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Thread: 4x5 Focusing Screens: THE FINAL WORD

  1. #31

    Join Date
    Nov 2001
    Posts
    129

    4x5 Focusing Screens: THE FINAL WORD

    >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.

  2. #32

    4x5 Focusing Screens: THE FINAL WORD

    ">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.

  3. #33

    Join Date
    Sep 1998
    Location
    Loganville , GA
    Posts
    14,409

    4x5 Focusing Screens: THE FINAL WORD

    "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.

  4. #34

    4x5 Focusing Screens: THE FINAL WORD

    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.

  5. #35

    Join Date
    Jun 2002
    Posts
    9,487

    4x5 Focusing Screens: THE FINAL WORD

    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.

  6. #36

    4x5 Focusing Screens: THE FINAL WORD

    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.

  7. #37

    Join Date
    Mar 2004
    Location
    Maine
    Posts
    190

    4x5 Focusing Screens: THE FINAL WORD

    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,

  8. #38

    4x5 Focusing Screens: THE FINAL WORD

    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.

  9. #39

    4x5 Focusing Screens: THE FINAL WORD

    Sorry, that was supose to be 'can't say' there is a final word....not 'can say'

    Dave Parker

  10. #40

    Join Date
    Aug 2000
    Location
    California
    Posts
    3,908

    4x5 Focusing Screens: THE FINAL WORD

    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

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