Page 3 of 3 FirstFirst 123
Results 21 to 27 of 27

Thread: Focusing loup

  1. #21

    Join Date
    Aug 2004
    Location
    Camano Island, Washington
    Posts
    360

    Re: Focusing loup

    John's comments above are similar to my experience with loupes. I started with a linen tester in the 1970's. later I bought a Toyo loupe. Lastly I purchase a Horseman loupe. The Horseman has provisions for different eyesight (correction) and is long - so I can use it with a fold-up back on my Technikardan. There are a lot of different designs that work for different needs. I have thought that the tilting Silvestri loupe is a very interesting design. The printer's loupe that Tin Can shows above also looks like a very interesting design. I tend to like loupes that are blacked-out on the sides. I do use drug store magnifying glasses as well to view the whole image - and to work with the camera.

  2. #22

    Join Date
    Jul 2008
    Posts
    3,904

    Re: Focusing loup

    Tilting loupe or free hand loupe/magnifier has the Great Advantage when used with wide angle lenses as the loupe/magnifier can be tilted or pointed towards the center of the GG image to enhance and aid in viewing. This is no small deal as wide the lens angle of coverage grows the more difficult it becomes to properly focus and evaluate the edges of the GG image. It is also why a fresnel lens becomes a serious problem as the lens angle of view increases..

    Opposite happens with much longer than normal focal length lenses or greatly reduced angle of view lenses. The GG image light intensity can be Greatly increased by using a fresnel lens. Typically a fixed focus distance loupe/magnifier has nil penalty in this specific case, but the fresnel lines can become a critical focus hindrance..



    Bernice

  3. #23

    Join Date
    Nov 2022
    Posts
    200

    Re: Focusing loup

    Quote Originally Posted by Bernice Loui View Post
    Tilting loupe or free hand loupe/magnifier has the Great Advantage when used with wide angle lenses as the loupe/magnifier can be tilted or pointed towards the center of the GG image to enhance and aid in viewing. This is no small deal as wide the lens angle of coverage grows the more difficult it becomes to properly focus and evaluate the edges of the GG image. It is also why a fresnel lens becomes a serious problem as the lens angle of view increases..

    Opposite happens with much longer than normal focal length lenses or greatly reduced angle of view lenses. The GG image light intensity can be Greatly increased by using a fresnel lens. Typically a fixed focus distance loupe/magnifier has nil penalty in this specific case, but the fresnel lines can become a critical focus hindrance..



    Bernice
    Thank you for the explanation Bernice. Does getting a high quality ground glass make a differnce in brighness and focus vs cheap glass ? I have found that a 7x loupe is just what i need, anything under that its much hard to focus.
    Last edited by Califmike33; 29-Nov-2022 at 22:12.

  4. #24

    Join Date
    Sep 1998
    Location
    Oregon now (formerly Austria)
    Posts
    3,193

    Re: Focusing loup

    Quote Originally Posted by Bernice Loui View Post
    Tilting loupe or free hand loupe/magnifier has the Great Advantage when used with wide angle lenses as the loupe/magnifier can be tilted or pointed towards the center of the GG image to enhance and aid in viewing. This is no small deal as wide the lens angle of coverage grows the more difficult it becomes to properly focus and evaluate the edges of the GG image. It is also why a Fresnel lens becomes a serious problem as the lens angle of view increases..

    Opposite happens with much longer than normal focal length lenses or greatly reduced angle of view lenses. The GG image light intensity can be Greatly increased by using a fresnel lens. Typically a fixed focus distance loupe/magnifier has nil penalty in this specific case, but the Fresnel lines can become a critical focus hindrance..

    Bernice
    I switched to a free-hand magnifying loupe years ago and have never looked back. It happened by accident. I was in Venice photographing and had left my loupe and reading glasses at home. An optician sold my some very fashionable blue-framed 3.5-diopter reading glasses and a small 5x retractable loupe, exactly like the one Benedict Cumberbatch used as Sherlock Holmes (see it here: https://www.amazon.com/Folding-Pocke.../dp/B004KNS2BW ).

    I still have both the glasses and the magnifier plus two or three more slide-open type magnifiers made for stamp collectors (got them at the philately shop).

    Yes, Fresnel lines can be a hindrance, but you can quickly learn to avoid focusing on them and position the real focus on the frosted side of the ground glass. Have a magnifier you can tilt at will really helps with viewing the corners.

    Best,

    Doremus

  5. #25

    Join Date
    Sep 1998
    Location
    Loganville , GA
    Posts
    14,343

    Re: Focusing loup

    Quote Originally Posted by Califmike33 View Post
    Thank you for the explanation Bernice. Does getting a high quality ground glass make a differnce in brighness and focus vs cheap glass ? I have found that a 7x loupe is just what i need, anything under that its much hard to focus.
    Thatís because your loupe is not focused on the grain side of the gg. Focus it there and it will be much easier. And a fresnel will help and once focused on the grain side of your gg fresnel lines or format lines will not be a problem.

  6. #26

    Join Date
    Jul 2008
    Posts
    3,904

    Re: Focusing loup

    Previously on LFF:
    https://www.largeformatphotography.i...nd-glass/page2

    Ground glass does make a difference. Current three are Sinar OEM, Linhof and K.B. Canham (replacement for the 5x7 Norma) all three are "medium" grit not extremely fine or coarse grind. None are used with a fresnel "brighter" due to previously mentioned trade-offs as lens focal length can range from near the limit of lens angle of 115 degrees (72mm Super Angulon XL to 780mm APO ronar on 5x7 or 38mm Super Angulon XL to 500mm Tele-Congo on the TK23s).

