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Brighter Ground Glass/Pacemaker Speed
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ben_hutcherson



Joined: 15 Jan 2017
Posts: 19
Location: Kentucky

PostPosted: Mon Jan 16, 2017 5:21 pm    Post subject: Brighter Ground Glass/Pacemaker Speed Reply with quote

I admit that I've been spoiled by "modern" laser etched fresnel focusing screens, but it still doesn't change the fact that I've found the stock glass screen on my new(to me) Pacemaker Speed Graphic next to useless.

I can just barely see it with the focusing hood, and an impromtue dark cloth(my black rain coat) doesn't help all that much.

I've removed the screen and given it a good scrubbing in soap and water, but it hasn't made a huge difference.

If my understanding is correct, however, transplanting a later fresnel Graflex screen onto my spring back won't work since mine is designed to have the ground glass surface directly in the film plane.

Are there any other alternatives? I've read about cutting a fresnel page magnifiier to fit in front of the back of the GG(i.e. the viewing side) and I'm certainly willing to give that a go if it would give any improvement.

Are there any other alternatives? I know I probably can't get MF or 35mm bright, but I'd at least like to get some idea if a certain movement is going to introduce vignetting or other issues like that. As it is now, the screen basically goes black around f/8 with my 135mm f/4.7.
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ben_hutcherson



Joined: 15 Jan 2017
Posts: 19
Location: Kentucky

PostPosted: Mon Jan 16, 2017 5:52 pm    Post subject: Reply with quote

For comparison, here's a Bronica SQ-Ai with an 80mm 2.8



A pre-war Rolleiflex with a 3.5 Tessar and a focusing screen stolen from a parts(late) Rolleicord



And the Speed-135mm 4.5 Optar wide open

[/img]


Last edited by ben_hutcherson on Wed Jan 18, 2017 2:19 pm; edited 1 time in total
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loujon



Joined: 12 Feb 2014
Posts: 13
Location: Western, PA

PostPosted: Mon Jan 16, 2017 8:10 pm    Post subject: Reply with quote

Hey Ben
I agree that the stock ground glass on it's own is terribly dim and I did something about that right away. You could try installing a Ektalite Field lens or like Fresnel in a slot that lies below the ground glass but I'm not 100% sure there is a slot in Grafic back. I am 100% sure there is a slot under the ground glass frame on the Graflok backs and Graflex provided the Ektalite Field lens (after it's introduction) w/ most if not all Graflok backs. Maybe you should/could start shopping for a S G Graflok back to swap out for your Graphic back. Just make sure it comes with the Ektalite Field lens under ground glass. It's a very simple procedure w/ only six screws to remove and you'll have a chance to clean and inspect your focal plain shutter out while your at it. Plenty of solid instruction on the matter right here.

You could also or try a replacement ground glass made by the likes of Steve Hopf which are certainly brighter then the stock ground glass and directly replaces the stock glass so your focus on the film plain will stay the same . If you go this route make sure it's cut to the same size of the Graphic ground glass so you can just remove & install the new piece.

Here's Steve Hopf's site
https://hopfglass.wordpress.com/

My 4x5 Peacemaker Speed Graphic came w/ a Grafic back but I had a 4x5 Speed Graphic Graflok back w/ the Ektalite Field lens and made the change right away. There is NO doubt it's a MASSIVE improvement. You still focus on the ground glass w/ the Ektalite field lens sitting in a specially made channel'slot set under the film plain/ground glass. So your loupe will sit on the gg/film plain but the Fresnel is still brightening the gg by at least a couple stops. BIG DIFFERENCE.

You can read a bit on the matter by browsing through the couple Graflex catalog/price list I'll provide for you. go down to where they go over the "15 more features" of the Peacemaker Speed/Crown Graphics and there is a bit of explanation of the slot under the ground glass.

I hope this helps you out a little as do the links I've added below.

Peace
LouisP

https://www.pacificrimcamera.com/rl/00029/00029.pdf
https://www.pacificrimcamera.com/rl/00532/00532.pdf
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ben_hutcherson



Joined: 15 Jan 2017
Posts: 19
Location: Kentucky

PostPosted: Mon Jan 16, 2017 11:31 pm    Post subject: Reply with quote

Thanks Louis-

Definitely some stuff to digest and some reading to keep me busy.

I've had the GG completely out of the spring back for cleaning(and inspecting the FP shutter) so I know changing it is straight forward.

If I could find an affordable Graflok I'd definitely swap them out.

A fellow local to me use to sell really nice fresnel screens with a split image and grids in whatever pattern you wanted, but mainly sold to the 35mm and MF market. I have one of his screens in my Rolleicord Va, and it's a great screen. Granted I'd not want the split image in an LF screen, although I think it was optional. It might be worth getting in touch with him-his were designed for drop-in install for cameras that were designed to have the GG surface against the frame, so they would seem to be ideal.

Like I said, I know it's impossible to exactly replicate the brightness of good MF screens since you're generally starting with a slower lens and are projecting over 4x the area, but it has to be better than what I'm seeing now.
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45PSS



Joined: 28 Sep 2001
Posts: 3669
Location: Mid Peninsula, Ca.

