90/4 Macro and protraits

[hankg]

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Anyone have a tight head and shoulders shot wide open with the 90/4 on the M8? I'm wondering if at f4 you get a roll off to softness after the hairline. f/5.6 or even f/8 close in on the 135/4 does it. I figure f/4 should be a large enough aperture close in to accomplish the same with a 90. I'm not looking for a DOF so thin that one eye is in and the other out of focus so I'm thinking f/4-5.6 is my sweet spot.

 

From what I have seen the 90/4 has a beautiful signature, nice smooth OOF and transitions. I had picked one up early on, loved the size but it backfocused badly and DAG said he could not adjust it. That put me off the lens and I sent it back (DAG was doing some other lenses for me so I sent the 90 along rather then send it back right off). However from what I have heard, many have lenses that are performing perfectly and I would like a long lens that has stellar close in performance so I'm going to give it another shot. Before I pull the trigger I'd like to see a tight portrait though.

[tashley]

These are the best I can do from what I have 'in stock', both at either F4 or 5.6 which is where I tend to use the lens. Both full shot then 100% crop. [EDIT: these crops are more like 150% uprezed automatically by Lightroom, sorry!]

 

The lens has an almost psychic ability to know when I want sharp and when I want soft - of course it isn't psychic, I must have unconsciously learned its ways, but the DOF at 1 metre and F4 is 1cm, at 5.6 is just under 2 cm and at f8 about 4cm. Further, on mine at least it is distributed so that the point of chosen focus is towards the back of the sharp zone at F4 which means that I kind of know where, on something like the rose, to focus to get what I'm after.

 

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Hope that helps

 

Tim

[hankg]

Thanks, the lens has stunning performance and beautiful rendering. I would think for a head and shoulders shot that you would be closer to 3 meters away with a 90. I have yet to see a shot at that distance with the head or just head and shoulders filling the frame -so I'm not quite sure how the DOF would look under those conditions.

[tashley]

Thanks, the lens has stunning performance and beautiful rendering. I would think for a head and shoulders shot that you would be closer to 3 meters away with a 90. I have yet to see a shot at that distance with the head or just head and shoulders filling the frame -so I'm not quite sure how the DOF would look under those conditions.

 

I just shot these at F4 ISO320, no people so it's a lion's head about 2/3rds human head size from about 1.2 metres. Then 100% crop (focus on right side of eye). Then 100% crop of a fly that landed nearby, gave me a second to focus and then flew off, just to show how easy to focus it is - and I didn't even put my magnifier on!

 

Owing to operator error (me) the 100% crops in my previous post were actually more like 150% - I set Lightroom to constrain maximum size and it up-rezed!

 

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Tim

[hankg]

Wow, that's an impressive display of RF focusing 'on the fly'.

 

The lion's head gives me a much better sense of DOF close in. It looks like I'll have plenty of latitude with the f4 limit and the transition from sharp to soft is very nice. I'm sold. Thanks again.

[vanhulsenbeek]

I got one as a present for my 60th birthday :-) and gave it a thorough run today.

Can only say I am very pleased, to put it mildly.

No focus problems as far as I can see (even with the adapter)

and a beautiful signature: one great little lens!

[phovsho]

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Very nice, Are you using the 1.25x magnifier?

Best

Murray

[tashley]

Very nice, Are you using the 1.25x magnifier?

Best

Murray

 

Thanks Murray,

 

I usually do (and on the first to shots did) but for the second two shots I was just trying to do a demo for the OP and was in the middle of a wide angle session so I didn't put the magnifier on.

 

I think the fly was more luck than judgement!

 

Tim

[tashley]

Wow, that's an impressive display of RF focusing 'on the fly'.

 

The lion's head gives me a much better sense of DOF close in. It looks like I'll have plenty of latitude with the f4 limit and the transition from sharp to soft is very nice. I'm sold. Thanks again.

 

LOL - i was just buzzing with excitement.

 

It's one of my favourite lenses, I sold the 90 cron for it because mine had backfocus issues whereas the 90 macro is bang on and weighs nothing. The hood is a bit fiddly though!

 

T

[hankg]

The hood is a bit fiddly though!

 

T

 

Yes I noticed that in the little time I had one. Which is odd because on my old 135/4 which uses the same 39mm filter and same hood the fit isn't quite so tight and it's easy to clip on and take off.

[tashley]

Hank, I just looked through your site - you have some very very nice stuff there!

 

Tim

[j. borger]

The 90/4 ME is a wonderful lens .. all you need for a long lens if you can live with f4.

F4 is enough to isolate the subject with a 90mm in my experience...

Although not head & shoulder portraits .... i hope these snaps from a horse show help (all pictures taken at f4).

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[lars_bergquist]

Hank, you wrote that the lens backfocused. Now the only things that can create appreciable 'backfocusing', i.e. focus shift, are large amounts of uncorrected chromatic aberration, in conjunction with plates or film without colour sensitization (which I think we can discount here) and large amounts of uncorrected spherical aberration.

