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correcting fresnell/ground glass instrallation.

 
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pauliefrog



Joined: 05 Nov 2002
Posts: 16
Location: Berkeley,.ca.

PostPosted: Mon Jun 28, 2004 5:16 pm    Post subject: Reply with quote

I have just acquired a Crown Graphic which has a Fresnell screen as well as a ground glass screen.It is very difficult to focus as it is very dark and the circles on the
Fresenll lens are very apparent upon viewing..Is this normal with the fresnell lens.Also what is the correct placement of the frenell lens and finally,how can I check to see if the front of the fresnell lens is in the same plane as the film in the film holder?Any help is very much appreciated.Thanks.
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Rangemaster



Joined: 06 Jul 2001
Posts: 412
Location: Montana, Glacier National Park

PostPosted: Mon Jun 28, 2004 5:31 pm    Post subject: Reply with quote

There have been many disscussions on the Fresnel placemnt in Grapic cameras on the fourm as well as a couple of articles on the web site, opinons vary, even Ron Wisner has wrote a great article on the subject. Myself personally throw the fresnels away due to the corseness of the circles and replace with a better viewing screen.

If you do a search through the fourms as well as the web site you will be able to find a pretty good amount of information on the subject.

Dave

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t.r.sanford



Joined: 10 Nov 2003
Posts: 812
Location: East Coast (Long Island)

PostPosted: Mon Jun 28, 2004 6:00 pm    Post subject: Reply with quote

Getting rid of the Fresnel condenser certainly will not brighten the viewing image. I tend to agree that Fresnel lenses, at least the "Ektalite" ones supplied for "Graphic" cameras, are dubious focusing aids, especially if you stop down to focus. What they do is brighten the image at the edges of the groundglass, and this can be an aid to composition (if not focusing).

Previous discussion of this vexed question here has provided more information in six months than you could get elsewhere in 40 years -- and I speak from experience!
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Rangemaster



Joined: 06 Jul 2001
Posts: 412
Location: Montana, Glacier National Park

PostPosted: Mon Jun 28, 2004 6:12 pm    Post subject: Reply with quote

I do actually produce ground glass screens that provide edge to edge brightness and are extremly fine for focusing, in my own tests I have found about 1 stop brighter than with a fresnel, and in my customers tests, they are reporting 1 - 3 stops brighter than with a fresnel..

Dave

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RichS



Joined: 18 Oct 2001
Posts: 1468
Location: South of Rochester, NY

PostPosted: Tue Jun 29, 2004 4:09 am    Post subject: Reply with quote

Dave: we'll see!

pauliefrog:

I would suggest keeping the fresnel. I have quite a few graphics and I'd hate to use any of them without...

I would also suggest taking a close look at the GG and fresnel to see if they're dirty and/or hazed. I had a couple that were terrible until I took them apart and cleaned them. Just a regular wash with warm water and dish detergent, let dry completely and then reassemble. It may make an amazing difference.

Although you sound like you don't like the view of the freznel? Some people do hate them. If you really want to get rid of it, then you could remove it. BUT, you would have to add spacers the exact same thickness of the fresnel plate between your GG and the face of the view panel otherwise your GG will not be in the correct film plane!


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45PSS



Joined: 28 Sep 2001
Posts: 4081
Location: Mid Peninsula, Ca.

PostPosted: Tue Jun 29, 2004 4:14 am    Post subject: Reply with quote



[ This Message was edited by: 45PSS on 2005-12-25 11:36 ]
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pauliefrog



Joined: 05 Nov 2002
Posts: 16
Location: Berkeley,.ca.

PostPosted: Wed Jun 30, 2004 1:46 am    Post subject: Reply with quote

Thanks to all for some very effective advice.I did remove both pieces and after giving them a bath, re-installed with the GG facing the lens(front) and the Fresnell lens facing the back of the camera.GOOD GRIEF!!!I can see.The desired result is now achieved with great clarity across the whole field of view.
Another question,please.I am interested in doing some macro work with my 2x3.Any advice as to which lens would give me good depth of field as well as sharp resolution when stopped down?I am very new to using this format. Great site.Totally hooked.Thanks.
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Dan Fromm



Joined: 14 May 2001
Posts: 2148
Location: New Jersey

PostPosted: Wed Jun 30, 2004 11:54 am    Post subject: Reply with quote

Quote:

On 2004-06-29 18:46, pauliefrog wrote:
Thanks to all for some very effective advice.I did remove both pieces and after giving them a bath, re-installed with the GG facing the lens(front) and the Fresnell lens facing the back of the camera.GOOD GRIEF!!!I can see.The desired result is now achieved with great clarity across the whole field of view.
Another question,please.I am interested in doing some macro work with my 2x3.Any advice as to which lens would give me good depth of field as well as sharp resolution when stopped down?I am very new to using this format. Great site.Totally hooked.Thanks.

