Jump to content
Sign in to follow this  
miboss

Backfocusing lenses. Is it a Leica-only disease ?

Recommended Posts

Advertisement (gone after registration)

Focus tests on Voigtlander 35/1.2 - pretty good for a lens which cost me €800 brand new. I think the first image at 1.2 is as one might expect, just a tad soft, with perhaps a tiny bit of front focus but even with a 1.25 magnifier, that could well be the idiot behind the lens. The second and and third at f2 and f4 respectively are every thing I could wish for. Three cheers for Mr. Kobayashi's quality control. Maybe Leica could send someone to Nagano to see how he does it.

 

Wilson

Share this post


Link to post
Share on other sites

Please help me understand this....

 

I just bought an M8 last week. I have back focus issue when I mounted it with 50 Asph Lux and shot at variouse f stop and speed@auto. Close focus, it is off by about an inch and teh focus area is totally out of focus.The further the subject, it back focus about 1, 2, or 3 feet behind. I did not even want to mount my Nocti on the camera and shoot @f 1 nor did I want to mount any other lens when I saw the problem.... Needless to saw the camera is going back today.

 

In this thread...

 

I am hearing that it is acceptable? - How can it be acceptable when I have so many other film M's that never gave me such issue? I focus @ the eye @ close distance or any distance, wide open and I get prints, big and small, with the eye focused.

 

I am hearing that we can adjust our focus to compensate? - Again, why get a Leica M if we can not focus exactly where we want to focus, rather that focus somewhere else and hope that it is correct. i.e. why focus the ears when we want the eyes focus?

 

I am hearing that we need to send our lens and M8 to get it calibrated to get them matched up? - I have a lot more than 10 M lens... Do I have to send them all with my M8 to get it calibrate? After that will I then have to send all my other film M cameras to get them calibrated since all my lens are now calibrated for my one and only digital M8?

 

Wow... Is this a mistake and is this the recomendation?

 

I envy those folks who do not have backfocus issue.

Share this post


Link to post
Share on other sites

I agree with IMR's sentiment.

 

It's a fundamental right of a camera owner to expect to be able to use the camera's controls to consistently focus an image. Any camera not meeting that basic need is failing in its design.

 

I'm a recent M8 owner and new to rangefinder shooting. I've been having trouble getting consistent focus with the 75 f/2 Summicron. I've been giving myself time to get used to split-image manual focusing, but have started to suspect something else at play and this thread seems to confirm my concern.

 

Could someone suggest a systematic way to test and determine the degree to which backfocusing may be present in a lens?

Share this post


Link to post
Share on other sites

I can only say this: the easiest thing to check is to toddle over to the local optician and check if there is some unnoticed eye problem, and use his test lenses between the eye and viewfinder window to see which one will make the rangefinder snap into focus. This is not being smug. I cannot focus correctly with my longer lenses with either the unaided eye or my fully corrected glasses, but I have one pair of spectacles that I cannot read with because they are to weak, but it gives me perfect focus on my M8's.

After that cause has been eliminated it is time to look further at the lens, camera, etc.

It runs contrary to logic, but one must have perfect eyesight at about 3 meters to focus correctly and consistently with a rangefinder camera.

Share this post


Link to post
Share on other sites
Focus tests on Voigtlander 35/1.2 - pretty good for a lens which cost me €800 brand new. I think the first image at 1.2 is as one might expect, just a tad soft, with perhaps a tiny bit of front focus but even with a 1.25 magnifier, that could well be the idiot behind the lens. The second and and third at f2 and f4 respectively are every thing I could wish for. Three cheers for Mr. Kobayashi's quality control. Maybe Leica could send someone to Nagano to see how he does it.

 

Wilson

 

Hi Wilson,

 

If you do some very gradual focus bracketing, I think you'll see that your F/1.2 image is out of focus a hair. As you know, at F/1.2 every hair of focus change counts. A good copy of the lens is quite sharp on center and, as I showed in the review, shows no noticeable focus shift as it is stopped down.

 

Glad you like the lens so far.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites
Please help me understand this....

 

I just bought an M8 last week. I have back focus issue when I mounted it with 50 Asph Lux and shot at variouse f stop and speed@auto. Close focus, it is off by about an inch and teh focus area is totally out of focus.The further the subject, it back focus about 1, 2, or 3 feet behind. I did not even want to mount my Nocti on the camera and shoot @f 1 nor did I want to mount any other lens when I saw the problem.... Needless to saw the camera is going back today.

 

In this thread...

 

I am hearing that it is acceptable? - How can it be acceptable when I have so many other film M's that never gave me such issue? I focus @ the eye @ close distance or any distance, wide open and I get prints, big and small, with the eye focused.

 

I am hearing that we can adjust our focus to compensate? - Again, why get a Leica M if we can not focus exactly where we want to focus, rather that focus somewhere else and hope that it is correct. i.e. why focus the ears when we want the eyes focus?

 

I am hearing that we need to send our lens and M8 to get it calibrated to get them matched up? - I have a lot more than 10 M lens... Do I have to send them all with my M8 to get it calibrate? After that will I then have to send all my other film M cameras to get them calibrated since all my lens are now calibrated for my one and only digital M8?

