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new backfocus thread-solution


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Here are the pictures. You just put your 2mm Allen wrench where the red arrow is, as shown in the 2nd picture and your turn slowly, 1/10th of a turn or less being careful not using excessive force Hello guest! Please register or sign in to view the hidden content. Hallo Gast! Du willst die Bilder sehen? Einfach registrieren oder anmelden! and just rotating, not pressing in any direction.   If you do not have an infinite point to adjust, you can try by shooting some books on a shelf, each at

Ok-ive been suffering with a bad "backfocus" problem for months. I was scared to adjust myself based on some posts here. Finally yesterday got fed up and took out the 2 mil allen key. Focus to infinity-adjust a bit. Focus to near limit-adjust a bit. Rinse and repeat (3 times). Focus is now spot on. Really easy adjustment. I adjusted with the noctilux so any error would be magnified well. I feel much better now-about the m8, about life in general....b

ron-there is a 2mil allen key adjustment in the center of the "roller cam" in the lens mount. i just set the lens to infinity-look at a vertical on the horizon-take lens off and turn the allen key a bit-lens back on to check infinity-rinse and repeat-then fine tun a bit at near and mid focus...b

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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

{snipped}

 

Actually, with the way the lenses appear to be focusing now, I'd say to Sthan to go

shoot some real shots and see what he thinks.

 

And I would send in that 90 now.... which certainly appears suspect given the 35 and 50 Lux are doing fine.

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Actually, with the way the lenses appear to be focusing now, I'd say to Sthan to go

shoot some real shots and see what he thinks.....

 

I agree Jamie, they seem very close, but it just all the different angles and positions of the various test shots would indicate to me the possibility of not having the ideal base from which to fully evaluate what's going on IMO.

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Eoin is right, I've been lazy and shot handheld.

When I see his shot of the ruler here, focus is spot

on "13". It seems I never achieve the same result.

 

I should redo it shooting on a tripod, same angle.

I made some test shots outside, on very geometrical

subjects.

 

It's still a mess : on some shots with the 50 mm, wide

open, frontfocus is still disturbing (say you focus on a

face, on the eye, and have more the lips in than the eye…).

Instead, stopping down at 2 or 2.8, it's alright.

The whole thing begins to be time consuming…

I wonder if I'm not to sending it to DAG anyway, to have

the whole thing spot on, with minimal or no focus shift.

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@ Jamie : I'm sorry, I think I'll pass the baby to Dan…

Last results with the 50 lux only : still not spot on at 1.4.

The rest is acceptable.

 

With all four, focus was on the core of the rose.

 

1. 50 Lux 1.4 Frontfocus like the devil

2. 50 Lux 4

3. 50 Lux 5.6

4. 50 Lux 8

 

PS : Regarding tonalities, the original flowers and foliage (and the original DNG images) are more saturated

of course than this JPEG version, but I'm quite impressed by the true to life tones the M8 achieved, without

any tweaking in PS whatsoever.

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Looking at the above backfocus test motivated me to pull out my 50 lux asph and try the same thing. I used a tripod and applied no sharpening to the RAW files. (This plant is not supposed to be flowering right now, but has three blooms)

 

It would seem all 50 lux asph lenses are not created equally, because I see no focus shift whatsoever in mine. I focused on the stamen in the front flower. From top to bottom, apertures were 1.4, 2.8, 4, 5.6 & 8.

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Interesting, Brent,

Mine is pre-ASPH, last batch, my first Leica lens, bought late 2005.

It seems all my lenses will visit your neighbour.

 

PS : A plant flowering which is supposed not to ? Seems you have a plant's shift instead of a focus shift∞

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Interesting, Brent,

Mine is pre-ASPH, last batch, my first Leica lens, bought late 2005.

It seems all my lenses will visit your neighbour.

 

PS : A plant flowering which is supposed not to ? Seems you have a plant's shift instead of a focus shift∞

 

I'll tell my neighbor to keep an eye out for your package and get it back to you quickly. Would you like me to first call him and ask if he can correct the focus shift?

 

The plant is a Christmas Cactus. It also sometimes flowers around Easter, but we've never seen a bloom on it at this time of year--very strange indeed.

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Christmas in April : quite a shift then, but a beautiful one.

Thank you for your kind word to Dan : I appreciate.

He's been very kind hiumself on the phone and will do his best.

I'm a bit tense with the idea of sending all my gear that way,

but I really have to get rid of that shift (like a cactus spike in

my eye…).

Cheers

Johan

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Christmas in April : quite a shift then, but a beautiful one.

Thank you for your kind word to Dan : I appreciate.

He's been very kind hiumself on the phone and will do his best.

I'm a bit tense with the idea of sending all my gear that way,

but I really have to get rid of that shift (like a cactus spike in

my eye…).

Cheers

Johan

 

Johan,

 

You know that you're not going to get rid of focus shift on the 35 Lux and Nocti lux; and Dan will need the M8 to ensure everything is properly adjusted, won't he?

 

The front-focus is discouraging... sorry it's not working.

 

@Eoin--that ruler test looks great... thanks for posting the picture.