Depth of field is controlled entirely by magnification and aperture. All lenses will give the same DOF at the same magnification and aperture. Ain't no magic way to get more DOF.

If you're going to work below 1:1, most decent 80-100 mm enlarging lenses will give you very good image quality from f/11 - f/22. DOF is another matter, but in my experience it doesn't pay to stop down below f/22. What's gained in DOF is lost in sharpness in the plane of best focus.

I've shot with a couple of enlarging lenses. The best I've used is a 4"/5.6 Enlarging Pro Raptar; on a 2x3 Speed it is great up to the highest magnification attainable. I have a 75/3.5 Boyer Saphir B, also a six-element lens, that's great up to 1:1, not so good above. I've also tried an 80/5.6 Minolta CE Rokkor-X; the Boyer is better, so much for the Minolta.

Focal lengths much longer than 100 mm or shorter than 75 are pretty limiting. Can't get enough magnification with longer, don't have enough working distance with shorter.

I use flash, mount the lenses in front of an ex-MP-4 Copal #1 Press shutter. I had SKGrimes make a female M39x1-to-male M40x0.75 adapter to let me mount enlarging lenses on a #1. $35 when they made it, prices may have risen since. The Wolly isn't in M39, but it fits into the front of the shutter. I've tied it down with lots of darkroom tape. Ugly, on the whole a sleazy expedient, but it works.

My best macro lens and the one I usually use is a 100/6.3 Reichert Neupolar. These are hard to find, nowadays expensive. It is usable on a 2x3 Speed from 1:8 to a bit over 2:1, is slightly better than the Enlarging Pro Raptar. At $14 and $16 delivered, respectively, mine were both good values.

I haven't tried a 105 Componon or El Nikkor. Either should work well, cost not too much, and screw into a #1. If I were you, that's what I'd look for, and, of course, an ex-MP-4 Copal #1 Press. I suggest the MP-4 shutter because it has an open shutter lever, i.e., is easier to use than the other Polaroid #1s.

Go for it!

Cheers,

Dan
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glennfromwy



Joined: 29 Nov 2001
Posts: 903
Location: S.W. Wyoming

PostPosted: Wed Jun 30, 2004 8:42 pm    Post subject: Reply with quote

The Polaroid MP-4 lenses are a pretty good item,too, and not at all expensive. They are made for close-up work and I recently picked up a set of four brand new ones, 35mm to 105mm, in barrel for about 20 bucks. They should also make good enlarging lenses. I was also pleased to find that the 75mm lens will cover 4X5.

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Dan Fromm



Joined: 14 May 2001
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Location: New Jersey

PostPosted: Wed Jun 30, 2004 10:13 pm    Post subject: Reply with quote

Quote:

On 2004-06-30 13:42, glennfromwy wrote:
The Polaroid MP-4 lenses are a pretty good item,too, and not at all expensive. They are made for close-up work and I recently picked up a set of four brand new ones, 35mm to 105mm, in barrel for about 20 bucks. They should also make good enlarging lenses. I was also pleased to find that the 75mm lens will cover 4X5.

Glenn, I have all of the MP-4 Tominons but the 105/4.5. You got yours a little below market, good for you.

They're not bad at all and are great values, but for use on 2x3 I prefer the lenses I mentioned. My 135s -- at the moment I have two -- are the worst of the lot and I wouldn't use them anyway because they're on the long side for a 2x3 Speed. Maybe on a bigger camera ...

The MP-4 Tominons are all best above 1:1. The 17/4 and 35/4.5 are very good, not that far behind the Luminars I've tried and certainly much less expensive, but there are many problems with using short lenses on a 2x3 Speed. They want a 35 mm camera or a proper view camera with a lot of bellows.

I didn't mention that I also use a reversed 55/2.8 AIS MicroNikkor at magnifications from 2:1 to 5:1. Super lens if stopped down to f/4, and at today's prices another great value. I like it so much that I sprung for a male 52 mm filter thread-to-#1 adapter for it.

I also didn't mention that some EL Nikkors, including, IIRC, the 105, are reversible. I haven't tried one yet, don't feel the need since I have lenses that are good enough, but expect that one would work well as a macro lens from, roughly, 1:10 to 10:1. The problem with using it at higher magnifications is getting the extension. That's the good practical argument for using short lenses above 2:1 or so on a short camera.

Cheers,

Dan
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pauliefrog



Joined: 05 Nov 2002
Posts: 16
Location: Berkeley,.ca.

