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 Post subject: ~3x3" on RB67
PostPosted: Sun Dec 14, 2008 12:05 am 
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The Lone Rangefinder
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This is just to duplicate my report on APUG regarding ~3x3" squares on the rb67 pro sd.

I dremeled out the baffles of a polaroid 545i back for the rb67 pro sd. The resulting frame size is a slightly irregular ~3" tall by ~2.75-3" wide, i.e., ~75mm tall by ~70-75mm wide. I verified that it works well with 4x5" polaroid sheet film using various lenses at different focus distances.

The irregular width that I am reporting is due to two kinds of light obstructions in the actual body of the RB. There are minor notch-like shadows at each corner, but a larger irregularity in the width is due to the mirror detent in the body, which produces a shadow at the film plane toward the top of the loaded film. This irregularity appears unavoidable unless one does a bit of surgery on the mirror detent itself (probably not worth the bother, but of course I may well try it and report later if there is interest).

I did see some corner shadowing with the RB 37mm fisheye, but this is actually from the built-in shade!

The irregularity in the frame dimensions is no big deal especially if you are going to do perspective correction. Or, for example, if you de-fish a 37mm shot, you will radially pinch the corners out, so the shadowing is taken care of. For normal perspective correction, you typically find yourself distorting the frame and then cropping back, so every extra bit of frame you can get may help.

I don't see any stray light effects thus far, though if one wanted to cut out some foam to prevent that, it'd be easy.

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"The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don't want it badly enough. They are there to stop the other people." -Randy Pausch, October 23, 1960 – July 25, 2008


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 Post subject: Re: ~3x3" on RB67
PostPosted: Sun Dec 14, 2008 2:01 pm 
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Camera: Nikon F/F3/F4, Fuji S2, RB67, Sinar 4x5/8x10
That's good to know, I"m hoping this winter to make an RB to Graflock adapter, so I can use the scan back I have with it. (I know they're inexpensive used, but I have everything sitting here)


erie

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 Post subject: Re: ~3x3" on RB67
PostPosted: Sun Dec 14, 2008 3:53 pm 
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The Lone Rangefinder
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Erie, I think you'll see that by modifying the mirror catch a wee bit, true 3x3 should be possible. I am very tempted to try the modification, my rb body is nearing the end of its natural life and thse days they only cost $100, like new :shock:

Now, I thought the attachment on the backside of the rotating adapter was a graflok... or some close cousin... anyway the polaroid backs are a dime a dozen now, maybe you could just get one of those and cannibalize the mount and make yourself a stitching back. I was thinking: wouldn't it be groovy if I could slap my dslr on the back as a sliding back? But of course the sensor sits way too far back. Need to cut out the sensor! I bet there is an old 5D somewhere that needs to be cut open to make a sliding back....

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"The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don't want it badly enough. They are there to stop the other people." -Randy Pausch, October 23, 1960 – July 25, 2008


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 Post subject: Re: ~3x3" on RB67
PostPosted: Mon Dec 15, 2008 6:45 pm 
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Camera: Nikon F/F3/F4, Fuji S2, RB67, Sinar 4x5/8x10
Keithwms wrote:
Now, I thought the attachment on the backside of the rotating adapter was a graflok... or some close cousin... anyway the polaroid backs are a dime a dozen now, maybe you could just get one of those and cannibalize the mount and make yourself a stitching back. I was thinking: wouldn't it be groovy if I could slap my dslr on the back as a sliding back? But of course the sensor sits way too far back. Need to cut out the sensor! I bet there is an old 5D somewhere that needs to be cut open to make a sliding back....

2x3 graflok. Hmm, that might explain the 2 or 3 "old style (w/ P adapter)" polaroid backs I've got sitting here, as well as a graflok 4x5 back that was leftover from another project. ;)

btw, a .065" spacer bewteen the P adapter and the graflok I have here is all I need, if I can find my way to the garage, I'm sure I have some .065 al. kicking around..

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 Post subject: Re: ~3x3" on RB67
PostPosted: Thu Dec 18, 2008 1:37 pm 
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Evil Emperor Palpatine
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Keithwms wrote:
This is just to duplicate my report on APUG regarding ~3x3" squares on the rb67 pro sd.

I dremeled out the baffles of a polaroid 545i back for the rb67 pro sd. The resulting frame size is a slightly irregular ~3" tall by ~2.75-3" wide, i.e., ~75mm tall by ~70-75mm wide. I verified that it works well with 4x5" polaroid sheet film using various lenses at different focus distances...



For those of you who are not familiar with the verb, "To dremel" I conjugate it below:

I dremel
You dremel
He, she, it dremels
We dremel
You dremel
They dremel

I dremelled
You dremelled
He, she it dremelled
We dremelled
You dremelled
They Dremelled

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 Post subject: Re: ~3x3" on RB67
PostPosted: Sun Dec 28, 2008 11:29 am 
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The Lone Rangefinder
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Erie, I just got the nutty idea to take out the mirror box entirely and scale focus. Maybe I could rig one of those horseman VFs for composition.

