Summicron 50mm f/2 sharpness question

[jankap]

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Volcaremus asks if his lens is sharp, not if it suffers from focus shift. 

 

So maximally sharp is the second red lego from the right. 

But is it really sharp? 

A lego stone is not the best subject to judge this.

Jan

[volcaremos]

Thanks jankap. You are correct my main question is if this famous lens is as sharp as you would expect. My concern is that having paid a lot of money for the privilege I can put my mind at rest that it is performing as expected.

 

So I have conducted a more rigorous test tonight (still under artificial light because it is dark when I return from the office).

 

I have taken 9 shots @ f2, f4 and f5.6. I have taken 3 shots at each aperture one focused on square pattern and the others a fraction front and back focused.

 

DropBox link to folder: https://www.dropbox.com/sh/esoi7wjytkb2f90/AAAGi1SQYAwd2iEmI7yyavN7a?dl=0 

 

So can we deduce that some calibration is needed on lens or camera? And although not my primary concern are there clear signs of front/back focus shift?

 

I greatly appreciate all helpful responses.

[lct]

Yes bit of misfocusing at f/2 here as expected. May come from the fact that your lens has not been calibrated for digital. Is it 6-bit coded?

[Michael Geschlecht]

Hello William,

 

Welcome to the Forum.

 

What type of tripod are you using & are you using a cable release?

Best Regards,

 

Michael

[volcaremos]

Hi

The lens is not bit coded. I used mini Manfrotto tripod and i used a cable release do i think cmaera shake can be ruled out.

[williamgm]

The latest short video from Thorsten Overgaard might be of help/interest, as it covers (some) of the subject of sharpness: https://www.youtube.com/watch?v=yk4woeP08LI

 

Geoff

[lct]

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[...] The lens is not bit coded. [...]

 

That's what i suspected. Happened to two of my pre-digital lenses which had focusing problems. Leica did a 6-bit coding and a calibration at the same time. Leica or a good workshop can do it for you as well. I would send in the lens with your test pics if i were in your shoes.

[jankap]

The file Sum f2 focused cannot be downloaded well. But that is not important.

The exif data are ok. The f2 front focus has ISO 400, 1/60 and the f5,6 focused has ISO 800, 1/24.

Are you sure your lens is not coded as the lens is recognized (50mm, f/2)?

 

Looking with Photoshop at 100% and 200% I don´t see a problem. What do you expect more?

I think, the lens could also handle a sensor with more pixels.

Jan

[lct]

focused (left) vs back focus (right)

 

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[Nordvik]

http://www.l-camera-forum.com/topic/234529-focus-shift-through-apertures/page-2?do=findComment&comment=3142553

[volcaremos]

The file Sum f2 focused cannot be downloaded well. But that is not important.

The exif data are ok. The f2 front focus has ISO 400, 1/60 and the f5,6 focused has ISO 800, 1/24.

Are you sure your lens is not coded as the lens is recognized (50mm, f/2)?

 

Jan I entered the lens detail manually on the camera hence the EXIF data.

Thank you all for your time and thoughts. It would seem that the sharpness you see in the tests is what is expected and focus shift a reality. Shop where I bought the lens said the same thing. They also told me that camera would have to go with lens for proper calibration. They would be happy to give me a full refund. So I guess I should stop worrying and start using the camera and lens. cheers

William

[pico]

Pico thanks for taking the time to write but not particularly helpful. Irony lost on me.

 

There was no irony.

[jankap]

William, you are welcome.

I had a small problem with the filterring of my not-coded Lux 35. I sent it to Wetzlar, they were very helpful by telephone.

Coding, adjusting were recommended.

The lens is repaired, adjusted and coded now and it is in an as new condition. But the costs were 500 Euro.

 

Perhaps you can live with somewhat miscalibration for a while?

 

Generally spoken/written, my lens is from 1996, but I am happy with it.

Jan

[lct]

A good workshop will do the job for less. Last time i worked with him (end of 2014) Will van Manen asked 175 EUR for a CLA and 85 EUR for 6-bit coding. Add to this 21% VAT if you cannot avoid it. 

[jankap]

Wil van Manen is ok. For a European it is difficult to avoid the VAT. 

Jan

[lct]

[...] For a European it is difficult to avoid the VAT. 

 

For an European consumer you mean. Otherwise VAT is recoverable in Europe of course. Suffice it to use the camera professionally.

[tobey bilek]

bracket focus to see if your lens is sharp somewhere.  It could be camera RF out {most likely} for the lens.  

 

It will not be fully sharp at F2.0 even if APO version.  Best to test with flash and tripod.   Hand held pics are never fully sharp.

[bocaburger]

For a test target, try a bottle with a lable that has a lot of small, sharp, black-on-white text which goes close to halfway wrapping the bottle.  Focus on the middle of the text (closest to you).  If it's sharp, with increasing blurryness toward the edges (which curve away from the camera), you're all good.  If the center is not sharp, but the text toward the edges is, you've got a miscalibration problem, however unless you have another lens known to be properly calibrated, there's no way to know if the problem is with the rangefinder or the lens.  If none of it is sharp, try focusing on the text at one or another edge.  If that's in focus but the center is out, it's also a calibration problem.   What I'm saying is, if there was something wrong with the lens other than calibration, then either you would never be able to get anything pin-sharp, or there would be more sharpness on one side or the other...something like that. 

[volcaremos]

Thank you all for your useful comments (apart from one person that is). I have followed your advice and after tests I exchanged my lens with one which appears to be slightly sharper. Happy to close this thread and go out there and take real pictures instead of tests. :-)

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Hallo,

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[DOUG66]

Hi William,

I have had the same problem with a 50 Summicron on an M8.  The Summicron was purchased with a M6 in 1993 and was designed for use on colour film, which is a multi layer emulsion.  I used it on Agfa 50ASA emulsion and it performed stunningly.  However on the M8 it back focused by 20mm at at 1 meter.

I have developed a chart to accurately measure back focus .  I will post you a copy of the chart and instructions if you PM me your postal address.  The chart will not transmit via the web as it contains a high definition section which locates the focus.  I optomised my lens at F2.8 by replacing the shim collar for one which is 125 microns larger.  If you are unable to do the surgery yourself contact Malcolm Taylor.  The results with my lens are stunning 30 dia. enlargements are no problem .

 

Doug.