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new backfocus thread-solution

bradreiman

By bradreiman
in Leica M8 / Leica M8.2

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Jamie Roberts

Jamie Roberts

Posted
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It doesn't matter, alas, how old they are :) I got a wonderful, perfectly mint and relatively new 75 Lux that, when checked, couldn't acheive infinity focus (which meant it was out everywhere).

 

So if your 35 and 50 lux are fine (and the Nocti should be wide open now too) then it's time to adjust the 90. Unless there's something very wrong, it shouldn't cost more than $100.

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JHAG

JHAG

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Thank you, Jamie, what would I do without youuuu… ;)

Well, the Nocti is almost on : slightly off though, and I will

see in real life pictures what's he's about (I mean when I'll

stop shooting letters on books and "7" and "6" and "5" on

the schools rules of my little one. :D

Problem is : If I send the 90 to Solms, I'll have to send the

M8 with it, I suppose. :(

 

PS : Jamie, may I abuse a bit of your kindness, and send

you by mail the 6 shots I made with the lenses, to have your

take on it ?

I had horrible misfocussing with a recent assignment, and pretty

ashamed to reply : "Oh, you see, my Leica is a bit out of focus

these days, might be a spring cold."

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wlaidlaw

wlaidlaw

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Thank you, Jamie, what would I do without youuuu… ;)

Well, the Nocti is almost on : slightly off though, and I will

see in real life pictures what's he's about (I mean when I'll

stop shooting letters on books and "7" and "6" and "5" on

the schools rules of my little one. :D

Problem is : If I send the 90 to Solms, I'll have to send the

M8 with it, I suppose. :(

 

PS : Jamie, may I abuse a bit of your kindness, and send

you by mail the 6 shots I made with the lenses, to have your

take on it ?

I had horrible misfocussing with a recent assignment, and pretty

ashamed to reply : "Oh, you see, my Leica is a bit out of focus

these days, might be a spring cold."

 

Sthan,

 

If you send your M8 and the 90/2.8 to Solms, I am guessing that it may well come back at an adjustment that will find your other lenses out. I suspect you may be getting yourself into a muddle with just too many variables. What I think you need to do is to find another M8 user within a reasonable distance, who is wholly happy that his M8 and a range of lenses are in adjustment and I don't mean by taking photos of granny and the kids, printed to 4" x 6". I mean tested either with rulers or lens focus charts, cropped and blown up hugely until the pixels sqeak. You can then compare your lenses on his M8 and his lenses on your M8 and then start to work out what is right and what is wrong. I like many other committed (maybe we should be - sorry British joke) RF users believe very strongly that it is a total nonsense to adjust the camera to a lens. The camera should be adjusted to a standard as should the lenses. Now if you have a lens that you are 100% sure is right, then you can use that as your standard to adjust the camera to. I think if you take any other approach, you could be funding the development of the M9, with payments to Solms.

 

Wilson

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JHAG

JHAG

Posted
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William,

I'm with you.

Problem 1 : other M8 owners of my Leica dealer are not pro : they just sent

it to Solms and waited 2 months.

Problem 2 : I cannot stay without the M8 for so long.

 

I adjusted all lenses, with Leica chart and rulers. As said,

none is spot on. Every lens is slightly front-focussing wide

open, slightly backfocussing at 4 or 5.6. Is it acceptable ?

I don't know yet.

 

PS : With my film camera (namely, my M7), all lenses are spot on.

Tolerance is greater there, I know.

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Jamie Roberts

Jamie Roberts

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William,

I'm with you.

Problem 1 : other M8 owners of my Leica dealer are not pro : they just sent

it to Solms and waited 2 months.

Problem 2 : I cannot stay without the M8 for so long.

 

I adjusted all lenses, with Leica chart and rulers. As said,

none is spot on. Every lens is slightly front-focussing wide

open, slightly backfocussing at 4 or 5.6. Is it acceptable ?

I don't know yet.

 

PS : With my film camera (namely, my M7), all lenses are spot on.

Tolerance is greater there, I know.

 

Please send me some shots. I think you're nearly there.

