Any adapter to center the external viewfinder ?

[Mak67]

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Hi guys,

 

I want to use a zeiss finder but find the parallaxe to be sometimes problematic due to rotational (panning) error...this also occur with the standart leica one.

I can understand why the hotshoe is not centered but can't make my mind on why they didn't made the external viewfinder with an extension to fit properly center ?

 

I was wondering if there is any hotshoe adapter to center the external viewfinder?

Or any tip to make my own.

Thanks

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[adan]

The plastic Leica finders (1970s-early 2000s) do have an offset to the left, that reduces the sideways parallax a bit. The briefly-made zooming 21-24-28 finder has even more offset, on a diagonal foot.

 

https://nolan.com/forum_imgs/three_24-25_viewfinders.jpg

 

https://d1ro734fq21xhf.cloudfront.net/attachments/00Gboa-30063784.jpg

 

Cosina/Voigtlander made a dual-shoe adapter, but the cure is worse than the disease regarding offset sideways - offset even more (to the other side):https://www.cameraquest.com/jpg5/v12e.jpg

 

As you can see, offsetting the viewfinder does usually make it larger. That, combined with the fact that the parallax error is a fixed ~1.5cm regardless of subject distance (perhaps visible at 0.7m, but completely irrelevant at 3m or 30m or 300m), and the fact that the finders are always "approximate" anyway (you always get more in the picture than your saw in the finder, as a safety margin), is probably the reason the revived current metal finders do not bother to provide "centering."

 

In other words, this is the real world - showing what the viewfinder lines show (approximately) and the actual 24 x 36 image captured. 21mm finder and lens. Note that at the distance of the line of people in the background, a field about 80m/80 yds wide, a composition error of 15mm would be about 1 pixel wide with a 24-megapixel camera. Or in this reduced-for-web image, about 0.2 pixels. Far less than the "safety margin error" Leica and others build in anyway, to minimize the chance of cutting off heads and so on.

 

You always get a bit more than you aimed for - you crop as desired (or not).

 

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[Mak67]

My problem is not framing error, but horizontal keystone, due to panning parallax error.

For exemple if you want to shoot a cube in front perfecy cube.

Thanks

[adan]

Ahh - understood.

 

Not really the forte of a rangefinder camera, since even if you centered the viewfinder left and right, you'll still get vertical parallax and keystoning (viewfinder 4 cm above the lens). And of course Leica's built-in viewfinder is even more decentered than the external ones (but we'll presume you are using a 16, 18, 21, or 24).

 

Realistically, if you need perfect avoidance of keystoning - you must look through the actual taking lens. Which means SLR, view camera - or with a recent Leica M digital, live view or the optional EVF. Which will even give you a grid overlay, for "cubing" everything up.

 

Even with a Linhof Technika, the external viewfinder is for fast grab-shots like mine above; if you really want everything "perfectly cube," you use the ground-glass on the back to see what the lens is really seeing and get everything lined up square in all directions.

 

https://assets.catawiki.nl/assets/2016/7/1/e/3/0/e30e6fd6-3f69-11e6-88b0-4e7774acf108.jpg

 

Or, of course, correct the keystoning in Photoshop, these days.

 

Or with digital's instant feedback, trial and error. Which is how I made this shot (M10, 75mm Summarit). Just took a shot - "Nope, too far right" - move camera a bit left - "Nope, still too far right" - move a bit more left - "Oops, too far left" - back a bit - until everything lined up square. For the final picture, my viewfinder was centered about on the top left winding knob.

 

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[Mak67]

Hi Adan,

Thanks for your reply.

I'm a long time rangefinder user, almost 20years(135/645/67/45).

For 95% of my photos, the lateral offset is not important, and might even a quality.

But i not totaly agree with you when you say i have to use a ttl cam for precise framing. The vertical keystone is really easy to correct using your mind or a proper level.

I have no problem making a «square» square using the external finder of my cambo wrc400, or even on my fuji 617 ... so i would probably be fine with a centered finder on my leica

If i don't find an adapter,i will probably end up glueing a new hotshoe properly placed on the top of the camera.