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Thread: Purple haze in lens

  1. #21
    Arch-Σigmoid Ausphotography Regular ameerat42's Avatar
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    Does

    Quote Originally Posted by poider View Post
    ...I was in Aperture priority mode and when I bumped it up to f/22 I got a purple haze in the centre of my photos, f/8 and f/1.8 were all fine...
    +
    Quote Originally Posted by Mark L View Post
    ... ISO 25600 might be your problem here...
    =
    Quote Originally Posted by arthurking83 View Post
    Possible, but pretty much unlikely.
    That is, simply setting the camera to ISO25600 won't cause purple flaring in this manner .. otherwise the camera maker has a lot to answer for!
    ...
    ?

    That "possibly" might end up being "likely"!

    Q: How many times do you have to look at a thread before it starts to gel?

    f/22 in the case of the 50mm lens used here is a smallish aperture of ~2.27mm.

    Our good friend "diffraction" might be at play here. The conditions were trying enough, and at f/22 with the ISO racing...!

    Peter, maybe another experiment is called for. Try photographing a white sheet of paper to fill about 3/4 of the frame.
    Do two runs: one in goodish sunlight, the other closer to your conditions for this lot, doing just what you did for these.
    CC, Image editing OK.

  2. #22
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    I will do some more tests in the future, I am not well currently and will get back to it when I recover...Thank you all for your input and suggestions, I will keep it going when I can
    Peter
    Nikon D3100, D72000, nikkor 18-300mm, nikkor 50mm, sigma 10-20mm, sigma 150-500mm, tamron 18-270mm, Olympus OMD EM10 MIII, zuiko 14-150mm, Olympus TG4

  3. #23
    Ausphotography Regular Hawthy's Avatar
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    I need to agree with Mark here. 5 pm. Mid-winter. Adelaide. Presumably dim light.

    First photo: f/1.8 and ISO 250 gives a reasonable picture.
    Second photo: f/22 and ISO 25,200 gives a purple haze.

    Going from wide open aperture to almost closed is really pushing the boundaries.

    I don't think that anyone can reasonably expect a DSLR to produce similar results in dim light when the ISO varies so greatly.
    Andrew




  4. #24
    A royal pain in the bum! arthurking83's Avatar
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    Quote Originally Posted by Hawthy View Post
    I need to agree with Mark here. 5 pm. Mid-winter. Adelaide. Presumably dim light.

    First photo: f/1.8 and ISO 250 gives a reasonable picture.
    Second photo: f/22 and ISO 25,200 gives a purple haze.

    Going from wide open aperture to almost closed is really pushing the boundaries.

    I don't think that anyone can reasonably expect a DSLR to produce similar results in dim light when the ISO varies so greatly.
    Would probably pay to be a bit more critical of the image tho.
    image one at ISO250 whilst 'reasonable' is badly affected by flare/haze. The grey-ish periphery of the image, mainly LHS, lower edge and RHS(probably worst affected) are the cues to that assessment.

    50/1.8 lenses are, in general, quite prone to flare/haziness/low contrast/etc in marginal situations such as contra light. Some nifty fifties are better than others, but I know Nikon's 50/1.8's are one of those that are.

    Closing the aperture down helps with increasing contrast rendering in some cases, but when there is still contra light present in the scene, the smaller aperture can also serve to concentrate the low contrast/flare spot.

    With respect to the underlined section of the reply:
    One of the main points in choosing a DSLR is their ability to maintain quality in the image at elevated ISO levels without compromising image quality too much.
    If the ISO value chosen in the second image was the cause of the purple haze affliction, then it's reasonable to assume that the purple haze would propagate at the periphery of the image, as in the the low contrast rendering in the f/1.8 image, and not move from the periphery to the centre of the image as it has done.

    The ISO value, in isolation, can't be the cause of the purple haze. If it were, then as I said earlier, the manufacturer has a lot to answer for. Simply upping ISO and that setting producing purple haze spots in an image is unacceptable.
    I have thousands of image shot at ISO52K which don't have haze spots in them, and the world of photography has literally billions of image available for viewing that show images at ISO25K with no haze effects.

    The cause of the purple haze spot is the f/22 aperture used(which concentrated the flare into the centre of the image).
    and what I think must be a strong reflective light source(ie. contra light) coming back at the lens which caused the low contrast areas in the f/1.8 image, and subsequently the haze spot in the f/22 image.

    The simple act of upping ISO to reasonably high values doesn't cause flare spots. Can highlight them in some situations, but doesn't cause the phenomenon.
    Nikon D800E, D300, D70s
    {Nikon} -> 50/1.2 : 500/8(CPU'd) : 105/2.8VR Micro : 180/2.8ais : 105mm f/1.8ais : 24mm/2ais
    {Sigma}; ->10-20/4-5.6 : 50/1.4 : 12-24/4.5-5.6II : 150-600mm|S
    {Tamron}; -> 17-50/2.8 : 28-75/2.8 : 70-200/2.8 : 300/2.8 SP MF : 24-70/2.8VC

    {Yongnuo}; -> YN35/2N : YN50/1.8N


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