PostPosted: Thu Jul 01, 2004 12:59 am    Post subject: Reply with quote

Build a better mousetrap etc..Can I(with the help of SKGrimes) fit a 75mm Tominon to a Copal "o" shutter?And Dan,you suggest a Copal"1".Would this fit the Pacemaker lens board(2 1/2 x 2 1/2.)?Or wouldn't the 75mm Tominon fit on a copal "O"?.Thanks,
Paul.
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glennfromwy



Joined: 29 Nov 2001
Posts: 903
Location: S.W. Wyoming

PostPosted: Thu Jul 01, 2004 3:26 am    Post subject: Reply with quote

Watch the infamous auction site and you should be able to pick up a new one in a Copal I for around 50 bucks. Maybe less.

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Dan Fromm



Joined: 14 May 2001
Posts: 2148
Location: New Jersey

PostPosted: Thu Jul 01, 2004 11:32 am    Post subject: Reply with quote

Quote:

On 2004-06-30 17:59, pauliefrog wrote:
Build a better mousetrap etc..Can I(with the help of SKGrimes) fit a 75mm Tominon to a Copal "o" shutter?And Dan,you suggest a Copal"1".Would this fit the Pacemaker lens board(2 1/2 x 2 1/2.)?Or wouldn't the 75mm Tominon fit on a copal "O"?.Thanks,
Paul.
As Dave suggested, you should be able to find a 75/4.5 Tominon in a Copal 1. That's "in" as in "the diaphragm is part of the shutter and the lens' cells are screwed into, respectively, the front and rear of the shutter." Polaroid used Tominons in shutter in CU-5, DS-34, DS-39, and possibly other cameras. According to Jim Galli (eBay id tpahjim), who buys lenses such as G-Clarons in barrel and sells them remounted in ex-CU-5 Copal 1s, the shutter used with 75s has a limited diaphragm that won't open real wide.

I've had an ex-CU-5 17/4 Tominon. It screws into the front of the shutter just like the MP-4 one I still have, but the CU-5 version has a shorter barrel. I also have and use an ex-CU-5 127/4.7 Tominon. It works well at normal distances.

The MP-4 Tominons are in barrel and are intended to be screwed into the front of a #1. For this reason, MP-4 Copal 1s don't have diaphragms, can't be used with "regular" lenses. Polaroid's idea was to save MP-4 users the cost of buying a shutter for each lens. So if you get an MP-4 75/4.5 in barrel, it will screw right into any #1 shutter.

For front-mounting, MP-4 shutters are the best choice because they have "open shutter" levers like regular cock-and-shoot Copals. I use mine with longer than normal lenses, including process lenses, as well as with macro lenses. Yes, adapters are required. The idea is to find a lens that can be bought and adapted for usefully less than the cost of the equivalent lens in shutter. Beware, although vignetting by the shutter isn't much of a problem on 2x3, it can be a problem on 4x5.

Got the idea? Polaroid bought Tominons in barrel and in shutter too. If you get the right bits (lens in shutter, lens in barrel and any #1) no adapters are required.

A Copal #1 will fit just fine on a 2x3 Pacemaker Graphic board BUT it will interfere with the front shutter trip mechanism's arm. The arm is that little tab that is supposed to push the shutter's trip lever. I've removed my Speed's front shutter tripper arm, since the body shutter release works well with only one of my lenses in shutter. The rest of the mechanism is still in place.

About any #1. Copal Press shutters' top speed is 1/125. When shooting closeup out-of-doors with flash, this is sometimes a little slow. It can force the use of a smaller aperture than desired to prevent getting too much exposure from ambient light. Earlier this year I lucked into a 210/6.3 Prinz (= Commercial Congo) in a cock-and-shoot #1, top speed 1/400, at quite a good price. Used off-brand lenses in #1 Copal or Synchro Compur sometimes sell for considerably less than used shutters usually bring. Watch for 'em.

Cheers,

Dan
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Dan Fromm



Joined: 14 May 2001
Posts: 2148
Location: New Jersey

PostPosted: Thu Jul 01, 2004 1:41 pm    Post subject: Reply with quote

Quote:

On 2004-06-30 17:59, pauliefrog wrote:
Build a better mousetrap etc..Can I(with the help of SKGrimes) fit a 75mm Tominon to a Copal "o" shutter?And Dan,you suggest a Copal"1".Would this fit the Pacemaker lens board(2 1/2 x 2 1/2.)?Or wouldn't the 75mm Tominon fit on a copal "O"?.Thanks,
Paul.
Paul, Dave:

A while ago I did some calculations to find out which focal lengths could be used at which magnifications on my 2x3 Graphics. Total extension is limiting. These cameras don't have much. And for short lenses at not too high magnification, the bed gets in the way. A press camera isn't the best tool for every job. Surprising, eh?

If you want a copy of the spreadsheet, send me your e-mail address in a private message and I'll send it to you. And then you'll be able to play, check and perhaps correct my assumptions and arithmetic, ...

Cheers,

Dan
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