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-   -   New M9 User: Inevitable RF Focus Questions (http://www.rangefinderforum.com/forums/showthread.php?t=164092)

adamjbonn 02-05-2018 11:26

New M9 User: Inevitable RF Focus Questions
 
I suspect the title says it all really!

Now I'm quietly confident that the overwhelming response here will be "send it in to Leica"

and OK fair enough

BUT

I'm curious about something.... Rather than I think there's a problem

Short version:

Are Leica lenses (SPECIFICALLY the 35mm F2.4 Summarit) able to focus past infinity?

Longer version:

I own 3 lenses

35 2.4 'rit
50 'cron
90 2.5 'rit

ALL OF MY LENSES FOCUS FINE

Min focus / infinity focus

If the RF patch is aligned, the image comes out in focus, and I mean even at a pixel peeping view!

The weird thing (or maybe not hence the question) is that the 35 focuses past infinity both on the RF patch and the resultant file

So in usage - no drama, turn the focus until the images align in the VF and get an in focus picture

It's just weird that the hard stop is past infinity

This might all be in my head... 35mm F2.4 and things that are at infinity don't exactly make superb test candidates... of course stopping down negates everything (and I wouldn't typically shoot infinity wide open anyway)

I've tested min focus with a ruler and tripod and that's spot on

Not being rude about the 35 2.4... but it does feel erm let's say cheaper than my cron (no surprise) and cheaper than my (older 2.5) 90 rit, is this just what's to be expected when one should've saved a few more pennies and got a 35 'cron :D

Let me just reiterate:

When the RF patch says it's in focus it's in focus, (at any distance) it's just that it seems it's possible to focus past infinity, this is NOT a case of my RF patch says it's in focus, but really it's not

Fraser 02-05-2018 11:47

If everything you want sharp is sharp then leave it alone, send it to Leica and they really make it a problem!

Ko.Fe. 02-05-2018 11:50

My 35 2.5 Summarit-M feels better than my 50 Cron. :).
And if focus tab is on infinity, two images in RF will collate. But. You must look at very far object. Something at another end in the city or at the Moon.

Richard G 02-05-2018 11:50

I’d say don’t send it anywhere and keep using it. My M9 has never been as good since it had to be looked at. My Monochrom is so much better in the shutter release. You have to have a good reason to let anyone touch your camera.

rfaspen 02-05-2018 12:08

First, you do need to focus on something quite far away to qualify as "infinity".

Second. When you get good focus at infinity, what does the distance scale on the lens say? Is it at the infinity mark?

If the hard stop of the lens is at some point beyond the infinity mark and your focus at infinity (RF images coincide) shows the lens at the infinity mark, then I'd say its absolutely no big deal and your particular lens is able to rotate a bit further than we expect. Not sure why....lower tolerances in the factory? Maybe, but who knows...

adamjbonn 02-05-2018 12:29

Quote:

Originally Posted by Fraser (Post 2787637)
If everything you want sharp is sharp then leave it alone, send it to Leica and they really make it a problem!


So do nothing?

Advice I adore and can follow to the letter, thanks :D

adamjbonn 02-05-2018 12:34

Quote:

Originally Posted by Richard G (Post 2787640)
Iíd say donít send it anywhere and keep using it. My M9 has never been as good since it had to be looked at. My Monochrom is so much better in the shutter release. You have to have a good reason to let anyone touch your camera.


It was at the mothership for sensor/cla/rf cal back in October... Just before I bought it

Iím not keen to send it off... besides, what would I say...

ďThe problem is that when the rf images are aligned, the image is in focusĒ :D

I think theyíd laugh at me!

adamjbonn 02-05-2018 12:39

Quote:

Originally Posted by rfaspen (Post 2787643)
First, you do need to focus on something quite far away to qualify as "infinity".

Second. When you get good focus at infinity, what does the distance scale on the lens say? Is it at the infinity mark?

If the hard stop of the lens is at some point beyond the infinity mark and your focus at infinity (RF images coincide) shows the lens at the infinity mark, then I'd say its absolutely no big deal and your particular lens is able to rotate a bit further than we expect. Not sure why....lower tolerances in the factory? Maybe, but who knows...

