Advice on Leica SBOOI and screw mount viewfinders
Old 1 Week Ago   #1
jcb4718
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Advice on Leica SBOOI and screw mount viewfinders

Could anyone give some insight into the reason for the aspect ratio of the Leica screw mount viewfinder and the SBOOI brightline finder? The SBOOI has a ratio of about 1:1.25 (24x36mm is of course 1:1.50) but for the near parallax 'dotted line' this reduces to about 1:1.50. So I'm tempted to imagine that when focussed on infinity there is an invisible 'dotted line' at the bottom in order to have the 1:1.50 film aspect for both near and far. If this is so, why was a 'dotted line' not included at the bottom? My IIIf viewfinder also has an aspect ratio of about 1.25 so you might imagine there should be two 'dotted lines' (top and bottom)so both near and far have the 1:1.50 aspect ratio. However, vertically, the viewfinder is pretty close to the lens centre (much closer than the SBOOI) so you would expect a much smaller parallax correction i.e. you would expect in any case the viewfinder to have an aspect ratio closer to 1:1.50. Can anybody offer any insights? Also how do folks use their SBOOI and in-camera viewfinder, in particular near vs. far?
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Old 1 Week Ago   #2
Rob-F
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I never knew what to make of the unusual SBOOI aspect ratio. I noticed it right away and thought it was strange.
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Old 1 Week Ago   #3
shawn
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Quote:
Originally Posted by jcb4718 View Post
If this is so, why was a 'dotted line' not included at the bottom?
The difference in framing between near/far is greater at the top of your viewfinder than it is at the bottom. The image on the film is inverted. The angle between the bottom of the viewfinder and the top of the physical film (bottom of the inverted recorded image) is smaller than the difference between the top of your viewfinder and the bottom of the physical film (top of the recorded image).

I think all of my rangefinders that have parallax adjusting frame lines do not change the position of the bottom of the frame.

Shawn
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Old 1 Week Ago   #4
Peter Jennings
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I'd wondered this, too. I just mounted my finder on my Sony A7 w/ 50mm lens and compared the view from the camera's evf and the SBOOI. What Shawn says appears accurate. The bottom view doesn't change that much when focussing at minimum focusing distance. Of course, the viewfinder sits higher on the A7 than it would on an M camera, so there is some added error there. Strangely, when focusing at infinity, the entire solid frame line is pretty accurate as well. It appears there is no need to imagine an additional set of broken lines.
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Old 2 Days Ago   #5
Richard Hannay
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Could the SBOOI be used on the Leica 1 model A?
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Old 1 Day Ago   #6
Erik van Straten
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Quote:
Originally Posted by Richard Hannay View Post
Could the SBOOI be used on the Leica 1 model A?
Absolutely, I do it all the time. The finder of the camera itself is only usable on infinity.

Leica I model A, Elmar 50mm f/3.5, 400-2TMY, Perceptol.

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Old 1 Day Ago   #7
Richard Hannay
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Thanks for this
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Old 1 Day Ago   #8
Richard Hannay
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Incidentally what did photographers do in 1929 before the sbooi. Isn't there another device that fits in the shoe which frames the shot?
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Old 1 Day Ago   #9
Richard G
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Pretty hard to catch Leitz out. On the M9 which is taller the SHOOC 135 finder is remarkably accurate. Only very close in with the DR Summicron have I noticed any upper frame clipping on the M9. Might be less on the M2 but I haven't tested it.
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Old 1 Day Ago   #10
Erik van Straten
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Quote:
Originally Posted by Richard Hannay View Post
Incidentally what did photographers do in 1929 before the sbooi. Isn't there another device that fits in the shoe which frames the shot?
The SBOOI is postwar. From about 1930 the VISOR was available, a very good finder, only it was mirrored. Usable for 35mm, 50mm and 135mm. I think Cartier-Bresson used this in 1932 when he got his first Leica. Slightly later there was the VIDOM, with parallax-correction, but also mirrored. This one could handle also 73mm and 90mm lenses.

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Old 1 Day Ago   #11
Richard Hannay
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Thanks Erik thats really helpful again
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Old 1 Day Ago   #12
bhop73
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I just use it and don't really think about how it works. The in-camera finder is barely useable for me since I wear glasses.
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Old 1 Day Ago   #13
David Hughes
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Quote:
Originally Posted by Richard Hannay View Post
Incidentally what did photographers do in 1929 before the sbooi. Isn't there another device that fits in the shoe which frames the shot?
Hi,

The first models with lenses that could be removed and changed did not appear until 1930 and you'd have very little, if any, choice until 1931 when longer lenses appeared (73 and 90mm from memory). Then the idea of different VF's must have occurred to them. Look at early models and you'll see the 50mm lenses' VF's had a little cover with a 2:3 hole in it to block out the full 50mm view.

Look at the horrors that passed for VF's on cameras other than Leitz and you'll see what a wonderful advance the early Leitz VF's on the body were. We are spoilt nowadays and just can't believe what happened then and was acceptable...

Although Leitz started the idea in 1930 of removable lenses, many firms offered their own lenses and a conversion of the body to take them.

Also, it's all a bit of a muddle, look at the catalogues of the time and you'll see lenses that aren't in the (modern) reference books and vice versa. A good example is the first wide angle 35mm lens which seems to have been listed (1931 catalogue) a year before it was made according to the reference books but I guess it depends on which book/author/editor you believe, mostly.

The universal VF was in the 1931 catalogue and covered the 35, 50 and 135mm lenses with the 135mm version having an extra dotted outline for 5 to 9ft range. How they used it escapes me, it's a "display" item only in my little world.

