M9 Frame Lines

[giordano]

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Sorry, but the thickness of the body has nothing to do with the magnification of the viewfinder.

 

Again, there are four versions of the viewfinder out there with magnifications of .58, .72, .85 and .91.

All of these analog bodies are the same size (except the M6ttl is 2mm taller, because of the extra electronics).

 

They went to .68 to make the 24mm framelines fit in the viewfinder. That's all there is to it.

 

I must be missing something. If the 0.72 finder on an M6 can have framelines covering the full-frame 28mm angle of view, why is it necessary to decrease the magnification in order to have M8 framelines covering the full-frame 32mm angle of view (i.e. the M8 24mm frame)? The only thing that springs to mind is that the optical path from the frameline mask to the eyepiece is longer on the M8 than on the M2-M7.

[jaapv]

Leica changed the magnification because they had to crop the viewfinder. By 1.33 to be precise... It has nothing to do with the length of the optical path.

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[thrid]

I must be missing something. If the 0.72 finder on an M6 can have framelines covering the full-frame 28mm angle of view, why is it necessary to decrease the magnification in order to have M8 framelines covering the full-frame 32mm angle of view (i.e. the M8 24mm frame)? The only thing that springs to mind is that the optical path from the frameline mask to the eyepiece is longer on the M8 than on the M2-M7.

 

On an M6 with the .72 finder the 28mm framelines are all the way at the edge of the viewfinder.

If you look through an M6 with .58 finder there is a comfortable amount of space between the 28mm markings and the edge of the viewfinder.

 

Now, if Leica had put a .72 finder in the M8, the widest lens you would have had framelines for was a 28mm, which gives you a 37mm due to the x.133 crop.

 

But many M shooters wanted the equivalent of a 28mm in 135 format (x1.0) photography on the M8.

 

So, you have a choice.

 

24mm x 1.33 = 31.92mm

21mm x 1.33 = 27.93mm

 

The 21mm essentially gets you the equivalent of a 28mm on the M8. But in order to make 21mm framelines visible in the fiewfinder they would have had to lower the magnification (.50ish?) to an unacceptable level. As a result the markings for the other focal lengths would have been tiny and overall focusing accuracy would not have been high enough.

 

The choice of the 24mm is a compromise, because you only have to lower the magnification to .68 to fit the framelines for that focal length in to the viewfinder. The 24mm turns in to a 32mm on the M8, which is not perfect, but a reasonably compromise.

 

I'm going to state the obvious here, but it's just like zooming in or out with a zoom lens or raising or lowering a magnifying glass. Leica simply reduced the magnification to the point that they could just barely slip in the 24mm framelines.

 

As for the thickness of the body and increased length of the 'tunnel', that something any engineer worth his salt can work around to maintain a given magnification.

Edited August 20, 2009 by thrid

[Shootist]

First off viewfinder magnification and the area indicated by the framelines are two different issues that are not codependent.

 

 

 

Yes they are. Just where have you been? Why would Leica offer .58x, .72x & .85x viewfinders if they weren't codependent.

Yes a 50mm frameline in any of the above magnification viewfinders will have the same coverage of the image you are capturing. But you can't get 21mm framelines in a .85x or .72x viewfinder. Those lines would be outside the viewfinder.

 

I think you are thinking of something totally different.

 

If they can get 28mm framelines in a film M, 35mm film FOV, then if it wasn't for the increase of the body thickness they would of been able to get 21mm framelines, 28mm FOV, on the cropped M8 sensor especially with the reduction of the magnification by .4x.

 

Please think real hard before replying.

[Shootist]

Leica changed the magnification because they had to crop the viewfinder. By 1.33 to be precise... It has nothing to do with the length of the optical path.

 

That is completely wrong. The cropped frameline take up LESS space inside the viewfinder, not more. The frame lines for any given lens on the M8 are much smaller then the same framelines on a film M.

 

They did not have to crop the viewfinder, not really sure what that means. If you measure the windows on a M8 and on a film M they are the same size.

What they had to do was increase the optical path. Since they had to do that they lowered the magnification by .4x so they could get at least 24mm, EFOV of 32mm on film, framelines.

A film M with .72 finder shows 28mm framelines, EFOV 28mm. The M8 only shows framelines for a EFOV of 32mm but yet it is .4x lower in magnification. It is because of the light path from front to back of the camera, Wider/thicker body.

[Shootist]

Hey Shootist,

Film Ms are not just about dead around here

 

John

 

I have one also and have had many in the past 3 years. But I buy them used and have sold all my film M's a few times in the last 3+ years. Only to buy another for some unknown crazy reason.

