Will 35mm Lux Asph backfocus on M9 ?

[Jamie Roberts]

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{snipped} Sure wish Leica had put a calibration feature in the M9 to circumvent these annoying issues.

 

Amen to that, Jeff!

[mat_mcdermott]

This issue is not isolated to the 35 lux Asph. I am just now starting to use the 35 Cron Asph on my M8s. I had bought this lens for my M7 and there is was married for a long long time. Had no problems whatsoever and it is a brilliant performer on film. This weekend I decided to do a bit of shooting with it on the M8s and noticed that the intended focus point was sharp enough, but all the DOF was behind the plane of focus. I corroborated this on a focus chart, and even at f/8 there is no DOF in front of the plane of focus. Nonetheless, the focus point is sharp at all apertures. It is the oddest behavior I have ever seen. My 21/24/28/75 all perform flawlessly, so I'm quite surprised at the 35 Cron Asph. My concern now is that if i have it adjusted, will it be off on my M7 and M9 (will sell one of my M8s to help fund the M9). Sure wish Leica had put a calibration feature in the M9 to circumvent these annoying issues.

 

I have noticed this with every lens I have put on my M8 from 18mm to 35mm. It's not that there's _no_ DOF in front of the focus point but far, far less than on film. Since it's a constant thing at all apertures I haven't bothered to delve into 'fixing' it and just take that into consideration when focusing.

[adan]

I'm with Henning in that the 35 f/1.4 a) will have the same focus shift on any camera, which will be less noticeable in a print of the same size from the M9 (less enlargement).

 

Leica M's have a calibration feature - it is called an Allen Wrench.

 

Seriously - the focus system of a Leica M is mechanical. Any calibration feature has to be a mechanical adjustment to the levers and such in the RF. "Breaking" the linkages to add some kind of firmware-based adjustment (doing what - driving a little solenoid to move levers based on the lens in use?!) would just add expensive complexity and more parts to get out of adjustment overall.

 

Again - you cannot think of a Leica M as just a cute little SLR with a window in it. It is not that, and never will be. If you can't live with that - don't try to change the M - just move on to an SLR.

[xrogers]

Some seem to have had fits with this lens, but I expect no backfocus issues with my 35 Lux asph on the M9.

 

A quick 35 Lux backfocus story.

 

I've posted here numerous times in response to 35 lux asph backfocus gripes that my lens worked beautifully. It does focus shift, but the point of focus is always within the depth of field. It is a gorgeous lens, my favorite on both film Leicas and the M8.

 

I'd been noticing that over the past few months, I'd been missing focus with the lens more and more. I thought maybe my eyes were failing (I just got glasses for the first time this year), and that maybe the M was going to become an issue for me.

 

It eventually got so bad that I did some real tests. Sure enough, the lens markedly backfocused. Augh! What happened?

 

I calmed down and went over the lens with some care. I found that the rear element group had come loose, about a third of a turn. Snugged it up, and the lens is back to dead on.

 

My lens doesn't backfocus. At all. I love this lens, and have zero interest in a replacement version. And I'm looking forward to seeing its corners again on a digital Leica.

 

Later,

 

Clyde

[Jamie Roberts]

I'm with Henning in that the 35 f/1.4 a) will have the same focus shift on any camera, which will be less noticeable in a print of the same size from the M9 (less enlargement).

 

Leica M's have a calibration feature - it is called an Allen Wrench.

 

{snipped}

 

 

Andy--I don't think of the M as a cute little SLR. And I know its focus mechanism is mechanical. But there is no good way of calibrating that mechanical system outside of Leica NJ or Solms.

 

Even Kindermann here in Canada, which does a great job, can't, for instance, check sensor alignment or mount vis-a-vis sensor, which is so much more critical for focus with digital than the actual rf mechanism.

 

So it would be nice to have something that "zeros" out minor mount differences or reports on a sensor mount out of spec. That would really help; even better would be some simple way to ensure mount and sensor alignment.

 

I mean, I remember poor Tim's 35 Lux ASPH experience, where he had back focus on the order of 15 feet at f 4 at 20 feet. I mean really--that's a misaligned system (he had two unfortunately so he thought it was the lens. It might have been--but nothing was in spec, and no Allen key / wrench can fix that).

[adan]

Jamie - I read you - I think

 

But that still means something moving something, correct? Otherwise, it may inform you of a problem, but a trip to the service shack is still required to physically change the location of the sensor, or adjust the RF.

