Leica’s Off Optical Axis Viewfinders???

[david strachan]

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Browsing through Dennis Laney’s “Leica Collectors Guide”, I see all viewfinder-cold shoe are off optical axis. When a viewfinder is attached to the camera it is viewing off the optical pathway of system and lens. This applies to all Leicas…except for the Leica SLR’s which necessitate optical path viewing.

 

Can someone advise why it is better to put the viewfinder off axis????There has always been room to the left of the top plate to move the flash shoe…it’s just taken up with script.

 

Can someone help me here please.I do not understand…isn’t it better to have your viewfinders in, above or along the optical axis???

Thanks in anticipation.

 

Cheers Dave S

Edited December 19, 2014 by david strachan
edit

[TomB_tx]

The closer the viewfinder is to the lens axis, the more the lens barrel & hood block the VF. For instance, the Canon 50 1.4 LTM lens blocks a lot of the older IIIc-IIIf Leica viewfinder, but was meant for the Canon cameras where the VF was farther from the lens axis. (The Leica LTM cameras had the VF between the RF windows.) The M models move the VF farther left as it incorporates the RF, like the older Canon (but better).

The M has some automatic parallax correction as focused, but there is always a slight difference in the view. However, if you use one all the time you learn the difference and how to shift a bit before snapping the shutter to compensate.

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[david strachan]

The closer the viewfinder is to the lens axis, the more the lens barrel & hood block the VF. For instance, the Canon 50 1.4 LTM lens /quote

 

 

Hi Tom

I have the sensational Canon P and the lens you mention. I see the hot shoe-auxiliary finder shoe is directly in line with the lens axis. The rangefinder view is also blocked by the lens and hood.

 

I haven't got a 50mm finder to try in the shoe, to test your thesis.

 

cheers Dave S

[gyoung]

Its all a compromise if the view is not through the taking lens. You just learn not to crop too tight and sort it out in the darkroom etc.

 

Gerry

[fotoism]

Don't mean to hijack the thread but I always wonder about a similar issue/question and maybe the answer is somehow related: Why is the tripod thread also off axis? It is not aligned with the lens, nor the body, nor the viewfinder window.

[gyoung]

It should be under the centre of gravity of the camera, but just as with the shoe on top sometimes bits of the camera inside get in the way, lens or viewfinder axis is irrelevant, its a balance issue

 

Gerry

[RogerW]

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I wonder if it is entirely a CG issue? The screw for a tripod on LTM cameras is almost under the shutter release button where it can best support any downward pressure, unless a cable release is used. Perhaps the design predates the cable release? Someone will know!

[TomB_tx]

Leica's traditional "end of the body" tripod position is a logical result of trying to keep the camera dimensions as small as practical, along with the body designed around the shutter mechanism. Without making the bottom plate thicker, the threaded socket had to extend into the body, and the take up spool space was available, and also needed a guide pin for the end of the spool. Putting the tripod mount there was an elegant mechanical solution, if not the best for stability. But Leitz made very rigid ball heads which worked well.

The M film cameras kept this traditional location, while the Leicaflex series centered it better like other cameras of the time. (Possibly also due to mirror vibration.)

[david strachan]

Don't mean to hijack the thread but I always wonder about a similar issue/question and maybe the answer is somehow related: Why is the tripod thread also off axis? It is not aligned with the lens, nor the body, nor the viewfinder window.

 

You're right Phil...I guess we are thinking alike...(the tripod mount on all Leicas is a bit crazy...far to one side)...but why not in the optical axis???

 

Accessory shoe and tripod mount should be in line with the lens...we're thinking. The Leica 1, model C (first interchangeable lens) was the only Leica which sports an accessory shoe directly over the lens path..

 

I wonder why Herr Barnack changed the configuration???

cheers Dave S

 

PS my Nikon FE2 has tripod mount directly in line and under the moving mirror (film plane would be perfect place)

Edited December 20, 2014 by david strachan
edit

[giordano]

I wonder if it is entirely a CG issue? The screw for a tripod on LTM cameras is almost under the shutter release button where it can best support any downward pressure, unless a cable release is used. Perhaps the design predates the cable release? Someone will know!

