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90mm Apo Summicron and Leica M9


Anil Kalagatla

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Hi:

 

I have a chance to buy a 2002 model 90mm Apo lens for my Leica M9 and I wanted to check to see if it's more trouble than not. I've looked through several threads on this topic on LUF and at the end I'm still unclear. Often I've found that one's biases tend to influence how one interprets the threads - in this case, I really want to buy the lens :-)

 

If the camera is reasonably well calibrated, what are the chances of a used lens bought online to have focusing issues - I seem to see more posts about this particular lens than other lenses (it could be that I'm just noticing these more). I'm checking with the seller, but not sure if they are able to verify or not.

 

Thanks in advance.

 

Anil

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My 90 f/2 APO-Summicron-M asph is spectacular on my M9-P, much more so than I felt it was on my M8. Perhaps you might balance the negative comments about focussing against the fact that the 90 APO has a thinner depth of focus wide open, close-up than the f/1 Noctilux so focussing accuracy is very important. Focus fall-off in front of and behind the area in sharpest focus is also sudden which emphasises mis-focus. Some users have reported back focus close-up, which would be a design parameter affecting all lenses but I haven't noticed this with mine.

 

The lens takes practice to use effectively - as many lenses do - but it can producing stunning results with a unique look (apart from it's R-mount twin sister of course). Your viewfinder will need to be spot on close-up and at infinity to nail focus reliably but when you do it's a staggeringly good lens.

 

Pete.

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My 90 APO-ASPH was virtually bolted onto my M9-P because I used it so much and I just left my Leica magnifier permanently in place on my viewfinder. I had to use my 28 Summicron for a few shots one day and removed the magnifier to take the shots and was gob-smacked at how crisp and clear the view was and how much extra contrast I could see through the viewfinder. Just in case it was haze or smear I cleaned all of the pertinent surfaces but it didn't alter the difference and I fell in love with the M viewfinder all over again. In my quest for sharpness I hadn't noticed the loss in contrast through the Leica magnifier (that was bought new). I found that I was able to still nail focus with my 90 APO-ASPH with the magnifier off so it's stayed off.:o

 

Pete.

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Firstly don't read too much into forum posts. All Leica lenses are good and hold prices well.

 

Of course when you buy second hand, do take care. Better to test and buy and buy from reputed dealers who will address issues if any. Some of the older lenses were designed for film cameras and may need adjustment for digital.

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I have just sent my Apo-Summicron 90 asph. to Solms to have it coded. I bought the lens new in 1998, when it came out.

The Leica service told me, that in any case it has to be serviced and adjusted additionally to coding - they wouldn't code without service (cost 510,- € coding and service), because the long lenses from the analog times have (often/sometimes) focusing issues.

Actually, I have noticed that my lens has some back-focusing on short distances (1-2 m), but have kept that in mind while focusing.

 

Greetings, Rolf

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I use a 1.4x magnifier, and I have a high hit rate focussing this lens. Way more so than the 75 Summicron.

 

Stunning lens.

 

That's exactly my experience. In spite of its smaller depth of focus the 90mm Summicron AA is easier to focus fully opened than its 75mm cousin. Its my conviction that this is due to the longer focus throw of the 90mm lens - it makes it slower to handle but much more precise. I made the same experience with the 1.5/85mm Summarex, which I was sure I couldn't focus exactly, but I found out this was not true because the focus throw is extremely long.

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That's exactly my experience. In spite of its smaller depth of focus the 90 mm Summicron AA is easier to focus fully opened than its 75 mm cousin.

As a matter of fact—and contrary to popular belief—on the same image format, a 90 mm lens has greater (not smaller) depth-of-focus than a 75 mm lens. Moreover, the Apo-Summicron-M 90 mm Asph has a significantly longer focusing throw than the Apo-Summicron-M 75 mm Asph. So of course the 90 mm lens is easier to focus.

 

For the life of me, I cannot understand those who say they prefer today's Leica M lenses' ludicrously short focusing throws.

Edited by 01af
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As a matter of fact—and contrary to popular belief—on the same image format, a 90 mm lens has greater (not smaller) depth-of-focus than a 75 mm lens.

 

The comment "same image format" is the distinction that confuses this. If you stay in the same place and point the camera in the same direct, the 90 mm lens will give a tighter image, and shallower depth of field than the 75.

