Backfocus Tests on M-Lenses

[JWW]

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Looking at the picture of the ruler, if you adjusted the m8 focus to the front maybe 2 inches so at 1.0 it would be front focused but still within the DOF circle (although right at the rear end of it), at 1.4, 2.0, and 2.8 should still be in the acceptable range?

[Eoin]

Eoin, what about a 50 Summilux, pre-Asph? It is meant to have a similar design and look to the 75 Lux, and is definitely softer wide open than a 50 Cron. The Noctilux is neat, but the bokeh often looks strained and weird.

 

I have considered the pre-Asph but, my intended use is @ f :/2.2 - f:/4 and I fear the 1.4 stopped down will be too sharp. perhaps I'm miss guided but the other side of the coin is if I don't try, I'll always wonder what would have been. That questioning in my mind would drive me crazy so the cost of trial with the 30% offer makes this a bit of a no-brainer with the option to sell on should it not deliver what I require.

 

I really don't know if I'll find what I'm looking for, I'm really missing my 85L and I've all but ruled out a return to dSLR's just for this lens. But I can still pick it out from amongst my images.

[marknorton]

Have to say the Noctilux is not my favourite lens to use. Mine has been back to Solms, focusses OK at f1 but is as critical as you'd expect; stop down and I get the same sort of results as Matthew. Until the increasing depth of field covers the focus shift, focussing is very hit and miss.

 

The issue I have is that if you do some focus testing and get a bad result, you do not really know whether it's the lens or the body which is off. To ensure interchangeabilty, both lenses and bodies need to be calibrated against known references, not each other.

 

For the body, the relationship between the position of the roller relative to the bayonet mount and the corresponding distance at which the rangefinder is co-incident would be interesting to plot and a bayonet adapter accessory which set the roller at, say, closest focus, 1, 2, 5, 10 metres and infinity would be very useful in pointing the finger of blame in the right direction to answer the question: Body or Lens?

 

I have 3 bodies and 15 lenses, and the whole issue of focussing alignment and focus shift is driving me nuts!

[jlm]

amen borther.

 

I'v spent about 10 hours myself, now my eyes are shot so I had to get a younger helper to do the eyeball work.

found this:

you need a good test target. I made three identical vertical plates about 3" x 4" and attached the same printed text to each. the center plate is the focusing plane, 6' from the camera (tripod), one palte 1/2" farther one 3/4" farther.

shoot at wide open, load images into photoshop using a bit of unsharp mask and compare.

found my 75cron and 50lux to be focusing about 1/2" back.

took a shot out the window at a wire fence about 200 yds away (75 wide open) image in PS was not so hot. tweaked the roller about ten times trying fo an improvement. (same shot at f5.6 look much better than f2, by the way.

re-shot the plates with the 75/2.0, now it is spot on, but of course my eyes are groggy.

 

tomorrow i'll try some more.

this was brought on by testing a friend's ancient 50/2, which was backfocusing about 1-1/4". made some shims, and now that my camera is more on, i'll try his lens again and try shimming.

 

this is not a lot of fun, by the way, and I would happily have a Leica tech do it and pay, but that is asking for no camera for god knows how long.

 

tomorrwo i'll post an image or two

[MP3]

Just received email and call from my local dealer. They will help to check, tune or change it for me. Good that the Noct is not putting bread for me =)

 

Eoin, Hope yours will work fine. I've also got the thought to change my Noct, 75AA to 50LuxPA, 75Lux and 90MEM = ) Hard to decide!

[MP3]

Jan, M8 does focus perfectly now with other 6 lens in the test.

 

I 'll try i out again with tripod at medium distance, just can't do it now.