 

The cable release predates the Leica camera. The first "Bowden Cable" patent was granted in 1896, and by 1908 the ancestors of the Prontor shutter were being supplied with the tapered-thread cable release socket that became almost universal for the rest of the film era.

[aesop]

Browsing through Dennis Laney’s “Leica Collectors Guide”, I see all viewfinder-cold shoe are off optical axis. When a viewfinder is attached to the camera it is viewing off the optical pathway of system and lens. This applies to all Leicas…except for the Leica SLR’s which necessitate optical path viewing.

 

Can someone advise why it is better to put the viewfinder off axis????There has always been room to the left of the top plate to move the flash shoe…it’s just taken up with script.

 

Can someone help me here please.I do not understand…isn’t it better to have your viewfinders in, above or along the optical axis???

Thanks in anticipation.

 

Cheers Dave S

 

 

...quick question, david strachan - have you confirmed that there is no compensation whatsoever built into the designs of the various accessory-shoe-mounted M viewfinders?

[david strachan]

...quick question, david strachan - have you confirmed that there is no compensation whatsoever built into the designs of the various accessory-shoe-mounted M viewfinders?

 

 

I'm not aware any viewfinders have compensation for lateral movements (X:Y axes) versus the common distance adjustment (Z axis) which we see on many viewfinders. So no, there is no adjustments for lining up the viewfinders along their optical axis.

 

A red herring? Perhaps I'm being delusional; heaven help me if I question the design...

 

 

I was just interested, that's all...perhaps I'll come across an answer one day.

 

cheers Dave S

[aesop]

I'm not aware any viewfinders have compensation for lateral movements (X:Y axes) versus the common distance adjustment (Z axis) which we see on many viewfinders. So no, there is no adjustments for lining up the viewfinders along their optical axis.

 

A red herring? Perhaps I'm being delusional; heaven help me if I question the design...

 

 

I was just interested, that's all...perhaps I'll come across an answer one day.

 

cheers Dave S

 

 

 

...hmmm, perhaps my previous post was not sufficiently lucid, david strachan.

 

There was no mention of movements nor adjustments of any sort in my post - what I did hint at was the possibility of the a *permanent* off-axis compensation being built into the design of each external Leica M optical viewfinder (that is, for each focal length). This would go some way towards addressing the same requirement for compensation that applies to the integrated viewfinder found on the Leica M. A viewfinder which, incidentally, happens to be situated off-axis.

 

As in all rangefinder viewfinder design, there will always be some trade-off on coverage for each focal length, with the optimum point being somewhere between minimum focusing distance and infinity (naturally).

 

I have managed to dredge up a 2003 thread from another forum - it features relevant input on the issue, including some very salient points from our own Andy Piper (adan).

 

Opinions of 24mm Brightline

I hope you find the thread informative. I did.

 

(Moderators, I trust the publication of a link to a thread on another photography forum does not constitute a transgression - I found no guidance on this specific point within the forum rules. In the event that such actions are forbidden, please accept my apologies and delete the offending link. Thanks.)

[MarkP]

There were a number of discussions here in the past regarding framing errors using OVFs for 21mm lenses with the Zeiss finder:

 

see this thread and my post #26 and it's references to other threads/posts

 

http://www.l-camera-forum.com/leica-forum/customer-forum/233445-zeiss-finders-m9-2.html#post2039013.

[david strachan]

There were a number of discussions here in the past regarding framing errors using OVFs for 21mm lenses with the Zeiss finder:

 

see this thread and my post #26 and it's references to other threads/posts

 

http://www.l-camera-forum.com/leica-forum/customer-forum/233445-zeiss-finders-m9-2.html#post2039013.

 

Thanks Mark; that thread helped my quandary.

 

I suspect it just does not matter having the finder shoe off axis. Even if it is off a lot.

For example a flash in a grip with connector to hot shoe...will show a very very small lateral shadow (in effect this flash shadow at different distance, of a focused subject...is akin to a far offset optical viewfinder.)

 

I feel it is resolved in my head. But I'll do some experiments with offset flash (emulating offset viewfinder) and try and work out the tiny amount of viewfinder offset...not enough to compensate for. I suspect it is the thickness of the frame lines or less.

 

Thanks everyone, for your thinking and responses...it's nice having you experts in LUF.

 

cheers Dave S