 

The 50 and 35 should be absolutely in focus wide open, but the all the "depth of field" such as it is at 1.4 should be "behind" the focal point.

 

As you stop down, since those lenses exhibit focus shift, the point of focus will move back.

 

Playing the percentages, if you get two working plus the Nocti bang on wide open, the chances are that the 90 is out of spec.

 

However, what William says is ultimately true--if you don't know your M8 is in spec it's hard to gauge if the lenses are out.

 

But what you're doing worked for me... just keep going and see if you can't nudge the point of focus into the field so you don't have front focus anymore.

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JHAG

JHAG

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Jamie,

MP don't allow attachments.

So it's directly here, if you don't mind.

1. 35 Lux 1.4

2. 35 Lux 4

3. 50 Lux 1.4

4. 50 Lux 4

5. Noctilux 1.0

6. Noctilux 4

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JHAG

JHAG

Posted
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The two last ones.

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Jamie Roberts

Jamie Roberts

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Hi Sthan,

 

So, bearing in mind that the right way to do this (as mentioned by Wilson is actually to get the camera adjusted to spec and then adjust the lenses to that...

 

I think you're close. You're right, though, the three are still front-focussed a very little tiny bit :) If it were me, I'd tweak the tiniest amount just so the 35 Lux is better wide open and so that it's "just on the edge of backfocus" when stopped down to f4 (it really does shift a lot!).

 

This would put the Nocti right in focus wide open as well.

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JHAG

JHAG

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Hi Sthan,

 

So, bearing in mind that the right way to do this (as mentioned by Wilson is actually to get the camera adjusted to spec and then adjust the lenses to that...

 

I think you're close. You're right, though, the three are still front-focussed a very little tiny bit :) If it were me, I'd tweak the tiniest amount just so the 35 Lux is better wide open and so that it's "just on the edge of backfocus" when stopped down to f4 (it really does shift a lot!).

 

This would put the Nocti right in focus wide open as well.

 

Jamie,

Thank you for your time.

Yes, the 35 shifts a bit…:rolleyes:

I might send this one only to Dan to correct this.

Then again, he'll need my M8 to do that, which is impossible for me.

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wlaidlaw

wlaidlaw

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My apologies; I'm used to using the silly check name thing that no longer exists on the forum :) I'm also really, really tired!

 

Apology humbly accepted and thank you for going back and doing the edit - now get a good night's sleep - Horlicks?

 

Wilson

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JHAG

JHAG

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Hi Sthan,

 

I think you're close.

 

Jamie, your average lens adjuster is back with his homework. :D

 

1. 35 Lux 1.4

2. 35 Lux 4

3. 50 Lux 1.4

4. 50 Lux 4

5. NoctiLux 1.0

then next post :

6. NoctiLux 2.8

 

Quoting John Lennon (Let It Be) : "I hope we passed the audition…"

 

PS : The 50 hadn't its filter so you have a nice non-black Leica strap.

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JHAG

JHAG

Posted
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Noctilux 2.8

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JHAG

JHAG

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A bit in the kicks.

Or beyond the Mull of Mc Intyre, to follow with the Beatling…:cool:

 

"Oh help me, please doctor, there's a pain, where there once was a heaaaart…"

 

1. 90 2.8

2. 90 5.6

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Eoin

Eoin

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Hi Sthan,

 

I'd recommend you change the way you shoot this chart. I've found much better accuracy if I mount a ruler horizontally on a wall and shoot along the length of the ruler with just enough angle that you can read the numbers

 

I have done this for all my lenses starting with all lenses wide open, shoot and see where each focal point lies. then shoot all lenses together at 5.6 and see where the focal point lies. Then you can see if you have any room to play with. I found by adjusting the cam my 28 cron's critical focus was just a fraction before the focal point at f:/2, my 50 lux and my 90 Cron were spot on. I decided to settle with that but now when I focus the 28 I always focus it from far to near, ie focus in to the subject, which always seems to give spot on focus.

 

Thankfully the 50 Summilux & 90 Cron have no focus shift, the 28 Cron is perfect at 2.8 but I did have to play with the cam to get the 50 and 90 to focus correctly. Now at least I know everything focuses and any misses are down to me. :o

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