Help with Technique - 90mm APO Summicron

[mountainrivera]

I am thinking this is purely user error. The lens seems to inexplicably seems to exhibit focus shift at times. I have taken many "test" shots these and these are just two recent examples - one OOF, the other in focus. Any tips appreciated.


Pic focused on the box but the grass is sharp.I shot hand held. I shot this at f2.4.

Pic 2

I focused on the ears. It seemed to have nailed this one. Shot at f2.0

 

[x-ray]

On the M9 that I had my 90 Apo Summicron would focus in front of the subject. I sent it off with the camera twice for calibration and each time when it came back it was off again. I've used M's most of my photo life and know how to focus. Finally I had to get ugly with Leica and they replaced it. After it was replaced I never had another focus problem.

The focus was off by a huge amount. I could focus on infinity wide open and the foreground 20 feet away was in focus and infinity was very fuzzy. The lens worked fine on my MP and M2 but not on my M9. Other lenses worked fine on the M9 and my film bodies. I had a similar issue with a 75mm CV lens on my film bodies. Some times it worked and other times it didn't.

 

[Rob-F]

The outlet box and the rabbit were shot at different distances, right? The rabbit appears to be much closer to the camera. So I'm thinking maybe the lens's focus cam is ground correctly at the closer distance, but out of tolerance at the longer one. I'm assuming, here, that your other lenses focus OK on the same camera. (Which camera is it--M9?) I can't imagine how Leica could make a mistake like that, but if your results are consist at given distances, I can't think of any other explanation but a focusing cam problem.

 

[mountainrivera]

Thanks. X-Ray - did you get a new camera or lens? Rob. These were at about the same distance. I just cropped the rabbit tighter than the box. I wanted to show the grass in the box. I only used it once in the real world (snapshots at a new years day dinner with the family) and shot with a flash at f4. Everything looked good at that aperture.

 

[x-ray]

Rob Leica swapped the internal assembly consisting of the lens cell and focusing cam with a demo unit they knew was good. No one could explain why it happened but it did.

 

[LCT]

DoF is extra thin there, more so than with a 50/0.95 at full aperture. Best way to check if the lens is faulty is using your EVF if you have an M240 or borrowing one around you. Otherwise, the only way i know is sending both lens and body in for adjustment.

 

[mountainrivera]

I am shooting on an M9 so no evf there but I do have a sony a6000 with peaking. I hadn't but just tried it on that. A couple of mis-focussed shots there too so perhaps the lens needs a tweak. I will send it to Dag. Leica seems out of control now as they said it would cost between 300-500 to look at the lens. Is that their going rate for a CLA?

DoF is extra thin there, more so than with a 50/0.95 at full aperture. Best way to check if the lens is faulty is using your EVF if you have an M240 or borrowing one around you. Otherwise, the only way i know is sending both lens and body in for adjustment.

 

[LCT]

I don't send bodies or lenses to Leica if i can avoid it. They are too slow to repair anything and they don't do a better job than good artisans like Don Goldberg in the US or Will Van Manen in Europe for more reasonable prices.

 

[Rob-F]

Rob Leica swapped the internal assembly consisting of the lens cell and focusing cam with a demo unit they knew was good. No one could explain why it happened but it did.

They swapped a different lens cell and cam into the original helicoid? Since each production sample can deviate a bit from the nominal design length by up to plus or minus five percent or so, Leica makes focusing mounts to match, I believe, five different focal lengths. That is, one at the nominal focal length, two longer, and two shorter. I wonder if the cell they changed yours to was a better match for your mount?

Leica engraves the focusing mount with a number, placed next to the infinity mark, that indicates the deviation, if any, from nominal focal length. As an example, my 50mm Summilux is engraved "14" in that location. As I recall, that would mean the true focal length is 51.4mm. My 90mm Tele-elmarit is engraved "05," which I think means 90.5mm. And my 75mm APO-Summicron is marked "50." I think that means that mine is an exact 75mm (correct me if I'm wrong).

I could see where a mount with a helicoid pitch meant for a slightly different focal length might cause the focus to be correct at some distances and off at others.

Just a wild guess, really.

 

[icebear]

I have a pre-asph 90 'cron which is my primary lens for concert shots, usually wide open or half a stop down. When I got an M9 I had slight front focus issues at shorter distances. I took the body and lens to Leica US. They checked the RF mechanism and sensor position, fine tuned it a little and then matched the lens to the in spec body. It works perfectly ever since. When focus is off now it's because the musician moved slightly or I missed the focus but not anything cause by the equipment. I am not sure if the regular repair experts for film M's can check and adjust the sensor position.

 

[Freakscene]

The focus cam on many 90 ASPH Summicrons does not follow focus properly. http://leica-users.org/v49/msg10637.html They were mostly accurate enough for film but the higher focus accuracy requirements of digital sensors and the greater capacity for digital files to be enlarged mean that the necessary tolerances are greater, and many seem to focus incorrectly on digital Ms when using the RF.

To test for focus shift you need to focus at one distance and shoot at different apertures. If the lens focuses accurately at some distances but not others at the same aperture, the problem is the focus cam.

Marty

 

[mountainrivera]

I decided to send it back to Leica and cross my fingers that the repair will be reasonable. I am waiting on the call and estimate. I will let you know the damage both physically to the lens and my wallet. Like LCT, I want to avoid sending both body and lens. My body is spot on with my 50mm 'lux and 25mm Zeiss so hoping the lens comes back fixed.

 

[jaapv]

I trust you did your test shooting on a tripod? DOF is so thin that the slightest movement of your head will throw focus out, especially at shorter distances.

 

[mountainrivera]

I trust you did your test shooting on a tripod? DOF is so thin that the slightest movement of your head will throw focus out, especially at shorter distances.

Honestly I did not.

 

[mountainrivera]

It took almost three months but just received my lens back from Leica. It is spot on in test shots I took. Haven't used it in real life yet. The 90 is a fairly complex lens from what i understand so glad I went back to the "factory" with this one.

 

[Cyriljay]

I have this lens and I use it very rarely .

I have used it several occasions and doubt it doesn't looks very accurate in focusing. So I guess my lens too have a focusing shift on my M8 😱

I must try it on My m6 and then again on M8. So I can find if anything wrong with the Lens.

 

[mountainrivera]

I owned this lens once before and it was never accurate and ended up selling it after sending it in to an independant repair person. This time I first reached out to youxin and he said the lens was complex and didn't want to mess with it. I decided to spend the extra bucks and go to Leica. Between the two lenses I must have had taken hundreds of "test" shots obsessing over the focus. This time I decided to go to Leica and seems like a good descision. I would go to Leica with this lens IMO.

 

[x-ray]

Glad to hear you got it straightened out.