maximized at 3.5x, covers a large 62 mm image circle, and wouldn't require an inordinate amount of extension. I am unaware of anyone on this forum testing this lens (maybe I am wrong?) and SK does not give any information on LoCA. But....it is tempting!
Documentation on the lens: http://kamery.atesystem.cz/site/assets/ ... 2_8-50.pdf

ray_parkhurst · Post by **ray_parkhurst** » Mon Oct 07, 2019 7:05 pm

I've been searching for this lens for quite some time, wanting it for 3.5x. This is the first I've heard of availability anywhere. At this point I still remain interested but in the meantime have picked up the RF3p5x and am slowly piecing together the components for a dedicated Sensor-Pan SnS system. Would be nice to see test results for the lens but I'm not ready to do the purchase and testing myself. Hopefully you or someone else will have a strong need and it works out.

RobertOToole · Post by **RobertOToole** » Mon Oct 07, 2019 7:23 pm

Hi Davids

One thing about that lens though, the SK MTFs are for f/2.3, f/2.5, f/3.4 and the mag is only 0.29x. I would ask them to provide updated MTFs at f/2.8 and 3.5x at least. Something seems strange about the lack of correct info!

As far as SK lenses go, I've been using the 4/28 and 4/35 without a center section so wide-open, stopped down to f2.2 or so on a tube lens and they are sharp, not as sharp as a small pixel pitch lens like a Xenoplan but they are impressive. Best part is I paid $50 for the 4/28 in the box and $100 for two 4/35s also in the box.

I posted a 2500px sample with the 4/28 at f/2.2 here if you are interested, sharp edge to edge image:

https://www.closeuphotography.com/blog/ ... at-4x-plus

Best,

Robert

chris_ma · Post by **chris_ma** » Mon Oct 07, 2019 7:46 pm

RobertOToole wrote:One thing about that lens though, the SK MTFs are for f/2.3, f/2.5, f/3.4 and the mag is only 0.29x. I would ask them to provide updated MTFs at f/2.8 and 3.5x at least. Something seems strange about the lack of correct info!

hi Robert,

are you sure about that?
the datasheet specifies 1/beta, and the curves seem more in line with a high performance lens around 3.5x then 0.29x.
But I agree about something being odd about the info, I don't really understand how they can measure a F2.8 lens at F2.3?

chris

ps: btw, Davids, what was the price quote for the xenon-sapphire line?

Davids · Post by **Davids** » Mon Oct 07, 2019 8:10 pm

Robert, your results are quite impressive! I do wonder what type of image circle your lenses can cover. What intrigued me so much about the micro-symmar is it’s ability to cover a large image circle (though I do agree, the dataSheet seems a bit off).

Chris, here are the quotes:
Xenon-Sapphire 4.5/95mm, ß' = 0.07X 62.5mm M52x0.75 25-1068013 $4,437
Xenon-Sapphire 3.9/95mm, ß' = 0.23X 62.5mm M52x0.75 25-1071819 $4,437
Xenon-Sapphire 3.7/96mm, ß' = 0.29X 62.5mm M52x0.75 25-1071818 $4,437
Xenon-Sapphire 3.5/96mm, ß' = 0.35X 62.5mm M52x0.75 25-1068012 $4,437
Xenon-Sapphire 3.2/96mm, ß' = 0.5X 62.5mm M52x0.75 25-1071189 $4,437
Xenon-Sapphire 3.2/97mm, ß' = 0.7X 62.5mm M52x0.75 25-1071190 $4,437
Xenon-Sapphire 3.2/97mm, ß' = 1.43X * 82mm M52x0.75 25-1076096 $4,720
Xenon-Sapphire 3.2/88mm, ß' = 1.75X * 82mm M52x0.75 25-1068014 $5,658

RobertOToole · Post by **RobertOToole** » Mon Oct 07, 2019 8:13 pm

chris_ma wrote:
RobertOToole wrote:One thing about that lens though, the SK MTFs are for f/2.3, f/2.5, f/3.4 and the mag is only 0.29x. I would ask them to provide updated MTFs at f/2.8 and 3.5x at least. Something seems strange about the lack of correct info!
hi Robert,

are you sure about that?
the datasheet specifies 1/beta, and the curves seem more in line with a high performance lens around 3.5x then 0.29x.
But I agree about something being odd about the info, I don't really understand how they can measure a F2.8 lens at F2.3?

chris

ps: btw, Davids, what was the price quote for the xenon-sapphire line?

Hi Chris,

From SK:

I do know that 1x on a SK MTF is written as 1/-1.0, 1/3x is written 1/-3.00 and 1/10x is 1/-10.00

So 3x would be 1/0.33x or in this case 3.4x would be or should be 1/0.29.?

Anyway 1/2.9 or 2.9x isn't 3.5x for sure

I've read about a couple hundred of these SK MTFs and I still could be 100% wrong!

