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Crown Graphic 75mm Lens
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Fri Nov 30, 2018 2:08 pm    Post subject: Crown Graphic 75mm Lens Reply with quote

Although the Schneider-K Super Angulon 75mm fits and permits focus on my Crown Graphic (4x5), it seems the bed is in the way. (I say "seems" because I have a small sample and the presence of the bed is a blur on a couple of images that could be a coincidence.) The bed won't drop with the 75mm lens, because the lens interferes with the mechanism, so I'm about to sell the lens.

However, I could swear that I've read here folks using 75mm lenses on a Crown Graphic and since any 75mm lens will have the same viewing angle, I'm wondering how this is possible. Thanks in advance.
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hsandler



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

PostPosted: Fri Nov 30, 2018 2:28 pm    Post subject: Reply with quote

I don't have that particular lens; perhaps it has a long retro-focus length, but with the 90mm WA Optar, the front standard is on the rear tracks to achieve focus, so the bed drops. The only way the bed should be prevented to drop is if the front standard is positioned right on the junction of the two sets of tracks. Rack the tracks back as far as they go with the front standard not extended at all, drop the bed, pull out the front standard to the end of the rear tracks, and then rack the tracks for focus.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Fri Nov 30, 2018 2:38 pm    Post subject: Reply with quote

hsandler wrote:
The only way the bed should be prevented to drop is if the front standard is positioned right on the junction of the two sets of tracks.


Precisely the problem. Oddly I hadn't noticed the bed in the frame before (though as I said, I haven't used the lens much in the years I've had it). But I take it that you can confirm that a 75mm lens will need to have the bed drop to clear. (Nothing longer does, I don't believe.) Or does this too depend on whether there is retrofocus (I suppose it does)?
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hsandler



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

PostPosted: Fri Nov 30, 2018 3:41 pm    Post subject: Reply with quote

Lobalobo wrote:


Precisely the problem. Oddly I hadn't noticed the bed in the frame before (though as I said, I haven't used the lens much in the years I've had it). But I take it that you can confirm that a 75mm lens will need to have the bed drop to clear. (Nothing longer does, I don't believe.) Or does this too depend on whether there is retrofocus (I suppose it does)?


I can only confirm that with a 90mm WA Optar, one does not need to drop the bed, at least when stopping down to f22. I think catching the bed in the frame will depend somewhat on the aperture, with less showing at small apertures

You might try a small amount of front rise to clear the appearance of the bed in the frame.
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45PSS



Joined: 28 Sep 2001
Posts: 3756
Location: Mid Peninsula, Ca.

PostPosted: Fri Nov 30, 2018 8:33 pm    Post subject: Reply with quote

The front standard can be put on the front rail section, bed dropped, rise and tilt set so the lens is centered to the image frame, and focused with the focus knob. (the camera was designed for this)
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Fri Nov 30, 2018 10:14 pm    Post subject: Reply with quote

[quote="hsandler"]
Lobalobo wrote:


You might try a small amount of front rise to clear the appearance of the bed in the frame.


Thanks. Thought of that, but the lens sits inside the body of the camera, making front rise impossible (at least without removing the sports-finder frame). Also, once I'm willing to alter the composition to remove the edge of the bed, I can simply plan to crop (as the interference is minimal). So not sure why this bugs me, but it does.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Fri Nov 30, 2018 10:16 pm    Post subject: Reply with quote

45PSS wrote:
The front standard can be put on the front rail section, bed dropped, rise and tilt set so the lens is centered to the image frame, and focused with the focus knob. (the camera was designed for this)


Thanks, but as I said in my original post, and initial response, because of where the lens sits at focus, right over the joint for the bed, I can't drop the bed.
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shutterfinger



Joined: 09 Mar 2007
Posts: 57

PostPosted: Fri Nov 30, 2018 11:25 pm    Post subject: Reply with quote

As long as the standard lock, rail side, is no more than half of the lock either side of the hinge point then the bed can be dropped before the standard is pulled out or after the standard is pulled past the hinge then repositined for correct focus.
Another alternative is to put a spacer between the lens and lens board so that the standard lock sits further back into the body.

A homemade lens board from Baltic birch plywood that sits into the throat of the bellows will not need the outer lip to be light tight and can be grooved for the lens board locks. Black acrylic also works for lens boards.
A little work but doable.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Fri Nov 30, 2018 11:47 pm    Post subject: Reply with quote

shutterfinger wrote:
As long as the standard lock, rail side, is no more than half of the lock either side of the hinge point then the bed can be dropped before the standard is pulled out or after the standard is pulled past the hinge then repositined for correct focus.


Thanks, but I get this. A number of posts, all of which are trying to be helpful and for which I'm truly grateful, have noted that dropping the bed should be possible "unless" and I guess what I'm saying is that my lens fits into the "unless." If I pull the lens into the body before dropping the bed, it falls off the inner rails before achieving the correct distance to focus; if I pull the lens onto the bed before dropping the bed, it can't be returned close enough to the film plane to achieve focus (and the tilt-and-rise combination to make the lens parallel and centered doesn't fix this problem).