[Jamie Roberts]

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Jamie - I read you - I think

 

But that still means something moving something, correct? Otherwise, it may inform you of a problem, but a trip to the service shack is still required to physically change the location of the sensor, or adjust the RF.

 

Yes... you got it.

 

And minimally it could confirm if something was out of whack apart from the RF mechanism itself--some way of checking the mount and sensor--and that might require a trip to service (where they could actually fix sensor or mount alignment).

 

Even better would be "something moving something," as you put it, to tweak things back to workable (within a certain set of tolerances, of course) more or less akin to the individual lens adjustments the dSLRs have these days. I wasn't thinking at all of something virtual and done in post.

[jaapv]

 

Leica M's have a calibration feature - it is called an Allen Wrench.

 

.

I know it is tongue-in-cheek, but just in case anybody takes this seriously: DON'T !

A very reputed M repairman explained to me at great length that the adjustment is for infinity only. There are two other adjustment points. Moving one will affect the others. Unless you are a habitual lottery winner, "adjusting" for infinity with the allen wrench will throw out the rest of the focussing at closer distances.

[markowich]

Again - you cannot think of a Leica M as just a cute little SLR with a window in it. It is not that, and never will be. If you can't live with that - don't try to change the M - just move on to an SLR.

 

can you think of the m9 as a cute little leica retro design camera with a minuscule glass window in it ?

why be condescending to (D)SLRs?

peter

[jaapv]

What do you mean he is trying to "keep the magnification of the subject constant"?

The magnification (let's assume you mean the size of the image on the sensor) is constant, when it's the same lens focused at the same distance.

Say it's a full shot of a friend standing: his image on the M8 sensor has the feet touching the bottom of the picture and top of his head touches the upper frame of the picture. Now you put the same lens on M9 without moving. The sensor is bigger so the friend's image now gains "air" below and above and occupies 18/24=75% of the picture height (M8 sensor is 27x18mm, M9 36x24). If what you want to do is increase the size of the friend's image so he again is 100% of the sensor's height, you INCREASE magnification. You do it here by walking towards the subject (although the real meaning of magnification would call for a change of the lens)

You should not compare DOF when walking in and out and changing focussing distances for the same lens put on different sensors-too many variables. What's the point?

DOF will depend now on CoC (which is 0.023mm for M8 and 0.030mm for M9) AND the focussing distance (given constant aperture).

The 35mm/1.4 summilux comes from the full frame world. It's image circle is for the 36x24 frame. It's shortcomings might show on the smaller sensor but are not so obvious on the full frme one, IMHO.

Well, it does make sense if you are trying to take the same image (with admittedly different perspective), which is what happens in the real world.

[SJP]

Sorry for the confusion (I was confused myself), excutive summary:

 

35 f/1.4 on the M8 has a smaller depth of field than 35 f/1.4 on the M9 (FF), due to the larger circle of confusion for FF. (1.46m DOF at 5m, and 1.96m DOF at 5m respectively). Less back/frontfocus problems on the M9 are to be expected.

 

35 f/1.4 on the M8 has the same perspective as a (roughly) 50mm lens on film/FF but it's depth of field is larger than a 50 f/1.4 would have on a FF camera. If you do an 'equivalent' focal length comparison it behaves roughly like a 50 f/2 would on film/FF (a 46.55 mm lens on FF at f/2, 5m has a DOF of 1.48m, note 35mm x 1.33 = 46.55mm). In terms of light capturing efficiency it is f/1.4 - that doesn't change.

[nugat]

Well, it does make sense if you are trying to take the same image (with admittedly different perspective), which is what happens in the real world.

 

 

A real world situation I can imagine is:

You were taking a picture with your M9/35mm/f.1.4 from 10 meters (5 meters). Your DOF was 7.84m (1.77).

Your M9 failed. You reach for your back up M8, move the lens from M9 to M8 . At the same 10 (5) meters and f1.4 your DOF is now 5.69m (1.34). You want to recompose so that the subject returns to the same height in the frame. You start backing off and find out that at 11.58m (5,73) your DOF is already same-7.84 (1.77) . But you need the subject still smaller and stop at 13 (6.5) meters. Here your DOF is 10.2 m (2.30). Meanwhile your perspective changed and it's a different picture altogether.

I would have on the back up camera a ready backup lens like a 28mm (Ultron 28/1.9 is nice) to match your main gear and keep the perspective unchanged. Saves time (changing lens, moving back and forward, recomposing) and worries.