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Crown Graphic 75mm Lens
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 01, 2018 9:50 pm    Post subject: Reply with quote

Dan Fromm wrote:
OP, why do you move the lens on the rails to focus?


It had escaped me when I wrote that the entire bed moves when focusing, including the portion inside the camera; that is, I simply misspoke.

Dan Fromm wrote:
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.


Glad that works for you. As I've explained above, in a couple of places, it doesn't for me because once the bed is dropped there isn't room to pull the standard forward into focus; the standard falls off the rails first.

Dan Fromm wrote:
Using the camera intelligently is the answer.


Well, I guess I'm not as intelligent as you are because I can't figure out a way to keep the standard elevated above rails that have fallen away. You must be truly brilliant.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sat Dec 01, 2018 9:55 pm    Post subject: Reply with quote

45PSS wrote:
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.


Thanks, but not sure I follow. I need the lens to move away from the film plane, not toward it, so I would put in the recessed board backwards and mount the lens on the protrusion, leaving shutter controls entirely exposed. It occured to me that this might not work because the board reversed wouldn't lock into the camera, but accessing the shutter controls shouldn't be a problem unless I'm missing something, which is, of course, entirely possible.
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45PSS



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

PostPosted: Sat Dec 01, 2018 10:42 pm    Post subject: Reply with quote

Quote:
I need the lens to move away from the film plane, not toward it, so I would put in the recessed board backwards and mount the lens on the protrusion

Duh, that might work. The nodes on the standard board are for the board locks so that extra thickness at that point needs to be accounted for.
This arrangement is called an extension.
I know of none made so you will have to fabricate one. Make sure the recessed side has enough room for the mount/retainer ring and the wrench to tighten it to turn freely.
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The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 02, 2018 12:59 am    Post subject: Reply with quote

45PSS wrote:
Quote:
I need the lens to move away from the film plane, not toward it, so I would put in the recessed board backwards and mount the lens on the protrusion

Duh, that might work. The nodes on the standard board are for the board locks so that extra thickness at that point needs to be accounted for.
This arrangement is called an extension.
I know of none made so you will have to fabricate one. Make sure the recessed side has enough room for the mount/retainer ring and the wrench to tighten it to turn freely.


All good advice and you have been enormously helpful. Thanks so much.
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hsandler



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

PostPosted: Sun Dec 02, 2018 2:59 am    Post subject: Reply with quote

Lobalobo wrote:

Glad that works for you. As I've explained above, in a couple of places, it doesn't for me because once the bed is dropped there isn't room to pull the standard forward into focus; the standard falls off the rails first.


OK, I get that you can't extend the standard forward enough to focus by positioning the standard itself, but what about if you "overextend" it a bit (see below) and ALSO crank the rear tracks forward too? I've got my Pacemaker Crown 45 in front of me here. When I drop the bed and position the front standard as far forward on the rear tracks as I dare go before it falls off while still being able to lock down the front standard, it is in a position wherein the front edge of the standard is in fact cantilevered a good 15mm in front of the edge of the rear tracks; it actually hangs several mm over the beginning of the dropped forward tracks. In other words, if I look at the depth of the baseplate of the front standard, I can actually cantilever nearly half of it over the end of the tracks. This buys me about 15mm of extension. NB: To cantilever it this much I have to crank the tracks forward just a few mm from the most rearward position so the baseplate of the standard clears the edge of the forward tracks (which descend out of the way as the tracks are cranked forward). OK, then, I can crank both sets of tracks even further forward with the focus knob as far as they can go in the dropped bed position. This permits about another 15mm or so of additional extension/focus adjustment. I can achieve a maximum lens board to focal plane distance of about 93mm. So if the lens data Dan cited is correct, you ought to be able to focus somewhat closer than infinity. It's a pain that this arrangement probably can't achieve very close focus, but then you could do the opposite strategy to focus a lot closer; i.e. position the standard on the forward tracks but as far back on them as possible while still being able to lock it, doing the tilt and shift thing to make the front standard parallel to the film plane again, and then cranking the tracks backwards as needed. This should achieve focus for close subjects with a dropped bed. Hopefully the range of focus distances that can't be achieved by one of these two set ups is small or nonexistent.
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Dan Fromm



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

PostPosted: Sun Dec 02, 2018 3:00 pm    Post subject: Reply with quote

OP, this https://vintagecameralab.com/graflex-crown-graphic/ site says that the 4x5 Crown's box is 10 cm deep. If 10 cm is correct -- please measure yours and tell us whether it is -- what you've been saying doesn't compute.

100 mm plus as much as 20 mm of inner bed rail in front of the box with the rail fully extended will put a 75 mm lens with 83 mm flange-focal distance well through infinity. Please measure lens board to GG distance with the standard at the front of the inner rail, bed dropped and the rail fully extended. And tell us the distance.

About a reversed recessed board. The words you're looking for are "top hat lens board." If my arithmetic is correct, not what you need.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 02, 2018 3:52 pm    Post subject: Reply with quote

[quote="hsandler"]
Lobalobo wrote:
So if the lens data Dan cited is correct, ... the range of focus distances that can't be achieved by one of these two set ups is small or nonexistent.
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 02, 2018 3:59 pm    Post subject: Reply with quote

Dan Fromm wrote:
Will put a 75 mm lens with 83 mm flange-focal distance well through infinity.