[sean_reid]

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I think part of it for me is having the wonderfull 50mm Lux first. Damn the Lux is really hard to beat, probably in my book the best 50mm lens i every used. That is saying a lot , I have pretty much tried them all. The drawing on the Lux is just so beautiful and the tab focusing and size makes it a huge winner for me. Just have a hard time justifying the Nocti and you all know me i will buy almost anything. This one though stops me in my tracks from hitting the add to cart button

 

Hi Guy,

 

This was my take on things back when you and I were discussing this last fall and I recommended the 50/1.4. I appreciate the strengths of the Noctilux but the two I really love are the 50/1.4 Asph and 50/1.5 Nokton. Both of those are much more versatile for my work and I also like that I can focus them more quickly.

 

Horses for courses,

 

Cheers,

 

Sean

[nscali]

Guys,

Here's my 2c worth....

The Noctilux is a bit of an indulgence. If you can justify the money, it is a unique lens.

It will never be as sharp as the 50 lux. That is not it's purpose in life. It does, however, have something special about it.

The 50 lux for my money is the best damm lens that Leica makes. I wish they all behaved as well as that lens. Tack sharp, nice, soft bokeh, sharp at all Apertures and distances.

I am sure many will concur...

Nicky

[Eoin]

Nicky, I tend to agree with you, it is a bit of indulgence, as are all leica lenses when you compare them to Zeiss or even CV's at a 10th of the price. It''s not the critical sharpness of a Summilux Asph I'm after here, while I agree how good the Asph is and it's current position as the best lens leica make, it's fingerprint is not what I'm looking for.

Puts describes the Noctilux as being able to record fine detail with smooth internal graduation but fuzzy edges up to f:/2.8. At f:/4 - f:/5.6 the nocti is comparable to the summicron at f:/2.8 - f:/4 but not as well corrected. This I am hoping will remove some of the facial skin texture(read flaws) I'm seeing. Yes for sure I could use a few layers and blurs in CS3 for this but I really don't want to have to enhance or hide things in post.

 

For sure the Nocti has a special look shot wide open at night with bright light sources turning into soft orbs of colour, that's there if I ever need it along with f:/1 but I'm looking for this to paint with a broad brush and less detail than the fine line Asph's. At the end of the day I'm looking for a look I can't quite describe with words, I've seen it with a few lenses here and there including some but not all nocti shots. I'll have to see first hand and for my own sanity if it gives me what I'm searching for.

 

Call it indulgence if you will, LOL. But there is nothing more gratifying than holding a print in your hand and you know you've nailed the mood, lighting and texture you had in your minds eye. Priceless self satisfaction.

[Peter Branch]

Have to say the Noctilux is not my favourite lens to use......

 

I have to agree with Mark - I've sold my 6-bit Noctilux. I used it for about 5 years with film and it justified its existance in my outfit because so many family members and friends wanted - and expected - me to take pictures at social events. For this often low light, (I never use flash), application it was a good tool. Since I got the M8 it moved swiftly from being an interesting lens with which to test the M8's capability to the one I never bothered to put in my day bag.

 

Why? Well it is very heavy - it has very "slow" focusing, (you have to turn the focusing ring a very long way to change focus), and it has too narrow a field of view for the sort of use to which I used to put it with film. I got a few good pictures with it but frankly it failed to match up to the performance of the other lenses in the bag. One can justify this by claiming a "special" look - and it has - but it is not really able to compete in todays world.

 

Specifically the focus shift - most noticable at f/2 - is more apparent with the M8. This makes using it difficult and the performance at close range with the larger apertures is in any case quite disappointing. As others have remarked it never really gives a sharp image under these conditions. All-in-all there are better options with the M8.

[nscali]

Eoin,

For what you describe it may be what you are looking for.

Keep in mind, with a correctly adjusted rangefinder, it will focus accurately up to f2, then it definitely softens from f2.8-f5.6. Call it focus shift if you wish. You will need to front focus an inch or so at those apertures. You can 'fool' the M8 by adjusting the hex screw anticlockwise a little to the point where wide open, the lens is on the verge of front focus.

All other apertures then appear a little sharper. The only issue with this is that it may throw your other lenses out.