This time I bought a M7 with .85x viewfinder.

They usually get used for 3-8 rolls of film when I first get them then sit unused for X number of months until I finally sell them.

 

If anyone really wants a film M there are plenty for sale on the used market. Leica doesn't make a dime on them.

[Shootist]

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The choice of the 24mm is a compromise, because you only have to lower the magnification to .68 to fit the framelines for that focal length in to the viewfinder. The 24mm turns in to a 32mm on the M8, which is not perfect, but a reasonably compromise.

 

 

The 24mm framelines on the M8 are smaller then the framelines for a 28mm lens on any film M. That is not why they lowered the magnification.

If you look through a film M viewfinder and switch between the 28 and 35 mm framelines you can get a reference as how big/small the 24mm framelines on the M8 are. Now it they are smaller then the 28mm lines and just bigger then the 35mm lines why would Leica need to lower the magnification to fit them in the M8.

It is because of the increased light path, thicker body, of the M8's viewfinder.

[jaapv]

That is nonsense. By that way of reasoning it would be impossible to fit different magnifications in the film M body.

[Valkyrie]

Page 102 of the M8 instruction manual identifies the M8 viewfinder has"an enlargement factor of 0.68 x." Page 124 of the M8.2 instruction manual says the M8.2 viewfinder has "an enlargement factor of 0.72 x." Unless this information is incorrect, it is clear the thickness of the body is not a limiting factor in the viewfinder magnification. Or maybe the M8.2 is thinner?!

[jaapv]

The only reason is they needed to fit framelines for a wider lens because of the crop of the sensor. Indeed the thickness of the body has absolutely nothing to do with it. The dimension of the rangefinder assembly are not even determined by it.

[thrid]

Please think real hard before replying.

 

 

Or what?

[Shootist]

The only reason is they needed to fit framelines for a wider lens because of the crop of the sensor. Indeed the thickness of the body has absolutely nothing to do with it. The dimension of the rangefinder assembly are not even determined by it.

 

Please get your head around this. A 24mm lens on the M8 capture a image that is smaller, narrower and shorter, then a 28mm lens on a film camera. If they can fit 28mm framelines into a x.72 VF on a film camera they could certainly fit the 24mm framelines, FOV of 32mm, on the M8 without reducing the magnification since the framelines for a 24mm lens are actually smaller on the M8 then they are for a 28mm lens on a film body.

The reason is the increase in body thickness.

 

Do you have a film M? If so pick something out in your house and frame it in the film VF with a 28mm lens attached or by bringing up the 28mm framelines and mark the spot you are standing. Now take the M8, original or update frameline of the M8.2, and do the same with the 24mm framelines. You will see you need to farther back from the subject with the M8 to get the same subject/s in the photo as you did with the film M with a 28mm lens. But yet the VF magnification is less on the M8 and the 24mm framelines nearly fill the VF. If it wasn't for the thickness of the body, increased optical path, Leica could of put in a x.72 finder and included 21MM framelines.

[carlmuck]

Please get your head around this. A 24mm lens on the M8 capture a image that is smaller, narrower and shorter, then a 28mm lens on a film camera. If they can fit 28mm framelines into a x.72 VF on a film camera they could certainly fit the 24mm framelines, FOV of 32mm, on the M8 without reducing the magnification since the framelines for a 24mm lens are actually smaller on the M8 then they are for a 28mm lens on a film body.

The reason is the increase in body thickness.

 

Do you have a film M? If so pick something out in your house and frame it in the film VF with a 28mm lens attached or by bringing up the 28mm framelines and mark the spot you are standing. Now take the M8, original or update frameline of the M8.2, and do the same with the 24mm framelines. You will see you need to farther back from the subject with the M8 to get the same subject/s in the photo as you did with the film M with a 28mm lens. But yet the VF magnification is less on the M8 and the 24mm framelines nearly fill the VF. If it wasn't for the thickness of the body, increased optical path, Leica could of put in a x.72 finder and included 21MM framelines.

 

You really shouldn't try so hard to make up this stuff.

 

The optical magnification of the viewfinder is not dictated by the thickness of the body (the length of the viewfinder lens). As has been pointed out there are 3 magnification's available (0.58, 0.72, 0.85) in the film line (and 4 (M3's 0.91) over the history of the M-film line), so the mag and thickness of the body are not inextricably linked.

