PDA

View Full Version : 4x5 Focusing Screens: THE FINAL WORD



Serge J-F. Levy
19-Nov-2004, 11:33
I have read several forums, several answers and still don't have a really solid sense of where to go with this question. Could someone who works in a professional capacity, who is extremely meticulous about focus, the quality of their images, the visibility of the image on the glass, alignment and so on please respond.

I have a linhof master technica (bought new two years ago) and I use lenses ranging from 90-210... for now. The groundglass that comes with the camera as some of you may know, is not suitable to composing an image because you can't see the entirety of it on the screen. I will be photographing in sub-freezing temperatures and possibly be keeping my camera in a hot car (so this is to address any issues people might see with the bosscreens.) I want brightness, but when I focus on the glass with a loupe, I will want to be able to see the subject crisply without disturbing fresnel lines.

Bob Solomon of HP Marketing was very kind to offer a lengthy thought out response which included using the Linhof fresnel on top of the GG. I fear that I will still get fresnel lines (also pricey.) Robert Maxwell told me a good bit about his screens, and the product seems enticing (are they milled to the precision that I require and are they really the BEST option?) The Bosscreen has worked nicely but has a major disadvantage to me in that it says "bromwell marketing" in the area that I will be composing. I find this terribly distracting and unfortunate. I also haven't had the chance to test it under the extreme conditions described above but want to avoid the potential for disaster on my outdoor shoot coming up in a week. I also want to say that Ted Bromwell is a very kind and honest businessman too.

Money is an issue, but I understand that often, you get what you pay for. So... please, what is the all around BEST solution?

I hope the responses will serve as definitive answers to future shooters seeking similar information.

Many thanks for your time.

-Serge

www.sergelevy.com

Matt Miller
19-Nov-2004, 12:21
FINAL WORD: Try a Satin Snow ground glass. High quality, custom cut, bright, & cheap.

KenM
19-Nov-2004, 12:42
I also have a Master Technika, which came with the Linhof Super Screen - combination plastic ground glass and fresnel. I purchased two Satin Snow ground glass replacements, and installed one of them onto my camera.

First, let me say that the workmanship is very fine, and the entire package was very well packed. For a very small shop, it was impressive. The grind is fine, and very even.

However, the glass that Dave makes is not a silver bullet that will magically make composition and focusing easier. The laws of physics still apply, in that the further off axis you get the dimmer the image will be, especially with wider angle lenses. In my case, I (just today in fact) removed the Satin Snow GG from my camera and reinstalled the SuperScreen.

I have issues with the SuperScreen (it seems to curve ever so slightly, and the grooves are visible under a loupe - yes Bob, I know - get a focusable loop), but the S.S. GG so much dimmer than with the fresnel that it was very difficult to use.

Please don't get me wrong - I'm not slagging Dave at Satin Snow. After all, as good as he his, he can't change the laws of physics. :-) My personal thoughts are that the GGs that Dave makes make great replacements GGs, and are a very good alternative for ULF users who need specially-sized GGs. His prices are great which makes the product all the more attractive.

I guess what it all boils down to is that a plain GG will always be dimmer than a fresnel-type screen, but the fresnel will always have issues with grooves, and perhaps focus shift (so I've read).

I don't need two of them, so contact me off-list if you're interested. The GGs have been sized for a Master Techinika, which makes them a perfect fit for you.

Michael Kadillak
19-Nov-2004, 12:54
Try the Linhof over screen as it is the cheapest (+/-$100) and will require no modifications of any kind. The grooves are something I learned to live with and it is really not that big a deal.

Since you will be stopping down to check focus, courseness with the image to get it to "pop" into focus is where I find the important variable. The super screens albeit improved are expensive when you take into account the cost to change the ground glass plane. Do the easiest thing first and go from there.

Cheers!

Bob Salomon
19-Nov-2004, 13:12
"I guess what it all boils down to is that a plain GG will always be dimmer than a fresnel-type screen, but the fresnel will always have issues with grooves, and perhaps focus shift (so I've read)."

