M8 + New 50mm Summilux - Focus ring issue?

[quarth]

Advertisement (gone after registration)

All - I am admittedly new to both the world of RF's, and obviously to the M8. But, in my hands, I have an M8 and a 50mm Summilux (f/1.4). I've been playing around with this in a controlled environment, and am thinking I ended up with a bad copy of the lens...

 

Here's what I see, and I'm hoping someone can shed some light...

 

1 - A-priority, f/1.4, M8 mounted on tripod with ruler used as the object on which to focus (set up at a 45 degree angle from the camera)

2 - Focus ring turned entirely to the right, such that the "." in "0.7" lines up with the 16 (set to minimum focusing distance)

3 - Move tripod such that center of frame is perfectly in focus in the VF

4 - Take picture #1

5 - Turn focus ring slightly to the left, such that the "." in "0.7" lines up with the 11 (instead of 16); this does NOT change the focus in the VF AT ALL (and, yes, I'm sure) -- the focus only changes after you continue rotating the focus ring to the left, past the 11, to the markings for f/8, f/4, etc; in fact, the focus ring is noticeably "looser" when rotated back and forth on the far right side (again, when the "." in "0.7" is between the "11" and "16" on the right side of the lens.

6 - Take picture #2

7 - Compare pictures #1 and #2 in the LCD (zoomed all the way in), and it is obvious that #1 is tack sharp, and #2 is out of focus (although the VF would've led me to believe both were in focus).

 

Assuming this is an issue (I can't imagine how it wouldn't be), is my best bet just to take the lens back to the dealer I purchased it from to have them exchange it out? (I've only had it for 2 days, and it was purchased brand new.)

 

Thanks....

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[adan]

First, with regard to 5) above - it is not unheard-of that some M rangefinders "disconnect" (stop moving) just prior to the absolute minimum focus of the lens. The RF mechanism hits a physical stop, and no longer tracks as the lens moves out that last fraction of a mm. I've seen references to this happening with practically every M model made, from the M3 on up. It is an adjustment problem that local Leica agencies should be able to tweak without a trip to the factory.

 

You can see this stop inside the mouth of the camera, up in the "roof": behind the main RF follower cam (a metal roller on an arm that touches the back of the lens and tracks its movement) there is a second little short arm made of twisted sheet metal that hits a small round bumper and limits the forward movement of the whole mechanism.

 

Leica only claims focusing down to .7 meters, so anything closer than that and you are technically on your own - but it is still usually handled as a warranty repair to tweak that arm and/or bumper location to allow a bit more travel so that the full travel of lenses (above and beyond the marked distances) function fully.

 

However, in that case, the RF should be RIGHT for your shot #2 and wrong for the closest-limit shot (#1) - where the cam has disconnected. So it sounds like you have a real RF misadjustment at least at the close end of the range, as well as the "disconnect" at .7 meters. Again, this should be repairable by Leica USA or the equivalent for other countries and not need to go back to Germany.

 

Curiousity. How's the infinity focus?

[quarth]

Adan - first, many thanks for the detailed response!

 

However, in that case, the RF should be RIGHT for your shot #2 and wrong for the closest-limit shot (#1) - where the cam has disconnected. So it sounds like you have a real RF misadjustment at least at the close end of the range, as well as the "disconnect" at .7 meters. Again, this should be repairable by Leica USA or the equivalent for other countries and not need to go back to Germany.

 

Curiousity. How's the infinity focus?

 

Makes sense to me. As for the infinity focus, I just did some additional testing, and it is spot on. I shot an object about 15 blocks away, and it was incredibly crisp. Backing the focus off from infinity just a smidge blurred the image slightly, as would be expected.

 

When you say this should be repairable by Leica USA, it seems that since this is a 2-day old lens, I would be better off just exchanging it for another "new" one. This is my only M8 lens, so I'm not too excited at the thought of sending the lens in to Leica for calibration, which I assume would take weeks, if not months. Thoughts?

 

FYI - I'm in Denver as well, and purchased the lens from a local camera shop.

 

Thanks, again!

[marknorton]

This lens has a complex focussing action and I had binding as well at the close focussing end. Mine was adjusted when the lens went back for coding but it does loosen with time.

 

As regards close focussing, I don't think you should assume that setting the focussing ring to minimum will set the lens to its closest focus. It's rated at 0.7m, so it's better to set the subject to focal plane (not marked, but around the front of the contact patch on the hot shoe) to this distance and then check you can focus on that.

