Page 10 of 11 FirstFirst ... 891011 LastLast
Results 91 to 100 of 101

Thread: The Computar lens and ULF coverage.

  1. #91

    Join Date
    Mar 2007
    Posts
    1,056

    Re: The Computar lens and ULF coverage.

    Quote Originally Posted by Kerry L. Thalmann View Post
    Don't believe everything you read...

    I bought my 360mm f9 Graphic-Kowa from Lens & Repro many years ago based on the same optimisitc coverage claims. I tracked down a Copal 3S sutter and had custom engraved aperture scales made by the late Steve Grimes. My goal was a nice 360mm lens for 11x14, and possibly larger formats.

    After all this trouble and expense, when I actually put the lens on the camera and tested it, I was very disappointed in the actual usable coverage. It was MUCH less than the claimed 86 degrees, and not really suitable for ULF (MAYBE 11x14 contact printing, definitely 10x12, if that's considered ULF).
    It's unfortunate to hear your disappointment with the description and performance that differ so much. I had taken Lens & Repro as a reputable firm source and I feel let down as i have always believed their descriptions.

    Quote Originally Posted by Kerry L. Thalmann View Post
    I verified that the construction was 4/4, and definitely NOT a 6/4 plasmat. Several other owners of this lens have also veriified that their samples are also 4/4 construction with coverage similar to a 14" Red Dot Artar. Other than inflated advertising claims, I'm not sure why this issue is still being debated.
    Exactly! It's the ads that really piss me off! LF is a community thing!

    Quote Originally Posted by Kerry L. Thalmann View Post
    The 360mm Graphic-Kowa is a 4/4 design with coverage consistent with other lenses of similar construction - no more, no less. It does have the advantage that the cells are a direct fit in a modern Copal 3S shutter, and it takes standard threaded filters. It makes a very fine lens for 8x10.
    That is perfect for much of my use! Also there's the claimed bonus of using the rear cell as a longer portrait lens. I hope that, at least is a valid proposition.

    Quote Originally Posted by Kerry L. Thalmann View Post
    [/B]I happen to have a Kyvyx Korporation Katalog from 1980 that has specs and comments from Jack Callahan on these lenses. The specs are comments are full of inconsistencies, peculiarities and errors.

    From the anecdotal evidence, it's clear that the construction of some of these lenses changed over time (the 210mm F9 Computars were 6/4, the 210mm Graphic-Kowas were 6/6 - some for the 240mm Computar and SOME 240mm Graphic-Kowas were 6/4). Since the vast majority of these lenses were sold in barrels, I suspect many were targeted for use on process cameras, ....
    That might also explain the disparity in claimed coverage as process lenses are often specified for coverage at 1:1 and not at infinity, hence that major difference?


    Quote Originally Posted by Asher Kelman
    My needs are satisfied with 8x10 but I'd have preferred to have a much wider coverage. I have yet to see any pictures with these lenses! I'd love the flexibility of being able to use this for 11x14, 16x20 and even 20x24! That would be a great lens!
    Quote Originally Posted by Kerry L. Thalmann View Post
    And, it wouldn't be a 360mm Graphic-Kowa. The 305mm f9 Computar easily covers up to 16x20.
    At what magnification?

    Quote Originally Posted by Kerry L. Thalmann View Post
    Off the top of my head, I can't think of any lens in the 300 - 360mm focal length range that covers 20x24 at infinity. Maybe a long Series V Protar, but the coverage specs of those lenses tended to decrease with focal length. In the 360mm focal length, you'd need a lens with 96 degrees of coverage to hit the corners of 20x24. A 300mm would need 106 degrees of coverege for 20x24.

    Kerry
    My needs for such a extraordinary wide coverage lens are for one learning stage in my transition to new studio portrait work with my camera obsucra. In this use, the film is on a vertical vacuum board in the next room, but not in a film holder, so I can change from one format to any other. I'd be happy being able to work at lens to subject distances of 4ft to 12ft and get coverage up to 20x24 of a person initially. (Subsequently, using much longer process lenses, I'll be using 50" wide paper, 74"-80" or so high). For now, now, 20x24 is all I'm aiming for. That's the max size I'm set up to process myself. So your suggestions of a 305mm Computar or the long series V Protar are much appreciated and worth considering for this stage of my Camera Obscura work.

    Thanks for so generously sharing your hard-earned experience on the entire series of Computar to Kyvyx and Kowa lenses! This will be a great resource for a lot of folks to come.

    Asher

  2. #92

    Join Date
    Mar 2006
    Location
    Austin, TX
    Posts
    435

    Re: The Computar lens and ULF coverage.

    Hi Guys,

    I worked for DO/Fujinon/Graphic-Kowa, Later VP of BBOI/B&J, still later stareded my own company in Texas.

    The Graphic Kowa's and APO Computars with 150, 210, 240, 305 were all 6 element plasmats covering around 85-90 degrees. The were wonderful lenses (I still have 4 or 5 of them). In those days (up until around 78-80) the 360 was a very different lens designed for some kind of special graphic arts camera that only covered around 5x7 or so.

    After the demise of BBOI/B&J, the owner/president and my career long friend, J.D. "Jack" Callahan started Kyvytar in Jersey and then moved to California. He had a deal with Kowa and he may have had some additional KGraphics made under his name.

    By the way, the Computar Symmetrigons were 4 element metrogon/topogon types covering about 70+ degrees optimized between 1:2 to inf, f 6.3. The principal developers were JanTerLuow, Dr. John Lawson, and to a lesser extent me. These were created to be competitive with typical plasmats at lower cost and were quite successful until the loss of the above companies.

