Close range backfocus

[FlashGordonPhotography]

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Be it far from me to criticize you, Jaap, but please tell us where the shims are.

.

 

Shims are directly behind the lens mount flange. Found that out when I replaced the rear mount that I had damaged a couple of years ago.

 

Gordon

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[xixi_gelly]

Re: this topic, I've had some issues with RF focusing in the past. It was swiftly and professionally handled by DAG. I tried making adjustments myself and went half-mad. Some people seem to have success with the DIY method but it's definitely not for me.

 

One question I've sometimes pondered: is there any rational justification in suspecting that frequent lens changes may slowly degrade RF accuracy over time? Considering M's get taken into war zones and all the abuse they get while still ticking along it seems unlikely.....but I can't help being a bit paranoid after my last RF focus nightmare.

[jaapv]

Not really. Up to the M240 the RF adjustment sometimes went out of calibration by mechanical impact, like vibrations from (old) light aircraft or being dropped, but the 240 is much improved in that respect.

[david strachan]

With my M-P ( and electronic viewfinder) the only lens I found to back focus was the Voigtlander 35mm f1.4 sc....fully open is fine, but closing aperture start to shift backwards...I can work with it though.

 

All my old Canon ltm's...perfect. 35mm f2, 50mm..f1.2, f1.4, f1.8, 135mm f4...wonderful lenses really.

Summicron collapsible 50mm (built in 1952) perfect focus also.  Elmar-c 90mm f4 ....perfect focus through the range.

 

I'm yet to find one OOF, except the Voigt 35...which is famous for it's focus problems (which probably isn't  a real issue anyway).

 

It's been said if you pixel peep...you'll find problems which can lead to dissatisfaction.

 

cheers...

 

PS I pixel peep anyway...   and am always amazed by modern imaging.

Edited November 29, 2016 by david strachan

[Alistairm]

I have found a technician in Sydney. Initial testing shows that both my Noctilux and my Summicron 50 APO need adjustment to focus at infinity, so it looks like a lens issue rather than a camera issue, but I'll know definitively in about a week.

 

I am quite content having to fiddle around with these things as part of the rangefinder experience, but looking forward to having everything properly calibrated again!

[Leica Jockey]

I have found a technician in Sydney. Initial testing shows that both my Noctilux and my Summicron 50 APO need adjustment to focus at infinity, so it looks like a lens issue rather than a camera issue, but I'll know definitively in about a week.

 

I am quite content having to fiddle around with these things as part of the rangefinder experience, but looking forward to having everything properly calibrated again!

I was told that lenses sometimes need to be shimmed in order to work perfectly on digital Ms because of the fact that the sensor is perfectly flat and film has more room for play. Essentially some lenses will need to be matched with your M digital body, but this means you may not be able to swap that lens onto another Leica M digital body and get the same results. The problem is Leica M 240 should have been designed with the ability to micro adjust the lenses the way DSLR do these days. I really think this is why the Leica M 240 has live view. 

[jaapv]

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Sorry, that is completely incorrect. Both lens and body -all lenses and bodies- must be adjusted to a common standard.

It may well be that lenses that perform well on film must be adjusted for a digital camera, but that is because they were inside the tolerance span for film, which is less flat and has a thickness, and outside the tolerance span for sensors.

After adjustment they will be just as good, possibly better, on all M cameras that are properly set up.

 

A lens will be never matched to a particular body. The only thing that could be done is when a critical lens is already properly adjusted, and a body as well, to get a super-match by tolerance matching. But both body and lens will still be within the tolerance span of the system and will not need to be readjusted when used with other bodies/lenses.

 

Let's not promote a myth.

[david strachan]

Exactly, as we expect from Jaap.

 

If it wasn't a "common" standard the M system wouldn't work at all...with any lenses.

 

Take your lenses along to have recalibrated, and if your camera is to specifications, you can expect "perfect" focus with your calibrated lenses.

 

cheers..

[lct]

Re focus shift of the CV 35/1.4 SC referred to by David above. It has nothing to do with the camera of course but it is a serious issue for me to the point that i don't use the lens anymore. May be used w/o focus problems at f/1.4 though. 

Edited December 19, 2016 by lct

[david strachan]

That's right lct.

 

Also have an older 28mm f3.5 ltm by Voigtlander.  That back focuses too.  You've given up on them, don't blame you.  It's very disappointing on the CV lenses they are so beautifully built and nice to use, in a tiny profile.

But we do like things exact...

cheers 

[jto555]

I personally find this need for regular (albeit infrequent) calibration A big, painful drawback with M cameras. Big enough to make me now seriously consider moving away from Ms after over 30 years of use.

I use the "holy trinity" of Canon lenses, 16-35 (Mk I), 24-105 (Mk I) and 70-200. The 124-105 need constant adjustment as an element pops regularly. It is not a back-focus issue but one where one side of the frame is out of focus while the other side is pin sharp. The only way around this is to get the lens adjusted every year by Canon. I have put the issue down to carrying my kit around in a roller camera bag and the vibrations pop a lens element. One would hope that the Mk II version of the 24-105, which is about double the price of the Mk I version, to be a bit more robust. So, Dear Santa...

My Leica kit, which is lighter, gets carried amount in a backpack camera bag to reduce those vibrations.

Even the big names have focus reliability issues!

[ModernMan]

Shims are directly behind the lens mount flange. Found that out when I replaced the rear mount that I had damaged a couple of years ago.

 

Gordon

 

 

I've noticed that my older M lenses (70's and 80's vintage) have shims behind the lens mount flange, as Gordon says. In one case (135/2.8) the flange itself was thinned by a small amount (although I'm not sure that was done by the factory).

 

However, on more recent lenses (produced in the last 5-8 years roughly) I've not encountered any shims on disassembly. Have others? Maybe its just luck of the draw -- I've only disassembled a half-dozen or so. But, perhaps the necessary adjustment to the properties of the particular optical cell are entirely custom machined in the mount now-a-days? As I understand it, the rangefinder cam has to be custom machined to accommodate any deviation from the nominal focal length anyway. So, I wonder how recently-manufactured lenses are "adjusted", particularly by non-factory technicians.

[Alistairm]

I took my gear in. Neither camera was adjusted at all. Both of the 50mm lenses were calibrated (the Noctilux 0.95 and the Summicron APO). Total cost was $250, which I don't mind as they're expensive lenses and both are now focusing perfectly on both of my M bodies. 

 

The also focus perfectly on the SL of course. I surmise that on non-rangefinder systems a lens being marginally out of alignment doesn't matter, as you're literally focusing "as the sensor sees it". But on the rangefinders any lack of alignment leads to a focus inaccuracy. A peccadillo, but one I can happily live with given the balance of the experience and now that I've found a brilliant technician in Sydney who can make the adjustment when required. 

 

Alistair 

[huckles]

@Alistairm, who is this technician you've found in sydney?

[Steve Ricoh]

Any UK technicians or dealers in the UK who can perform adjustments to the M240 and/or lenses, anyone know?

[Alistairm]

@Alistairm, who is this technician you've found in sydney?

@huckles 

 

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