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Thread: Cheap filters

  1. #21
    Gary Holliday's Avatar
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    An 89B should be fine with SFX, but having a closer look at the eBay descriptions for your filter and mine, he states two different wavelengths for the supposedly same filter. Mine says transmission starting at 720nm and yours at 700nm. Both are comparable with an 89B and R72 according to him. An R72 is a bit strong for SFX.

    You can use this chart for an indication where all the IR filters start transmission.
    http://www.eazypix.de/ir/filter/filter.html

    But this was the point of my original post is that an unbranded filter may not be as accurate as it claims.

  2. #22
    Gary Holliday's Avatar
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    Forgot to mention that Lee only do an 87 resin filter and yes there is a market for a 100mm 89B! As we have SFX and Rollei IR to play with.

    There is also this Kood filter.
    http://cgi.ebay.co.uk/ws/eBayISAPI.d...tchlink:top:uk
    Last edited by Gary Holliday; 05-28-2007 at 07:44 AM. Click to view previous post history.

  3. #23
    Bob F.'s Avatar
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    With an 89b, Ilford suggest rating at x16 filter factor (4 stops). I've used 6 - 12ASA in the past - not had a chance to shoot the new stuff yet - so you should certainly have got somewhere close to correctly exposed negs. Is it possible you accidentally went the other way and closed down 4 stops (done that myself more than once on the spur of the moment when adjusting for reciprocity or bellows factor etc...).

    Cheers, Bob.

  4. #24

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    Quote Originally Posted by Bob F. View Post
    With an 89b, Ilford suggest rating at x16 filter factor (4 stops). I've used 6 - 12ASA in the past - not had a chance to shoot the new stuff yet - so you should certainly have got somewhere close to correctly exposed negs. Is it possible you accidentally went the other way and closed down 4 stops (done that myself more than once on the spur of the moment when adjusting for reciprocity or bellows factor etc...).

    Cheers, Bob.
    Dear Bob,

    I'll second your EI 6-12 recommendations (and 6 rather than 12) but thought you might like Frances's phrase for stopping down instead of opening up (as we've all done) -- 'photo dyslexia'.

    Cheers,

    R.

  5. #25
    Steve Smith's Avatar
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    I suffer from 'photo dyslexia' as much as anyone else but when I did this test, I actually wrote down the exposure details which is rare for me!
    My longest exposure was two seconds at f11 which is four stops above Ilford's 1/30 f5.6 recommendation for bright sun so something should definitely have registered on the film.
    Looking again at the only frame with any density, the very slight darkening is at the corners i.e. where the Cokin filter holder plastic does not extend to the edge of the filter. This reassures my belief that what I got was light reflecting off the rear of the filter.

    Steve.

  6. #26
    Steve Smith's Avatar
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    Filter Update

    I have received my 3 pack of SFX with the gel filter to fit a Cokin P holder. The difference between this filter and my supposed 89B resin filter is huge.
    When you look through the Ilford filter, you can see everything in a dark red/purple colour and you can see that foliage is lighter than other parts of the image. The only way you can see anything through the resin filter is to hold it up to the sun. In which case it appears as a dull red disc.
    This confirms my opinion that the cheap filter is deeper into IR than the Ilford filter.
    I was going to put them both on my D100 to see the difference but I don't need to. It is obvious that the D100 sensor is sensitive to IR at lower frequencies than the film.
    As I said before, enough digi-nonesense, time to use some film (again). Hopefully with better results this time.


    Steve.

  7. #27
    Bob F.'s Avatar
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    Glad you resolved the problem: less pleased that the eBay advert was wrong in claiming #89b/R72 compatibility. Worth sending it back for a refund? He should refund your costs too as his advert has an incorrect description.

    It sounds more like one of the #87 series which are, as you found, far too deep into the IR for SFX. I have an 87c that I used with the old Maco IR. Possibly the new Rollei film has similar sensitivity, but IDK.

    Reassured to learn that photo-dyslexia is not just me :o ...

    Cheers, Bob.

  8. #28
    Steve Smith's Avatar
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    Success!!!

    Ilford SFX + SFX filter + Recommended exposure = perfect images!! (as far as exposure goes).

    Despite wide bracketing in both directions, the exposures at f22 for 1/2 second in bright sun (equivalent to Ilford's f5.6 for 1/30s) seem to be the best. Although I have not printed any yet to be certain.



    Steve.

  9. #29
    Steve Smith's Avatar
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    Quote Originally Posted by Bob F. View Post
    less pleased that the eBay advert was wrong in claiming #89b/R72 compatibility. Worth sending it back for a refund? He should refund your costs too as his advert has an incorrect description.

    I checked out the listing and it actually says 'similar to 89B/R72' rather than compatible so I don't think I will bother about a refund.

    Steve.

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