 

Keep in mind that the distance scale is approximate too, engraved on the focussing ring independently of the lens adjustment - on mine, the 0.7 goes beyond the index mark but not as far to the right as yours.

[Shootist]

Do you wear reading or distance glasses? If so you may need a diopter.

When not using the correct diopter to correct for my vision on any of my M's I can turn the focus ring slightly on any M lens I have and it looks the same through the Rangefinder patch in the viewfinder.

With the correct diopter installed any movement of the focus ring changes the image in the Rangefinder patch.

[adan]

Mark(quarth): If this is your only lens, you probably need to make sure the problem is in the lens, and not the camera RF adjustment, before returning the lens.

 

Fortunately, with instant feedback from digital, you can likely determine this quickly at your shop by trying a couple of other fast, small-DOF lenses at .7 meters and reviewing the images in-camera - another 50 'lux, and/or 50 crons or a 75. If all the lenses have trouble, it's likely a camera misadjustment, and its the CAMERA, not the lens, that needs a trip to Allendale. If the others focus OK, then you can do your return on the spot for one that you know behaves.

[ho_co]

Advertisement (gone after registration)

Mark--

Welcome to the Leica world!

 

Is this the way you intend to use the lens? If so, by all means exchange it.

 

The fact that the RF lines up properly at infinity using the Summilux indicates to me that both body and lens are working fine.

 

Both Mark and Dan have experience here that I don't have, but judging from:

1) what you say about the focus being 'looser' over the space where the rangefinder isn't tracking; and

2) what Mark says about the cam tracker not necessarily tracking the lens fully to its closest focus distance;

I would say that the looseness in the focusing is probably due to the lens's not pressing against the rangefinder cam tracker.

 

From what I read here, your lens is fine, but you've rotated the focus ring to a point closer than the rangefinder tracks.

 

Usually, one focuses by rotating the lens while looking thru the viewfinder, not by adjusting the tripod. And you say the lens is sharp when set at the rangefinder limit, and when it is set at infinity. Since you can't use the lens in its closer range without a tape measure, is that close distance of that much importance to you? If so, I think Mark is right that you should have the block adjusted to allow the tracking roller to track the lens closer if that is possible.

 

Remember, as mentioned above: A standard focus ring is made for all 50/1.4s. Different focusing helicoids (focus mounts) are matched to any deviation from the design focal length for each particular lens head. The lens head is mounted to the proper helicoid, and the focus ring is mounted over the helicoid. The engraved distances are only approximate. You don't focus by scale but by rangefinder.

 

It may be that your lens focuses closer than the rangefinder focuses, but this isn't normally of much use since the lens isn't as highly corrected as some others for closest focus.

 

If your dealer knows Leica, discuss it with him. If he's not particularly familiar with the M series, you might want to discuss it with someone at Leica Technical in New Jersey.

 

I understand that you are new to the Leica system and want to be sure everything works fine, and you should be sure after paying these prices.

 

But remember, rangefinder lenses are different from reflex lenses because you're not looking through them. On a reflex lens, the manufacturer simply has to adjust infinity and then set a close-focus stop. On a rangefinder, all the focus information has to be conveyed mechanically, so the focus mechanism (neglecting AF designs) is more complicated.

 

And remember, Leica bodies and lenses are bench-built, not mass produced. They are engraved, not stamped; they are made of metal, not plastic; and the company doesn't offer "professional grade," "midprice grade" and "consumer grade" lenses. It's easy to make everything work the same if you stamp it out of plastic.

 

My opinion is that your lens has a quirk. It doesn't strike me as an important quirk, but before I told you to listen to me, I'd suggest that you talk to someone whom you know to be in a position to speak knowledgably about it. And I'm not saying that it is a quirk that isn't important to you. Obviously it is and you should satisfy yourself about it.

 

From what you describe, I think the lens is fine, but the quirk raises questions. I think the overthrow is simply a product of Leica's assembly process, which is unlike that of every other lens maker on the planet.

 

I guess that's more than two cents' worth. Didn't mean to be so longwinded. But I am sure you can quickly get it sorted out.

 

And as I said above: Welcome to the Leica world!