PostPosted: Tue Jan 17, 2017 8:40 pm    Post subject: Reply with quote

Quote:
I've removed the screen and given it a good scrubbing in soap and water

Did you use A.) a scotch bright or B.) a wire brush to give it a good scrubbing?

Warm water and dish detergent usually works well and brightens the ground glass 1 to 2 stops. I've had a few that needed to soak in soapy water for a half hour to come clean.

The bosses that the ground glass sits on was ground down .020-.030 inch when the Ektalitre Field Screen was added. The distance the bosses were ground down is 1/2 the optical distance of the Field Screen.

A fresnel can be notched so that it fits around the ground glass mounts then is attached by adhesive at the edges or similar to mount it in front of the ground glass.
The ribbed side of a fresnel always faces the ground glass.
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Dan Fromm



Joined: 14 May 2001
Posts: 2017
Location: New Jersey

PostPosted: Wed Jan 18, 2017 12:35 pm    Post subject: Reply with quote

Ben, f/2.8 is more than a stop brighter than f/4.5. Why do you expect y'r Graphic's screen to be as bright as your SQ-A's?
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ben_hutcherson



Joined: 15 Jan 2017
Posts: 19
Location: Kentucky

PostPosted: Wed Jan 18, 2017 2:18 pm    Post subject: Reply with quote

Dan Fromm wrote:
Ben, f/2.8 is more than a stop brighter than f/4.5. Why do you expect y'r Graphic's screen to be as bright as your SQ-A's?


If you read, I specifically said that I know it CAN'T be. Yes, the SQ lens is 1.5 stops brighter and it's also projecting over(roughly) 1/4 the area. The SQ-Ai is usable in broad daylight with no hood, and I know that's asking way too much of any 4x5 lens and screen combo.

Still, I'd like a GG on the Speed that doesn't black out in the corners! Also, it would be nice to have a screen where I can see SOMETHING at less than f/5.6 or so.
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Dan Fromm



Joined: 14 May 2001
Posts: 2017
Location: New Jersey

PostPosted: Thu Jan 19, 2017 1:16 pm    Post subject: Reply with quote

Ben, do you use a loupe to focus? I ask because my dimmest lens, a 60/14 Perigraphe, isn't that hard to focus. I use a 3.6x Toyo.
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Henry



Joined: 09 May 2001
Posts: 1556
Location: Allentown, Pennsylvania

PostPosted: Thu Jan 19, 2017 8:31 pm    Post subject: Reply with quote

Hang onto it, Dan; it's discontinued. Two years ago a used one went on the auction site for $129. See item no. 321743112540. Glad I bought mine when I did!
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IanG



Joined: 04 Aug 2006
Posts: 69
Location: United Kingdom

PostPosted: Sun Jan 29, 2017 6:00 pm    Post subject: Reply with quote

All my Graflex cameras have new or re-ground screens, the originals are appallingly dim. You can fit a Fresnel to the rear (outside) of the focus screen, you can't fit one under with the corners notched as mentioned in an earlier reply as it causes a focus shift.

I was comparing my Crown Graphic with a 150mm f4,5 lens with my Wista 45DX (combination screen)and 150mm f5.6 lens and the Crown;s screen was 3.5 stops dimmer,. A new screen got me over 1.5 stops brighter later adding a fresnel added about another 1.5 stops overall it's now about half a stop dimmer. (That's off axis brightness.) You need to shim the brackets that hold the glass in place when the fresnel is added or the focus hood doesn't lock in securely

Now focusing my Crown Graphic is really easy with just the focus hood which is important as often I need to work quickly hand-held.

Ian
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45PSS



Joined: 28 Sep 2001
Posts: 3669
Location: Mid Peninsula, Ca.

PostPosted: Sun Jan 29, 2017 8:14 pm    Post subject: Reply with quote

Quote:
you can't fit one under with the corners notched as mentioned in an earlier reply as it causes a focus shift.

I've done it in the past on a Meridian 45B and it had no effect on focus.
Have you ever tried it?
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IanG



Joined: 04 Aug 2006
Posts: 69
Location: United Kingdom

PostPosted: Tue Jan 31, 2017 5:29 pm    Post subject: Reply with quote

45PSS wrote:
Quote:
you can't fit one under with the corners notched as mentioned in an earlier reply as it causes a focus shift.

I've done it in the past on a Meridian 45B and it had no effect on focus.
Have you ever tried it?


Yes, I tried it with a British wood/brass half plate field camera, it has a slight effect on focus shift but it might not be noticeable with a dim screen.

Ian
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45PSS



Joined: 28 Sep 2001
Posts: 3669
Location: Mid Peninsula, Ca.

PostPosted: Tue Jan 31, 2017 7:36 pm    Post subject: Reply with quote

It may depend on the optical characteristic of the fresnel used also.
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jerryg



Joined: 04 Apr 2017
Posts: 16
Location: spokane wa.

PostPosted: Sun Mar 25, 2018 5:08 pm    Post subject: Reply with quote

I recently purchased glass from a seller on ebay, the glass is thicker than the stock glass. does the thickness of the glass change the focus?
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45PSS



Joined: 28 Sep 2001
Posts: 3669
Location: Mid Peninsula, Ca.

PostPosted: Sun Mar 25, 2018 7:25 pm    Post subject: Reply with quote

Shouldn't if installed correctly. The image is formed on the ground side and the ground side faces the lens.
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