View Full Version : Small, fuzzy spots on the image.


Glen Vandermolen
October 17th, 2011, 12:52 PM
My FS100 has small, black, fuzzy spots on the image. They're small, but very noticable when set against a bright background, like the sky. They appear to be dust particles.
I've used two different lenses and the spots are still in the exact same location with either lens. I've blown air on the sensor, even black balanced the camera, to no avail. Anyone have any ideas?

Doug Jensen
October 17th, 2011, 01:48 PM
The problem is not with the lens. There is contamination on the glass in front of the sensor. This is a common problem with the FS100 because the flange depth is so shallow. You're gonna have to clean it with sensor cleaning supplies. Tip: The image is flipped on the sensor, so if you've got a spot at the top of the picture, the dirt will be at the bottom.

Glen Vandermolen
October 17th, 2011, 02:00 PM
Thanks, Doug.
I take it sensor cleaning supplies are not the same as lens cleaning supplies? I am, of course, very cautious about touching the actual sensor. I didn't realize there was a glass plate in front of it. It must be very thin.

Glen Vandermolen
October 17th, 2011, 03:06 PM
Here is a still with the spots in the red circles.

Doug Jensen
October 17th, 2011, 04:50 PM
Glen, a dirty sensor will usually only manifest itself when you are shooting at a small f-stop. That's one of the reason I prefer to shoot everyting at f/4 and above. Looking at your still photo, I'd bet you were close to f/16. Just a guess.

I use lint-free swabs (look like Q-tips) and soft cotton wipes that I used to use to clean the heads on Betacam gear many years ago. They have worked great for me, but I couldn't tell you where to get them.

The first FS100 that Sony lent me before NAB arrived with a filthy sensor, so I had the advantage of experimenting with somebody else's camera. :-) I have cleaned my own FS100 several times since without any bad incidents, but you do have to be careful not to leave more crap that you clean off. BTW, I have never had to clean my F3 and it gets 10x more use than the FS100.

Disclaimer: Don't blame me if you ruin your camera -- but with that said, I have found that the sensor (or the glass in front of it) is not very fragile. I am not afraid to scrub it when necessary. But don't blame me if you ruin your camera!

Glen Vandermolen
October 17th, 2011, 04:56 PM
Thanks again, Doug.
You are correct, I was shooting at F22, almost closing down th lens. I really need a variable ND filter. I also prefer to shoot at higher (or is that lower?) F stops.
I used to use coffee filters for cleaning video heads. They don't leave any lint behind.

Jean-Philippe Archibald
October 17th, 2011, 05:47 PM
You should find sensor cleaning tools at your local pro still camera shop. I am using this: VDust Plus sensor cleaning kit ? removing water, oil stain. (http://visibledust.com/products3.php?pid=416)

I found it at a local shot in pack of 4 (they are reusable if keeped clean) with the cleaning solution for 21.95$ CDN. I don,t know if this is the same solution used on lenses. I have the exact problem a few times since I got the FS100, and so far I only had to dry clean the sensor (I am just using the VSwab without the solution). Pretty easy to do. You blow the sensor before and after.

Dave Morrison
October 17th, 2011, 07:26 PM
If you follow the instructions explicitly, you shouldn't have any problems cleaning the sensor. I've done it a bunch of times on my DSLR's. The only mistake I ever made was using too much of the cleaning fluid. If you put too many drops on the wand, you'll leave residue on the chip. You only want to get the wand JUST damp enough to take the dust off. The fluid must have a lot of alcohol in it as it evaporates very quickly IF you use it sparingly.

Rob Katz
October 17th, 2011, 08:10 PM
Glen, a dirty sensor will usually only manifest itself when you are shooting at a small f-stop. That's one of the reason I prefer to shoot everyting at f/4 and above. Looking at your still photo, I'd bet you were close to f/16. Just a guess.

