Is back focussing lens specific?

[nscali]

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I am goin nuts!

My 50mm Noctilux appears to have back focus issues.

In other words the object behind the 'focused' (about 2-3cm) area is in focus, yet the subject is slightly out.

On the other hand, my 35mm summicron appears to be OK on the same shot.

When I intentionally throw it out of focus slightly (using the 35mm) the image seems to be that way.

I understand that the 35mm lens will be more forgiving but I am trying to determine if

the camera is at fault or is it just the lens?

Any thoughts?

Thanks,

 

Nicky Scali

[ho_co]

Nicky--

It can be lens specific, since each lens is different and has its own focusing cam.

 

It can also be a misadjusted camera rangefinder, in which case (barring lens differences), all lenses would show the same error.

 

There have been several threads on this topic, and I think the consensus is this:

1) check the body with other lenses to be sure it's not the body

2) individual lens focus can be adjusted by Leica if necessary

3) apparently we're suddenly discovering the problem because digital sensors are less forgiving of focusing inaccuracy than film

 

See also http://www.leica-camera-user.com/digital-forum/12697-m8-backfocus.html.

 

--HC

[nscali]

Howard,

Thanks for the reply.

It seems as though the problem exists on the other lens but it is not as apparent.

If you shoot the same thing twice, one focused, the other just slightly out, the one that was shot just slightly out of focus appears every so slightly sharper on screen.

Something you may not pick up.

The 50mm lens obviously 'amplifies' the problem.

Is it worth getting adjusted?

 

Thanks,

 

Nicky

[robbegibson]

I was told by someone at Leica in NJ back in November (when I called re my Noct doing the same thing) that the lenses sold now that are marked 'digital' (which includes the 6-bit coding) are focus adjusted to much tighter tolerances than pre-digital. He said that they will check and adjust focus for no extra charge if requested when a lens is sent for coding. OTOH, my noct is still in warranty, so they should check and fix if coding isn't desired.

 

I think it's interesting that most of the complaints are about back-focus and few are about front-focus.

 

Robbe Gibson

[ho_co]

Is it worth getting adjusted?

Nicky, as far as I'm concerned, it is.

 

It bothered you enough to ask about it; it won't go away on its own.

 

If you can train yourself to focus, and then to crank the focus a bit forward before taking the picture, then it may not be worth the time and effort.

 

But if you're trying to get a person's eyes sharp while you're both moving (at least if you're both breathing ), while also trying to get a good expression, you've got enough on your mind.

 

I say let Leica check and adjust it.

 

What Robbe says is interesting; I've been surprised at how many people are running into the problem, and it sounds as if Leica is aware that something needs tweaking in their production procedures. The problem seems to be mainly with the Noctilux, but an acquaintance used the new 28/2.8 at an LHSA meeting in Solms and found that it also tended to backfocus.

 

--HC

[nscali]

Howard,

Just sent the camera & 50mm lens in to my dealer to get adjusted. I assume it will go back to Germany.

I suppose the principal is that when you spend this amount of money on a kit you would want the focus to be accurate...

I think you are right. The digital senor has obviously caused this issue to come out, and quite truthfully if I didn't have the Noct. lens I honeslty would't have picked it up.

I felt that all my images from the 35mm lens were a little 'soft' but thought that it was just a characteristic of the camera. Until now I have only been comparing against my Canon 5D, which is pin sharp. Clearly there are probably a lot of M8's out there with the same problem, just undiscovered and Leica are waiting for the problems to come to them.

Thanks for your replies.

Nicky

[ho_co]

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Nicky--

You're welcome. Glad to help where I can.

 

But now I'm beginning to wonder if my response isn't possibly an over-reaction. Just for informaton's sake, check out posts 25-28 of the thread http://www.leica-camera-user.com/digital-forum/12697-m8-backfocus-2.html.

 

I'm not sure why so many people have noted focus issues with the M8. Maybe it's because we can view the image immediately at 100%? Maybe digital just seems more in- or out-of-focus? If so, why should that be?

 

It looks like something we need to be aware of with the M8, and I'm very curious why the problem has suddenly arisen. I worked for Leica for a number of years, and we almost never had any complaint of lenses not focusing correctly. This sounds like something related to digital, because a rangefinder camera requires focus accuracy. And although I don't doubt that Robbe was told that Leica will be taking more care in setting focusing cams, I don't understand why that should suddenly become necessary. Leica has always had very tight tolerances for everything.

 

--HC

[FT2509]

Hi,

I am new in this forum and in Leica community (with M8); I had constated the same focus problem (arround 2/3cm out of focus) with my new 6bits coded Noctilux. My french dealer had noted the same problem with another new Noctilux and both of them go back to Solms. Regards.

[pelikan1931]

I tried a demo M8 with noctilux, the same problem, the focus patch does not match at infinity, maybe this is another of those "bugs", maybe it is difficult to accomodate all those lens.