R72 filter for Cokin P series?

Discussion in 'Alternative Processes' started by ggriffi, Mar 11, 2005.

  1. ggriffi

    ggriffi Member

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    I am wondering if someone sells a R72 infra red filter that fits Cokin "P" series filter holder. I have searched a bit, but have become rustrated trying to wade thru all of the filter choices. Can any of you help?

    Thanks,
    Gary
     
  2. ras351

    ras351 Member

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    I know Lee make a polyester 'R72' filter in 100mm square which you could cut down and mount in one of their 84mm 'Cokin' mounts. If you ask they could probably even supply one in the correct size although my local listing shows the next standard size down as being 75mm. Cokin make an 89B (007) resin filter but unfortunately I don't think they do an R72. I use 100mm filters and the options there are limited as well. Hopefully someone else will chime in with some other options.

    Roger.
     
  3. Bob F.

    Bob F. Member

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    Indeed - I have the Lee polyester filter. Sandwiched it between mount board to fit a Cokin P holder.

    Bob.
     
  4. colrehogan

    colrehogan Member

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    R72 is basically the same as an 89B.
     
  5. ras351

    ras351 Member

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    Hi Diane,

    Yes, the 89B should block 50% light below 720nm however I found differences between the Cokin 89B and a screw on Hoya R72 with Maco 820c IR film. This, along with some manufacturers quoting different transmission thresholds (0% and 50%), is what confused me thinking the 89B and R72 were different yesterday.

    Looking through both the Cokin 89B and the Hoya R72 at a light source you can see a difference in the amount of red transmitted. I suspect the Cokin differs to the standard 89B as the cutoff is more gradual - it may block 50% of light at 720nm but it looks to be transmitting more than 0% at 680nm.

    Also I just had another look at the Lee filter (haven't used it yet) and it's halfway between an 88A and 87 as it begins transmission above 730nm instead of 720 and 740 respectively. 50% transmission is probably around 780nm which will make it black to SFX200 and some of the IR films.

    Another option for Gary might be the Ilford SFX filter which is supposed to be close to an 89B and is available in a Cokin P size. Unfortunately Ilford are dropping SFX200 from their catalogue so it may not be available for much longer. Gary, what film will you be using this filter with and how important are transmission characteristics?

    Roger.
     
  6. ggriffi

    ggriffi Member

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    Roger,

    Right now I have and will be shooting HIE but will also be shooting some the Maco soon. The Ilford filter is it a glass filter or resin? THe only reason that I am looking for something in a resin is that I want to be able to use the filter with two different lenses that I have. I realize that the Cokin filter may not be optically what the glass filters are, I can't justify the expense for two glass filters versus the Cokin or the Lee equivalent with the financial secretary. :O(
     
  7. colrehogan

    colrehogan Member

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    Can you actually get a filter with SFX outside of the UK? I've yet to see an Ilford SFX filter here.
     
  8. ras351

    ras351 Member

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    Hi Gary,

    The Cokin 89B filter is optical resin and isn't too expensive although it's more expensive than the standard Cokin B&W filters. Look for a P007 filter in their catalogue. As mentioned it may not be a true 89B but it still works okay.

    The Lee 87 filter is polyester which you mount between a couple of pieces of either cardboard or plastic. It's about the same thickness as film and you can cut it with a pair of scissors. The mounts are available from Lee but you may need to buy a box of 10 of them - you could always make your own from thin mountboard. Price wise it's comparable to the Cokin 89B filter but may cost you slightly more if you can't get a P size and have to buy the 100mm square version. You also have to add in the cost of the mounts if you buy them. I haven't yet tried mine but the IR effect should be more pronounced than the Cokin 89B due to the higher cutoff frequency.

    The Hoya R72 I mentioned is glass but only seems readily available as a screw on and is quite expensive in larger sizes so we can ignore that.

    I don't know much about the Ilford SFX filter but it's probably similar to the Cokin 89B.

    One final cheap option you have is to try a piece of unexposed but processed E6 film. You cut it to size and mount it in the same manner as a polyester filter and the results are close to an 89B although it lets through a little more red light. Cost is probably 10% of the other filters but even cheaper if you know someone who's forgotten to remove the darkslide from their 4x5 camera.

    Regards,
    Roger.
     
  9. ggriffi

    ggriffi Member

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  10. ras351

    ras351 Member

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    Hi Diane,

    Last year when I bought some SFX200 to try I was asked if I needed the filter but declined as I was going to use the Cokin. At the time it was listed in the catalogue although like you I've never actually seen one. This is of course in Australia so it could vary between countries.

    Regards,
    Roger.
     
  11. ras351

    ras351 Member

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  12. colrehogan

    colrehogan Member

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    Thanks, I always wondered. In the UK, I think the filter came with the film. I'll just keep using my CoCam R72 (resin) or 89B gel filters.

    Maco hasn't said anything other than that when they are ready to ship, they'll let me know. (If I've read their reply correctly.)