 

You also seem to be confusing the FOV of the lens and the FOV of the viewfinder. To use your example then the 0.72 v/f of an M6 should have plenty of space for a 24mm frame lines, but there aren't. Your thought experiment simply points out that the M8 and M6/M7/MP viewfinders are engineered to different criteria. For the M8 that is that a 24mm lens mounted can be framed in the built-in viewfinder. For the M-film it is that a 28mm lens can (just barely and with out glasses) be framed in the built-in V/F.

 

The system (frameline masks and v/f magnification) is engineered to produce the view you see in the viewfinder. The system's magnification (and range of lenses supported) is NOT a byproduct of the pieces being assembled.

Edited August 21, 2009 by carlmuck

[adan]

First of all, I hope it is obvious to everyone that if you stand at the opening of a tunnel 50 feet long, and at the opening of a tunnel 75 feet long, the far end of the 75' tunnel will appear smaller than the far end of the 50' tunnel. That is basic perspective.

 

The M8 is unique in having a longer tunnel to look through - by 10% or so, than any previous M body. The body is thicker, the tunnel is longer.

 

Notice that so far, I have not needed to mention magnification or framelines - we are just talking about the apparent size of the window at the far end of the hole through the camera. It is smaller on the M8.

 

Now - the smaller window means that at the same magnification, the M8 cannot take in the same amount of scenery as a film M's viewfinder. Evidence - there are no framelines for a 21mm lens. If a 21 cropped on the M8 = a "28mm" lens, then Leica should have been able to stick with the classic .72x magnification and put in lines for a 21mm lens right where the 28mm lines appear in a .72x film M.

 

Except that - oops - they couldn't. Not enough room, because the window looks smaller, because the tunnel is longer. An M8 finder cannot accomodate a true 28mm field of view any more than an M3's can.

 

And this is where Thrid is correct - he just has cause and effect mixed up. The .68 magnification was needed to squeeze in the 24 lines (= 32mm field of view) because the extra body thickness had made the window too small for them to fit at .72x - which they would have in a regulation-length .72x film viewfinder, because it can (just) handle 28mm field of view, compared to which 32mm FoV is easy.

 

Valkyrie: You are correct regarding the spec listed in the M8.2 manual - BUT in the online spec sheet Leica lists both M8 and M8.2 as having .68x viewfinders - twice. Occam's Razor says one typo is more likely than two.

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[lars_bergquist]

The idea that the magnification of the finder is limited by the depth of the body is an interesting one. Like so many interesting ideas, it is wrong.

 

If that were the case, how could Leica offer three different magnifications in the M7, without altering the body? And a screw-mount Leica has a 0.5x finder --- so a LTM camera must be a foot thick, no? The field of view (= magnification) of the finder is determined by the combination of the focal lengths of the eyepiece and the lens in front of the beamsplitter prism.

 

The old man from the Age of Brilliant Finders

[adan]

Lars - the apparent size of the opening at the front is affected by the depth of the body.

 

If you tape off the edges of the front window to make it smaller, that affects FoV just as much as "the combination of the focal lengths of the eyepiece and the lens in front of the beamsplitter prism."

 

If you move it away from the eyepiece by 3mm by making the body thicker, that also affects FoV.

 

Yes, any magnification Leica wants (within reason) can be installed in the optics behind that window, and the depth does not especially limit that (in fact, a longer tunnel should give more leeway to play with the optics)

 

BUT - the M8s body thickness does make the window look smaller, and the smaller window makes for a narrower field of view for any given optics/magnification (including no optics at all - think of looking through the top plate eye opening without any viewfinder optics installed - the opening on the other side of the top plate will look smaller in a thicker body - yes or no?).

 

Once the M9-or-whatever comes out, it will be easy to solve. If the M9 is still thicker than an M7 (I think it will be) and still uses .68x magnification (or lower) to allow a 28mm frameline (and I bet it will), then the question will be - why won't a plain vanilla .72x finder work? Answer: the only other difference is body thickness. QED.

 

On an LTM camera, .5x works nicely for the window sizes and tunnel length involved (BTW, you do know that many of the LTM viewfinders are periscopes, so the length is much longer than the body thickness - the front window is offset by 3/4" or so from the eyepiece centerline?)

 

See this image - the VF eyepiece is just below the "We.." in "Wetzlar" - the front window is centered beyond the "z" in "Leitz".

 

Leica IIIc K Gray

 

If the body were thicker, a different set of optics would give a 50mm view out the more distant window - just as .68x optics give a 32mm field of view with a body thickness of the M8, and .72x optics give a 28mm field of view with the thinner M7 body.

