when I have a small f-stop around 22 and my camera is pointing at a bright image, then all these white dots appear scattered around the frame. does anyone know what they are? when I open the f-stop they fade out.
does anyone know what these white dots are that appear on my video?
- Thread starter RealJasonBourne
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With your lens wide open, and with a bright light, your depth of field is zero. You are most likely seeing VERY small bits of dust on the inside of your camera...either on the back of your lens or on the video block. If you add a neutral density filter, which would allow you to stop down a bit, the spots start to disappear. If you could stop down 2 or 3 stops...say to a 5.6...your image should be clean.
thanks for the response. do you think I should buy one of those cans of air to try and blow the dust off? heres a vid showing the white dots https://www.youtube.com/watch?v=uPgNxjQQKKo
You can try an air can, but I suspect that your problem is going to be deep inside the camera where you can't get at it. Your camera may have a built in "ND" (neutral density filter) switch
on the side of the lens, which would say "ND-1" and "ND-2". You could also experiment with
a Rosco gel filter (like the ones that you would use on your lights)...they make an ND filter that
you could temporarily hold in front of your lens to see if it helps. If it works, you could then invest in a screw-on ND filter for your camera lens.
on the side of the lens, which would say "ND-1" and "ND-2". You could also experiment with
a Rosco gel filter (like the ones that you would use on your lights)...they make an ND filter that
you could temporarily hold in front of your lens to see if it helps. If it works, you could then invest in a screw-on ND filter for your camera lens.
when I film indoors i dont see them, but if i bring the aperature to 22 and point my camera at the lightbulb then i can see them
i think the lens im using is too old for any add ons, its a 17.5-70mm angenieux lens for my bmpcc. maybe ill bring it to a camera shop and see if they can fix it.
thanks
Dust usually appears as black spots. Since it's an older lens that you probably bought used and the spots have a slightly irregular shape, I suspect it might be fungus inside the lens. You can check by removing both lens caps and looking through it toward a bright light. If you see any haziness or things that look like water marks on the lens surfaces, it's probably fungus. This can be fixed if it's caught soon enough, but if left for too long it will permanently etch the lens coating.
wow it probably is.... i paid top dollar for this lens and gave them perfect feedback on ebay
thanks for letting me knowI haven't seen the effects of fungus, and I would guess that is dust on the front of the lens, and the lens is getting hit by stray light (like a reflector on camera right). Living in the desert, we simply don't have to worry about fungus, but we do have to worry about dust... a lot.
It is definitely not sensor dirt.
The irregular shape is not unusual. The lens has some distortion going out towards the edges, and they get more oblong as it moves out.
If it is fungus, it will show up on other shots in the same place/pattern. (Some lenses have rotating parts, so try setting all settings to the same, and test it out with a flashlight aiming at the camera from the lower right and lower left corners. The pattern should be the same, with a few moving white dots of flare.
It is definitely not sensor dirt.
The irregular shape is not unusual. The lens has some distortion going out towards the edges, and they get more oblong as it moves out.
If it is fungus, it will show up on other shots in the same place/pattern. (Some lenses have rotating parts, so try setting all settings to the same, and test it out with a flashlight aiming at the camera from the lower right and lower left corners. The pattern should be the same, with a few moving white dots of flare.
its old lens, it has dust.. clean it if you can, but you really need to work with your framing and light control. If your letting stray light like this hit the lens, so much that it brings out the dust, your also losing contrast and detail. Matte box, french flags, scraps of black foil... control any stray light hitting the lens.
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