Thanks for your help and taking the time for the careful response. But as for your solution, it depends what you mean by "well through infinity." Does not appear to me that I'll get the full range of focus, as also expressed by the earlier post by hsandler.
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Dan Fromm



Joined: 14 May 2001
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PostPosted: Sun Dec 02, 2018 5:24 pm    Post subject: Reply with quote

Lobalobo wrote:
Dan Fromm wrote:
Will put a 75 mm lens with 83 mm flange-focal distance well through infinity.


Thanks for your help and taking the time for the careful response. But as for your solution, it depends what you mean by "well through infinity." Does not appear to me that I'll get the full range of focus, as also expressed by the earlier post by hsandler.


How deep is your Crown's body?

Does my suggestion work or not?

In an early post I remarked "However, focusing travel is limited with the bed dropped." You can't have everything, may have to slide the front standard forward from the infinity position to focus much closer. I rarely use my short lenses for closeup work so don't have to do this. Did once try a 38/4.5 Biogon this way, had to slide the front standard forward.

Graphics aren't the best cameras for every application. but they work better with short lenses than press camera without linked inner and outer rails.

About getting front rise without removing the wire frame finder. Cut away the top of the box. This is not a new idea. Some camera manufacturer or other -- Linhof comes to mind but I might be mistaken -- made press/technical cameras with boxes whose upper front was hinged to allow front rise.

About "well through infinity." That was a mental slip. If the camera's dimensions are as I understand them and the lens is a 75 mm Super Angulon, with the bed dropped, the front standard on the front of the inner rails, and the lens focused as close as possible, the lens should be focused closer than infinity. If all is as I understand it, with the front standard at the rear of the fully retracted inner bed the lens will be focused well through infinity, i.e., ~ 20 mm closer to the film plane than the infinity position, and nothing in front of it will be in focus. With the front standard ~ 20 mm in front of the rear of the fully retracted inner bed the lens should be focused at infinity.
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IanG



Joined: 04 Aug 2006
Posts: 74
Location: United Kingdom

PostPosted: Sun Dec 02, 2018 7:54 pm    Post subject: Reply with quote

MPP Micro Technical cameras overcome the same problem with a cone as part of the lens board allowing the standard to fit the rear rails while the front is dropped.

Ian
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Lobalobo



Joined: 11 May 2007
Posts: 59

PostPosted: Sun Dec 02, 2018 10:31 pm    Post subject: Reply with quote

Dan Fromm wrote:
In an early post I remarked "However, focusing travel is limited with the bed dropped." You can't have everything.


Not sure of your point. You seem to think I'm insulting the camera. Instead, I'm looking for a solution to a problem. I do sometimes focus on an object relatively close in the foreground with a wide-angle, blurred view of the background. If I can accomplish this without having to crop, I'd like to. Never claimed it was important in any fundamental way. Anyway, thanks for your time.
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Lobalobo



Joined: 11 May 2007
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PostPosted: Sun Dec 02, 2018 10:32 pm    Post subject: Reply with quote

IanG wrote:
MPP Micro Technical cameras overcome the same problem with a cone as part of the lens board allowing the standard to fit the rear rails while the front is dropped.

Ian


Exactly what I have in mind, or something like it. I'm looking around for something that will work. Your advice is much appreciated.
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Dan Fromm



Joined: 14 May 2001
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PostPosted: Sun Dec 02, 2018 11:34 pm    Post subject: Reply with quote

Lobalobo wrote:
Dan Fromm wrote:
In an early post I remarked "However, focusing travel is limited with the bed dropped." You can't have everything.


Not sure of your point. You seem to think I'm insulting the camera. Instead, I'm looking for a solution to a problem. I do sometimes focus on an object relatively close in the foreground with a wide-angle, blurred view of the background. If I can accomplish this without having to crop, I'd like to. Never claimed it was important in any fundamental way. Anyway, thanks for your time.


The camera has less focusing travel with the bed down than with it in the normal position. This means that when the bed is dropped you can't change the focused distance continuously between infinity and the near focusing limit with the bed in normal position. The usual solution is to move the standard forward from the infinity position on the inner rails until the subject is in focus.

By the way, I just read this discussion from the beginning. You've only just mentioned what your real problem is. Inability to "focus on an object relatively close in the foreground with a wide-angle, blurred view of the background." Stating this clearly at the start would have been helpful.
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Lobalobo



Joined: 11 May 2007
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PostPosted: Mon Dec 03, 2018 4:38 pm    Post subject: Reply with quote

Dan Fromm wrote:
By the way, I just read this discussion from the beginning. You've only just mentioned what your real problem is. Inability to "focus on an object relatively close in the foreground with a wide-angle, blurred view of the background."


Nope, that's not my "real" problem. My problem, as stated from the start, is that I want to be able to use my 75mm lens without cropping the edge of the bed out of photos. That's still my goal; the only reason I mentioned the kind of photos I sometimes capture is because, for some reason, you seemed to doubt that I had a legitimate purpose. But, again, thanks for your time.


Last edited by Lobalobo on Sat Dec 08, 2018 1:24 pm; edited 1 time in total
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hsandler



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

PostPosted: Mon Dec 03, 2018 6:02 pm    Post subject: Reply with quote

Lobalobo wrote:
My problem, as stated from the start, is that I want to be able to use my 75mm lens without dropping the bed or cropping the edge of the bed out of photos.


So if you drop the bed, crank the rails forward as much as possible and pull the front standard out so it's actually a bit beyond the end of the rear rails (cantilevered, as I described in a post above), how much closer than infinity can you focus?
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