Backfocusing 75mm lux

[cmogi10]

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I have finally accepted that im going to have to get my backfocusing 75mm lux fixed,

I was just wondering if you guys had any suggestions who to send it too, what kind of price I should look to pay and how long it should take.

Thanks!

Carl

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[edhohoho]

I have seen people recommend DAG (Don Goldberg) for correction of backfocusing on lenses like the Noctilux. Sorry, I don't know how much he charges, but I also hear he can have a relatively long turnaround time if it's a busy time of year. Sherry Krauter of Golden Touch is also a well known Leica repair person.

 

I have also read that if you send your lens to Leica to be 6-bit coded, they will also make sure that your lens focuses according to specifications. But I guess some people have been unhappy with some of the repairs done on lenses and M8s of late.

[colorflow]

I sent my Lux 50 asph to Don just before Christmas and he turned it around in less than two weeks. I did request to have it back asap. The lens is now perfect. I spent 8 months dealing with Leica on the same lens - couldn't convince them there was a backfocusing problem which Don saw right away. Call Don and ask about cost and how long.

 

Alan

[ho_co]

I have all my work done by Leica. They have sent my 75/1.4 to Solms for the same issue you mention. I haven't received a cost estimate; the repair acknowledgment estimated 4-6 weeks turnaround, but I assume it will be longer.

 

Don G is highly respected in the business. Leica has always done good repair work for me. For lens work, those two are the only names that come to mind.

 

But remember, the Summilux 75 is a special lens. According to the LFI article, one reason it was discontinued was the fact that it is likely to show backfocus on the M8. It might be best to let Leica set it up.

 

--HC

[carstenw]

Before you send it away, how much is it backfocusing by, and which other lenses do you own? If there are no other "disagreeing" critical lenses (90/2, 50/1.4 especially), and if it doesn't backfocus by too much, then you might bring it into range with a tweak to the rangefinder wheel.

[glenerrolrd]

Leica worked on this problem with my 75 Lux since last July..but its solved. First I would suggest that yo carefully consider your requirements. Perfect focus calibration is clearly subjective and whats acceptable to one photographer/technician may not be to another. Do you plan on using yours for a lot of available light portraits at close distances? wideopen? This is the most difficult. All Lux s exhibit some focus shift as you stop down. The 75 less than the 35 or 50 (at least thats my experience). In normal usage the apparent DOF covers the focus shift but not always ...if its calibrated for 1.4 spot on ...you may see some back focus at 2 and 2.8. So my view is if you need some tolerance please put it on the front side at 1.4 so that 2.0 and 2.8 become optimum . As you can see lots of room for different points of view. Second.....do you need 6 bit....if you do its only done in Solms for the Lux s. This is because of difficulty in getting and installing new mounts. NJ told me that they tried doing the Luxes but that the mounts themselves require fine tuning and that Solms is better equipped to do this work. Third....don t expect you lens to be calibrated when asking for 6 bit. While they are supposed to check for focus accuracy both in NJ and Solms. My experience is they don t. Others can of course disagree..but if you ask Leica you will find that 6 bit is handled as a volume repair ....no time to make any adjustments and you surely will not get fine tuning . Fourth....its a lot easier to adjust the M8 than a Lux . The first move is always to see if fine tuning the M8 focus can bring the lens into acceptable tolerances. Sometimes the best answer is to split the difference between lenses. On my 75 I wanted it dead on ..the only reason I have it is for wide open available light portraits. On the 35 Lux I accepted a very small amount of front focus at 1.4 because the focus shift moves this to slight back focus at 2.8...but this works as the 35 Lux is for Street photography often in bad light but rarely close up . Having made most of the mistakes possible on this repair...I would recommend that you get you M8 right first and really know the focus characteristics of each lens . Then I would outline my priorities and try to avoid Solms if possible. I couldn t and will eventually get my Lux s sorted out ..my 35 and 75 are now a joy to use . The 50 Lux and 50 Noctilux are both on there 3rd visit to Solms and have been with Leica since july and may respectively.