It would be in SKs best interest to show an MTF for 1/3x rather than 3x I would think?

Best,

Robert

(update: Just fixed an error!)

Davids · Post by **Davids** » Mon Oct 07, 2019 8:33 pm

Robert,

I may also be confused, but I do think the MTF is for 3.5x. The way I interpret it is 1/magnification=0.29. This works out since 1/3.5 =.29 , though I could be interpreting this all wrong!
Now, why they have MTFs for f’=2.3 and 2.5 when the lens is listed at 2.8 is beyond me!

chris_ma · Post by **chris_ma** » Tue Oct 08, 2019 1:33 am

hmm, I think that the 3.4x vs 3.5x question could be explained with a rounding error:

1/3.5 = 0,2857... which would be rounded up to 0.29
1/0.29 = 3,44827.. which would be rounded down to 3.4

also the datasheet davids linked to has MFT curves which are very close to other high end 3.5x lenses. they would be really poor compared to 0.29x lenses. I just compared them to the XS line again, and while they don't list the same lp/mm, the general interpolated data looks very similair:

3.5x:
https://schneiderkreuznach.com/applicat ... -2_117.pdf

0.29x:
https://schneiderkreuznach.com/applicat ... -0.29x.pdf

what I still don't understand how one can measure a lens with F2.8 max aperture at F2.3 - maybe the removed the iris for testing?

thanks for the price info on the X-S Davids, I was always curious, would have expected them to be even more expensive.
chris

RobertOToole · Post by **RobertOToole** » Tue Oct 08, 2019 9:22 am

chris_ma wrote:hmm, I think that the 3.4x vs 3.5x question could be explained with a rounding error:

1/3.5 = 0,2857... which would be rounded up to 0.29
1/0.29 = 3,44827.. which would be rounded down to 3.4

Makes sense to me.

what I still don't understand how one can measure a lens with F2.8 max aperture at F2.3 - maybe the removed the iris for testing?

Schneider MTFs are all simulated as are all Rodenstock MTFs and almost everyone else other than Sigma, Leica and Zeiss AFAIK.

Also FYI Sigma, Leica, and Zeiss are the only manf. that test every lens at the final stage.

Robert

RobertOToole · Post by **RobertOToole** » Tue Oct 08, 2019 9:26 am

Davids wrote:Robert, your results are quite impressive! I do wonder what type of image circle your lenses can cover. What intrigued me so much about the micro-symmar is it’s ability to cover a large image circle (though I do agree, the dataSheet seems a bit off).

Chris, here are the quotes:
Xenon-Sapphire 4.5/95mm, ß' = 0.07X 62.5mm M52x0.75 25-1068013 $4,437
Xenon-Sapphire 3.9/95mm, ß' = 0.23X 62.5mm M52x0.75 25-1071819 $4,437
Xenon-Sapphire 3.7/96mm, ß' = 0.29X 62.5mm M52x0.75 25-1071818 $4,437
Xenon-Sapphire 3.5/96mm, ß' = 0.35X 62.5mm M52x0.75 25-1068012 $4,437
Xenon-Sapphire 3.2/96mm, ß' = 0.5X 62.5mm M52x0.75 25-1071189 $4,437
Xenon-Sapphire 3.2/97mm, ß' = 0.7X 62.5mm M52x0.75 25-1071190 $4,437
Xenon-Sapphire 3.2/97mm, ß' = 1.43X * 82mm M52x0.75 25-1076096 $4,720
Xenon-Sapphire 3.2/88mm, ß' = 1.75X * 82mm M52x0.75 25-1068014 $5,658

Don't forget X-S are made for a 3.5 micron sensor, the M-S is made for 5-7 microns.

Found this slide in my SK folder on my laptop, interesting.

Some of the info on this slide is different from the data sheet, for one the SK data sheet shows 7 element design, this slide says 6 elements.

Best,

Robert

ray_parkhurst · Post by **ray_parkhurst** » Tue Oct 08, 2019 11:58 am

The image circle keeps shrinking! Now I remember why I gave up on this lens (other than it is made of unobtainium)...the WD of 31mm was not going to support my lighting system. Plus I need minimum 67mm image circle. Only the longer FL 3.5x inspection lenses like the XD and such supported all of my requirements.

Davids · Post by **Davids** » Tue Oct 08, 2019 12:18 pm

Thank you for sharing that slide, Robert. That is definitely something to take into consideration.
Also, the working distance of 31mm may bit a bit limiting but to be expected with a focal length of 50mm.
If I were adept at testing I'd ask the dealer to send both the micro-symmar and the xenon-sapphire to compare. The price difference and extension required is nothing to shrug at.
If I can find a Componon 2.8/28 I'd give it a go stacked on my apo-digitar macro 5.6/120. Although, now that you've shown how amazing that little lens is, it's nearly impossible to find one