 

Anyone have Stefan Daniels' email? I can just ask him "Was the extra thickness of the M8 body a factor in designing the .68x viewfinder for the M8?" and see what he says (unless he's up to his ears in S2/M9 at the moment.)

Edited August 21, 2009 by adan

[Shootist]

First of all, I hope it is obvious to everyone that if you stand at the opening of a tunnel 50 feet long, and at the opening of a tunnel 75 feet long, the far end of the 75' tunnel will appear smaller than the far end of the 50' tunnel. That is basic perspective.

 

The M8 is unique in having a longer tunnel to look through - by 10% or so, than any previous M body. The body is thicker, the tunnel is longer.

 

Notice that so far, I have not needed to mention magnification or framelines - we are just talking about the apparent size of the window at the far end of the hole through the camera. It is smaller on the M8.

 

Now - the smaller window means that at the same magnification, the M8 cannot take in the same amount of scenery as a film M's viewfinder. Evidence - there are no framelines for a 21mm lens. If a 21 cropped on the M8 = a "28mm" lens, then Leica should have been able to stick with the classic .72x magnification and put in lines for a 21mm lens right where the 28mm lines appear in a .72x film M.

 

Except that - oops - they couldn't. Not enough room, because the window looks smaller, because the tunnel is longer. An M8 finder cannot accomodate a true 28mm field of view any more than an M3's can.

 

And this is where Thrid is correct - he just has cause and effect mixed up. The .68 magnification was needed to squeeze in the 24 lines (= 32mm field of view) because the extra body thickness had made the window too small for them to fit at .72x - which they would have in a regulation-length .72x film viewfinder, because it can (just) handle 28mm field of view, compared to which 32mm FoV is easy.

 

Valkyrie: You are correct regarding the spec listed in the M8.2 manual - BUT in the online spec sheet Leica lists both M8 and M8.2 as having .68x viewfinders - twice. Occam's Razor says one typo is more likely than two.

 

 

Thank you, Thank you, Thank you.

Finally someone that understand.

Edited August 21, 2009 by Shootist

[giordano]

The idea that the magnification of the finder is limited by the depth of the body is an interesting one. Like so many interesting ideas, it is wrong.

 

If that were the case, how could Leica offer three different magnifications in the M7, without altering the body? And a screw-mount Leica has a 0.5x finder --- so a LTM camera must be a foot thick, no? The field of view (= magnification) of the finder is determined by the combination of the focal lengths of the eyepiece and the lens in front of the beamsplitter prism.

 

IIRC the distance between them also comes into the equation. In other words you can (within reason) have any magnification you want, or any field of view you want, but as long as you stick to the basic inverse-Galilean design used in all M viewfinders the relationship between the two depends on the thickness of the body.

[Shootist]

You really shouldn't try so hard to make up this stuff.

 

 

Well I'm not making it up.

 

No where did I say they are linked. But going there they are linked for the Effective Field Of View of the viewfinder and the widest framelines that can be displayed and viewed through the viewfinder.

 

Sorry but if most of you would just get you head out of your backside you may see the light.

Edited August 21, 2009 by Shootist

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[Shootist]

The idea that the magnification of the finder is limited by the depth of the body is an interesting one. Like so many interesting ideas, it is wrong.

 

If that were the case, how could Leica offer three different magnifications in the M7, without altering the body? And a screw-mount Leica has a 0.5x finder --- so a LTM camera must be a foot thick, no? The field of view (= magnification) of the finder is determined by the combination of the focal lengths of the eyepiece and the lens in front of the beamsplitter prism.

 

The old man from the Age of Brilliant Finders

 

The magnification is not dependent on the dept/thickness of the body. The Field Of View of the viewfinder along with what the widest framelines that can be seen is dependent on the thickness of the body combined with the magnification of the viewfinder.

 

That is exactly why in a film M with a x.85 VF you can only have 35mm framelines as the widest and with the x.72 28mm lines and with the x.58 21mm lines.

Because the magnification is less the FOV of the VF gets greater. Because the tunel is longer on the M8, as Adan has so intelligently pointed out and which is what I've been saying in way to many post, Leica had to drop the magnification down from x.72 to x.68 but yet only gets a maximum VF Field Of View equaling that of a 32mm lens, 24mm lens cropped by 1.33.

 

 

What I really don't understand is why so many bright, intelligent, smart and wealthy people on this forum can't figure this out even after it being explain to them many time.

Maybe simple logic and common sense escapes them.