Serge is not a photographer so confused answers he doesn't need.

First the Linhof fresnel fits on TOP of the ground glass - not under the ground glass so there is no way it can effect focus.
Second the purpose of the fresnel on 45 is the same as on 35 or MF. It spreads the light evenly across the screen and makes the image brighter.

Enhanced screens usually incorporate a fresnel of some sort (not the Boss screen which uses wax).

As for the grooves. With the loupe focused on the grain side of the GG the grooves form a fresnel are minimized. However the Linhof back was designed so that the fresnel can easily be removed by swing the chrome hold downs to the side so if they are distracting, it can be removed for critical focusing, and then replaced.

And yes the Super Screen is an anser for some but Serge needs a grid system and we no longer will offer the overlay so there is no grid available for the Super Screen any longer - unless you know of a dealer with one in stock. We are out of stock and the supplier of the grid has reaised their price to a point where it would no longer be saleable.

Tracy Storer
19-Nov-2004, 13:22
The final word is that different workers feel differently about these viewing issues. Posters above have cited the physics of it. (Ron Wisner has a good article on his site explaining these issues http://www.wisner.com/viewing.htm (http://www.wisner.com/viewing.htm))
My two cents opinion is that the best option for ease of both composition and focusing is to use a standard GG with a removable fresnel. Compose with the fresnel in place, remove it for critical focusing. "you get what you pay for" also applies to the effort you "spend" while working. My feeling with removable fresnels is that, since it is removed for the critical focusing stage, even a cheap fresnel will do, I use a cheap "page magnifier" bought at Barnes and Noble for my composing with my 5x7, then put my loupe directly on the bare glass. Good luck, and have fun with it.
Tracy Storer http://www.mammothcamera.com (http://www.mammothcamera.com)

KenM
19-Nov-2004, 13:24
"Serge is not a photographer..."

Boy, I'll bet Serge is suprised to hear that he's not a photographer...

Tracy Storer
19-Nov-2004, 13:25
Took so long typing, Bob beat me to the "removable fresnel" answer.
Best,
Tracy

Bill_1856
19-Nov-2004, 13:36
Would you please explain what you mean about the Technika GG being unsuitable for compostion because the entire image can't be seen. I don't understand....

David R Munson
19-Nov-2004, 13:42
I don't suppose you personally know anyone else who shoots 4x5, do you? If you do, see how their GG's look to you. I replaced the original glass on my Linhof monorail with a Beattie screen and love it. I've never had any problem at all viewing the entire image or checking critical focus with this screen, and it is definitely brighter than the original groundglass. My only gripe about it, really, is that it is quite possible to accidentally put some scratches in the "ground" side if you do much work with things like Grafmatics and remove the groundglass repeatedly in the field. Mine's starting to look like it's been around the block a few times.

Frank Petronio
19-Nov-2004, 13:49
I don't think you'll ever be satisfied so long as you split hairs over which fresnel is "best." The really right answer is to avoid using a fresnel and learn how to use a simple, old-fashioned ground glass with a good technique and darkcloth. Look at the fresnel as a nice luxury, not as an essential, and don't worry about it so much - use one when it works, but accept that with with some wide angle lenses it isn't going to work as well, or you're going to get lines, or you'll have to grid the ground glass itself (with a pencil!)

Bob Salomon
19-Nov-2004, 14:16
"you'll have to grid the ground glass itself (with a pencil!"

His ground glass is a grid screen. that is the standard screen on a Linhof.

Brian Ellis
19-Nov-2004, 14:25
Nobody is going to be able to tell you the one all around best solution because there isn't one. If there were everybody would buy it and all the products except the one all around best one would disappear. Everything you can use is a compromise in some way. You'll just have to decide which compromise is lmost palatable to you.

