again on adjusting m4 rf

[nzeeman]

i got info from fellow member on how to adjust rf on m4. but i have on small problem - on my m4 i can only adjust roller screw because previous owner dented inner two screws so they cannot be moved with screwdriver.

if i adjust images to be good in infinity my camera and i put lens on 1m my images become one when i am 1m and 5 cm away from object. that means my point of focus will be 5 cm in front of subject.
and if i adjust it for 1m i reach infinity on lens on objects that are on 20m from me. so focus is behind them.

so my question is - if i put it to frontfocus on 1m for about 2-3cm i have correct focus until 8-9m but then i start to have focus point behind them.
do you think that on that distances DOF will cover for that mistake?

 

[payasam]

At greater distances, and with the small or medium apertures generally used, depth of field will cover much focussing error. If you get near focus right, far objects will take care of themselves. Typically, the larger apertures are used mainly for shorter distances. I have improved the focussing of my M2 somewhat, but it is a damned tricky business for someone with no experience.

 

[awilder]

My experience with M camera rf adjustments is to first set the calibration to exact infinity adjustment with your lens. Then take several test shots stopped down 1-2 stops from full aperture at exactly 1 meter with bracketing distance scale focus adjustment in small increments from where the camera's rf is focused on the distance scale (1.05 meters in your case) down to 1 meter on the scale. Examine the results with a high powered loupe to see how far off the actual focus. You might be surprised in that that may not actually be off at all or all that much. If the focus is way off, send it to a good Leica tech for a repair, I'm sure it's fixable.

 

[srtiwari]

My M4 Rangefinder has gone out of Horizontal alignment. I am having some difficulty with actually identifying the action required. I cannot seem to correctly identify the part "eccentric shaft on the rangefinder roller-arm". I do have a picture of the area but still am a bit confused 😱
Can anyone help ?
Subhash

 

[ferider]

My M4 Rangefinder has gone out of Horizontal alignment. I am having some difficulty with actually identifying the action required. I cannot seem to correctly identify the part "eccentric shaft on the rangefinder roller-arm". I do have a picture of the area but still am a bit confused 😱
Can anyone help ?
Subhash

How about this:

Does this help ?

Roland.

 

[srtiwari]

Thank you Roland. It couldn't have been more to the point, or clearer !
Subhash

 

[srtiwari]

Oh, Oh ! More problems. This one is confusing.
Even when I manage to rotate the screw (as in the picture above) about 15-20 degrees I do NOT see any change in the distance between the 2 images of an object about 200 yards away. They remain about a distance equal to about 1/6th the width of the patch. I would have thought that much rotation would have produced a discernible change !
Thank you for any help (Again) !
Subhash

 

[srtiwari]

Vic,
Did it work when you tried it ?
Subhash

 

[ferider]

Subhash, didn't realize it was so much (1 6th of the patch is a lot) with your camera. It usually can be done to fix small misalignments, and only by twisting the screw a few degrees. You might consider sending your camera for professional adjustment.

Sorry,

Roland.

 

[srtiwari]

No problem Roland. I'll send it out. Don't know how it happened tho'. I took it out to shoot last weekend, and later noted inability to merge the two images at infinity.

 

[maddoc]

Roland, that is the best instruction I have seen ever, better is not possible ! 🙂

I have managed to adjust the RF (horizontal) of my M2 exactly the way as you have described it. (I had bought it with sellers comment "RF is off at infinity) and it was way off, images in the RF patch didn't overlap at infinity when lens was set to infinity)

From my experience it only takes a few degrees to adjust, not really turning the screwdriver but only applying a little torque force.

Thanks again for posting this !

Gabor

How about this:

Does this help ?

Roland.

 

[payasam]

Roland has given us an excellent drawing. I'll only add one bit of advice I got from Youxin Ye: that a drop or two of oil (I put it in with the point of a needle) makes the screw easier to turn. You need a perfectly fitting screwdriver, of course. I'd also say that 1/6 of a turn should make a hell of a difference.

 

[nzeeman]

you say that just few degree turn will be enough - in my case i had to turn it about 10 degrees. i dont know what type of the mechanism lay in screwing roller - so i was wondering - what would happen if someone rotate screw whole 360 degree turn - would it be the same thing? or something would change?

 

[awilder]

The screw is actually an ecentric design, thus a 360 degree turn puts you back were you started. I've never found it took very much rotation to effect a significant change and for those needing a fairly large amount of rotation of this screw indicates that possibly to top should be removed by a good repair tech for futher adjustment.

 

[srtiwari]

I wrote to the Youxin Ye, and his response was -
"The main prism is dislodged. I will need to do realignment."
Since I had used the phrase "way off", he was likely referring a magnitude of problem that would NOT correct with just a turn of the screw. So, I guess that is the other caveat in this situation.