[mweiner]

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Carsten, I want to make sure I understand your recommendation to tweak

the rangefinder wheel to improve a lens's focusing if

one's other lenses are not "disagreeing".

 

I have these leica lenses:

28 f2 A

32 f2 v IV

35 f1.4 A

50 f2 non A

50 f1.4 A

75 1.4

90 2 non A

 

On my black M8 body, returned from Solms yesterday,

all focus accurately wide open.

On my silver body, all focus accurately wide open except:

35 f 1.4 shows 6 inches back focus.

50 f 1.4 shows 6 inches back focus.

 

Are you advising there is a tweak of the rangefinder wheel on

the silver body that can bring the 35 and 50 into correct focus

without putting the other lenses out of focus?

 

BTW: OT, with my 75 Summilux, the point I focus on

is just on the very far side of the field of focus

(ie tending toward front focus but ok), then at f2-f4

it is perfect.

[ptomsu]

My 1,4/75 is coming back from Solms next week or so - it is the third time there and I am really hoping this time it will work.

 

All my other lenses have gone through that process and are perfect now.

 

So one needs to be really patient but it is worth the wait :-)

[carstenw]

Michael, it sounds like you don't have much choice but to send the 75/1.4 back. The 50/1.4A and 90/2 are both also critical wrt. focus tweaking, so "fixing" the 75 could easily put the other two out of adjustment. However, were it my lens, I would simply try it, to see if I could find an adjustment which made them all happy. If not, tweak it back for the other lenses and send the 75 in.

[ho_co]

...don t expect you lens to be calibrated when asking for 6 bit. While they are supposed to check for focus accuracy both in NJ and Solms. My experience is they don t. Others can of course disagree..but if you ask Leica you will find that 6 bit is handled as a volume repair ....no time to make any adjustments and you surely will not get fine tuning ...

Roger--

I agree that there is no checking for focus accuracy when the mount is changed; but I don't know where so many of us got the idea that that checked would be done. As I recall, the sales points of the 6-bit conversion simply said that the lens would be checked for "optical centration."

 

Well, duh... If you change the mounts, you need to be sure the lens is still centered before returning it to the customer.

 

They've always made it clear that the 6-bit conversion is done almost at cost.

 

I'm glad you reminded us that some of us are expecting too much from the 6-bit coding.

 

 

BTW: OT, with my 75 Summilux, the point I focus on is just on the very far side of the field of focus (ie tending toward front focus but ok), then at f2-f4

it is perfect.

 

Michael--I wish I could say that! At a distance of about 9 m, my 75/1.4 backfocuses about 3 m at around f/4.

 

Also--A lot of people believe in tweaking their rangefinders themselves. I don't except in emergencies. There are three or four different adjustments that are all relevant to getting the rangefinder to work over its range. I don't see any purpose to adjusting one of those and not the others. It's like checking air pressure for one tire and not bothering about the others. I don't want to argue, just stating my opinion.

 

--HC

[Jamie Roberts]

{snipped}Michael--I wish I could say that! At a distance of about 9 m, my 75/1.4 backfocuses about 3 m at around f/4.{snipped}

 

Not wanting to argue about self-adjustment here either Howard, but misfocus like that is hardly "backfocus" or optical design: it's defective.

 

Send that lens or your M8--or both--to someone competent. There's just no way the focus on a properly operating 75 Lux--or any other Leica M lens--is off by 9 feet when focusing 30 feet away at f4!! How on earth could you shoot anything at all with such a system?

[ho_co]

Jamie--

I agree. But I've been using the lens on film quite contentedly for 20 years. So if I send it in, I have to admit my inattention or (dare I say?) stupidity.

 

But you're absolutely correct. I first noticed it on holiday in my first extensive use of the M8; and after returning home, I made some shots specifically to find out whether those were flukes.

 

They weren't. I sent the lens to NJ, and they've sent it to Solms.