FWIW I've used original equipment Fresnels that came with my Ebony and Tachihara cameras, I've used the after-market Beattie screen, I've used a BosSreen on three different cameras inlcuding an 8x10 Deardorff, and I've used three or four plain ground glass screens. I didn't care for any of the Fresnels because the texture interferes with focusing and I didn't feel like buying multiple Fresnels for different focal length lenses, nor did I look forward to taking them on and off the camera all the time. I liked the BosScreen best and never had a problem in the heat of Florida summers, I don't know about cold because it doesn't get cold in Florida. At the moment I'm using a plain Linhof ground glass on my Master Technika and like it pretty well but may decide to replace it with another BosScreen. I can't see the entire image at once but I've done enough large format photography by now that moving my head around a little doesn't bother me and it's pure pleasure to watch the image pop into focus with that ground glass as compared with the Beattie screen that preceded it.

Bob Salomon
19-Nov-2004, 14:34
"(are they milled to the precision that I require"

If you are talking about the image plane then this statement is meaningless.

On a Linhof the image plane is the bottom surface of the ground glass. This surface sits on the focusing shims on the back. The factory or the service center adjust the shims, not the screen, to the exact position required for optimal focus. In the case of your camera this was done long before it was delivered to you.

There is nothing Maxwell, or any other manufacturer, can do for you to mill the screen for greater precision at the image plane.

Some manufacturers may grind the glass finer or polish it to make it brighter but this will normally remove some of the "bite" of the screen which is what makes the image snap into focus quickly and surely.

Michael Rosenberg
19-Nov-2004, 14:55
Serge,
You have some very good answers above. I would add my thoughts on the subject. I have tried a variety of screens, and recently tried the Satin Snow (cheap, and always need to take a sparee gg with me). I have the Master 2000, and it is a very fine camera. I have a problem with my retina and do not dark adapt well at all. And I am almost nightblind. I generally use wide angle lens, and have photographed a lot of architectural interiors and in slit canyons.

The critical issue with focusing is having an image on the ground glass of sufficient contrast that allows distinction of two adjacent points when racking the lens in and out. Fresnels will blur and cut down on the contrast due to the lines, but different fresnels will be different in this effect (due to the deepness of the rings, type of plastic, spacing of the rings). The cheaper the fresnel, the worse it is.

The problems with the Linhof Super Screen is as people described. The lines are bothersome. If you go this route I think you have to remove the screen to do the fine focusing.

The Boss screen - I went through two of them. Had bubbles form when my pack was in the overhead compartment on a cross country flight. Very nice screen thougth - probably the finest, but replacing them so often was not an option.

The Satin Snow - no different than any other screen except that it gives a much finer image making contrast more evident. As someone pointed out the physics still apply - it is hard to focus with wide angles.

The 20/20 Brightscreen. Nice screen, very fine lines of the fresnel, but with focal lengths below 150 the light drops off. This has the integrated gg/fresnel. I no longer use this screen for that reason.

The Maxwell screen. Bill will talk your head off, but he knows what he is talking about. The fresnel is incorporated into the gg. His is the best screen so far that I have tried. I had one on my first camera, and then bought another for my Master 2000 when I got the camera. This screen has very fine fresnel lines that have not interfered with my seeing the image, and is as contrasty as a naked gg. I have used it in a variety of circumstances, and even with a 58 mm lens in dark factory buildings. I highly recomemd this screen. I suggest that you order it with the corners intact, since normally people like them cut off and that is how he has them made. But he can have them made with the corners intact. And by the way, the grid with the screen is the finest I have seen, and are unobtrusive.

Another note, if you use a 6X loupe you will get an additional stop of brightness. An 8X will add nearly a stop-and-a-half. Again, you get what you pay for, so if light to critically focus is an issue buy a very good loupe.

I hope this helps.

Regards,

Mike www.npr-photography.com

Serge J-F. Levy
19-Nov-2004, 15:15
First of all, thank you to everyone for putting the time and effort into these responses.

Second of all, I've noticed that these forums about large format photography so frequently become small inquisitions if not full blown Kenneth Starr type investigations rooting out deep and powerful emotions on matters of a merely technical nature... but then I remember that we are all engaged in a form of artistic pursuit, and this enlivens strong feelings in people.