 

Wow... Is this a mistake and is this the recomendation?

 

I envy those folks who do not have backfocus issue.

 

The first step would be to have the camera checked to make sure that the RF is correctly adjusted. Until that is confirmed, all other tests can be misleading.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites

Advertisement (gone after registration)

Hi Wilson,

 

If you do some very gradual focus bracketing, I think you'll see that your F/1.2 image is out of focus a hair. As you know, at F/1.2 every hair of focus change counts. A good copy of the lens is quite sharp on center and, as I showed in the review, shows no noticeable focus shift as it is stopped down.

 

Glad you like the lens so far.

 

Cheers,

 

Sean

 

Sean,

 

Here is my focus bracketing series. I still think the lens is a touch soft at 1.2 but these are big magnifications, as the chart is taken at 2 meters distance and it is not something that terribly worries me. Part of it is the old thing again, somewhat lower contrast as much as focus softness. The contrast seems noticeably higher to me at f2.0.

 

Wilson

Share this post


Link to post
Share on other sites

Do an Internet search for "Canon f/1.2 50mm focus problem" and see what you get. It's not a Leica only phenomenon!

 

(And yes, the brand-new flagship Canon f/1.2 50mm lens doesn't always focus accurately with all cameras, most notably, the 5D)

 

When last I heard (two months ago) "they were working on it."

Share this post


Link to post
Share on other sites
Sean,

 

Here is my focus bracketing series. I still think the lens is a touch soft at 1.2 but these are big magnifications, as the chart is taken at 2 meters distance and it is not something that terribly worries me. Part of it is the old thing again, somewhat lower contrast as much as focus softness. The contrast seems noticeably higher to me at f2.0.

 

Wilson

 

Gotcha. You're right about the effects of lower contrast on one's impressions of resolution. I hope it works out well for you.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites
Sean,

 

Here is my focus bracketing series. I still think the lens is a touch soft at 1.2 but these are big magnifications, as the chart is taken at 2 meters distance and it is not something that terribly worries me. Part of it is the old thing again, somewhat lower contrast as much as focus softness. The contrast seems noticeably higher to me at f2.0.

 

Wilson

 

Gotcha. You're right about the effects of lower contrast on one's impressions of resolution. I hope it works out well for you.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites
I know Micheal the brand new ones are the ones that folks are having focusing issues with are more the concern. I don't disagree here. i have seen them being built in the factory last month and it is amazing how it is done and we did see the calibration room for every lens that goes out the door. So i know the frustration , a couple of mine are being adjusted also even a pretty new 50 lux

 

just back from NJ. brand new 75 cron was set "beyond infinity" - will be ready in a few weeks. sigh.

Share this post


Link to post
Share on other sites
Hi Andy,

 

That's similar to what many people have experienced, unfortunately. Did you happen to notice if there was much static in the area where this happened? Conditions? Dry?

 

Cheers,

 

Sean

 

Sean

thanks for the question...

it was literally on the beach,,pretty humid and hot 35degrees and 80% humidity at a guess, but nothing spectatular.

 

Jerusalem today was as fascinating as always and had a great time even wIthout the M8!

Travelled light with my baby Canon and all was well:)

 

the falafel were tasty and the turkish coffee strong, just like it should be;)

 

regards

Andy

Share this post


Link to post
Share on other sites
The first step would be to have the camera checked to make sure that the RF is correctly adjusted. Until that is confirmed, all other tests can be misleading.

 

If the focus shift increases with the increasing of the distance of the subject, than it could be the same problem my M8 had: the sensor is mounted too far (frontfocus) or too close (backfocus) from the lens. A matter of a fraction of a millimiter. In my tests before sending it to Leica, all lenses couldn't reach infinite (focus on images was closer > frontfocus). This is independent from the rangefinder.

I am expecting the M8 back next week.

Share this post


Link to post
Share on other sites
It is hardly intentional - It would be better to call it unavoidable....

Jaap--

Compare the ways Leica and most Japanese brands design high-speed lenses:

 

In general, the Japanese tend to design so that the lens is quite soft wide open; the f/1.4 tends to be there as a kind of 'advertising aperture,' there if you need it, but you would really prefer not to open beyond f/2.

 

Leica, on the other hand, designs so that the open aperture is still fully usable. It's not as good as stopped down, but not just a 'last chance' opportunity.

 

In other words, Leica uses its design tools differently from others to control how the focus shift works. This makes the lenses more expensive (the designs are more stressed) but gives the Leica lenses the performance that is their hallmark.

 

The presence of focus shift is unavoidable; but how its presence is used is calculated.

 

--HC

Share this post


Link to post
Share on other sites
I can only say this: the easiest thing to check is to toddle over to the local optician and check if there is some unnoticed eye problem, and use his test lenses between the eye and viewfinder window to see which one will make the rangefinder snap into focus. This is not being smug. I cannot focus correctly with my longer lenses with either the unaided eye or my fully corrected glasses, but I have one pair of spectacles that I cannot read with because they are to weak, but it gives me perfect focus on my M8's.

