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  1. #1
    engelfoto's Avatar
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    Any examples of Maco 820c Aura 4x5 with a Red 29

    Anybody have any examples of the aura effect at all? Is there any? Or do you have to go to the opaque filters (89-87) in order to get the right wavelengths to create the halo effect?

    In other words, I'm wondering if visible light would cause the AURA emulsion to blow out before you got any halos, while going true IR filtration would create the right environment.

    I really want to use the film on my large format camera, but focusing is such crapshoot with IR and my old equipment that isn't perfect. I was told I only need a fraction of a mm closer to the subject and I got back the negs and they were blurry. I want to shoot wide open for the shallow depth of field, so I feel like Red 29 is the best for me. But I want that halo effect.

    What about the 70 filter?
    Jeffrey Engel
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  2. #2
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    You won't see the halo effect with anything less than an opaque filter with this film. You really need to go to at least an 89B. I prefer an 88A or 87. As for focusing, I just focus as normal and don't worry about any IR focus correction. What is your subject matter that you are shooting wide open?
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    Overexposure helps with the aura effect, regardless of precisely which filter you choose, but yes, you should see more aura effect with a T50 of 710nm or longer. I have however seen it with overexposed film with a filter with a T50 of only 695nm.

    710-715 nm is visually opaque at first sight but if you hold it over your eye, excluding all other light, you will see a very dim image after a few seconds.
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  4. #4
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    If that film is the same or similar to Rollei 400 IR, then I can report that I haven't really seen it even with an opaque filter (#87) and substantial overexposure.

    Here are some examples of captures that were definitely on the high side of exposure, and I see basically no 'aura' or halation: 1 and 2. The edges are extremely crisp and sharp except for some motion blur. No 'glow' at all.

    Maybe I am wrong, but the 'aura' effect is simply halation, no? If that's the case then perhaps I could see it better with 220 film, these were on 120. Anyway it's still not clear to me what people mean by 'aura,' unless it is simply halation. Of course if you want halation then that can be arranged
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    Yes, it is halation, and no, I'm pretty sure it isn't the same film. Of course, the bigger the format, the more subtle the halation.
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  6. #6
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    Quote Originally Posted by Roger Hicks View Post
    Overexposure helps with the aura effect, regardless of precisely which filter you choose, but yes, you should see more aura effect with a T50 of 710nm or longer. I have however seen it with overexposed film with a filter with a T50 of only 695nm.

    710-715 nm is visually opaque at first sight but if you hold it over your eye, excluding all other light, you will see a very dim image after a few seconds.
    I don't know what T50 means but if I had to guess it would be "threshold 50" on those charts I've seen where using a particular filter will have numbers associated with various wavelengths. So, you're saying that at 695, if the number is great (or less?) than 50, I should be able to get a halo effect?
    Jeffrey Engel
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    engelfoto's Avatar
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    Quote Originally Posted by keithwms View Post
    If that film is the same or similar to Rollei 400 IR, then I can report that I haven't really seen it even with an opaque filter (#87) and substantial overexposure.

    Here are some examples of captures that were definitely on the high side of exposure, and I see basically no 'aura' or halation: 1 and 2. The edges are extremely crisp and sharp except for some motion blur. No 'glow' at all.

    Maybe I am wrong, but the 'aura' effect is simply halation, no? If that's the case then perhaps I could see it better with 220 film, these were on 120. Anyway it's still not clear to me what people mean by 'aura,' unless it is simply halation. Of course if you want halation then that can be arranged
    Yeah, it means no anti-halation layer. And that's why you don't get it with the Rollei 400. The Rollei 400 is a different film altogether from what I've read of the Maco stuff. Maco 820c I think is the same as the new Efke stuff, but Efke doesn't make the non-anti-halation "Aura" version.

    I just happened to come across a bunch of it is all.
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  8. #8

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    Quote Originally Posted by engelfoto View Post
    I don't know what T50 means but if I had to guess it would be "threshold 50" on those charts I've seen where using a particular filter will have numbers associated with various wavelengths. So, you're saying that at 695, if the number is great (or less?) than 50, I should be able to get a halo effect?
    Yes, T50 is the wavelength at which 50% is transmitted. As the slope is normally VERY steep, it can be taken as a convenient single reference point for IR effect. With a T50 of 695 (less than 50% transmission under this figure) you should be able to see a modest halo effect with generous exposure. It's a mixture of halation and irradiation, so it's easiest to see in bigger enlargements. But as already suggested, a T50 even a little higher at 715 will give a stronger effect, though a good deal depends on the steepness of the slope. I've not tried a B+W 093 (completely opaque visually, 87c equivalent) because the sensitization of 820c is not much above 800 nm (the 820 figure is the limit of sensitivity, not the dye sensitization preak).
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  9. #9
    Ole
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    Hang on a second!

    The "wood effect" where vegetation shows up as white is wavelength-dependent, and with this film you need to filter out as much as possible of the visible light. A 695 filter does this nicely, but a 720 would be better.

    The "aura" effect is halation, and will show up on any film without some kind of anti-halation layer, at ANY wavelength! BUT: 120 film uses the backing paper as an important part of the halation control, so that will show less of it. Sheet films are big, so a 1/2mm of halo won't be easy to spot. 35mm film is best for the halo, as a 1/2mm is over 1/50 of the image height.
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  10. #10
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    Quote Originally Posted by Ole View Post
    Hang on a second!

    The "wood effect" where vegetation shows up as white is wavelength-dependent, and with this film you need to filter out as much as possible of the visible light. A 695 filter does this nicely, but a 720 would be better.

    The "aura" effect is halation, and will show up on any film without some kind of anti-halation layer, at ANY wavelength! BUT: 120 film uses the backing paper as an important part of the halation control, so that will show less of it. Sheet films are big, so a 1/2mm of halo won't be easy to spot. 35mm film is best for the halo, as a 1/2mm is over 1/50 of the image height.
    Thanks Ole, I did take this into account. I don't want a pure IR effect, I just want some of that halo, with some of that IR, even if it's a little bit. I'm looking for sharpness, but with that diffuse glow. I may not get it entirely, but I think it'll show better on the large prints on intend on making.

    This is why I was wondering if anybody has any actual pictures they can show me of a Red 29 or 70.

    I've seen the famous IR comparison chart but on that chart where they show different filters with Maco 820c, the Red filters are missing. lol... typical.
    Jeffrey Engel
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