    Lynn

  3. #93
    Jim Graves Jim Graves's Avatar
    Join Date
    Jul 2007
    Location
    Sacramento, Calif., USA
    Posts
    892

    Re: The Computar lens and ULF coverage.

    Quote Originally Posted by Lynn Jones View Post
    ... The Graphic Kowa's and APO Computars with 150, 210, 240, 305 were all 6 element plasmats covering around 85-90 degrees. ...
    Lynn ... You don't mention the 270mm ... plasmat also???

  4. #94

    Join Date
    Mar 2006
    Location
    Austin, TX
    Posts
    435

    Re: The Computar lens and ULF coverage.

    Quote Originally Posted by Jim Graves View Post
    Lynn ... You don't mention the 270mm ... plasmat also???
    Yes, sorry, that one too.

    Lynn

  5. #95
    Vaughn's Avatar
    Join Date
    Jan 2007
    Location
    Humboldt County, CA
    Posts
    7,595

    Re: The Computar lens and ULF coverage.

    Quote Originally Posted by Lynn Jones View Post
    ...
    By the way, the Computar Symmetrigons were 4 element metrogon/topogon types covering about 70+ degrees optimized between 1:2 to inf, f 6.3...
    Lynn
    One of these (210mm/6.3) came with my new 4x5 (Indian clone of a Deardorf Special) back in the early 1980's. What a sharp crisp lens it was! I use one for 5x7 now.

    Vaughn

    PS -- Jim, I'll give that 270mm a work-out this week-end!

  6. #96

    Join Date
    Mar 2007
    Posts
    1,056

    Re: The Computar lens and ULF coverage.

    Quote Originally Posted by Kerry L. Thalmann View Post
    Don't belive everything you read...

    I bought my 360mm f9 Graphic-Kowa from Lens & Repro many years ago based on the same optimisitc coverage claims. I tracked down a Copal 3S sutter and had custom engraved aperture scales made by the late Steve Grimes.
    Hi Kerry,

    My Copal 3S arrived, (with a pristine 300 mm Congo lens that I'll likely sell). The cells of the 360mm Graphic Kowa fit perfectly into the 3S shutter. I didn't know whether or not to use the thin brass ring spacers.

    Did S.K. Grimes use the spacers? On the scale, what was the aperture range? Was it to 6.8? I don't feel I can accurately measure the front cell diameter to determine the lowest f-stop. Did you make a second aperture scale for just using the rear element and what would that focal length be, if you remember?

    360mm f9 Serial number 600208
    Graphic Kowa
    Copal 3S Shutter
    Construction: Unknown

    Reflections observed:

    4 reflections front and rear elements, 2 of them appear as one. So, at first one might think there are just 3. However, one reflection splits as lens is tilted and reflections approach edge and the pair appear separately and there are a total of 4 reflections.

    Asher

  7. #97

    Join Date
    Jul 2006
    Location
    Valley of the Sun, AZ
    Posts
    682

    Re: The Computar lens and ULF coverage.

    I just got this Computar brochure and thought it might be good to post it here. Interestingly, it only gives the half-field angle, rather than image circle, but the usable image circle has been discussed at length previously in this thread.
    Attached Thumbnails Attached Thumbnails Computar f9 lens brochure - p1s.pdf   Computar f9 lens brochure - p2s.pdf   Computar f9 lens brochure - p3s.pdf   Computar f9 lens brochure - p4s.pdf  
    They are ill discoverers that think there is no land, when they can see nothing but sea.
    -Francis Bacon

  8. #98

    Join Date
    Jul 2006
    Location
    Valley of the Sun, AZ
    Posts
    682

    Re: The Computar lens and ULF coverage.

    last page:
    Attached Thumbnails Attached Thumbnails Computar f9 lens brochure - p5s.pdf  
    They are ill discoverers that think there is no land, when they can see nothing but sea.
    -Francis Bacon

  9. #99

    Join Date
    Mar 2008
    Posts
    361

    Re: The Computar lens and ULF coverage.

    Some useful stuff John, thank you.

  10. #100

    Join Date
    Dec 1999
    Location
    Forest Grove, Ore.
    Posts
    3,696

    Re: The Computar lens and ULF coverage.

    This is interesting information. I considered this lens for 8x10. But, after searching and querying, I could not learn whether the reputed, huge coverage of these lenses could stand up to enlarging. Most of the commentary related to contact prints.

Similar Threads

  1. Computar 150mm coverage?
    By Donald Hutton in forum Cameras & Camera Accessories
    Replies: 2
    Last Post: 11-Mar-2006, 14:37
  2. 135 lens coverage
    By ronald moravec in forum Lenses & Lens Accessories
    Replies: 8
    Last Post: 14-Jul-2005, 23:12
  3. Computar enlarging lens
    By Richard Schlesinger in forum Darkroom: Equipment
    Replies: 2
    Last Post: 12-Jul-2005, 18:38
  4. Best guess Glennview's ~210mm ~F/8 lens that covers 11X14 is a Computar?
    By Donal Taylor in forum Cameras & Camera Accessories
    Replies: 8
    Last Post: 4-Jun-2004, 17:17
  5. Lens hood required when using large coverage lens on small format?
    By Bill Glickman in forum Lenses & Lens Accessories
    Replies: 1
    Last Post: 31-Jul-1999, 15:06

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
  •