Regards, David

PS If you want an idea of how advanced then they were look in the 1931 catalogue where a third to half a page is devoted to pointing out that the Leitz Camera has a self capping shutter...
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Old 1 Day Ago   #14
lxmike
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Not sure of the ratio, all l know is the SBOOI is one fine finder
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Old 1 Day Ago   #15
Erik van Straten
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Quote:
Originally Posted by lxmike View Post
Not sure of the ratio
The SBOOI is 1:1. You can keep both eyes open.

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Old 1 Day Ago   #16
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My experience with the SBOOI was not good on my IIIf. It was a wonderful viewfinder to look through, with the 1:1 magnification as Erik says, but it did not seem to correspond to what I got on film. Recently I have bought a VIOOH, which has also different settings for 35, 50, 85, 90 and 135 lenses, as well as parallax correction, manually changeable from 1 meter to infinity. This seems to accord more closely with what is recorded on the sensor of my A7S. I can't test on film at the moment as I'm travelling away from the IIIf.
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Old 1 Day Ago   #17
jcb4718
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I think I have figured out why the aspect ratio is not quite 3:2 at least at infinity. At the closest distance, the framelines are close to 3:2 and I imagine pretty exact. Towards infinity two things come into play: parallax and a slight magnification of the image relative to the (fixed) framelines. When looking through the finder, the effects tend to cancel at the bottom of the frame but add at the top. It appears therefore that the bottom frameline is good enough at all distances but 'near' and 'far' framelines are needed at the top. This leaves the sides and I think that Leitz, to keep the framelines simple, chose to ignore the slight 'sideways' magnification'. When you draw it out it's apparent that this error doesn't matter much in practice provided what's of interest is within the solid framelines.

I also wear glasses and have added correction lenses to my Leica IIIf viewfinder and my SBOOI finder. For the camera, using a hacksaw, file and drill, I fashioned a small rectangular plate having a hole exactly the size of the camera eyepiece. I covered one side with double sided tape, cut away the tape over the hole, and secured it in place by pressing it over the eyepiece. For the correction lens I obtained one made for a film SLR, the type that slips over the camera eyepiece. I removed the sides using a Stanley knife and attached it to the aluminium plate using, down each side, a thin strip of double sided tape; the top lip of the correction lens helped to locate it. For the SBOOI I obtained a very old correction lens of 19mm diameter, the type that slipped into an adapter also designed for films SLR cameras. I carefully cut a ring (outer diameter 19mm) out of the double sided tape. It was then a simple job to fix the correction lens over the end of the SBOOI. The camera viewfinder works well but if you want more than 0.5 magnification, the SBOOI works well, too.

See 4 postings below for a photo of the arrangement...

Last edited by jcb4718 : 23 Hours Ago at 13:55. Reason: Location of a photo added
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Old 1 Day Ago   #18
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I have tried to upload a photo of the correction lenses in place. I have kept to the rules about the image size but for some reason it has not appeared. Can anyone suggest what I am doing wrong?
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Old 1 Day Ago   #19
Erik van Straten
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Quote:
Originally Posted by jcb4718 View Post
I have tried to upload a photo of the correction lenses in place. I have kept to the rules about the image size but for some reason it has not appeared. Can anyone suggest what I am doing wrong?
The best way to go is first to load the image up to Flickr and then copy/paste it into RFf.

I am quite curious how your construction looks.

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Old 23 Hours Ago   #20
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Quote:
Originally Posted by David Hughes View Post
Hi,

The first models with lenses that could be removed and changed did not appear until 1930 and you'd have very little, if any, choice until 1931 when longer lenses appeared (73 and 90mm from memory). Then the idea of different VF's must have occurred to them. Look at early models and you'll see the 50mm lenses' VF's had a little cover with a 2:3 hole in it to block out the full 50mm view.

Although Leitz started the idea in 1930 of removable lenses, many firms offered their own lenses and a conversion of the body to take them.

Also, it's all a bit of a muddle, look at the catalogues of the time and you'll see lenses that aren't in the (modern) reference books and vice versa. A good example is the first wide angle 35mm lens which seems to have been listed (1931 catalogue) a year before it was made according to the reference books but I guess it depends on which book/author/editor you believe, mostly.

The universal VF was in the 1931 catalogue and covered the 35, 50 and 135mm lenses with the 135mm version having an extra dotted outline for 5 to 9ft range. How they used it escapes me, it's a "display" item only in my little world.

Regards, David

.
Do I remember seeing a fixed lens (ie hockey stick) Leica I with a 35mm lens and viewfinder? The viewfinder had a large front 'window'. Don't seem to be able to find any references to it but haven't trawled through Westlicht old auctions.
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Old 23 Hours Ago   #21
jcb4718
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I think I have uploaded it the viewfinder arrangements...
Attached Images
File Type: jpg Leica IIIf fixed dioptre low res.jpg (173.3 KB, 8 views)
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Old 23 Hours Ago   #22
Erik van Straten
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Quote:
Originally Posted by Dralowid View Post
Do I remember seeing a fixed lens (ie hockey stick) Leica I with a 35mm lens and viewfinder? The viewfinder had a large front 'window'. Don't seem to be able to find any references to it but haven't trawled through Westlicht old auctions.
I've never seen a picture of it, but it is known that Leitz experimented with a Leica I model A type of camera with a fixed "WEISU" and a fixed Elmar 35mm f/3.5. The advantage would be that no rangefinder was needed as the 35mm lens had enough dept of field.

The Elmar f/3.5 35mm was good enough.

Leica I model C, Elmar f/3.5 35mm nickel, WEISU, 400-2TMY, Perceptol.

Erik.

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