 

As I understand your comment, if you move forward with the 75, so the framing is the same as the 90, the depth of field is greater with the 90. Intuitively, that doesn't sound right, but I can't say it's that relevant - apart from lens comparison, I can't think why I would do that.

 

The alternative is to take two images from the same spot, and crop to the same field of view. This is surely the same effect as using a cropped sensor, which would also suggest a greater depth of field with the 75 (being the cropped image).

 

What am I missing?

 

Same sensor, same location, the longer focal length lens has a shallower depth of field, doesn't it?

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...If you stay in the same place and point the camera in the same direct, the 90 mm lens will give a tighter image, and shallower depth of field than the 75...

Yes of course complicating simple things is a pleasure for some in this forum.

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The comment "same image format" is the distinction that confuses this.

Wait, oops! You're right—depth-of-focus does not depend on image format. I added the "same image format" part without really thinking about it. Technically, it's not wrong, though ... :o

 

 

If you stay in the same place and point the camera in the same direct, the 90 mm lens will give a tighter image, and shallower depth-of-field than the 75 mm lens.

Sure.

 

 

As I understand your comment, if you move forward with the 75 ...

I didn't say anything about moving forward.

 

 

... the depth-of-field is greater with the 90.

I didn't say anything about depth-of-field.

 

 

What am I missing?

You are missing that depth-of-focus is not depth-of-field.

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As a matter of fact—and contrary to popular belief—on the same image format, a 90 mm lens has greater (not smaller) depth-of-focus than a 75 mm lens. Moreover, the Apo-Summicron-M 90 mm Asph has a significantly longer focusing throw than the Apo-Summicron-M 75 mm Asph. So of course the 90 mm lens is easier to focus.

 

For the life of me, I cannot understand those who say they prefer today's Leica M lenses' ludicrously short focusing throws.

 

Can you elaborate on this? As far as I am aware, if the aperture and sensor are the same and you move to keep the subject the exact same size in the frame DOF is nearly identical, regardless of focal length. Of course angle of view changes with the different focal lengths and perspective changes with the change in shooting position, but DOF is the same.

 

Or is it that as you are further back with the longer lens you have potentially less focus throw to work with and therefore it is more difficult to achieve accurate focus.

 

Gordon

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As a matter of fact—and contrary to popular belief—[...] a 90 mm lens has greater (not smaller) depth-of-focus than a 75 mm lens. Moreover, the Apo-Summicron-M 90 mm Asph has a significantly longer focusing throw than the Apo-Summicron-M 75 mm Asph. So of course the 90 mm lens is easier to focus.
Can you elaborate on this?

Your question has nothing to do with the quoted statement—but here we go ...

 

 

As far as I am aware, if the aperture and sensor are the same and you move to keep the subject the exact same size in the frame, depth-of-field is nearly identical, regardless of focal length. Of course angle of view changes with the different focal lengths and perspective changes with the change in shooting position, but depth-of-field is the same.

That's a common misconception. When shooting with different focal lengths from different distances so that the magnification at the plane of focus is constant (and everything else is constant, too, namely image format and aperture) then depth-of-field will be wider with the shorter focal length.

 

However there are cases where the difference will be negligible. Comparing two telephoto lenses with similar focal lengths (here: 75 mm and 90 mm) is such a case. Shooting at close-up range would be another.

 

But then, in my post above I wasn't talking about depth-of-field in the first place.

 

 

Or is it that as you are further back with the longer lens you have potentially less focus throw to work with and therefore it is more difficult to achieve accurate focus.

This is an aspect I hadn't thought of before—you're right: focusing at longer distances is more difficult than at shorter distances. However that's not due to the focusing throw but inherent to geometry. The longer the distance, the less accurate an optical range meter with a fixed metering base will be. With the Leica's range finder, it's easy to tell 1 m from 2 m but it's hard to tell 100 m from 200 m ... and next to impossible to tell 1,000 m from 2,000 m or any greater distance. But then, the greater the distance, the less important it is to meter that distance accurately, due to the nature of depth-of-field.

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If this is the first time you are going to work with a 90 on an M you'll need some practice, but with this APO Summicron 90 not more than with other 90's. It will be more often a joy than not. Marvellous selective focus! For me still the reason I do not long for the Noctilux 0.95 in this respect.

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