Belive it or not, I have 2 M8 bodies. One is calibrated like the above for the Noctilux and the 35 lux asph (same issues with focus shift). The other is adjusted properly where those lenses experience a little focus shift from 2.8-5.6, but all others like the 50 lux, 50 cron, 35 cron, 28 elmarit all focus correctly.

Nicky

[Peter Branch]

........ One is calibrated like the above for the Noctilux and the 35 lux asph (same issues with focus shift). The other is adjusted properly

 

Some older members of this forum may remember that when the first f/1.2 Noctilux was launched it was "unofficially" recognised that each lens should ideally be matched to a specific body for best performance. M3 preferred. This was a "difficult" topic for Leica who sought to maintain the “Any lens on any body” principle - but - they did somehow manage to engineer an improvement if one sent both a lens and body for "calibration" - never "matching" - but everyone knew what the game was.

 

Tolerances have been much tightened since those days but I think we are seeing a version of this same issue with the M8, which is so much more analytical.

 

As an observation the accepted method of defining a focusing point back in those days was to fix a piece of contrasting colour cotton thread to the object and use the rangefinder to bring the thread into exact focus. It was surprising how much more accurate and consistent this technique was compared with trying to focus on numbers etc.

[MP3]

Eoin,

For what you describe it may be what you are looking for.

Keep in mind, with a correctly adjusted rangefinder, it will focus accurately up to f2, then it definitely softens from f2.8-f5.6. Call it focus shift if you wish. You will need to front focus an inch or so at those apertures. You can 'fool' the M8 by adjusting the hex screw anticlockwise a little to the point where wide open, the lens is on the verge of front focus.

All other apertures then appear a little sharper. The only issue with this is that it may throw your other lenses out.

Belive it or not, I have 2 M8 bodies. One is calibrated like the above for the Noctilux and the 35 lux asph (same issues with focus shift). The other is adjusted properly where those lenses experience a little focus shift from 2.8-5.6, but all others like the 50 lux, 50 cron, 35 cron, 28 elmarit all focus correctly.

Nicky

 

Hi Nicky

 

I got the same observation as you do. If Solms or my official Leica center here can front focus my Noct with 0.25 - 0.5 inch at f1, the lens will be perfectly usable from f1 to f2, it will still exhibit backfocus substantially from f2.8 to f4. Then dop will cover up from f5.6 onwards. This is at close focus situation. Medium focus situation may get better performance. I shall try it out with my Leica repair center here, hope that they need not to ship it back to Solms.

 

Cheers

Matthew

[BerndReini]

I own the 50 lux aspherical as well as an old 50 cron. I just borrowed my friends Noctilux for a week, and decided I am using my 30% voucher on one. I will be using it EXCLUSIVELY at f1 because this is when it shines. I know it's not everyone's cup of tea but boy it is special.

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[marknorton]

Hi Nicky

 

I got the same observation as you do. If Solms or my official Leica center here can front focus my Noct with 0.25 - 0.5 inch at f1, the lens will be perfectly usable from f1 to f2, it will still exhibit backfocus substantially from f2.8 to f4. Then dop will cover up from f5.6 onwards. This is at close focus situation. Medium focus situation may get better performance. I shall try it out with my Leica repair center here, hope that they need not to ship it back to Solms.

 

Cheers

Matthew

 

Seems to me this lens should be set up at the front focus limit at f1 so that stopping down will give the maximum chance of keeping the thing in focus. Maybe it is already and f1 is just too extreme.

[marknorton]

I own the 50 lux aspherical as well as an old 50 cron. I just borrowed my friends Noctilux for a week, and decided I am using my 30% voucher on one. I will be using it EXCLUSIVELY at f1 because this is when it shines. I know it's not everyone's cup of tea but boy it is special.

 

Certainly the case that if you ever shoot at f1, you will not have to worry about focus shift on stopping down...

[BerndReini]

When my friend bought his, we had the luxury of testing and choosing between three different lenses and he picked his according to exactly that specification. I heard that it takes forever to get the Noctilux with the voucher and I'm just hoping that when I get mine it will be adjusted correctly at f1.