I also had a vision of a mirror that you pull up and out of the body, insert a darkslide across there, and thus get waistlevel composition plus 8x8cm capture.

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;) keithwms

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My APUG Gallery

"The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don't want it badly enough. They are there to stop the other people." -Randy Pausch, October 23, 1960 – July 25, 2008


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 Post subject: Re: ~3x3" on RB67
PostPosted: Sun Dec 28, 2008 5:14 pm 
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Film Shooter
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Keithwms wrote:
Erie, I just got the nutty idea to take out the mirror box entirely and scale focus. Maybe I could rig one of those horseman VFs for composition.

I also had a vision of a mirror that you pull up and out of the body, insert a darkslide across there, and thus get waistlevel composition plus 8x8cm capture.


Wouldn't it be easier, to rip out the mirror mechanism and insert a fixed 45 deg. angle semi-transparent mirror? Then you have both: image and sharpness control and a totally unobstructed view. After all, when Canon and Nikon could do that, why couldn't you?

Cheers,
René

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 Post subject: Re: ~3x3" on RB67
PostPosted: Sun Dec 28, 2008 7:51 pm 
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The Lone Rangefinder
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Yes, that's basically what I meant by the second idea: just make a slip-out mirror box. It'd be nice to have it with a protective glass so that you just pull it up, slide in the cover and voila.

I think I'll try it. The only things preventing ~8x8 capture are the little ridges that seat the mirror, and these would seem to be easily removed.

This is worth doing. 8x8 actually fills a good bit of 4x5 sheet film, and at close focus most of the rb lenses cover 8x8 amply. I suspect that the lenses from 127-360 may well cover at infinity too.

Say René, why aren't there any focus assist accessories for GG focusing? I am thinking that a simple contrast detection accessory should be doable.

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;) keithwms

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"The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don't want it badly enough. They are there to stop the other people." -Randy Pausch, October 23, 1960 – July 25, 2008


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 Post subject: Re: ~3x3" on RB67
PostPosted: Mon Dec 29, 2008 8:39 am 
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Film Shooter
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Keithwms wrote:
Say René, why aren't there any focus assist accessories for GG focusing? I am thinking that a simple contrast detection accessory should be doable.


I have no official info on that, but I guess, there are several issues:
1. with old lenses you sometimes have a focus shift, when stepping down the aperture. But stepped down, the GG gets very dim, the eye is then better at focusing.
2. GG dimness in general
3. focusing aids are available, though basically mechanical or opto-mechanical, taking into account the swing of the lens board or simple coupled meters (as in press cameras)
4. I guess, nobody would have bought that ten or fifteen years ago, as the cost would have been prohibitive - and nowadays nobody needs it anymore, as you shoot mainly digital and can use the digital back for assisted focusing.
The usual focus-assist device is the 8x or 10x GG-loupe!

GG-focusing would have been only interesting for LF photography, as in medium-format, AF systems became available soon after the 35mm systems. And the LF folks would have to deal with all the above mentioned problems.

Cheers,
René

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 Post subject: Re: ~3x3" on RB67
PostPosted: Tue Feb 17, 2009 7:19 pm 
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Joined: Mon Apr 23, 2007 12:34 pm
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Camera: Nikon F/F3/F4, Fuji S2, RB67, Sinar 4x5/8x10
GG focusing is the easiest way when you have an RB rotating adapter on a view camera, cheap too, I mean how much does a junk RB back cost from KEH's as-is section? The best focus assist device I've found is a pair of high power reading glasses, the darn loupe is always banging around on things in the studio, in the field it's a downright PITA.


erie

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 Post subject: Re: ~3x3" on RB67
PostPosted: Tue Feb 17, 2009 7:52 pm 
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The Lone Rangefinder
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How about this: two RBs stacked together. Identical lenses on both. The RB underneath has the mirror box removed, the other has only the mirror and no film back. The focusing panels of both RBs are fastened together.

Yes, this 20 lb, 8x8-format mega-TLR could be yours for only... what... ~$400 :shock: 8)

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;) keithwms

keithwilliamsphoto.net
My APUG Gallery

"The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don't want it badly enough. They are there to stop the other people." -Randy Pausch, October 23, 1960 – July 25, 2008


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 Post subject: Re: ~3x3" on RB67
PostPosted: Tue Feb 17, 2009 7:55 pm 
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Joined: Mon Apr 23, 2007 12:34 pm
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Camera: Nikon F/F3/F4, Fuji S2, RB67, Sinar 4x5/8x10
hmmm, let's see:

Bad case of GAS............check, check, check

Really love RB's..............check

Full time work.................check

Full time school..............check

Damn, no time or money left.

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