Viewfinder Glass Shifted?

[alpinecine]

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Bought my M10 in Oct 2017. I was cleaning it today and found some dust inside the front viewfinder. Upon further checking, I saw this weird glass edge exposed on one side. Even when you look straight at the viewfinder, not from an angle, you can still see the edge. I don't remember seeing that before... It looks to me like one of the glasses in the viewfinder has somehow detached and shifted, which also explains the dust. I traveled with it a few times but always kept it right beside me so I know it was never dropped or anything like that. 

 

Anyone have an idea if this is a shifted glass and reason for the dust inside? Or am I just overreacting?

 

If it is problematic, shall I send it to the dealer who sold it or straight to Leica in NJ? Thanks!

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[adan]

Dust in the finder is its own issue - my first M10 (Feb. 2017) shows some, including a big lump behind the eyepiece (back), my later body shows none (yet.)

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As to the finder construction, I'm not sure I know which piece you think may have slipped, in your pictures. But here is how it "normally" looks, based on looking at my own two M10s (which both work perfectly):

 

There is a flat glass cover plate, with semi-silvered mirrored stripes across the top and bottom. The bottom one is there to slightly darken the bottom of the viewfinder so that the red LED metering numbers-symbols show more clearly (been there since the first M6 in 1986). The top one is just for cosmetic balance, in the taller M6ttl/M7 and digital cameras. And on the digitals, also camouflages the little red blinking LED for self-timer countdown.

 

Behind that is a thick matte-black "picture frame" with an inward bevel - the big fat white reflection in your 2nd picture is the bottom bevel of that frame.

 

Behind THAT is a cropped black circular metal mask - looks like (__)

 

Behind THAT is a curved piece of glass - the first "lens element" in the viewfinder, which is a "wide-angle" lens of sorts, to shrink the world by 27% to fit into the viewfinder (thus the viewfinder shows everything at 0.73x life-sized).

 

Behind THAT is a rectangular black mask - and it is normal for that to be noticably off-center to the mask in front of it. And appears with a bit of pin-cushion distortion, because you are looking at it through the curved glass layer.

 

Behind the rectangular mask is a solid block of glass, that is split diagonally (as seen from above) and semi-silvered along the split to capture and reflect the second RF image coming in from the window over below the shutter dial, and combine it with the main viewfinder image, to make the "focusing patch" double-image you align when focusing. In your first picture, the split is just barely visible as a thin diagonal pale line leading from the lower left of the front of the finder (foreground) to the bottom right of the eyepiece circle (background).

 

Because of the off-centering of the two masks, the distorted view of the rectangular black mask through the curved lens in front of it, and the split through the block behind everything else (hard to see except in the brightest light), it can indeed look like something out of whack.

 

*******It is also possible******, although I cannot swear to it because of the other distortion effects, that everything behind the fat black beveled frame is slightly canted to the right - towards the lens - as an initial form of parallax correction, in addition to the moving framelines.  Again, that is how both my own M10s look.

 

The cutaway view of an original M2 here seems to reveal such a very slight sideways cant may be designed in: https://lavidaleica.com/content/overview-m-system

 

But so long as your framing and focusing are behaving normally, it is not an actual slippage of anything, just optical illusions.

 

Here is a cutaway diagram of the M viewfinder (post-M3) - top image. However it is the slightly older finder of the M2-M9, with the additional third corrugated frameline illumination window (fat yellow arrow) which you can ignore - current Ms replace all that with LEDs to light up the framelines. It also just barely shows those two front masks, as thin black lines on the front of the first and second chunks of glass inside. And in the M10 finder (new design, thinner body) the spacing may be slightly different at the front.

 

https://imgur.com/gallery/oHdig

[250swb]

 

 Or am I just overreacting?

 

 

 

I think you nailed it.

 

My viewfinder looks exactly the same, just behind the front glass the next component is slightly asymmetric with more of a 'half moon' showing to the right. 

Edited July 26, 2018 by 250swb

[alpinecine]

Thanks for the very informative explanations! 

I think I saw those dust particles and started panicking...

Shall I send it in to get rid of the dust? Or just keep using it until something breaks?

Edited July 27, 2018 by alpinecine

[250swb]

Keep using it.

[jaapv]

Thanks for the very informative explanations! 

I think I saw those dust particles and started panicking...

Shall I send it in to get rid of the dust? Or just keep using it until something breaks?

Nothing will break. That is an utter rarity. The viewfinder-rangefinder -in fact the whole camera- is built like a tank.

 

My M8 went straight into a ravine and slammed on the rocks a few meters down. Any other camera would have been a collection of plastic shards, little wheels and screws. The M8: cracked body shell, broken shutter, dented top plate, bent bottom plate with dents and scratches, sensor shifted, rangefinder slightly out of adjustment. No damage at all to the rangefinder optics and mechanics.  If the shutter curtains hadn't been slammed into the down position it would still have been functional, more or less.

1800 Euro repair -replace shutter, replace front body shell, replace top for cosmetic reasons, replace bottom. adjust. Oh, and free focussing mechanism on the Summicron 35 and adjust.

 

Dust can be a cosmetic annoyance, but as long as it does not interfere with the viewing, of no significance.

[250swb]

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I've only ever sent one Leica back because of dust that interfered with the view, and that was during the notorious dust problem with early MP bodies, and then it wasn't even dust but a gigantic flake of something that deposited itself slap bang in the middle of the viewfinder.