Third, I am a photographer, thank you to some of you for noticing this oversite. I am rather new to large format photography, but pride myself in having derived my living solely from magazine photojournalism and fine art sales of my personal work. To that effect, I currently have a solo-exhibition of 35 prints at the Leica Gallery in Tokyo, Japan (stop by when you have a spare moment), an exhibit at the Alice Austen House Museum in New York, and one more at the University of the Arts in Philadelphia.

Fourth, I just felt compelled to warrant my inquiry with the substantiation of having little money (an artist) and a lot of pride and perfection in what I do... I feel a lot of other people in this forum do to, and may benefit from this wonderful string of answers about a shocking detail of large format photography; you drop several thousand dollars on a piece of equipment, yet constantly learn that it is never quite ready to start working without another addition, another back, another lens, or another adjustment. It's a revelation to the new comer and as one member pointed out, it is an excellent idea to really learn as much as possible on your own while benefiting from other's mistakes.

Cheers,
Serge

www.sergelevy.com

Serge J-F. Levy
19-Nov-2004, 15:48
I read the "user terms" pretty carefully and think it is ok for me to ask this: does anyone have a linhof superscreen for the master technika with a grid on it that they would be willing to sell?

-Serge

www.sergelevy.com

Bob Salomon
19-Nov-2004, 17:06
There are no Super Screens with a grid on it. The Super Screen is a plain focusing system. To add a grid to it you would need the discontinued Linhof CM Grid Overlay for the Super Screen.

The Super Screen is not discontinued, only the CM Grid Overlay is.

Sorry I said you were not a photographer. When you called yesterday I thought you said you were an artist.

Bob Salomon
19-Nov-2004, 17:10
"The problems with the Linhof Super Screen is as people described. The lines are bothersome. If you go this route I think you have to remove the screen to do the fine focusing."

Again wrong information.
You can not remove the grooves from a Super Screen regardless of what you try to do.

The Super Screen is a single piece of acrylic with a grooved side and a smooth frosted side. The grooved side can not be detached from the smooth side. The Super Screen is a solid piece of acrylic and not a sandwich construction.

So you must have mistaken something else for the Super Screen.

JimL
19-Nov-2004, 19:25
I've settled on a BosScreen with a removable fresnel, even though it's said a fresnel shouldn't be used with that screen. I found that even though the BosScreen scatters light better than the Linhof groundglass I had, to me the light falloff was still unacceptable without the fresnel. With the fresnel on, I get even illumination with most of my lenses, and the BosScreen, which shows fine detail very sharply, is a pleasure to focus with, especially in the corners with w.a. lenses. I don't mind the fresnel grooves - the only thing that bothers me is that my fresnel is getting pretty scratched up from the loupe.

Jim

Jim Rice
19-Nov-2004, 19:40
This seems to be the ultimate voodoo issue. Along with the utility of wide-angle mount screw-in filters, no one seems to really know. So myself, I'm going to stick with my stock Wisner screen, and probably go with a W/A polarizer. Go figure.

Tom Diekwisch
19-Nov-2004, 23:19
I'd always recommend the Maxwell. Super bright and accurate. I had Maxwell install a super wide angle screen, and it really makes life easy.

Graeme Hird
20-Nov-2004, 01:38
"Sorry I said you were not a photographer. When you called yesterday I thought you said you were an artist."

What does that mean Bob? Can't he be both? :)

Jonathan Brewer
20-Nov-2004, 03:38
'To that effect, I currently have a solo-exhibition of 35 prints at the Leica Gallery in Tokyo, Japan (stop by when you have a spare moment), an exhibit at the Alice Austen House Museum in New York, and one more at the University of the Arts in Philadelphia.'.................................

Showing that it is possible for a person to be rich and broke at the same time.

