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Thread: ND Filters unwanted reflections

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    ND Filters unwanted reflections

    I have recently Purchased a new lens Canon EF S 10 - 22 and with it i decided to splurge and get new 100mm filters and i am extremely happy with them.
    Formatt Hitech Firecrest ND 13 (3.9)
    and
    Formatt Hitech Gradual soft edge ND 2 (0.6)


    3 minutes @ f. 20
    ISO 100
    12mm

    As you can see there is no colour cast which is where most other filters fail! minimal vignetting (shot at 12mm) and some sun glare, which does not concern me as i was testing the filters by shooting almost directly into the sun.

    The problem i would like some help with, or even an answer as to why it is occurring, is regarding the bottom left corner where you can see what appears to be the lens rings (and White text?) reflecting off the filter and into the lens. Is this because i was shooting towards the sun and duration of the shot and unavoidable or is there something i can do about this?

    I took another shot 30 seconds @ f. 11 which had similar issue but it was much less noticeable so i realize this is something that gets worse the longer the exposure.

    One thought i had was getting foam tape to cover everything except with glass however cutting this/finding something the right size may prove difficult.
    Last edited by EdanTrevethickPhotography; 26-02-2015 at 5:18pm.

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    I haven't really had any issue like this before, but I'm guessing it may just be the angle it's on towards the sun.
    I haven't used or heard much about the Formatt filters.

    Have you tried a lens hood at all?
    Cheers, Travis

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    Thank you for your response however a lens hood wont work as they are slide type filters not screw on.

    I did try other other shots and they had no problems so maybe your right and its just the angle. Oh, and the fact it was quite intense sunlight at the time of the photo.
    Last edited by EdanTrevethickPhotography; 26-02-2015 at 6:07pm.

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    Administrator ricktas's Avatar
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    I am thinking lens flare to, but where the sun is hitting the lens front element, behind the filter, and then reflecting that light on to the 'back' of the filter. I reckon at least testing it with different weather conditions and differing angles relative to the sun, you could determine the actual cause. At least if you know it happens when the sun is in the upper right corner position, for example, you then now how considering framing shots so the sun is not in that position.
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    A royal pain in the bum! arthurking83's Avatar
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    Use your hands(or a piece of cardboard) or something to shade the filter from the direct line of sight of the sun.

    Being a wide angle, of course you need to keep your shading at a bit of a distance sometimes, but it works.

    Also, try the same test with a much wider aperture stop too.
    If the lens does f/3.5 try that.

    Each situation will require a certain aperture value, eg. if you want everything from .05m to infinity in focus, of course you probably want to use aperture at f/11 or something like that, but if you don't need it then try using the most efficient aperture value.

    That is, if you're shooting mainly everything at infinity or thereabouts, f/4(if it's sharp) or f/5.6 will be fine for most UWA focal lengths.
    I suppose this takes a few test shots to work out which aperture gives you good sharpness where you need it, plus minimising reflective glare and suchlike.

    I have a couple of Hitech filters(150mm) and also a few Lee's too(100mm) and they all reflect back in some way.

    Like telyward said, it's simply the way that the sun being in front of the lens, hits the filter and front of the lens and hence causes reflections to form.
    Tilt/swing/shift/move the framing a mm this way or that way will probably remove some of these reflections .. but can cause others. It's about balance.

    Time of exposure probably contributes a little to the formation of these reflections on the rendered image, but I think it's more likely to be due to the chosen aperture values.
    A wider aperture won't eliminate the reflections .. they're there no matter what camera/lens setting you choose .. but a wider aperture will minimise they're formation back onto the sensor.
    That is, they will be rendered much more blurry. Again, this isn't elimination, it's minimisation, so the side effect is that you get a loss of contrast in that area where the reflections are.

    The tape idea is also a good one, but you may still get reflection from most tape types, eg. gaffer, or electrical, or any other semi shiny type tape.

    I know you can get non reflective type material, which looks basically like suede or velour type material which is very good at minimising reflections.
    This stuff is sometimes used internally in the lens(check the inside rear of your lenses).
    I have no idea on where you get the stuff tho, I've seen websites that sell it, but never bookmarked them for future reference.

    To start off tho, the easy things to do are .. wider open aperture and try using a shading method to see if this works for 'ya.
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    Thank you for the responses guys, i have taken a few more test shots and had more success eliminating the reflections when the sun is at a different angle to the filter and also by shading the lens

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    I had the same problem, although the filters, lens and situation where all quite different. This problem can arise any time there is white print on the front of the lens and the filter is far enough away from the surface of the print to allow it to be reflected back into the image. If using shallow depth of field then you will only get a small increase in veiling glare but a small aperture will show the actual print in the image, because of the greater depth of field.

    In my case the problem would show up when photographing car interiors, no direct sunlight to be seen at all as this was usually done in the shade! My solution was to use non reflective tape on the front of the lens. Problem solved, in all circumstances.




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