That said, I hadn't thought about the spacer idea; what I need is a lens board with depth. I wonder if I can have one 3D printed. But even if I could, I'd worry there wouldn't be enough play on the rails inside the camera to focus properly.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 01, 2018 12:02 am    Post subject: What All this Says about Graflex Design Reply with quote

Whatever the resolution, my experiments, and all of your generous responses, suggest something interesting about the 4x5 Graflex cameras. Specifically, because a 75mm lens barely catches the end of the bed, and because it's hard to imagine compressing the bellows enough to focus an even wider lens, the drop bed design must be primarily for the purpose of permitting tilt, not for the purpose of clearing a wide-angle lens. That is, I'd be surprised if the designers imagined a customer using anything wider than 90mm in which case there is no need to drop the bed except to accomplish movements.
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45PSS



Joined: 28 Sep 2001
Posts: 3756
Location: Mid Peninsula, Ca.

PostPosted: Sat Dec 01, 2018 12:26 am    Post subject: Reply with quote

Do you have a digital caliper or precision ruler?
Set the lens to infinity, measure the rail end to the bed distance ( edge of the bed or the guide blocks on each side of the rails )
Next focus to the lens closest focus distance, probably 3 to 3 1/2 feet. Measure the end of rail to the same point used at infinity, this is the movement needed for normal focus distances. Its likely 25mm or less.
Graflex Corp. designed their cameras based on an engineers rule so all parts measurements are in inch, tenths, hundredths, thousands of an inch.
Measuring with standard fractional rules results in some weird fractions such as 1/67 or 1/133.

Edit:
If the lens is currently mounted with a retainer ring switch to a mount flange.
A flange requires 3 screws to attach it to a lens board, mounts on the front of the board and will add 5 to 10 millimeters forward position for the lens.
A spacer can be put between the board and flange if needed.
SKLGrimes has them for $35 = shipping.
http://skgrimes.com/
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 01, 2018 1:39 pm    Post subject: Reply with quote

45PSS wrote:

If the lens is currently mounted with a retainer ring switch to a mount flange.
A flange requires 3 screws to attach it to a lens board, mounts on the front of the board and will add 5 to 10 millimeters forward position for the lens.
http://skgrimes.com/


Thanks so much for these suggestions. I'm going to look into them.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 01, 2018 2:23 pm    Post subject: Reply with quote

45PSS wrote:
A flange requires 3 screws to attach it to a lens board, mounts on the front of the board and will add 5 to 10 millimeters forward position for the lens. A spacer can be put between the board and flange if needed.


Just measured with a caliper and I need 18mm of extension. Just occurred to me that instead of a flange and spacer, I could also simply flip a recessed lens board. The issue is that the recessed boards advertised don't give the depth of the recess.
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Dan Fromm



Joined: 14 May 2001
Posts: 2039
Location: New Jersey

PostPosted: Sat Dec 01, 2018 4:00 pm    Post subject: Reply with quote

Lessee now, according to Schneider, at infinity the 75/5.6 SA's flange-to-film distance is 82.8 mm. The 75/8's is 82.7 mm. According to the bible, 10th edition, the 4x5 Crown's minimum extension is 52.4 mm.

With the front standard at the rear of the inner bed rails, racking the rails 20.3 mm forward will bring the lens to focus at infinity.

OP, why do you move the lens on the rails to focus? The Crown has linked inner and outer bed rails. This allows the focus knob to move both sets of rails, even with the bed dropped. However, focusing travel is limited with the bed dropped.

I don't have a 4x5 Graphic, do have a couple of 2x3 Crowns. My solution to limited focusing travel with a short lens, the bed dropped and the front standard on the inner rails is:

push the standard all the way back on the inner rails

drop the bed

run the rails all the way back

pull the standard forward on the inner rails so that the lens is focused slightly through infinity, making sure not to pull the rails out

focus normally on the GG using the focusing knob to move the rails and standard

The one problem with this procedure is that because my cameras have no bed stops on the inner rails pulling the standard forward from the full rearwards position can introduce unintended swing. The cure for this is what the late Fred Lustig called a chinaman. Pictures of such a device with explanation are here: http://www.galerie-photo.com/telechargement/dan-fromm-6x9-lenses-v2-2011-03-29.pdf See figures 27 - 30.

About recessed boards for Graphics. Ain't none. Some years ago I discussed making one for a 4x5 Pacemaker Graphic with Adam Dau of skgrimes. Not possible. And a recessed board isn't the answer to the OP's problem. Using the camera intelligently is the answer.
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45PSS



Joined: 28 Sep 2001
Posts: 3756
Location: Mid Peninsula, Ca.

PostPosted: Sat Dec 01, 2018 9:00 pm    Post subject: Reply with quote

Quote:
About recessed boards for Graphics. Ain't none. Some years ago I discussed making one for a 4x5 Pacemaker Graphic with Adam Dau of skgrimes. Not possible

By the time the edges of a recessed board are formed the opening for the shutter if large enough for the #0 shutter to mount one will not be able to operate its controls.
This is assuming 1/8 inch thick material is used for the board such as aluminum in the standard board.
SKGrimes list the #0 mount thread as 32.5mm with a .75mm thread pitch.
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