Brian Ellis
20-Nov-2004, 05:13
A question of Mike Rosenberg (or anyone else) for my education - why do larger magnification factors in a loupe add brightness? I've used loupes ranging from 4x to 8x. I settled on 4x because the bigger mag factors tended to magnfiy things I didn't want magnified, such as the texture in a Fresnel screen. But if an 8x loupe adds a stop and a half of the brightness (as compared, I assume, to a 4x loupe) maybe this would be worth the extra magnfication of unwanted things.

Robert A. Zeichner
20-Nov-2004, 06:30
About 10 years ago I was on a quest for something to brighten the image on my 4x5 (a Horseman 45FA at the time). I invested in a Brightscreen and due to manufacturing "mistakes" ended up ruining every negative made on a week-long trip. I can't really carp too much about that as my money was chearfully refunded and it spurred me on to do some scientific investigation on the topic of ground glass alignment that resulted in an article for View Camera. I test every camera's gg that I use now to confirm that its focusing surface is coincident with the film plane and all has been well since in that regard.

What I have gotten used to and have come to prefer is just using a finely ground standard gg. I make them myself and scribe grids of whatever style I like using a .03 mechanical pencil. I layout the grid on my laptop, print it out and set the gg over it on a lightbox and just trace. Works great. For grinding the glass, I use the materials and technique recommended in an article by my friend Dick Dokas. This was published in PhotoTechniques awhile back and I believe you can even see it on line at their web site. Again, works great. It's not the brightest viewing system there is, but I too dislike the lines you see when using Fresnels and I enjoy the peace of mind of knowing that there will not be any alignment issues.

Michael Rosenberg
20-Nov-2004, 14:02
Brian,

There is an increase in brightness because the loupe is gathering the light and focusing it on your retina. This was first pointed out to me by Bruce Barnbaum. Different people will be satisfied with different magnification loupes - and what they get use to. Honestly, with a 6x loupe (I wish I could find a good 8X loupe) I do not notice the fresnel lines on the Maxwell screen. I think your mind will get use to anything eventually and ignore it.

Bob,

My mistake regarding the superscreen. I was thinking of the fresnel.

Serge,

Design your own grid and print it out on overhead transparency film then put it on top of your gg.

And in general, many people rarely check to see that the loupe is properly focused for the front surface of the gg. And often the loupe will get knocked around and no longer be in focus. Put a pencil mark on the gg surfact, and focus the loupe on that, then tape the loupe so it cannot change!

Regards,

Mike

Paul Fitzgerald
20-Nov-2004, 23:58
Hi there, just a thought that nobody picked up on. Serge wrote:

" I will be photographing in sub-freezing temperatures and possibly be keeping my camera in a hot car (so this is to address any issues people might see with the bosscreens.)"

That is not a really good idea, the metal and glass will drop to the wind-chill temp. in less than a minute. Rough on the equipment, better to leave it in the trunk. Better still are large zip-lock plastic bags for your lenses and film holders. Put everything in the bags while they are cold so you don't get a condensation problem.

Happy Thanksgiving.

Bill_1856
21-Nov-2004, 08:04
Serge, there's nothing magic about a view camera except it's size, and if you can't see the viewscreen to adequately compose your picture then you should consider that it ain't gonna be your bag. It's not something to be ashamed of, just to accept and work around it. I love working with my 4x5 equipment (and have for over 50 years), but the fact is that I've never made any spectacular images with it, whereas I seem to do quite well with 35mm (and now digital). There's an old saying: "the Shoemaker should stick to his last," which probably applies nicely.

Serge J-F. Levy
21-Nov-2004, 09:16
"there's nothing magic about a view camera except it's size"

Bill, I would imagine there would be a small insurrection over that comment, but from my limited experience with the medium, let me state (other than the aforementioned larger negative) that I have learned to greatly enjoy the philosophy and practice behind shooting with a 4x5 camera. Slowing down to a snail's pace has forced me to redirect my focus (per se) from the spontaneity of the decisive moment to the other elements of a great composition that can inform a stunning image. That's not to say that my 35mm work lacks these qualities, I just feel that 4x5, in the way that I am using it, forces me to slow down considerably and spend more time listening to the less apparent influences in my work. Let's not forget that for years, press photographers (including Felig aka Weegee) were able to use this medium in a much more spontaneous fahsion than the one I describe. So, in addition to the size, the forced contemplative nature of the process and finally the different aspect ratio, I'm sure every person could offer an individual remark upon their nuanced love for the medium.

