Sensor reflection/ghost images

I bet a polarizer filter would completely remove any reflection or at least help. This must be a phenomena due to having a sensor so close to the back element of the lens. I dont see this issue with my Leicas, but im thinking its because the adapter sits them pretty far away from the sensor.Surprising that the client wanted to shut down the shoot...how embarrassing! Try the polarizer and rotate it around until the reflection goes away and let us know if that's a fix or not. :)
 
danstone said:
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.


Help!
Click to expand...

Another thing to consider is the fact that if the window was above the interviewee a simple on camera or matte box top flag could have eliminated this problem. Get into the habit of stepping in front of your camera and looking straight into the lens. If you see any reflections in the lens glass creep the flags in until you eliminate as many reflections as you can. Thats a habit you will see on every professional set.
 
Every camera has its downsides (and I'm not making excuses for the camera because I own it), but you have to work around them. If you had that much of an image issue, you might have to move the camera for a different shot. Maybe angle the camera so it's not pointed directly towards the window. Check your image first for any strangeness (I suggest using an external monitor or EVF) so you don't end up with a problem like this in the edit room.
 
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Here are some more samples. Make sure you watch it in HD.

Having the client shut down the shoot because of this was, indeed, embarrassing. I bought this camera because I had plans to buy several for an upcoming documentary we've been commissioned to produce. I thought the downscaling might give us more creative freedom but it turns out the opposite is true. There's a lot to worry about with these that we don't have to worry about with a pro camera.

The thing I don't get is where this camera's place is in a professional production. If you need to set up a video village and carefully plan each shot around the camera's shortcomings, wouldn't it make more sense to just shoot on a better camera? I guess wedding videos and ultra low budget industrials?

I really do appreciate your feedback, guys.
 
danstone said:


Here are some more samples. Make sure you watch it in HD.

Having the client shut down the shoot because of this was, indeed, embarrassing. I bought this camera because I had plans to buy several for an upcoming documentary we've been commissioned to produce. I thought the downscaling might give us more creative freedom but it turns out the opposite is true. There's a lot to worry about with these that we don't have to worry about with a pro camera.

The thing I don't get is where this camera's place is in a professional production. If you need to set up a video village and carefully plan each shot around the camera's shortcomings, wouldn't it make more sense to just shoot on a better camera? I guess wedding videos and ultra low budget industrials?

I really do appreciate your feedback, guys.
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I shot in situations like this over the last weekend and NEVER saw anything like that. That is REALLY bad. I wonder if maybe there is a layer missing on your sensor, or it's something specific to the lenses. I shot with Sigma 30mm F1.4, Tokina 11-16, Bower 85mm F1.4 and Sigma 17-50 F2.8 lens. I went back through the footage to check it and I don't see anything like this. I have a few lens flares but they look like lens flares, not reflections which I see in what you have.

Sony is really good at getting back with people. I think it is worth making the call.

That said, do they make anti-reflective glass? Maybe something like that in the adapter to help with this situation. Like I said, I've made it happen before even on my camera, but NEVER this bad.

Also, there was some discussion about lens adapters. If light is leaking into your adapter, it can cause this as well. While specifically with the AF100, I do remember it being a nikon adapter causing the problem. Maybe put a lens cap on, then film around rotating your camera and see if you get any light showing up which would be from a leak. I am going to fix the inside of my lens mount adapter so it is flat inside and not reflective like it is now.
 
That's good to know. I think I might reach out to them.

Most of these shots were with the stock zoom lens (no adaptor). I'm wondering if your lenses have an anti reflective coating on the rear elements that kills the image reflection coming from the sensor - a coating that the stock zoom doesn't have.
 
I tried to see if the Sigma or your Sony had any details on their product pages, but no, they don't say.

But that did get me thinking about one thing, the distance from the rear lens element on your camera to the rear lens element on the 30mm is a lot different. The adapter pushes the lens quite a bit away. I bet that has something to do with it as well.
 