 

--HC

[colorflow]

I must be lucky with my 75 Lux which focuses spot on at 1.4 with no apparent focus shift when stopped down. No such luck with my APO 90 which is having a lengthy stay first at NJ and then on to Solms. It's off by 5 feet at 25 ft...

 

Alan

[Jamie Roberts]

Jamie--

I agree. But I've been using the lens on film quite contentedly for 20 years. So if I send it in, I have to admit my inattention or (dare I say?) stupidity.

 

But you're absolutely correct. I first noticed it on holiday in my first extensive use of the M8; and after returning home, I made some shots specifically to find out whether those were flukes.

 

They weren't. I sent the lens to NJ, and they've sent it to Solms.

 

--HC

 

Hey Howard, I hope it all works out for you! And there's nothing particularly inattentive about using that 75 Lux as a near-focus portrait lens for a very long time, where I suspect the effect was minimised

 

But it's true that whenever I buy a used lens from any source, I mentally add the $100 or that Kindermann or DAG will charge to inspect and set up the lens (and of course if it needs to be cutomized it will cost more, I guess. I've never had to do that yet). The 75 Lux--like the 35 Lux--is pretty tricky I guess.

[ho_co]

... there's nothing particularly inattentive about using that 75 Lux as a near-focus portrait lens for a very long time, where I suspect the effect was minimised ...

Jamie, that's a good explanation that I may just appropriate! And it's actually pretty close to accurate.

 

--HC

[cmogi10]

the way it seems my lens doesnt really have any problems focusing close, it's middle and long distances that give it the most trouble.

This is frustrating though. I don't know how to adjust the rangefinder of my camera and don't want to touch it if I could potentially screw things up.

I also cant afford to be without the lens for months at a time.

 

=\

[cmogi10]

Well It's on it's way to Leica.

Hopefully I'l see it again not to far in the future.

[mweiner]

mweiner wrote:

Carsten, I want to make sure I understand

your recommendation to tweak

the rangefinder wheel to improve a lens's focusing if

one's other lenses are not "disagreeing".

...

Are you advising there is a tweak of the rangefinder wheel on

the silver body that can bring the 35 and 50 into correct focus

without putting the other lenses out of focus?

 

carstenw wrote:

Michael, it sounds like you don't have much choice but to send the 75/1.4 back. The 50/1.4A and 90/2 are both also critical wrt. focus tweaking, so "fixing" the 75 could easily put the other two out of adjustment. However, were it my lens, I would simply try it, to see if I could find an adjustment which made them all happy. If not, tweak it back for the other lenses and send the 75 in.

 

I did take a 2mm allen wrench to the infinity focus

wheel on my silver M8, to bring my 50mm 1.4 A lux

into correct focus without throwing my 75 1.4 out of focus.

(I was testing the lenses at 10 feet, wide open and evaluating

at the maximum zoom possible on the M8 LCD screen -- likely

fairly extreme pixle peeping.)

I was finally successful and the result also fixed the

back focus of my 35 1.4 A -- tho in order to minimize its back focus shift that lens needs tweaking so the focus point is at the back rather than the front of the field of focus ).

 

The bottom line is that using the allen wrench I was able to

bring the silver body into the same state as my recently

Solm's adjusted black body so that all of my 7 lenses focus

accurately (to my peeping standards) on both bodies --

tho the 35 is BF from f2 to 4.

 

Much of the credit goes to Don at DAG who had previously

adjusted the 75mm 1.4 and my old 50mm summicron (Canadian from

the 80's) which he says is one of the more tricky to adjust.

The 75 remains accurate (point of focus within the file of focus)

at all f stops despite it's focus shift.

 

The turnaround times were in the order of 6-8 weeks

due to his being swamped by all requests for his services related

to his taking up slack related to Leica's problematic customer service.

However, he was responsive by phone and email.

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Hallo,

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[ho_co]

Bravo, Michael! Glad you were able to tweak it into submission!

 

--HC

[carstenw]

Great, sometimes you can get lucky! I am glad it worked out.