...QUOTE]

 

"Unnoticed eye problem"? LOL I feel sorry for Leica having to sort all these claims about focusing problems. After all, the typical M8 owner is a presbyopic geezer who can't see anything within 3 feet of his face, not even the liver spots on the backs of his hands.

Which fact really makes me wonder why all the obsession about sharpness or, is it in fact the reason for all the obsession about sharpness. If there's enough acuity, due to the lack of an AA filter, maybe the print looks a lot sharper from a distance of 3 feet than otherwise.

Could it be that a young person who sees clearly at a distance of one inch would see M8 prints as brittle and full of jaggies and other aliasing artifacts?

You can't say, can you? Heh, heh, heh.

 

The situation reminds me of the phenomenon of aging audiophiles who can't hear a thing beyond 10 Khz, but who staunchly defend vacuum tube amplifiers and vinyl records as the pinnacle of perfection.The only difference being that the Leicaphiles can back up their claims with MTF numbers even if they themselves would be sweating bullets to pick out a Summicron shot from a Quantaray at a distance of 10 inches.

 

George Deliz,

Presbyopic Geezer without liver spots. At least I don't see any.

Share this post


Link to post
Share on other sites

Erwin Puts explains why Leica lenses show more focus problems:

 

Testreports

 

Zeiss has claimed that their lenses are designed to exhibit less focus shift than is usual, but part of the claim is based on a different location of the focal plane: a kind of average position so to speak. Not as good for best wide open performance, but better for stopped down performance. Leica has adopted the opposite approach: optimize for wide open performance and let the focus shift be compensated by depth of field.

Share this post


Link to post
Share on other sites
Sean

thanks for the question...

it was literally on the beach,,pretty humid and hot 35degrees and 80% humidity at a guess, but nothing spectatular.

 

Jerusalem today was as fascinating as always and had a great time even wIthout the M8!

Travelled light with my baby Canon and all was well:)

 

the falafel were tasty and the turkish coffee strong, just like it should be;)

 

regards

Andy

 

So much for static in that case. I'm glad you're having fun nonetheless.

 

Cheers,

 

Sean

Share this post


Link to post
Share on other sites

Every time there is a thread like this one about the M8 back focus problem it seems to get steered off track to focus shift.

 

I have now had four M8 bodies with severe back focus faults out of the box. Not focus shift, not operator error, not eyesight problems, not old lenses, just plain and simple severe back focus.

 

Sooner or later Leica and some of their defenders here will have to admit that this camera or Leica's assembly, calibration or quality control has a serious problem.

 

Now I know some people here have M8s that focus correctly with all their lenses and I know that some here have some lenses that focus and some that don't which is obviously a lens problem,but there are still a lot of people here and on other forums who have M8s that don't focus properly with any of their lenses. (just because you can get by due to DOF doesn't mean the cameras not faulty)

 

Come on, lets stop pretending there is no problem here. Its not a characteristic its a fault!!!!

Share this post


Link to post
Share on other sites
I can only say this: the easiest thing to check is to toddle over to the local optician and check if there is some unnoticed eye problem, and use his test lenses between the eye and viewfinder window to see which one will make the rangefinder snap into focus. This is not being smug. I cannot focus correctly with my longer lenses with either the unaided eye or my fully corrected glasses, but I have one pair of spectacles that I cannot read with because they are to weak, but it gives me perfect focus on my M8's.

...QUOTE]

 

"Unnoticed eye problem"? LOL I feel sorry for Leica having to sort all these claims about focusing problems. After all, the typical M8 owner is a presbyopic geezer who can't see anything within 3 feet of his face, not even the liver spots on the backs of his hands.

Which fact really makes me wonder why all the obsession about sharpness or, is it in fact the reason for all the obsession about sharpness. If there's enough acuity, due to the lack of an AA filter, maybe the print looks a lot sharper from a distance of 3 feet than otherwise.

Could it be that a young person who sees clearly at a distance of one inch would see M8 prints as brittle and full of jaggies and other aliasing artifacts?

You can't say, can you? Heh, heh, heh.

 

The situation reminds me of the phenomenon of aging audiophiles who can't hear a thing beyond 10 Khz, but who staunchly defend vacuum tube amplifiers and vinyl records as the pinnacle of perfection.The only difference being that the Leicaphiles can back up their claims with MTF numbers even if they themselves would be sweating bullets to pick out a Summicron shot from a Quantaray at a distance of 10 inches.

 

George Deliz,

Presbyopic Geezer without liver spots. At least I don't see any.

 

It seems you have not much experience with rangefinders - this aspect is nothing new. In my book it is kinda stupid, when there is a problem, not to start eliminating causes at the beginning of the chain and work your way through the whole process. The ideological approach is not very effective in most cases

Share this post


Link to post
Share on other sites
just back from NJ. brand new 75 cron was set "beyond infinity" - will be ready in a few weeks. sigh.

 

I know I've read about this problem before but can't find the reference. What's the best way to tell if your lens is not focusing correctly on infinity?

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...