9 Orange Spots during Shoot (GH4)
 

Hi All,

On the image below, you can see 9 orange spots that have become illuminated during an outdoor video shoot for a wedding.

http://i1379.photobucket.com/albums/...pszxoelubf.png

Does anyone know if this is due to the sensor, or to do with the aperture of my camera or lens? I've done a bit of reading about this issue, and it seems I'm not alone. Fortunately, I have shot with it since with no problems.

I do wonder if this will happen again though, and if it does, I guess I will need to return it.

Thanks to anyone who is more aware than I am and can share details regarding the issue.

Kind regards,

Craig

Re: 9 Orange Spots during Shoot (GH4)
 

Did you have a filter on the lens and if so what type of coating does it have?

Re: 9 Orange Spots during Shoot (GH4)
 

I was shooting with the 12-40mm f/2.8. No filter, but obviously it was raining. Could the rain have caused the dots?

Thanks Jim.

Re: 9 Orange Spots during Shoot (GH4)
 

OK that's interesting. It may be that a drop or two on the front element acted as a tiny lens to form the smaller image of those orange buoys. Usually defects on the front element have little effect on an image. Were you at the shorter end of the zoom? It should be pretty easy to test the theory with a couple of drops of water and a point light source.

Re: 9 Orange Spots during Shoot (GH4)
 

That sould make sense, Jim. Thanks. I don't think I was at the extreme wide of the lens, probably somewhere in the middle. It's hard to say, as it was so long ago that I filmed this.

Thanks though - I haven't noticed it since, so the sensor I can assume is fine. I think what you have said makes a lot of sense too. I'll check the footage again to see if I can find any other issues arising on that day to see if it was just the buoys or not... they seemed to be pretty luminous in the footage though, frustratingly.

Re: 9 Orange Spots during Shoot (GH4)
 

If you are talking about the orange/pink dots up around the tree line and into the sky I'll tell you exactly what it looks like to me. I've seen almost identical spots on the Sony EX cameras. We were told that they needed the sensor blocks replaced. A brilliant techo I know said lets have a look.

Using high power magnification he discovered that it was actually minute particles sitting on the sensor surface. He actually went to a special surgical positive pressure clean room and used a fine surgical vacuum sucker to suck out the particles and lo and behold the spots disappeared. Way cheaper than new 3 CCD blocks. If the dots get worse as you close the iris down and nearly or totally disappear when the lens is wide open I would think this would almost confirm the case. Point the camera at a bright light source and stop right down to check the theory.

How easy is it to clean the sensor on a GH4 I wouldn't know but I would be checking it out for sure.

Good luck

Chris Young
CYV Productions
Sydney

Re: 9 Orange Spots during Shoot (GH4)
 

Given the orange buoys, and the spots being the same color and roughly the same distribution, I'd vote for a reflection internally on one of the lens elements. Some Sony video cams had a "blue dot" issue with bright lights at certain focal lengths - I experimented and found it was something causing a reflection in the lens, again, only at certain focal lengths, but definitely repeatable, you could actually produce multiple dots at just the right spot as another element could pick up on the first reflection on the other element surface...

I'm guessing that the rather "bright" orange probably stood out against the grey and green "background", and one of the lens element surfaces caused it to "ghost" appear on an internal lens surface, which was then captured by the sensor.

Sometimes cameras catch some "strange" phenomena that can ultimately be traced to shutter abnormalities, internal lens reflections, and I suppose sometimes "real ghosts" <wink>. Happy halloween...