I'd still like to know if this problem is being caused by the surface shape of the rear element. This presupposes that the issue is NOT being caused by filter reflections. I'd love to test this myself, but I STILL don't have a FS100 yet (sigh). I have some Nikkor lenses that have very flat rear elements but others are extremely convex and would be highly unlikely to contribute to an internal reflection....regardless of anti-reflective coatings.
 
That is a good point, the rear element of the Sigma 30mm is curved:

http://www.sigmaphoto.com/shop/30mm-f14-ex-dc-hsm-sigma

The tokina 11-16 is also curved at the last element:

http://nikonrumors.com/2012/01/26/new-tokina-at-x-11-16-f2-8-pro-dx-Ⅱ-lens-announced.aspx/

The bower 85mm last element is curved as well:

http://kurtmunger.com/vivitar_85mm_f_1_4_reviewid192.html

And the Sigma 17-50 is curved also:

http://www.sigmaphoto.com/shop/17-50mm-f28-ex-dc-os-hsm-sigma

I cannot seem to find a diagram of the lenses from Sony, but here is an older zoom from Sony with a flat last lens piece:

http://www.dyxum.com/lenses/detail.asp?idlens=313

I hadn't considered this before. I still think distance is a factor as well, the further away, the more I would imagine the light falls off, but still, good point. Check some of the nikons you are talking about to see if the lens construction at the back is curved or flat.
 
Rick Burnett said:
That is a good point, the rear element of the Sigma 30mm is curved:http://www.sigmaphoto.com/shop/30mm-f14-ex-dc-hsm-sigmaThe tokina 11-16 is also curved at the last element:http://nikonrumors.com/2012/01/26/new-tokina-at-x-11-16-f2-8-pro-dx-Ⅱ-lens-announced.aspx/The bower 85mm last element is curved as well:http://kurtmunger.com/vivitar_85mm_f_1_4_reviewid192.htmlAnd the Sigma 17-50 is curved also:http://www.sigmaphoto.com/shop/17-50mm-f28-ex-dc-os-hsm-sigmaI cannot seem to find a diagram of the lenses from Sony, but here is an older zoom from Sony with a flat last lens piece:http://www.dyxum.com/lenses/detail.asp?idlens=313I hadn't considered this before. I still think distance is a factor as well, the further away, the more I would imagine the light falls off, but still, good point. Check some of the nikons you are talking about to see if the lens construction at the back is curved or flat.
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Really interesting that your rear elements aren't flat. I'll bet that's exactly why you don't have the reflections. Mine are all completely flat, including the stock zoom lens. So it may just come down to the stock lens (or any lens with a flat rear element) not being a very good combination with this camera (which is a shame because the stabilizer is downright amazing). Thank you for looking up those lens specs, by the way.
 
I looked at three of my lenses just now and I may be overstating the "flatness" of the rear elements. My 28-70mm f2.8 is a beast and has a rear element with a slight curve:
http://www.kenrockwell.com/nikon/2870afs.htm

My 80-200mm f2.8 has a slightly flat rear element, but it sits SO far up inside the lens barrel that I doubt it would ever present a problem:
http://www.kenrockwell.com/nikon/80200.htm

My 12-24mm f4 has a very curved rear element as do my other primes. I wasn't trying to minimize this reflection issue and I hope there's a logical explanation for it, but ANY air/glass interface is open for discussion in this topic.
 
Wow, that is unacceptable and i've not seen anything to that degree either. I'll have a go later and see if i can create it, i have many, many lenses here.

One thing i find odd is that you highlight the stabiliser making the reflections move. So the question is what is actually being reflected, because it seems to be an element that isn't stabilised and therefore an element further towards the front of the lens. (Trying to wrap my head around how the light would be working with a stabiliser on, so could be completely incorrect here)

However in your original post you had non stabilised lenses showing the same thing? To the same degree?

I notice that both the 18200 and the 1855 have masks at the rear end so it shouldn't be errant light getting through. Plus if this is stock lens then no adapter to allow light to leak.