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Johan,

 

You know that you're not going to get rid of focus shift on the 35 Lux and Nocti lux; and Dan will need the M8 to ensure everything is properly adjusted, won't he?

 

The front-focus is discouraging... sorry it's not working.

 

Yes, I know that, Jamie.

He promised me to get it done in around 10 days, for the 4 lenses,

and to correct the focus shift.

I cannot see another solution. Solms would be a month or even two.

Anyway, thanks again for all your advice and support.

Yours,

Johan

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Hi Johan:

 

You will not have this problem with the Cron 50 you just bought:)

 

I had backfocus problem with the Lux 50 asph at 1.4. DAG adjusted that so it is spot on now. Still focus shifts but the increasing DOF takes care of that.

 

Although I suspect front focusing would be tougher to correct. Will have to machine off a few thousandths at the collar? I have a Lux 50 v2 from 1960s that front focuses. Never bothered to get it corrected.

 

Alan

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Last week, for some reason my rangefinder went out of whack, I noticed that because I ended up focusing systematically behind my intended target and looking closer, the RF was not aligned properly at infinity.

I took a few shots of a scale and realised that at 1.5m I was backfocusing by over 10cm... After seeing the pictures of where the infinity adjustment was on this forum, I took a knife (no small allen key here...) and messed up with the infinity alignment, checking with a magnifier and all my lenses until it was right. This thing is really sensitive to minor rotations, I fear that I'll have to do it again.

After redoing the tests I ended up with much better focusing accuracy (it mostly fits what I need), at 1m:

-Leica 35 cron asph back focuses by ~5mm at f2 and no visible focus shift

-Nikkor 50 SC front focuses by 7mm at 1.4, 11mm at f2, and is spot on at f2.8

-Nikkor 85 PC back focuses by ~6mm at f2 and no visible focus shift

 

Less than 1cm at 1m is probably close to the error I am doing even with a magnifier, and good enough for all my shooting.

 

I am happy, reading this forum saved my M8 a trip back to Solms

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I'll tell my neighbor to keep an eye out for your package and get it back to you quickly. Would you like me to first call him and ask if he can correct the focus shift?

 

The plant is a Christmas Cactus. It also sometimes flowers around Easter, but we've never seen a bloom on it at this time of year--very strange indeed.

 

hello! i am new here altho ive been reading since i got an m8. for years i shot with nikons (which i still have) but, like most i wanted a leica system.

 

now i have one and altho some problems i love it.

i too have some focus shift and i also dont want to send my stuff to solms.

i have dealt with tibor @ samys in los angeles. ive brought my camera/lenses in and put my lenses on their m8s. they say thay have never heard of correcting focus shift w/allen wrench.

so they wernt much help.

 

anyway thankfully to this thread, i downloaded and tested with the nikon focus chart.

 

1st problem is i printed the chart at the 8 1/2 x11 size and its very small if im to be at a 45% and a distance that allows me some focusing range.

i used that size anyway, but im not sure im exactly 45%.

i suspect an accurate 45% is important.

 

heres what i got: all wide open:

28mm=16mm front focus

35mm=16mm back focus!

nocti=24mm back focus

75mm=spot on.

 

now if there wasnt such a difference between the 28 and 35, id be ready to roll with the 2mm hex wrench!

 

please advise! which way do i start turning? is this a problem that can be fixed with front cam adjust?

 

im not willing to send my stuff to solms, i hear nothing but nightmares. i need my equipment (just like everyone else i know) but i hear of a dan person here, and, i would love to hire him to do my repairs if thats a possibility.

 

i would like to learn to do it myself, but only if i have a good back up repair person!

 

thanks to all on this forum, you have all been helpful and ive also seen some lovely work.

ill be glad to post some pics when ive sraighten all this out!

-best, melissa

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Melissa,

 

I think as I advised further back on this thread, I think you currently have far too many variables to start sending individual lenses away. Adjusting rangefinder infinity with a 2mm allen key job only changes the rangefinder and does nothing for any lens. Check the infinity on your 75mm lens, ignoring other focus distance setting. Adjust if necessary (see lots of other threads for methodology) but BE GENTLE. One of the planets or the edge of the moon on a clear night makes a perfect infinity target. Then retest focus and infinity on other lenses. See if you can build up a logical picture of where the errors lie.

 

Ideally the Nocti and the 35 Lux should be set up by a competent lens technician, with a very small amount of front focus (about 50/50 or 60/40 behind/in front focus zones relative to the focus point is about right I think). Then any aperture shift will work in your favour. The Nocti, which shifts quite a lot may end up with say 1/4 behind and 3/4 in front. The Lux, if it is working right should aperture shift to the theoretical ideal of 1/3 behind and 2/3 in front.

 

Hope this helps.

 

Alternatively you can send your M8 and all the lenses to Don and he will do all the hard work for you and get it all perfect.

 

Wilson

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(quote)

Ideally the Nocti and the 35 Lux should be set up by a competent lens technician, with a very small amount of front focus (about 50/50 or 60/40 behind/in front focus zones relative to the focus point is about right I think). Then any aperture shift will work in your favour. The Nocti, which shifts quite a lot may end up with say 1/4 behind and 3/4 in front. The Lux, if it is working right should aperture shift to the theoretical ideal of 1/3 behind and 2/3 in front.