 

--HC

[stunsworth]

I thought lenses were not rangefinder coupled on an M under 1 metre. Is this the case or am I imagining it? <grin>

[michael_b_elmer]

I think your camera and lens are OK, and that you are just using and testing them in a way which may not be quite appropriate.

 

First make sure that your sight through the rangefinder is correctly adjusted, eventually by using the proper correction lens (the calculation of the proper lens is a job for an optician guided by the information on the rangefinders correction in your M8 user's guide).

 

Then by using the rangefinder, measure a the closest focusing distance and take your picture (I understand that the camera and lens work perfectly at infinity, when using the camera correctly).

 

After that, you can measure the distance from the object to the sensor plane to check what is the closest focusing distance of your camera and lens - but as you will see, the sensor plane is not indicated on top of the M8 as the film plane was on the former M's. Therefore, any measurement which is not performed by using the built in rangefinder, cannot be completely precise.

 

This means, on the other hand, that you cannot reverse the procedure - like you have done - since you cannot measure the exact distance in any other way than by using the rangefinder.

 

You will, however, probably discover that the indications of distance on the lens are reasonably precise, but not 100 percent.

 

If the picture you took at the closest distance possible measured with the rangefinder, is as sharp as it should be, then your camera and lens are working just fine, and you have no problems at all, because this is the way they should be used.

 

If the indications on the lens are not 100 percent precise, then take note of that and leave it at that. You do not need those indications for precise work but only for setting the hyperfocal distances where you always give some margin, so that the exactness of the indications on the lens does not matter in practice.

[marknorton]

Steve, the rangefinder goes down to 0.7m...

[robsteve]

I thought lenses were not rangefinder coupled on an M under 1 metre. Is this the case or am I imagining it? <grin>

 

That was the limit with the M3. Some M3 could be adjusted to .7m, others not.

[stunsworth]

Thanks guys, I am more than happy to be corrected <grin>

[wizard]

Mark,

 

just to second what others have said: Don't give your lens or camera back prematurely, as indeed you seem to have fine working samples. If your lens focuses correctly to infinity (and it seems to do that) and if at the same time the focus indicated in the VF is correct, i.e. if the two images in the rangefinder have merged into one, everything is as it should be.

 

The particular copy of your lens may allow to set the focus a little closer than the regular minimum focusing distance of 0.7m, and the cam tracker in your camera may just lose contact with the lens cam when doing so, but both of that is not a fault. Think of it, when you use the camera, you will always use the rangefinder to correctly focus the lens. If the images you obtain thís way are tack sharp, everything is fine. Leica could probably adjust your lens such that it doesn't focus to closer than 0.7m, but in my view you would have gained nothing then (in fact you would have lost your lenses ability to focus a little closer).

 

Cheers,

 

Andy

[adan]

I sense a misconception among the advisers here:

 

Being correct at infinity does NOT mean a Leica M rangefinder is correctly adjusted throughout its focus range - there are separate adjustments for infinity and the close range (one has to do with adjusting the position of the main RF roller in the camera on an excentric axle, and the other involves the position of the roller on the lever arm - the radius or effective length of the RF lever.

 

It is easily possible for a camera to be correctly set for infinity, but have a progressive error creep in as the lens (and RF mechanism) focus closer and closer.

 

All in all, it is more likely that a camea is out of adjustment than that a lens is - the lens has only one part to be correct or not (the surface that contacts the RF roller), whereas there are many points within the moving parts of the rangefinder where errors can creep in.

[quarth]

All - Thank you so much for all the advice. Just to be very clear, as I think there is some confusion.. the focus is tack sharp when set to infinity. The focus is also tack sharp when set to 0.7m (i.e., the focus ring is rotated all the way to the minimum focusing distance).

 

The issue is that when I back off the minimum focusing distance a bit, nothing changes in my VF (i.e., the images are still aligned). So, I can actually back off from the minimum focusing distance about .5cm, and see absolutely no change in the VF. It is this .5cm that I referred to as "looser" in my original post.

 

The practical issue, here, is the fact that if I am focusing on a subject close to the minimum focusing distance using the VF, it can appear in the VF that the subject is in focus (i.e., the images are aligned perfectly), while in reality, it is not.

 

My plan is to take it back into my dealer this weekend and, as was mentioned, try a few other fast lenses on it, and see if I have the same results. If I'm lucky, they'll have another 50 1.4, in which case it would be a very easy comparison...

 

Thanks again to all for your help!