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04-25-2012, 10:20 PM   #1
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Strange ND Filter Issue

I was using a B+W 10 stop filter for the first time on my Tamron 17-50mm and I ran into this banding issue you can see on the bottom of the picture . Any ideas what is causing this? It occurred several other times as well.

Edit: Ugh, Lightroom added a watermark to this stupid picture.

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04-25-2012, 10:29 PM - 1 Like   #2
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That looks like flare, the sun is hitting the filter. Are you using a hood?
04-25-2012, 10:32 PM   #3
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QuoteOriginally posted by twitch Quote
That looks like flare, the sun is hitting the filter. Are you using a hood?
Interesting.

No I was not using a hood. But does flair manifest as a straight line at the bottom of the picture? The line appears in other shots shot in different locations as well.
04-25-2012, 10:42 PM   #4
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It's dependant on the angle and intensity of the sun hitting the filter, although a straight line is a little weird. By the way it's affecting the top 95% of the picture, not the bottom 5%. Use a hood and point away from the sun and it should go away if my theory is right. I have the same filter and you simply can not have the sun directly falling on any part of the filter during a long exposure. A hood will help a lot, but even then you can't have the sun in frame.

04-25-2012, 10:44 PM   #5
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Also, are you covering the eyepiece during the long exposure?
04-25-2012, 10:46 PM   #6
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Now there's a thought.....
04-25-2012, 10:46 PM   #7
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QuoteOriginally posted by twitch Quote
It's dependant on the angle and intensity of the sun hitting the filter, although a straight line is a little weird. By the way it's affecting the top 95% of the picture, not the bottom 5%. Use a hood and point away from the sun and it should go away if my theory is right. I have the same filter and you simply can not have the sun directly falling on any part of the filter during a long exposure. A hood will help a lot, but even then you can't have the sun in frame.
Thanks for the advice. I will conduct a few experiments to see why the flare is absent at the bottom. I didn't know about not having the sun in frame.
04-25-2012, 10:48 PM   #8
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QuoteOriginally posted by Nass Quote
Also, are you covering the eyepiece during the long exposure?
I don't remember if I did. What effect does that have?

04-25-2012, 11:53 PM   #9
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It can let light leak onto the sensor, similar to this
04-26-2012, 11:07 AM - 1 Like   #10
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QuoteOriginally posted by Nass Quote
It can let light leak onto the sensor, similar to this
With the mirror up, during exposure? I think not. It is a good idea to cover the eyepiece immediately prior to an auto exposure because light coming in can affect the meter reading, but light coming through the eyepiece will never hit the sensor.

Anyways, Sol, what you have there is lens flare.

Last edited by johnyates; 04-26-2012 at 11:14 AM.
04-26-2012, 12:09 PM - 1 Like   #11
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QuoteOriginally posted by johnyates Quote
With the mirror up, during exposure? I think not. It is a good idea to cover the eyepiece immediately prior to an auto exposure because light coming in can affect the meter reading, but light coming through the eyepiece will never hit the sensor.

Anyways, Sol, what you have there is lens flare.

What it (leaving the viewfinder uncovered) CAN do is affect the exposure. The light meter sensors are in the viewfinder, so light entering the eyepiece can contribute to the calculation, which is not something you want it to do.
04-26-2012, 01:45 PM - 2 Likes   #12
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QuoteOriginally posted by johnyates Quote
With the mirror up, during exposure? I think not. It is a good idea to cover the eyepiece immediately prior to an auto exposure because light coming in can affect the meter reading, but light coming through the eyepiece will never hit the sensor.

Anyways, Sol, what you have there is lens flare.
Sorry, this is factually false. On a 3m long exposure using ND110, if you don't cover the viewfinder, it is perfectly possible to get a light leak in through there. Suggest you google this, you'll find it's well documented. I've had it plenty of times myself.

Last edited by Nass; 04-26-2012 at 02:06 PM.
04-26-2012, 05:16 PM   #13
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Thanks for all the replies. I will do some test shots in the next few days, once it stops raining. Hood on, hood off, viewfinder covered, uncovered etc.

Should make for an interesting comparison.
05-02-2012, 05:34 PM   #14
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QuoteOriginally posted by Nass Quote
Sorry, this is factually false. On a 3m long exposure using ND110, if you don't cover the viewfinder, it is perfectly possible to get a light leak in through there. Suggest you google this, you'll find it's well documented. I've had it plenty of times myself.

I believe that Nass is on the right track here. I have seen similar results created during the use of IR filters and long exposures when not covering the eyepiece. This is why we are provided with eyepiece covers...

Did you get a chance to attempt to replicate these conditions with the eyepiece covered?
05-02-2012, 06:56 PM   #15
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QuoteOriginally posted by shadowsonoureyes Quote
I believe that Nass is on the right track here. I have seen similar results created during the use of IR filters and long exposures when not covering the eyepiece. This is why we are provided with eyepiece covers...

Did you get a chance to attempt to replicate these conditions with the eyepiece covered?
It's been raining here for a week. I will update the thread once I've done the tests. Probably this Friday.
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