Again, everyone's response has been very informative.

-Serge

www.sergelevy.com

Jon_2416
21-Nov-2004, 16:21
>Sorry I said you were not a photographer. When you called yesterday I thought you said you were an artist.

>--Bob Salomon HP Marketing Corp., 2004-11-19 16:06:48

Typical Bob--rude, deceptive, and arrogant. Boy, do I wish Linhof would drop that clown at their distributor. When ever I need anything for my TK45, I try my absolute hardest to avoid the dinosaurs at HP.

Gary Gibson
21-Nov-2004, 16:58
">Sorry I said you were not a photographer. When you called yesterday I
thought you said you were an artist.

>--Bob Salomon HP Marketing Corp., 2004-11-19 16:06:48

Typical Bob--rude, deceptive, and arrogant. Boy, do I wish Linhof would
drop that clown at their distributor. When ever I need anything for my
TK45, I try my absolute hardest to avoid the dinosaurs at HP."

It mustn't be forgotten that Bob and HP are merely re-sellers of widgets - tradsemen who just sell tools. And heaven forbid that anyone should ever create anything with what they sell.

HP (and Linhof) are perhaps missing the days of so much advertising being photographed on Large Format. I was in Munich recently and there was discussion of the Hasselbaldisation of Linhof due to it's market contracting more than projected and that like Hasselblad there is a need to hitch to a bigger, richer, digital partner and become leaner in the process.

Bob Salomon
21-Nov-2004, 17:07
"like Hasselblad there is a need to hitch to a bigger, richer, digital partner and become leaner in the process."

You must have miised the point, Gary.

Linhof's owner also own Anagramm a manufacturer of high end digital scanning backs. Has owned them for a while and Linhof and Anagramm have been mutually marketing each other's products since the start of Anagramm which was before the current owner purchased Linhof.

The latest Linhof/Anagramm system is the Digi Repro copy camera system which was introduced a Photokina.

Gary Gibson
21-Nov-2004, 17:45
Not at all Bob - Anagramm was very much part of the discussion. I was there for meetings at the big Texas Instruments R&D facility at Friesing in Munich's "silcon corridor". One of TIRIS's former research directors has been working in the "corridor" for 25 years and is now a consultant there (and a very good photographer). Anagramm was what would be the sweetener in any deal. The talk was of a "major" partner. Anagramm is good with some technology and expertise approaching the cutting edge, but small - many feel too small. In fact now I think back, it was more that Linhof would be a side aquisition that happened to come as part of the bundle with Anagramm.

Frank Petronio
21-Nov-2004, 18:16
One other thing - a lot of people really can't fully see the image on their ground glass no matter what gadgets they hang off the back of their cameras. Even top commerical photographers. Many frame the shot with generous margins, use a loupe to focus on obvious focus points, and then shoot the first of many Polaroids to get the composition and details of the image "just right."

Their is no sin in using Polaroids, other than being slow and expensive.

Michael S. Briggs
21-Nov-2004, 21:00
Serge, as you can see from the differing answers, there is no one best viewing screen.

I prefer a plain ground glass because I find the lines of Fresnel lenses distracting. I tried a Bosscreen, which was nice for seeing fine detail, but no brighter than a regular screen -- but the overwhelming drawback is that it delaminated on the first field trip I used it on.

With lenses from normal focal length and up, I have no trouble seeing the entire scence at once. With shorter lenses, there is a hot spot effect from the angles that the rays strike the ground glass. With a long focal length, the light rays arrive almost perpendicular to the screen. Their paths are deviated into a conical bundle by the ground glass, depending on the coarseness of the screen. With a long lens, when you place your head far enough behind the screen, some of the deviated rays reach your eye from all portions of the screen and you see the entire image. With a short focal length lens, rays away from the center strike the screen at an angle. The screen deviates the rays into a bundle, but the opening angle of the bundle isn't large enough to fully compensate for the incident angles. Hence, regardless of the position of your head, you only can only see a portion of the ground glass as bright. A Fresnel of the correct focal length will focus the bundles to a common point so that the entire screen is bright.