 

This aberration is caused by the fact that with spherical lenses, peripheral rays tend to focus at a different distance than axial rays. So spherical is a problem with fast lenses. When stopping down, we cut off peripheral rays and use only axial, which means that the focus is weighted differently. The need to combat this condition (and other problems caused by this phenomenon) is why aspherical surfaces are used.

 

The Macro-Elmar is not a fast lens. The problems associated with slow lenses of restricted angle of acceptance are, typically, chromatism and astigmatism, which do not cause focus shift.

 

Theoretically, focus shift could occur in, say a 35 mm 1.4 lens, or any other fast lens of short focal length. But spherial aberration would have to be so bad that the lens would not produce a sharp image at any f-stop. It could also be caused by either extremely bad design, or a total absence of quality control, of the mechanical focusing system (helical, cam, rangefinder).

 

My only two lenses that might exhibit the symtom are off to Solms for coding, so I cannot run any controlled tests. I intend to do so when they return. But, considering the above, I do think that unless I can be shown incontrovertible results of acceptably conceived and executed experiments – not anecdotal evidence – the backfocusing phenomenon is largely due to 'pilot error'.

 

I may of course have totally misunderstood basic optical science. If so, tell me, by scientific argument. Those are the only I respect.

 

The old man from the Age of Tape-Measure Focusing

[tashley]

Hank, you wrote that the lens backfocused. Now the only things that can create appreciable 'backfocusing', i.e. focus shift, are large amounts of uncorrected chromatic aberration, in conjunction with plates or film without colour sensitization (which I think we can discount here) and large amounts of uncorrected spherical aberration.

 

This aberration is caused by the fact that with spherical lenses, peripheral rays tend to focus at a different distance than axial rays. So spherical is a problem with fast lenses. When stopping down, we cut off peripheral rays and use only axial, which means that the focus is weighted differently. The need to combat this condition (and other problems caused by this phenomenon) is why aspherical surfaces are used.

 

The Macro-Elmar is not a fast lens. The problems associated with slow lenses of restricted angle of acceptance are, typically, chromatism and astigmatism, which do not cause focus shift.

 

Theoretically, focus shift could occur in, say a 35 mm 1.4 lens, or any other fast lens of short focal length. But spherial aberration would have to be so bad that the lens would not produce a sharp image at any f-stop. It could also be caused by either extremely bad design, or a total absence of quality control, of the mechanical focusing system (helical, cam, rangefinder).

 

My only two lenses that might exhibit the symtom are off to Solms for coding, so I cannot run any controlled tests. I intend to do so when they return. But, considering the above, I do think that unless I can be shown incontrovertible results of acceptably conceived and executed experiments – not anecdotal evidence – the backfocusing phenomenon is largely due to 'pilot error'.

 

I may of course have totally misunderstood basic optical science. If so, tell me, by scientific argument. Those are the only I respect.

 

The old man from the Age of Tape-Measure Focusing

 

 

 

Lars, I'm afraid backfocus and focus shift are two different things. A lens can backfocus at any aperture and not have focus shift, whereas focus shift is (usually) the tendency to backfocus increasingly as you stop down, as you state and for the reasons you identify.

 

A badly aligned lens (elements or mount or mechanics out of whack) of any focal length can back or front focus, regardless of whether it has an inherent tendency to focus shift.

 

I had a 90 cron that almost never focussed correctly - and when it did, it was due to pilot error! I swapped it for the 90ME and have had good focus (when I want it) ever since. In fact, out of the nine Leica lenses I have had, all purchased new, three have arrived with backfocus issues, regardless of what they do as you stop them down. It is not as uncommon as it should be.

 

Best

 

Tim

[hankg]

Lars it wasn't focus shift. Just about every used lens I have bought and occaisionaly a new one does not have it's focus aligned correctly with the cameras RF. This is easily fixed by a compentent tech. I believe they shim the mount to get the distance to film/sensor plane aligned correctly.

 

I sent a 21/2.8 preASPH, a 50/1.4 preASPH and the 90/4 Macro to DAG for adjustment. The 21 and 50 came back focusing perfectly. Here was his comment on the 90:

 

Your Summilux 1.4/50mm lens was back focusing & I was able to adjust it so it's right on. To give you an idea of how far it was off- I shimmed the optics 0.0003 of an inch away from the flange... Your Elmar 4/90mm lens is also focusing beyond focus but only 1/2 as bad as your 21mm lens was. Due to the lens optical design, I don't see a way to adjust only the optics & not the nechanical focus at the same time & since the mechanical focus of this lens (part that controls the following arm of the camera) is right on I'm forced to leave it as is.

The fact that Don could not adjust the lens put me off the lens and I sent it back. Perhaps Leica has the means to calibrate the 90/4 but I would be very careful to get a copy that was focusing dead on wide open near and far.

[hankg]

The 90/4 ME is a wonderful lens .. all you need for a long lens if you can live with f4.

