PDA

View Full Version : Sensor reflection



DM_rider
07-25-2011, 01:34 PM
I am using a Fotodiox adapter and the tokina 11-16 in this shot. I am fairly certain that this is happening because it's a cheap adapter, but, before I buy something else, I want to be sure it's not happening with the better adapters. Anyone else having this happen?

Left of the couch and to the right of the lamp
http://www.2shared.com/file/fDkcY5BC/00026.html

speedracerlo
07-25-2011, 03:49 PM
it would be better if you can post a vimeo link instead of a download
I have reflection problems with even my Voigtlander and same problem with a cheaper Kipon adapter for Contax
Although I haven't tried any of the adapters with the internal baffles, I don't think that will really solve the issue because the problem is the surface of the CMOS sensor is very shiny and it's pretty much reflecting back the light towards the lens and then back which makes the image see doubles and ghosting
I assume that lenses with anti-reflective coating might fare better with less ghosting, but I haven't seen it completely go away with any of my lenses..

Postmaster
07-25-2011, 09:59 PM
Have you checked if the reflections are not from a fader ND? Thatīs where 90% of my reflections are coming from.

Frank

Mark Crabtree
07-26-2011, 05:41 AM
I have the same problems using fader ND.

Barry_Green
07-26-2011, 08:06 AM
The FS100 has "sensor reflections", easily observable with no fader in front. I tested it with/without the fader, the only difference was (surprisingly) the color of the sensor reflection. With a candle and no fader, the reflection was green; when I put the fader in the optical path the reflection turned red. Wasn't expecting that.

millerandmiller
07-26-2011, 08:12 AM
Yep have the reflections but you just work with them like flare. The GH2 also does the same thing.

Barry_Green
07-26-2011, 08:54 AM
About the only thing you can do about "sensor reflections" is use a different lens. If a lens is specifically coated on the rear element to reduce flare, then maybe that particular lens will show fewer sensor reflections. But yes, most if not all video cameras with interchangeable lenses are subject to the same phenomenon.

Another thing you can do on some cameras, but not the FS100 or Gh2 obviously, is engage the built-in ND filter. That can have the effect of changing the optical path enough to eliminate the reflections.

Rick Burnett
07-26-2011, 09:17 AM
I've had reflection problems with both my AF100 and FS100 in this regard. In addition, I stopped using a UV filter on my lenses because they were causing reflections as well. As Barry says, I've seen this with most CMOS sensors I've used.

Douglas Villalba
07-26-2011, 10:52 AM
Does it happen more with full frame 35mm still lenses or does it happen with APCs as well??

DM_rider
07-26-2011, 02:43 PM
Does it happen more with full frame 35mm still lenses or does it happen with APCs as well??

I never had it happen with my 7d. Flares, yes. But with the fs100, many times it's an actual green reflection of whatever the camera is pointing at, not just a flare.

Barry_Green
07-26-2011, 02:56 PM
That's because the 7D isn't a video camera, and doesn't have the same sensor protection glass in front of it that video cameras do. What you're talking about is known. Yes, it's an actual green reflection, and it moves opposite of the light source. It happens when you shine a bright light into the lens. It happens on pretty much every interchangeable lens video camera out there, including the F3, the FS100, and the AF100. It's just one of those things that you have to know about and deal with.

txdp
07-26-2011, 03:02 PM
Ahhhh. Remembering a shot I did with the f3 with a hot set of closed blinds. I saw green ghosting, I just thought it was some kind of strange flare....good to know

matteo1
07-26-2011, 03:48 PM
So that's what that is. I did a test to see how FS100 dealt with out-of-focus highlights and as I panned across a backlit tree up popped the green ghost. As the camera moved, so did the ghost. To bad it's there, because I really like the way the image looked.


37402

NeedCreative
07-26-2011, 07:07 PM
I've had reflection problems with both my AF100 and FS100 in this regard. In addition, I stopped using a UV filter on my lenses because they were causing reflections as well. As Barry says, I've seen this with most CMOS sensors I've used.

Good tip Rick. I saw more of this with UV filters on, even more with matte box and 2 sets of 4x4s in front of it. Being careful and using good glass I rarely see it unless a something bright is shining directly into the lens, and even then it has to be just right (the sun doesn't do it for example)

thxdave
07-26-2011, 07:48 PM
This is one of the reasons that effective antireflective coatings on lenses and filters are so expensive.