I use lint-free swabs (look like Q-tips) and soft cotton wipes that I used to use to clean the heads on Betacam gear many years ago. They have worked great for me, but I couldn't tell you where to get them.

The first FS100 that Sony lent me before NAB arrived with a filthy sensor, so I had the advantage of experimenting with somebody else's camera. :-) I have cleaned my own FS100 several times since without any bad incidents, but you do have to be careful not to leave more crap that you clean off. BTW, I have never had to clean my F3 and it gets 10x more use than the FS100.

Disclaimer: Don't blame me if you ruin your camera -- but with that said, I have found that the sensor (or the glass in front of it) is not very fragile. I am not afraid to scrub it when necessary. But don't blame me if you ruin your camera!

glen-

i hope the submitted info provides you thoughts as to resolving your issue.

doug-

not to hijack the thread but to ask two related questions:

why do you think the fs100 appears to be prone to a dirty sensor?

when you say "shooting at everything above f/4" do you mean those f/stops headed towards f/1.8 or do you mean those f/stops headed toward f/22?

again, thanks in advance and i apologize for the newbie type question, (it was the way you phrased your answer that confused me)

be well

rob
smalltalk productions

Doug Jensen
October 18th, 2011, 05:22 AM
Rob,

I think the FS100 is prone to getting a dirty sensor because, compared to other cameras, the sensor is barely recessed into the camera body. When you take off the lens, it is sitting right there practically in the open air where anything can land on it. The more you change lenses, the more chances there are for stuff to stick.

When I say ""shooting at everything above f/4" I mean with a larger aperture opening -- f/4, f2.8, f2, etc. F-stops are fractions, so f/4 is actually a larger number (and a physically larger opening) than f/16. That's why when you change from f/4 to f/16 it is referred to as "stopping down" the lens. " Down" means a smaller hole, "up" means a bigger hole.

I hope that helps.
http://www.vortexmedia.com/DVD_FS100.html

Rob Katz
October 18th, 2011, 09:32 PM
doug-

thanks for the quick and thoughtful response.

be well

rob
smalltalk productions

Serena Steuart
October 20th, 2011, 04:55 AM
Thanks again, Doug.
You are correct, I was shooting at F22, almost closing down th lens. I really need a variable ND filter. I also prefer to shoot at higher (or is that lower?) F stops.


At f/22 you will also have suffered diffraction softening of the image. A fixed ND filter (0.9) would have got you into more useful territory, but people seem to like the idea of a variable filter.

Glen Vandermolen
October 21st, 2011, 10:08 PM
At f/22 you will also have suffered diffraction softening of the image. A fixed ND filter (0.9) would have got you into more useful territory, but people seem to like the idea of a variable filter.

Hi Serena,
The reason some of us are leaning toward a variable ND filter is because the FS100 could use an ND filter wheel, like the F3 and AF100. Lacking this, the variable ND filter is a cheaper option.
It's just easier - and cheaper - to use one variable ND filter instead of several ND filters in varying degrees of shading.
I expect fixed shaded ND filters would be more optically clean, but I'll lose a little of that for the convenience of a variable filter.
Some camera operators don't like variable ND filters, but whatever. I'm willing to give one a try.

Doug Jensen
October 22nd, 2011, 06:47 AM
As I demonstrate in my FS100 training DVD, there are no detrimental side effects to using a variable ND polarizer unless you really go to the extreme limits of the filter. And then the side-effects are hard to miss.

Otherwise (at least with the two brands I have tested) there is no color-shifting, unusual patterns, image softening, or any other problems. The image just gets darker or brighter -- which is exactly what it is supposed to do. I would not hesitate to use a variable ND on any camera.

Richard Crook
October 22nd, 2011, 08:41 AM
Before you start touching ANYTHING to the sensor, get a simple hand blower and blow air into the sensor, holding the camera straight down. This works most of the time. Swabbing the sensor should be done as a last result. Be careful not I touch the blower to the sensor,