 

Hope this helps.

 

Alternatively you can send your M8 and all the lenses to Don and he will do all the hard work for you and get it all perfect.

 

Wilson

 

oh thank you wilson for replying. i live in las vegas where there are many brightly buildings.

would that work for infinity?

i do have some shots from new zealand that have the "sounds" in them and those ar at infinity.

anyway i think what youre saying here is make the decisions based on the infinity image rather than the close ones.

 

i would like to contact don, or from here on at "the don" my email address is wire5377@hotmail.com i would like to send everything to the don!

 

and thanks! melissa

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Hi Leica factory has a special rangefinder adjustment jig, I have seen My local dealer had one too. So It looks very very complex mechanism.

I will not adjust mine myself If it is with-in Leica warranty.

 

1) warranty? ---> send to Germany or Local dealer If they have this jig

2)No warranty---> try yourself 1st--->OK? / No good-------->>> Send to Germany or local dealer

 

 

 

Thanks for all of user info.

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Melissa,

 

I think as I advised further back on this thread, I think you currently have far too many variables to start sending individual lenses away. Adjusting rangefinder infinity with a 2mm allen key job only changes the rangefinder and does nothing for any lens. Check the infinity on your 75mm lens, ignoring other focus distance setting. Adjust if necessary (see lots of other threads for methodology) but BE GENTLE. One of the planets or the edge of the moon on a clear night makes a perfect infinity target. Then retest focus and infinity on other lenses. See if you can build up a logical picture of where the errors lie.

 

Ideally the Nocti and the 35 Lux should be set up by a competent lens technician, with a very small amount of front focus (about 50/50 or 60/40 behind/in front focus zones relative to the focus point is about right I think). Then any aperture shift will work in your favour. The Nocti, which shifts quite a lot may end up with say 1/4 behind and 3/4 in front. The Lux, if it is working right should aperture shift to the theoretical ideal of 1/3 behind and 2/3 in front.

 

Hope this helps.

 

Alternatively you can send your M8 and all the lenses to Don and he will do all the hard work for you and get it all perfect.

 

Wilson

 

 

I agree, Wilson, there is much confusion about. Wil van Manen explained the procedure to me today when I sent him a 90 AA which was returning soft horizons despite focussing correctly. One must differentiate according to the way lenses are built. First there is the coupling between the lens and the rangefinder by the excentric wheel, which everybody is fiddling with. That is only to make the rf patch match up correctly when the lens mount is at infinity.

Then there is the lens mount, which connects through a sloping helical to the wheel. This is separate unit, which is adjusted separately by the factory for correct coupling to the rangefinder. Tolerances can be relatively loose on this, as the helicoid has quite a mild slope and a long throw. This is to compensate for any wear etc.

Then there is the optical cell which is fixed into the lensmount and adjusted to very narrow tolerances by shims to obtain exact distance to the sensor plane. As optical cells vary sligthly in focal length this is done individually for each lens.

The technician will (if he has the camera, which is not always needed) return the rangefinder coupling to the correct setting, then he will check/adjust the lens mount to infinity and then he will turn to the shimming. To find infinity he will use a collimator with a focal length of 20.000 metres. Often a lens will be within factory tolerances, but technicians like Don or Wil will be able to narrow these tolerances individually, so the end result is a perfectly focussing lens.

It all goes to show that the Allen Key method is fine as a quick field fix, but certainly not a solution.

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I agree, Wilson, there is much confusion about. Wil van Manen explained the procedure to me today when I sent him a 90 AA which was returning soft horizons despite focussing correctly. One must differentiate according to the way lenses are built. First there is the coupling between the lens and the rangefinder by the excentric wheel, which everybody is fiddling with. That is only to make the rf patch match up correctly when the lens mount is at infinity.

Then there is the lens mount, which connects through a sloping helical to the wheel. This is separate unit, which is adjusted separately by the factory for correct coupling to the rangefinder. Tolerances can be relatively loose on this, as the helicoid has quite a mild slope and a long throw. This is to compensate for any wear etc.

Then there is the optical cell which is fixed into the lensmount and adjusted to very narrow tolerances by shims to obtain exact distance to the sensor plane. As optical cells vary sligthly in focal length this is done individually for each lens.

The technician will (if he has the camera, which is not always needed) return the rangefinder coupling to the correct setting, then he will check/adjust the lens mount to infinity and then he will turn to the shimming. To find infinity he will use a collimator with a focal length of 20.000 metres. Often a lens will be within factory tolerances, but technicians like Don or Wil will be able to narrow these tolerances individually, so the end result is a perfectly focussing lens.

It all goes to show that the Allen Key method is fine as a quick field fix, but certainly not a solution.

 

What Jaap said!

so happy im not required to understand that in order to make a picture!

 

now that we know its best to go to a good repair person, and that there are a few available do you believe that one should have 2 bodies? if so should one send everything in all at once and have bodies and lenses calibrated together?

 

tia, melissa

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