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Thread: SK 35 odd flare effect

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    SK 35 odd flare effect

    I'm relatively new to MFD, and I'm finding that I'm getting "smeary" flare for light sources near the edges of my SK Digitar XL 35. See, for instance:



    This is on a P45, f/8 4s exposure; that's at about 15 degrees horizontal shift with no center filter (since I was planning to stitch, and pulled the CF just in case it was causing additional flare issues).

    I'm trying to figure out whether this is expected behaviour for the lens, or if something needs to be cleaned somewhere, or...?

    Thanks!

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: SK 35 odd flare effect

    I haven't had a flare that severe with the 35XL before. Is this a one off situation with a bright off image light or do you see it regularly?

    The obvious suggestion would be that it's typical flare from a point source across the lens. Some folks religiously use a lens or compendium shade to avoid these situations. With the 35XL folks will often add a permanent shade using a range of step up filter rings from the front element, wide enough to avoid vignetting.
    Last edited by GrahamWelland; 25th May 2013 at 20:27.
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    Re: SK 35 odd flare effect

    That tends to happen in some lenses when there is a point light source just outside the very edge of the image circe of the lens. I do not think it's a problem with the 35mm SK. I usually shade the lens with my hand or my filter wallet.

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    Senior Member thrice's Avatar
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    Re: SK 35 odd flare effect

    I've had a couple of odd ones with the 35XL, this one is the oddest.
    I think it is because I had a polariser and an uncoated grad in front of it and the reflection of the aperture off the sensor bounced through the optical system a few times.



    8 minute exposure on the P45.

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    Re: SK 35 odd flare effect

    The problem with these light reflections are not (always) the lens, it is the P45+ back.
    The reflection is caused by the glass on top of the sensor.
    You can see the main problem in the image of Daniel Kennedy on the right of the street lights. This reflection must be the problem of the glass.
    The reflection in the image of mkphotomedia is probably a mixture of both: the glass on top of the sensor and a light source on the left side of the image. If you put a lens shade or hold your hand close to the lens, than you should have no problems.

    When my P45+ had some severe dust spots beneath the glass, I've sent the back to Phase One and they put a new glass on top of the sensor. Since then the problem with this ghostly images are gone.

    Try this: if you hold your back with the sensor against a light source and if you see the same reflections like on the image of Daniel Kennedy (five round reflections), than you will have this problem on every image and is hard to remove them in photoshop. The only solution is to remove the glass and change it.

    All newer PhaseOne backs seems to use a different glass on top of the sensor and you never have this problem. Now I can use my p45+ back to shoot streetlights without any problems.

    I hope this helps,
    Berthold

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    Re: SK 35 odd flare effect

    Daniel,

    Very nice shot. I am curious, by flare, are you referring to the group of colored hexagional lights around the largest streetlight in the right side? Or just the star burst on all the street lights. The way the grouping comes out of the starburst to me adds to the night effect.

    The star burst from what I have read is a effect created by the design of the aperture blades, rounded, non-rounded. I have found that both the SK35 and SK43 create this star burst effect, but I like it especially with sunrise/set work.

    The Rodenstock 28 which still has the same copal shutter 0 gets a very hard magenta/or bright band in the lower portion of the image directly across from the light source which will have a very detrimental effect on the image.

    This same issue is prevalent in most 35mm lenses also, some Nikon's like the 24mm 1.4, 35mm 1.4 etc. all with the rounded aperture blades create very little starburst effect, whereas the 24-70 will often create it. The Canon 14mm F 2.8 also will create the effect.

    On the flare posted by the OP, I have seen this before on my Sk35, mainly on shifts, where you are not in the center of the image circle and thus the flare will take on a smear look. You can consider a hood for the SK35 to help prevent this. The Lee Wide angle hood is an excellent and inexpensive way to help prevent this type of flare. If you are using the physical CF, you will need the Lee wide angle hood and the Lee 72mm Wide angle adapter ring. You can still shift to 12mm with the hood on with no vignetting. I keep mine on all the time with the Sk35 and 43.

    Paul Caldwell

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    Re: SK 35 odd flare effect

    Thanks, everyone! The flare in my case was from a bright but slightly-off-image-circle source, but I've occasionally seen the 'hex flare' that Daniel ran into. Pulling the center filter has seemed to correct (or at least reduce) the effect for me--when it's happened, I'll end up shooting a second shot with no filter (and with the filter factor corrected out) so I can Photoshop the highlight area back in.

    I'll check out the Lee system; I'm thinking that I might also just do the same solution I've often done when hooding the Canon 17TS-E: take a small Rogue FlashBender and wrap it around the lens barrel, then form the FlashBender so as to block the offending point source but not vignette. Might be a bit more difficult on the SK given the vastly smaller barrel and the rest of the bits and pieces connected to it, but we'll see.

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