F4 is enough to isolate the subject with a 90mm in my experience...

Although not head & shoulder portraits .... i hope these snaps from a horse show help (all pictures taken at f4).

 

Very nice. The amount of contrast between subject and background your samples exhibit is perfect. I don't need to have the sort of dramatic contrast between OOF and sharp foreground that can be gotten at 1.4 with the 75/1.4 or wide open with the 90/2. At those apertures I don't get enough of the face in focus for the application I have in mind.

 

This shot from the 135/4 at 5.6 (I think- maybe it was a 1/2 stop more open) shows fall-off from the sharp eyes to the soft sides of the head/shirt. This is actually a bit more fall off then I need. From what I have seen at this distance wide open the 90/4 should get close to this result.

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[Guest guy_mancuso]

Someone may want to grab this , pretty good price on a used one..

 

 

PopFlash.Photo: LEICA 90MM F/4

[lars_bergquist]

Tim, and Hank,

in that case I am not the only one who is incapable of making the distinction between 'back focus' and focus shift. Most of the complaints I have read say that backfocus occurs when the lens is stopped down. On the other hand, if 'back focus' is just a bad job by the mechanical focusing, then it should about just as often be 'front focusing'.

 

What you are saying is that just a few years ago, Leica quality control just disappeared. All of a sudden, they sent out lenses that focused all over the place. Or do you mean that the sensor of the M8 is assembled in such a sloppy way that focus goes to the dogs? In that case, all lenses used on the same camera should be affected.

 

Or is it that the supposedly great emulsion thickness of film took care of all misalignment in the past? Technical Pan had an extremely thin emulsion – it was close to impossible to develop the film without scratching it! – but I never had any focusing problems with it.

 

The old man from the Age of Tri-X

[hankg]

Tim, and Hank,

in that case I am not the only one who is incapable of making the distinction between 'back focus' and focus shift. Most of the complaints I have read say that backfocus occurs when the lens is stopped down. On the other hand, if 'back focus' is just a bad job by the mechanical focusing, then it should about just as often be 'front focusing'.

 

What you are saying is that just a few years ago, Leica quality control just disappeared. All of a sudden, they sent out lenses that focused all over the place. Or do you mean that the sensor of the M8 is assembled in such a sloppy way that focus goes to the dogs? In that case, all lenses used on the same camera should be affected.

 

Or is it that the supposedly great emulsion thickness of film took care of all misalignment in the past? Technical Pan had an extremely thin emulsion – it was close to impossible to develop the film without scratching it! – but I never had any focusing problems with it.

 

The old man from the Age of Tri-X

I don't know if back focus (or front focus) is the correct term to describe an out of calibration (optics to flange) lens. But the problem I was describing is just a lens maladjustment that usually can be fixed by adjusting the optics to flange distance so when your RF is in focus so is your lens. I have no idea if Leica QC is better or worse now then before. The RF on my M8 was perfect (I had it checked) and the 90/4 I bought was not. My past experience with Leica quality has been very positive.

 

I think the increased number of 'out of spec' lenses is a result of the ability of users to inspect every shot immediately at big enlargement with the M8 -how many film camera users processed film and made a set of 20 x30 prints to check focus on a lens they just purchased. If you only got 5x7 prints from the local drugstore you might never know you had a problem. Now every one is a lens tester. I spoke to one retailer and he's got a pile of Noctilux that he can't get to focus wide open on the M8. It's something he never had to deal with before.

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[tashley]

Tim, and Hank,

in that case I am not the only one who is incapable of making the distinction between 'back focus' and focus shift. Most of the complaints I have read say that backfocus occurs when the lens is stopped down. On the other hand, if 'back focus' is just a bad job by the mechanical focusing, then it should about just as often be 'front focusing'.

 

What you are saying is that just a few years ago, Leica quality control just disappeared. All of a sudden, they sent out lenses that focused all over the place. Or do you mean that the sensor of the M8 is assembled in such a sloppy way that focus goes to the dogs? In that case, all lenses used on the same camera should be affected.

 

Or is it that the supposedly great emulsion thickness of film took care of all misalignment in the past? Technical Pan had an extremely thin emulsion – it was close to impossible to develop the film without scratching it! – but I never had any focusing problems with it.

 

The old man from the Age of Tri-X

 

 

Lars, one of the longest threads one here has examined this in horrible detail and through it and the experts who have contributed to it I have learned to distinguish between backfocus and focus shift, as I described above.

 

And yes, Leica QC is to blame. It seems well documented in particular that a batch of coded mounts were off and required the lenses to be adjusted. I personally have had glass that backfocuses at all apertures, from new, and other glass that does not but does suffer from focus shift.

 

None of this is rocket science: if I and others have many lenses work perfectly and some that don't, it is quite clearly not an issue with the sensor.

 

I cannot understand why people have problems in believing things that challenge their beliefs despite the evidence.

 

Tim