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Thread: Lensn2shutter Fresnels

  1. #1

    Lensn2shutter Fresnels

    Hello everybody!

    I was just wondering if any of you have bought/used the fresnels that Lensn2shutter sells via "that auction site?" It seems like a really good bargain (far less than Canham is asking for their fresnels) but I'm just curious about the quality. Why the huge price difference? Are the Canham fresnels that much better?

    Thanks!

    Christian

  2. #2
    jim landecker JimL's Avatar
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    Lensn2shutter Fresnels

    Judging from the specs he gives, these look like PVC fresnel lenses, like the ones found at this site. The specs for thickness and groove pitch are identical. As for his claim that mounting them behind the groundglass won't cause a "significant" shift in focus, as explained in threads such as this one, the focal plane will shift by approximately 2/3 the thickness of the fresnel. If a shift of 0.012" is acceptable to you, then by all means go ahead - I personally wouldn't find it acceptable. PVC is softer than the acrylic used in the thicker fresnel lenses found on typical view cameras, so a cover glass would be advisable for behind the gg mounting. The Canham ones are probably more expensive because they have a finer groove pitch, are made of acrylic, are perhaps custom made to his specs for focal length, are cut to size for his cameras, and are priced according to what the market will bear for large format accessories.

    Jim

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