    IMO, best to learn how to see and focus on a good plain ground glass. Consider learning this skill as an investment into your view camera future which will pay off once wide angle lenses are used and viewing the image with the lens stopped down to exposure aperture to check areas of perceived to be in focus.


    As for a ground glass loupe or magnifier, the Horseman 7x also sold as Calumet 7x and likely made by Peak in Japan has been the go-to direct on GG magnifier for decades. Previously on LFF:
    https://www.largeformatphotography.i...64058-4x-loupe

    Free "floating" ala hand held magnifiers can be anything from a lens with about 25-30mm focal length to simple single element magnifying glass to a Cooke or Hastings triplet magnifier commonly used by jewelry, machinist, linen inspection and more. Edmund optics has a info sheet on magnifiers that is helpful:
    https://www.edmundoptics.com/knowled...se-a-magnifier

    Back in the inspecting film on the Light Table that was common days, the industry standard LT loupe was the Schneider 4x.. It was good in many was and ubiquitous a processed film among those working with film lots and demanded a quality magnifier.. The Schneider 4x had a interchangeable base diffusion or opaque, focusable and detachable neck string.. Used one of these for many years.. In the later 90's Schneider introduced a 6x aspheric versions of this loupe.. Tried it at the Schneider promo, liked it lots, it was pricy for a loupe (think it was $250 1990's U$D). This 6x Schneider aspheric loupe had excellent optical performance out to the edges of the magnifier with excellent color rendition and the slightly higher magnification was another plus. Still have and use this 6x aspheric to this day.. IMO, it is too big physically for GG work, but it does work very good as a GG magnifier/loupe. It is this textured gray finish as listed by a current eBay seller:
    https://www.ebay.com/itm/304518253089

    Later ones are silver with a different case style. Rodenstock also offered an aspheric loupe about the same time. It was a 4x, not as good optically as the 6x aspheric Schneider. Rodenstock re-designed their aspheric loupe as a 6x version which is much improved.


    Bernice




    Quote Originally Posted by Califmike33 View Post
    Does getting a high quality ground glass make a differnce in brighness and focus vs cheap glass ? I have found that a 7x loupe is just what i need, anything under that its much hard to focus.

  7. #27

    Join Date
    Nov 2022
    Posts
    200

    Re: Focusing loup

    Quote Originally Posted by Bernice Loui View Post
    Previously on LFF:
    https://www.largeformatphotography.i...nd-glass/page2

    Ground glass does make a difference. Current three are Sinar OEM, Linhof and K.B. Canham (replacement for the 5x7 Norma) all three are "medium" grit not extremely fine or coarse grind. None are used with a fresnel "brighter" due to previously mentioned trade-offs as lens focal length can range from near the limit of lens angle of 115 degrees (72mm Super Angulon XL to 780mm APO ronar on 5x7 or 38mm Super Angulon XL to 500mm Tele-Congo on the TK23s).

    IMO, best to learn how to see and focus on a good plain ground glass. Consider learning this skill as an investment into your view camera future which will pay off once wide angle lenses are used and viewing the image with the lens stopped down to exposure aperture to check areas of perceived to be in focus.


    As for a ground glass loupe or magnifier, the Horseman 7x also sold as Calumet 7x and likely made by Peak in Japan has been the go-to direct on GG magnifier for decades. Previously on LFF:
    https://www.largeformatphotography.i...64058-4x-loupe

    Free "floating" ala hand held magnifiers can be anything from a lens with about 25-30mm focal length to simple single element magnifying glass to a Cooke or Hastings triplet magnifier commonly used by jewelry, machinist, linen inspection and more. Edmund optics has a info sheet on magnifiers that is helpful:
    https://www.edmundoptics.com/knowled...se-a-magnifier

    Back in the inspecting film on the Light Table that was common days, the industry standard LT loupe was the Schneider 4x.. It was good in many was and ubiquitous a processed film among those working with film lots and demanded a quality magnifier.. The Schneider 4x had a interchangeable base diffusion or opaque, focusable and detachable neck string.. Used one of these for many years.. In the later 90's Schneider introduced a 6x aspheric versions of this loupe.. Tried it at the Schneider promo, liked it lots, it was pricy for a loupe (think it was $250 1990's U$D). This 6x Schneider aspheric loupe had excellent optical performance out to the edges of the magnifier with excellent color rendition and the slightly higher magnification was another plus. Still have and use this 6x aspheric to this day.. IMO, it is too big physically for GG work, but it does work very good as a GG magnifier/loupe. It is this textured gray finish as listed by a current eBay seller:
    https://www.ebay.com/itm/304518253089

    Later ones are silver with a different case style. Rodenstock also offered an aspheric loupe about the same time. It was a 4x, not as good optically as the 6x aspheric Schneider. Rodenstock re-designed their aspheric loupe as a 6x version which is much improved.


    Bernice

    Ok for now i will keep my ground glass and fresnel and practice my craft. I did get the Peak 7x loupe new off ebay its on order. Thanks again for your replies and everybody else also.

Similar Threads

  1. Best loup for ground glass focusing?
    By Ralph Upchurch in forum Gear
    Replies: 22
    Last Post: 20-Dec-2006, 12:02
  2. Replies: 9
    Last Post: 25-May-2002, 14:44

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •