How to Prevent Filter Flare?

Juan Swartz · December 9, 2009

I'm using a 4x4 Classic Soft 1

homemade filter holder

Canon 7d, 50mm 1.8

This is my first time using a square filter, and I keep getting hardcore mirror reflections from lights in the scene, obviously there's some way to prevent this because there's practical lights in movies all the time, so how do they solve this issue?

Flares in action

Edited December 9, 2009 by Juan Swartz

Adrian Sierkowski · December 9, 2009

you need to block light out from comming into the back of the filter, as well as utilize eyebrows and side flags for a mattebox to shield the lens as much as you can.

Pro matteboxes have a rubber or foam doughnut on the back of them which is the same size as the front diameter of the lenses you're using (often more than 1 per matte box) to make sure no stray light gets in from behind, and my Arri MB has and eyebrow as well as side flags which inch in and out of position to cut as much stray light as possible. This combined with mattes in the front which accommodate the FoV of certain lenses (e.g. 20-25mm) and block out everything else also help eliminate stray light problems.

Though, truthfully that looks a lot more like LENS flare to me. My Nikon 50mm F1.4 exhibited the same issues when mounted to a digital camera.... film lenses are very well designed and coated to eliminate a good deal of flare...and still lenses often aren't.

Juan Swartz · December 9, 2009

you need to block light out from comming into the back of the filter, as well as utilize eyebrows and side flags for a mattebox to shield the lens as much as you can.
Pro matteboxes have a rubber or foam doughnut on the back of them which is the same size as the front diameter of the lenses you're using (often more than 1 per matte box) to make sure no stray light gets in from behind, and my Arri MB has and eyebrow as well as side flags which inch in and out of position to cut as much stray light as possible. This combined with mattes in the front which accommodate the FoV of certain lenses (e.g. 20-25mm) and block out everything else also help eliminate stray light problems.

Though, truthfully that looks a lot more like LENS flare to me. My Nikon 50mm F1.4 exhibited the same issues when mounted to a digital camera.... film lenses are very well designed and coated to eliminate a good deal of flare...and still lenses often aren't.

Thanks for the quick response. I did a little test to see if it actually is lens flare, and there is some, a faint purple orb, but it's not nearly as intense as the filters. What's the trick with having light sources in front of the lens outside the matte box flags jurisdiction?

Adrian Sierkowski · December 9, 2009

great lenses which don't flare as much is the simple answer, but even the best of lenses will flare a bit when you blast light into them. chances re your filter is exacerbating the situation. and any harder source will make it worse.

Recently while shooting with Ultra Primes, which are great lenses, I had problems with flare from lights not even in the frame... just happens and you gotta work 'round it however you can. In your case, i'd recommend finding some lenses which handle the bright sources in frame better, and, as mentioned, loosing the filter for a bit. Lenses designed for DSLRs should hold up a bit better on a DSLR than those for a film SLR. This has to do, I think, with the angle at which the lens bends the incoming light-- the DSLR glass (like digital cine glass) puts it out more "straight on" towards the lenslets which are mounted on the CMOS chip of the camera (if memory is serving me right now.)

Juan Swartz · December 9, 2009

I was afraid the answer would be something like that. Too bad not everything can be fixed with duct tape and hope.

Adrian Sierkowski · December 9, 2009

I know it's unfortunate. I still havn't bought a DSLR because all my good nikon glass does similar things on digital cameras and there's no way I'm re-buying lenses I'm not super thrilled about... mainly DSLR auto-everything lenses.

In fact, here's an image off of my Nikon 50mm F1.4 from a Nikon DSLR with a very similar flare.. but this lens was naked, and a horrible expression from me.

Daniel Carruthers · December 9, 2009

I found I had the exact same lens flare problems

it turned out the flares where cause by my UV filter, with a 4x4 black promist in front of the circular UV

once I took the uv filter off the flares disappeared

I never really understood why it happend? The filters on there own didnt cause any flares but when they where used together they did?

So I would recommend taking off any circular UV or haze filter and see what happens?

December 9, 2009

lens flare usually from sources at obtuse angles, unless your shooting directly into the sun with a crap lens. just extend the matte box, reorient your frame.

Jim Hyslop · December 9, 2009

I found I had the exact same lens flare problems
it turned out the flares where cause by my UV filter, with a 4x4 black promist in front of the circular UV

once I took the uv filter off the flares disappeared

I never really understood why it happend? The filters on there own didnt cause any flares but when they where used together they did?

So I would recommend taking off any circular UV or haze filter and see what happens?

The light bounces off the front of the UV filter, then off the back of the promist filter then into the lens. If you only have one filter on, then the light bouncing off the front of the filter doesn't have any effect - it just dissipates into the room.

--

Jim