lens adjustment

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back alley

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what exactly is involved in a lens focus adjustment?

can i send in a lens without the body it is going to be used on?

from reading another current discussion here at rff it would seem my lenses likely need to be adjusted (tho they seem fine to me) and it has me thinking about it...
 
Depends on the lens and the camera. Fast lenses F1.4 and faster, Fast TelePhoto- best to have the lens and the camera to adjust for each other.

It certainly can't hurt to send the camera and lens together, except for down-time. I have good luck with the Sonnar conversions and the J-3's. However- sometimes "strange things" happen between RF lenses and bodies.

What is onvolved: I use Shims on the Jupiters to set the distance between the optics and the Focus Mount. On the two Noktons I just got in, I used two layers of Copper Tape to build up the RF Cam. Effectively the same as shimming the lens, but easily reversible and does not require disassembling the lens.

On the more extreme side: adjusting the spacing between the glass elements to change the focal length.
 
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From http://www.rangefinderforum.com/forums/showthread.php?t=92517:

Bill Pierce said:
You may find the following interesting. When I was using film Leicas as my workhorse cameras, it was almost automatic that when you bought a new M2 or M3, you sent it to someone like Norm Goldberg. First, he would relubricate the camera which had probably been sitting on a shelf for at least a year. Second, he would null-null the rangefinder mechanism; that is, to the limit of the accuracy of the measuring tools, go for absolute accuracy, no acceptable tolerances. In this way, all your bodies matched. You would also send him all your lenses. The rangefinder cams would be matched to your null-null bodies, which often meant the rangefinder cams had to be reground. Thus, whatever lens/body combination you used, you achieved a high level of focusing accuracy.

Unfortunately, Leitz will not make the necessary custom tools available to zero the M8/M9 rangefinders to top flight repairmen like Norm's son, Don. Their overworked in house repairman take a long time to deliver and, in my personal experience, often do a bad job that should have never left their shop. As far as I know, they do not offer any kind of null-null service to the general public. Those folks with multiple high-speed lenses and several digital bodies, the real Leica users, are hurt the most.

Here’s the interesting conversation from the Digilloyd site.

Correspondence with Erwin Puts on Leica M9 focusing.
Erwin Puts is well known for his Leica and other photography expertise, and in my exploration of the backfocus issues with my Leica M9, I decided to ask him what his Leica M9 focusing experience had been.
DIGLLOYD: I’ve been having multiple issues with calibration of focus for the M9 and lenses— backfocus in particular. Easy to repeat in the field or a target with various lenses, and that's using the 1.25X magnifier. How has your experience been with focus calibration? Do you take special steps to ensure calibration?

Hi Lloyd,
This is a difficult topic. When testing camera/lens combos with the M9 I often need to adjust focus distance to get best contrast and sharpness. The fact that the focus is not always accurate has different causes: the focusing cam on the lens might be out of tolerance or the accuracy of the rangefinder even in combo with 1.25 magnifier is not sufficient.

DIGLLOYD Too bad. I came to the same conclusion, and was hoping you had some "magic". My experience shows that getting perfect focus with more than one or two lenses for the M9 is a serious challenge.

I use two methods' one crude and one systematic. Crude: On a tripod I focus as best as I can, make the picture and enlarge on the display: if sharp OK if not sharp slightly defocus in one direction and if this is sharper continue. If it is not sharper try the other direction.

DIGLLOYD: I have used the same approach, which I deem “LCD zoom focus”. Alas, the M9 does not zoom in to actual pixels, or even sharp pixels, and the low-res screen further degrades the accuracy of that approach. Close, but no cigar. I discuss the whole composition and focus area at length in my review of the M9. I don’t know why Leica can’t offer a once-per-second Live View, it would help. Or a decent LCD screen. Or sharp actual pixel zoom.

Systematic: on a tripod I have a slider mechanism with 1mm distance scale. I focus accurately and have the slider in mid position. Then I take a series of pictures moving the slider in 1cm steps in both directions for a range of 5 cm. On the computer I select the best image.

DIGLLOYD: I sometimes use a slider setup with a 1mm engraving. It works. But it’s useful only for close up work, not at any distance. And of course some lenses don’t perform as well as when focused close, and some also exhibit shift focus when stopping down, so it’s very tedious for each aperture, and not very interesting for real world images.

The back focus issue is a sign that the rangefinder is at its limits. But so are many DSLR cameras. There you can individually calibrate a lens for the AF system.
— Erwin

DIGLLOYD: We are in agreement here in general. Yes, AF isn’t perfect, but it can focus off-center, and in conditions where a rangefinder is hopeless, and it can do so very quickly. Using Live View zoomed in with a loupe eliminates the focus issue for a DSLR entirely. I've rarely had to calibrate lenses for AF, but it’s a great feature. For precision work, Live View is mandatory anyway, as it eliminates a variable. Even contrast-detect AF can be unreliable, with both Nikon and Canon, observed by experience. The reason we don’t see Live View with the Leica M9 or S2 is that CCD sensors do not support it.
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Click to expand...
 
very interesting stuff Roland. my 35, and 50 pre-asph luxes were both serviced by Sherry by previous RFF owners, and she had to send them to Solms for the special focus/mount alignments, and they ended up focusing fine at min / inf. wide open and stopped down on all my film M's and M8, and multiple RD1s, as well as previous owners various M's.

My 2 75/1.4 luxes were both German ones and I don't know if they were ever sent back, but have heard there is also a machine for that lens.

Have also heard that DAG has serviced many of these same lenses, without needing to match to a specific body, and customers have been happy with results. He can probably get it done without specific machines, but possibly more time consuming than having a special purpose testing/alignment stuff.

Have also heard of many that have sent their lenses, both pre-asph, and 35 asph (v1) and 75/1.4 to Solms, and have not been happy with results or had to send back multiple times.
 
Brian, is it true that some lenses can be/should be adjusted not with shims but by "bending" parts - I am thinking of the collapsible Summicron.

Greetings, Ljós.
 
That and an infinity test (for collimation), Joe, are the most important.

I'm not Brian, but yes, Ljos, the collapsible Summicron is collimated by bending the notches that hold the barrel in the focus helix.
 
Just back from a walk with the Nokton 50/1.1 on the M8. I built up the RF cam by 0.05mm, and it is spot on with the M8. Popflash has an interesting note on the Zeiss Sonnar-C being optimized for film and front-focussing with Digital.

I've also read that the Summicron is collimated by bending the latches for the collapsible mount. All of my early Summircons have been spot-on, and the lenses appear to be individually fit with optics and optical fixtures. It appears to have been made to a Spec and no allowance for small changes to be easily made.
 
I think DAG adjusts lens focus to closely match an M8 standard. I've not sent an M-digital body to him, but have sent most of my M-mount lenses... some were bought used so I was interested in having them checked out or given CLA. One lens didn't need any tweaking (Planar-ZM), one could not be adjusted for unknown reasons (35/1.4 Nokton), and all others needed at least some adjustment for optimum focus on the M digital bodies.

Apparently the M8/M9 are pickier about focus due to their high resolution. And the more resolution you buy, the pickier the cameras get, as I've been reading about medium-format digital focusing problems.
 
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