Well the infinity mark is quite large, itís not like aligning a line to a dot

It PERHAPS sits slightly to the far side of the middle of the ∞ symbol but if so very, very fractionately

You raise a good point about infinity, and my first thoughts were that all the things I was thinking were at infinity werenít

But the 50 and 90 pointed at the same things say theyíre in focus at infinity, so I wondered if infinity was the same with all the lenses but then I thought that sounded daft...

adamjbonn 02-05-2018 12:44

Quote:

Originally Posted by Ko.Fe. (Post 2787639)
My 35 2.5 Summarit-M feels better than my 50 Cron. :).
And if focus tab is on infinity, two images in RF will collate. But. You must look at very far object. Something at another end in the city or at the Moon.

My 90 2.5 is on par with my cron... Iím starting to wish Iíd got a 2.5 35 too!

Perhaps Iím not finding things far enough away, but the 50/90 has an aligned rf patch on the same subjects, yet the 35 doesnít

Archlich 02-05-2018 12:47

Mind show some pictures? That would help determine which part went wrong.

adamjbonn 02-05-2018 13:04

Quote:

Originally Posted by Archlich (Post 2787656)
Mind show some pictures? That would help determine which part went wrong.

Well Iím not saying no, but Iím not sure how some pictures of in focus things, that are far and little because its 35mm will say a right lot?

Huss 02-05-2018 15:46

Quote:

Originally Posted by adamjbonn (Post 2787648)
So do nothing?

Advice I adore and can follow to the letter, thanks :D

Do nothing. If the focus matches up to the RF patch, that is perfect.
Do not send it anywhere. Do not let anyone touch it and mess it up.

:angel:

davidnewtonguitars 02-05-2018 18:15

I'm still trying to get my head around the "past infinity" part.

Huss 02-05-2018 19:04

Quote:

Originally Posted by davidnewtonguitars (Post 2787703)
I'm still trying to get my head around the "past infinity" part.

Let me help...

Past the infinity mark on the focus scale of the lens.

:D

Rob-F 02-05-2018 19:07

Quote:

Originally Posted by davidnewtonguitars (Post 2787703)
I'm still trying to get my head around the "past infinity" part.

It just means that the lens doesn't come to a stop at the infinity mark, but keep on turning for a distance afterward. Long telephoto lenses are sometimes made that way to allow for thermal expansion that might cause an error if some tolerance were not built in. Leica Rangefinder lenses shouldn't require that, being only 135mm at most. The OP's rangefinder might just be a little off. They can be adjusted DIY with a little care.

adamjbonn 02-05-2018 23:47

Quote:

Originally Posted by davidnewtonguitars (Post 2787703)
I'm still trying to get my head around the "past infinity" part.

When you focus a RF you turn the focus ring until the 2 split images are aligned

When I am focusing on infinity with the 35 the split image will be still be slightly Ďsplití when on the hard stop of the lens

Which might mean that Iím not pointing it something far enough away, except that my 50/90 report the same object is in focus at the hard stop

adamjbonn 02-05-2018 23:56

Quote:

Originally Posted by Rob-F (Post 2787710)
It just means that the lens doesn't come to a stop at the infinity mark, but keep on turning for a distance afterward. Long telephoto lenses are sometimes made that way to allow for thermal expansion that might cause an error if some tolerance were not built in. Leica Rangefinder lenses shouldn't require that, being only 135mm at most. The OP's rangefinder might just be a little off. They can be adjusted DIY with a little care.

When you focus a RF you turn the focus ring until the 2 split images are aligned, from the little I know, the symptom of a misaligned RF is that the split image focusing reports the subject is in focus, but the resultant image is not in focus

I donít have this problem, when my RF split image is aligned my pictures are in focus, even on the 90

It just seems that my 35 is able to focus past infinity and my other lenses canít or that Iím not using a far enough away target, except that with the same tatget my 50/90 say that the object is infinity

Of my three lenses, I would expect the 35 to have deepest DOF as itís the widest

adamjbonn 02-06-2018 05:17

having played some more today, I'm starting to think that I've been testing on things that the lens considers closer than 'at infinity'

David Hughes 02-06-2018 08:52

Hmmm, well, um; nothing on this planet is at infinity, neither is the moon, nor any of the planets you can see at night, nor the galaxies you can see at night but one or two stars are near enough for infinity testing; try Antares which is near Mars in the mornings but won't be for long...

Regards, David


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