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Thread: 4.6" Watson Wide Angle Holos (Holostigmat)

  1. #1
    Roger Hesketh
    Join Date
    Nov 2010
    Location
    Wirral UK
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    14

    4.6" Watson Wide Angle Holos (Holostigmat)

    I have had a good day today. I have been preparing descriptions to sell lenses on Ebay that I have not been using when I had a lovely surprise.

    Whilst checking lens coverage figures for the description I discovered that this Watson wide angle that I have will apparently cover 8x10. I bought it to use as a wide angle lens on 5x7 but a couple of weeks later, before I had had a chance to use it, for it's proposed use it was superseded by the purchase of a 4" Cooke series VIIb wide angle anastigmat.

    I no longer intend to sell it.

    I knew it was a lens with wide coverage 110 degrees but had never considered that such a short lens could possibly cover 8x10. It probably rather sad this but I am really rather excited about this. Their is nobody here whom I could tell about it who would share my enthusiasm. So I thought I would share my unexpected good fortune with you.

    Has anybody had any experience of using one of these lenses on 8x10 ? If so how well does it cover?

    Thanks in advance

    Roger

  2. #2

    Join Date
    Dec 2001
    Location
    NJ
    Posts
    7,439

    Re: 4.6" Watson Wide Angle Holos (Holostigmat)

    Yeah, yeah, yeah. 4.6 inches, 110 degrees, 13 inch circle. Yeah, sure, 13 inches computes.

    Remember that coverage is a sometime thing. Consider Berthiot's coverage claims for the f/14 Perigraphe Ser. VIa: 115 degrees in 1912, 106 degrees in the 1930s, 100 degrees in the late 1940s. As far as I know, the lens was never redesigned. I'd be happy to be proved mistaken.

  3. #3

    Join Date
    Sep 2007
    Location
    AZ
    Posts
    4,150

    Re: 4.6" Watson Wide Angle Holos (Holostigmat)

    I don't know the Holostigmat, but the American RD Gray made some Extreme Wide Angles that were advertised somewhere at 115 degrees. Here's a period ad that lists a 4.2" covering 8x10. I'll have to check mine.


  4. #4
    Roger Hesketh
    Join Date
    Nov 2010
    Location
    Wirral UK
    Posts
    14

    Re: 4.6" Watson Wide Angle Holos (Holostigmat)

    Well I tried the lens on a camera today. I did not make any exposures but I did examine the image on the ground glass closely. Yippee it works! It took a bit of faffing about to get getting the lens close enough to the ground glass to achieve infinity focus though. Big camera, long bellows It took a bit of doing to get the lens close enough without the image being vignetted by the compressed bellows.
    It will be better once I have made a proper lens board for the lens rather than just taping it to the front of another one.Click image for larger version. 

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    With the lens wide open the image is soft all over but even wide open the plate is fully illuminated. You have to stop down quite a long way to achieve an acceptable level of sharpness. In fact I was rather surprised just how far I needed to stop down to achieve acceptable definition until I realised I was reading from the wrong aperture scale. The lens is a double convertible. 4.6" with both and 8" with just a single component. I was thinking that it was strange that one would have to stop down to somewhere between f22 - f32 for the image to become sharp however on the other scale that point is f11.3 the first figure marked on the aperture scale. Even with that relatively small amount of stopping down the image looked sharpish to me. Their is a fair bit of illumination fall off across the plate though so it makes it more difficult to judge the edges of the plate but at f22 it all looked sharp to me.

    I have no idea what the full coverage of this lens is as you can see from the attached picture I was only just able to achieve infinity focus. No scope for camera movement. Just to see if it was possible Garret I tried a 4.2 inch lens and was unable to bring it close enough to the ground glass to focus it. I hope you have better luck with your camera.
    I am delighted. It is a fortuitous combination of focal length, angle of coverage and format which means that almost the entire coverage of this lens can be recorded on the film. It is a very wide lens though and the illumination fall off is really quite marked and I really would appreciate some advice as to how to cope with that problem in a cost effective manner please. I read somewhere that a 120mm lens on 8x10 gives a similar angle of view to a 20mm lens on 35mm.Well this is a 114mm lens. I have never used a lens with such a wide angle of view before but I am certainly looking forward to using this one now.

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