I'll try a combination later on and see if i can work anything out

cheers
Paul
 
Here are some quick tests i've just tried whilst waiting for a render to complete!

[EDIT seems that the images have become super down sampled, i hope you can still see the effect]

First up is 18200, i tried to make it as bad as i could and you can see the reflection here. I cannot make the same kind of vertical reflections shown in the sample video, i tried a variety of windows to see if i could make it worse. It moves around under stabilisation as well.

18200 Reflection.jpg

This next one is a Voigtlander 28mm rangefinder lens, so very short distance to the sensor. I've circled a magenta glare but i'm not convinced this is the same thing because this particular lens acts like that on stills too, the coatings aren't very good and it's low contrast (lovely lens though!)

CV28 Reflection.jpg

Next up a CZ 28-70 zoom, fairly well defined here too

CZZoom Reflection.jpg

Next a 28mm CZ distagon f2.8. This seems the worse of the bunch actually

CZ28 Reflection.jpg

Now a 21mm Voigtlander, very close to the sensor, almost no reflection (that i can see or create), Very curved front and back elements

CV21 Reflection.jpg

With the 21mm above though if you move to the side, you can see a reflection which can then be obscured by moving a hand

CV21 No Side Reflection.jpgCV21 Side Reflection.jpg

So what conclusions? Well in the above scenario it doesn't look as bad as danstones examples.

It really seems seems to be reflecting something from the front element. The example with the 21mm shows this very clearly and Franks examples with the ND seem to agree. It seems better with rangefinder lenses, perhaps because they are so much closer to the sensor, or perhaps the front elements seem more curved. If you close focus it goes away, focus on the window and it's more pronounced.

Perhaps the design of the lens is an important factor in making it more obvious? I don't think it's as clear as curved front or back though.

However danstones original issue was how pronounced his version was, so that points to something wrong however what could be different to his FS than to mine or Ricks? Or perhaps the scenarios he shot in seemed especially bad. I guess his foreground elements were obscuring the window?

Frank demonstrates very easily that you can create very obvious reflections with an ND, which is problematic in itself. Again that's at the front of the lens. If those NDs were angled, not flat on, perhaps that would mitigate that. Or maybe those heliopans are not very good?

any more ideas?
Paul
 
An ND or UV or Polarizer on the front DEFINITELY create reflections like Frank showed. For this reason, I try not to have anything in front of the lens. This has been a problem on ALL my cameras.

But, from the OP examples, I've still yet to see ANYTHING that bad. Was there anything in front of the lens? (glass wise) I've seen other people's kit lens shots and they've never shown anything that was that bad either. If you have absolutely nothing in front of the lens, then either the lens has an issue or the camera must (in terms of maybe something missing on the sensor). Since your shooting conditions weren't anything out of the ordinary.
 
I came in this morning and realized the rear elements of my lenses are not flat, after all. So now I'm wondering if the reflection is coming from a flat surface of an interior element.

I'm going to reach out to Sony (once I figure out how) and see what they say. I'll keep you posted.

Thanks again, guys!
 
Rick Burnett said:
An ND or UV or Polarizer on the front DEFINITELY create reflections like Frank showed. For this reason, I try not to have anything in front of the lens. This has been a problem on ALL my cameras.

But, from the OP examples, I've still yet to see ANYTHING that bad. Was there anything in front of the lens? (glass wise) I've seen other people's kit lens shots and they've never shown anything that was that bad either. If you have absolutely nothing in front of the lens, then either the lens has an issue or the camera must (in terms of maybe something missing on the sensor). Since your shooting conditions weren't anything out of the ordinary.
Click to expand...

For most of these shots I had nothing in front of the lens. When we were on set the first thing we tried was removing the filters (thinking they were causing the reflections). The reflections looked the same with and without filters.

I feel you on the filters, though - I've been in situations (with other cameras) where you're trying to rig the filters to alleviate a weird reflection... ugh. Not fun.
 
Not at all. It's why, for night shooting, for me anyways, filters are an absolute no. Definitely keep us posted!
 
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