Sensor reflection/ghost images

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danstone

Active member
Hey guys,

I've read a little about this on other forums and want to get your thoughts.

We just shot a spot with the Epic and I thought it might be fun to throw my FS100 into the mix as a C-camera to see if we get anything usable. The FS100 footage looks decent with the exception of a strange phenomenon. In high contrast situations the sensor reflects light onto the back of the lens which shows up in the image. In other words, when there's a light bulb in the middle of a dark backdrop you actually see the light bulb and a a ghost image of the bulb. Filming into the sun (which I love to do) or anything with a bright background is basically a no-go with this camera because of this reflection.

For the life of me I can't figure out why I'm getting these reflections. I'm trying to figure out if this is an issue with the camera or certain combinations of lenses. Have you guys experienced this? I'm using Red Pro Primes (PL) and a set of old Zeiss SS.

I tried the same tests with a 7D, a Red One and a Red Epic, none of which have this reflection.

Thoughts?
 
The reflections have been confirmed in many threads here. Some people claim the sensor self-reflects in green, but I personally only witness ghosting in semi-translucent white...

I first noticed it when I put my Canon FD 50 F1.4 lens on, using a dumb adapter without any baffle and no mattebox, so I accepted it as something normal considering - but later on, it tuned out they are still present even without an adapter (using the kit lens), and/or with a mattebox ith french flag. Just like yourself, I'm not certain how it's being created :(
 
No, it doesn't have to be the adapter - I can also see the ghosting with the kit lens... Really haven't found any pattern yet.
 
If it occurs consistantly, there's a factor outside of the camera contributing to the problem. The casue can be isolated and fixed. Most the relection issues posted on this forum was from usage of cheap adapter, vari ND, certain lens(?), etc...or any combination of those. I've only seen one rare case of weird green lens flare but that's certainly not relection or ghosting issue.
 
Agreed, it's definitely from the sensor. And it's so weird because none of our other cameras do it. I don't get what's different about the FS100. Bummer because it definitely puts restraints on what you can film with this camera.

For those who have the camera and haven't seen it, put the stock lens on, go outside and film an approaching car or train with headlights on - day or night. You'll see a greenish ghost image of the headlights floating somewhere in your frame.

For those who don't have the camera and haven't seen it, I'm going to pull some clips and post them tomorrow. It's pretty bad on mine. I pretty much can't have any practical lighting in my shot (fluorescent overheads, light bulbs, street lights, headlights, a specular, etc).
 
Sample Footage

Sample Footage

Here's a link to some sample footage. This is with the stock lens only, no filters (took the matte box off in an effort to figure out what the reflection could be coming from).

You can see it much better in HD.

 
In the video example posted it just looks like a lens flare to me. If this is the worst of it I don't think it seems like too much of an issue. Though, this comes from someone who doesn't own the camera, just my two cents.
 
Make sure you watch it in HD. Lens flare doesn't usually look like a reflection of what you're filming. In the first shot I can even make out the guy's head and glasses in the reflection.
 
I recently shot some night footage on the streets, stock lens and several Nikkors, the reflection was all over the place. It was worse in some shots than others, but hard to make any sense of, it may have to do with the angle of the incoming hotspot. When you look at the sensor it has the same green tint that these reflections have. I haven't figured out a workaround, other than to avoid pointing the camera at bright lights that move.
 
Same here. It just looks like plain old internal reflections of the lens elements inside the lens itself.
 
The internal lens elements should be coated. Isn't there an issue with the scarlet and the same kind of thing. From memory it was an interaction of the OLPF and the sensor, which would make sense in these cases too.

Easiest thing to do is to start a new trend, internal reflections are the new lens flare

cheers
Paul
 
Thanks for the input, guys. Talked to my rental guy (who has a couple of these in inventory) who confirmed the sensor reflection and said it's there with pretty much any lens you use. He laughed at the fact that I'm so complainy about the camera and I guess he had a good point. He doesn't consider it a "problem" because the camera's target user is stepping up from the DSLR world which is used to crappy color, strange blocky artifacts, noise and moire -- something like this, which would be a deal breaker in the pro world, is a non-issue to users who are really mostly looking for shallow depth of field.

Shortcomings aside, I have to say we were all totally impressed with the camera's low light ability and overall picture quality. It doesn't hold up very well under heavy color correction (which is expected of an 8-bit color space) but if you bake in a look that's close to where you want to be, it puts DSLRs to shame.
 
Ugh - just had my first client freak out this week because of this camera and, to be honest, I'm ready to punt it toward the nearest dumpster. We volunteered to film something for a local nonprofit and thought it'd be cool to actually use the FS100 for a real project. The client (who knows nothing about video) commented repeatedly about the sensor reflections. The reflections were such a hinder to our project that the client (who, again, has never been involved in video production) requested we stop the shoot and get a different camera. That's serious.

We brought the little bit of footage we did capture back to the studio and were horrified. A window above the interviewee (and out of frame) caused a reflection that completely covered her face and upper body. You can't tell me this is normal or acceptable.

What is going on? Is there anything anyone can think of that would eliminate this - or at least improve it? Our RED ONE doesn't do this. Our 7D or 5D don't do this. My friend's AF100 doesn't do this. At this point I can not envision using this camera for a real client in a professional setting. Am I doing something wrong or is this an oversight that Sony hopes will be overshadowed to those so enamored by mere shallow depth of field?

We tried the stock lens with and without a light-sealed matte box with ND and a Hot Mirror (UV) - as well as some old Nikons in the same set up.

Help!
 
Hmmm, I've seen this on occasion, but I just filmed two entire days and didn't see it. We looked through all the footage and we aren't seeing reflections in anything actually. We used No ND filter, and a cheap EOS adapter. The lenses were tokina 11-16, Sigma 30, and Sigma 17-50 I think it was.

Not that I haven't seen the problem, but, I can see it while I am filming if it does it and I just reposition the camera some. Never saw it with my 7D. Did see it with my AF100.
 
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