For a short focal length lens with a plain ground glass, with a little practice you can move your head around and build up the scence in your mind. If you can't see the entirely of a 4x5 ground glass image from a 210 mm lens, I think something is wrong. Are you holding your head at the correct distance?

Is your dark cloth totaly opaque? Any light leaks will reduce your ability to see the image on the ground glass. On a bright day I wear sunglasses, which I take off to view the screen. This helps my eyes adapt more quickly to the brightness of the ground glass image.

I prefer about a 4X to 6X magnifier. Higher powers don't really show any more detail because of the grain of the ground glass. I am dubious about the idea that higher powers loupes will give a brighter image -- my experience is that lower powers are easier to use. It seems intuitive that a higher power will spread the light over a larger image and reduce the brightness. The comparison may depend on the particular magnifiers -- a higher quality loupe may have a larger entrance pupil to capture more of the light rays.

P.S. Bob S. is giving advice about the equipment he knows best. His signature discloses that he represents HP Marketing Corp., so he isn't being deceptive.

Dan Jolicoeur
22-Nov-2004, 14:03
A little off topic, but you mentioned cold weather. You can pick up an old polaroid reflex hood pretty cheap. They have an amazingly brighter image with some magnification to it. It works pretty good in the cold weather keeping your nose and mouth out from the GG. The only problem is you either have to stand on a stool, or on your knee's if your tripod is not at the correct hight.

just a thought,

David Parker
28-Nov-2004, 22:57
Hello everybody, this has been a very interesting and information filled topic, I have enjoyed it greatly.

now to get on topic, I can say there is a 'Final Word' when it comes to ground glass or focusing screens, there is a great amount of personal preference that comes into play when choosing a focus screen. And has been mentioned, changing the laws of physics is nearly impossible, there are ways to improve brightness, IE Fresnel, of course you will pick up artifacts in your focus picture due to the magnification lines inherant to the fresnel. With any type of ground glass you will have a optical axis that you deal with due the light and optical properties of the lens.

Our screens are high quality finely ground glass, which does help a small amount with light transmission due to the fine grain and eveness of the focus side of the screen, but we are still limited due to the way the light path is projected. Currently we are testing some different optical coatings for our screen that if the work out correctly with offer better and more even light transmission properties, we are also working with some actual custom formulations of the actual silica that is used to make glass, using some of the many different elements in nature that transmit light a little differently, but again, we are dealing with the laws of optics.

The issue of focus screens in all types of photography, again is personal preferance, and what works for one, may be unusable to another.

The one thing that I strive to do with my screens is offer a low cost alternative for a focus screen, as has been stated, it is not a magic bullet, just a great quality screen at a very reasonable price. Heck in the past, I have made usuable screens with a piece of glass and translucent 'scotch tape'.

All I can recommend to anyone looking for a screen is to try as many different types as you possibly can and settle on the one or combination of items that match you needs as close as possible.

One one other note, I do have grid templates available for download on my website, that can either be traced onto the ground side of the glass, or can be printed on clear overhead transparancies and then cut to fit and mounted over the viewing screen.

www.satinsnowglass.com

Good Shooting Everybody.

Dave Parker

Ground Glass Specialties.

David Parker
28-Nov-2004, 23:07
Sorry, that was supose to be 'can't say' there is a final word....not 'can say'

Dave Parker

Jim Noel
26-Mar-2005, 09:39
This is a very informative discussion. I have used a Maxwell screen on the camera of a friend, and have been trying to get in touch with him for over a year. Can anyone give me the contact information?
In the meantime, I will continue to use a $5 book magnifier over the ground glass until time for critical focusing. I have one for each of my LF cameras.
Thanks,
Jim