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Distance Settings on Crown Tube Viewfinder

 
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 08, 2018 1:36 pm    Post subject: Distance Settings on Crown Tube Viewfinder Reply with quote

Having received so much excellent advice on my previous questions, for which I'm grateful, I thought I'd try a new.

Turning the distance dial on a just-purchased Tube Viewfinder for my Crown Graphic appears to do absolutely nothing. This would surprise me more if I had even the slightest clue what turning the dial is supposed to do. Adjust for parallax? Integrate somehow with the rangefinder (which my camera does not have)? Any ideas are welcome.
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hsandler



Joined: 27 Apr 2016
Posts: 15
Location: Ottawa, Canada

PostPosted: Sat Dec 08, 2018 4:33 pm    Post subject: Re: Distance Settings on Crown Tube Viewfinder Reply with quote

Lobalobo wrote:
Having received so much excellent advice on my previous questions, for which I'm grateful, I thought I'd try a new.

Turning the distance dial on a just-purchased Tube Viewfinder for my Crown Graphic appears to do absolutely nothing. This would surprise me more if I had even the slightest clue what turning the dial is supposed to do. Adjust for parallax? Integrate somehow with the rangefinder (which my camera does not have)? Any ideas are welcome.


Itís just for parallax, anditís not coupled with the rangefinder. The dial moves the peephole, which is off centre, relative to the framelines if I recall. Perhaps it is broken. I think the start position can be adjusted if you unscrew the rear peephole, but be careful if itís tight; I cracked the outer bushing, which I think is brittle plastic, when I tried to unscrew a seized one. Anyway, the wire frame viewfinder also has parallax adjustment, either the height that you pull out the front wire frame, or the height of the rear peepsight, depending in which version of speed graphic.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 08, 2018 7:47 pm    Post subject: Re: Distance Settings on Crown Tube Viewfinder Reply with quote

hsandler wrote:
Itís just for parallax, anditís not coupled with the rangefinder. The dial moves the peephole, which is off centre, relative to the framelines if I recall. Perhaps it is broken. I think the start position can be adjusted if you unscrew the rear peephole, but be careful if itís tight; I cracked the outer bushing, which I think is brittle plastic, when I tried to unscrew a seized one. Anyway, the wire frame viewfinder also has parallax adjustment, either the height that you pull out the front wire frame, or the height of the rear peepsight, depending in which version of speed graphic.


Thanks for such a complete and knowledgeable answer.
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45PSS



Joined: 28 Sep 2001
Posts: 3757
Location: Mid Peninsula, Ca.

PostPosted: Sat Dec 08, 2018 8:18 pm    Post subject: Reply with quote

https://www.flickr.com/photos/thirteenthumbs/shares/c33d6G
Its called Optical Viewfinder.

The Sports Finder is much easier to use.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 08, 2018 8:30 pm    Post subject: Reply with quote

Thanks for the diagram.

45PSS wrote:
https://www.flickr.com/photos/thirteenthumbs/shares/c33d6G
Its called Optical Viewfinder.


What's called an "Optical Viewfinder"? Do you mean the "tube" finder (which I an others refer to as a "tube" finder to distinguish it from the sport finder and the rangefinder, each of which are sorts of "optical" finders.

Quote:
The Sports Finder is much easier to use.


Not for a lens locked inside the camera body and not, I don't believe, for a telephoto lens, which has a field of view narrower than would be displayed in the sports finder at the lens's actual focal distance from the film plane.
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hsandler



Joined: 27 Apr 2016
Posts: 15
Location: Ottawa, Canada

PostPosted: Sat Dec 08, 2018 8:57 pm    Post subject: Reply with quote

Lobalobo wrote:
Thanks for the diagram.

45PSS wrote:
https://www.flickr.com/photos/thirteenthumbs/shares/c33d6G
Its called Optical Viewfinder.


What's called an "Optical Viewfinder"? Do you mean the "tube" finder (which I an others refer to as a "tube" finder to distinguish it from the sport finder and the rangefinder, each of which are sorts of "optical" finders.

Quote:
The Sports Finder is much easier to use.


Not for a lens locked inside the camera body and not, I don't believe, for a telephoto lens, which has a field of view narrower than would be displayed in the sports finder at the lens's actual focal distance from the film plane.


What Graflex called the optical viewfinder is your tube finder. I guess it's "optical" because it does have lenses in it (probably reverse Galilean). It can be used with telephoto lenses by use of a mask at the front (item 7 in the diagram that a post above linked). I'm not sure it can be used with wide angles.

The sports finder, what I called the wire frame finder, is nice in that it self-adjusts for lens focal length, so you can use it more or less with any lens. If you use a telephoto lens, the act of extending the bellows will necessarily narrow the field of view of the wire frame, seen through the peephole at the back of the camera, simply because the wire frame is further away. Try it with your 75mm lens and see if the frame you see corresponds with the ground glass. It can't be exact, because some lenses of the same focal length need to be different distances away from the focal plane depending on their optical design.
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45PSS



Joined: 28 Sep 2001
Posts: 3757
Location: Mid Peninsula, Ca.

PostPosted: Sat Dec 08, 2018 9:28 pm    Post subject: Reply with quote

and frame guides were made to fit inside the wire frame to reduce it for roll film formats if memory serves correctly. they are rare. i've made some from 1.4 inch foam core using the ratio of the image area to the frame size of the finder frame to scale by.
i misspoke, its not a sports finder its the "open frame finder". ist clickstops are for 6, 15 feet and infinity.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 09, 2018 1:33 pm    Post subject: Reply with quote

hsandler wrote:
The sports finder self-adjusts for lens focal length, so you can use it more or less with any lens. If you use a telephoto lens, the act of extending the bellows will necessarily narrow the field of view of the wire frame, seen through the peephole at the back of the camera, simply because the wire frame is further away.


This is true only if the angle of view from the lens is normal, by which I mean the listed focal length of the lens matches the distance of the lens to the film plane when focused at infinity. Not all lenses have this characteristic; telephoto lenses don't and neither to retrofocus lenses.

Quote:
Try it with your 75mm lens and see if the frame you see corresponds with the ground glass.


The 75mm lens focuses while deep in the body of the camera and so I can't use the sports finder on that lens.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 09, 2018 1:39 pm    Post subject: Reply with quote

hsandler wrote:
What Graflex called the optical viewfinder can be used with telephoto lenses by use of a mask at the front.


Right, which is why I've purchased the masks that match (or almost match) my lenses. The problem is that the parallax adjustment doesn't work on the finder; not that I would have relied on it much or at all anyway. Just bugs me that a component doesn't work; the collector's side of me, I suppose. Thanks.
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45PSS



Joined: 28 Sep 2001
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Location: Mid Peninsula, Ca.

PostPosted: Sun Dec 09, 2018 9:18 pm    Post subject: Reply with quote

If you know your lens horizontal angle of view then when composing its fairly easy to approximate where the edges of the frame will be, no mask necessary.
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