View Full Version : Dust on the sensor
02-21-2008, 06:11 PM
Quick question.... What is everyone doing to double check that we are not having any dust on the sensor during a shoot?
Let me give a quick example--- I know the obvious, like quickly changes lenses and don't leave it exposed for too long... change lenses if able in a dust free environment (IE: inside somewhere).
But lets say you want to gently shoot some air at the sensor- is that okay?
(again, I know about not shaking the can of air or holding it upside down.. He he...)
02-21-2008, 07:42 PM
I have a follow up question about the sensor. Does the sensor always carry a charge like my D1X, that will cause dust to stick like a magnet? There is a set procedure that one needs to take when cleaning the Nikon, i.e., using an external power supply to open the shutter and to break the electrical connection so the dust can come off the sensor more easily. Does the RED manual specify anything like this sort of procedure for cleaning?
02-21-2008, 09:47 PM
I wouldn't use a can to blow air into the camera! Better to use a bulb style blower to avoid possible propellants ending up on your OLPF (the optical low-pass filter in front of the sensor).
I have had dust on the OLPF a couple of times. In both cases it could be seen on the LCD just by pointing the camera at a blank field (like a white wall) and then panning and tilting around a bit. The little blurry blob jumps out at you. Note that this was before they moved the OLPF further from the sensor. I believe that the visual effect of typical dust is now much less than it was, but I've not seen one yet. I am now in the habit of checking for dust after every lens change.
Also note that in both cases the dust was easily visible by eye when shining light down the barrel of the camera with lens off. I used a bulb blower to remove the dust -- came off very easily.
Note that in one case, the dust made its way onto the OLPF without a lens change. The dust blob must have been in the chamber already and then made its way onto the OLPF at some point during the day.
02-22-2008, 02:44 AM
Some may be getting the sensor and OLPF mixed up. The first piece of glass in the mount is the OLPF, the sensor is protected behind the filters.
IF the OLPF is far enough away from the sensor any dirt should NOT be seen. I'm not sure with the RED if this is the case. Someone else may confirm.
You could do a proper dust check with a point source of light, and a high res monitor such as a SONY HD24 or 24" TV Logic. Any dirt on the sensor will show up on the screen as a dark spot, not show a parallax and not move. If there is something on the sensor it WILL be recorded, and MUST be cleaned.
If the dark image or spot does move around, that would most likely be on your OPLF. This practice takes time to master, and generally done before the job starts.
02-22-2008, 05:16 AM
You're correct, I was forgetting about the OLPF being in front of the sensor. Having said that, is there a chance dust could work its way behind the OLPF onto the sensor and if so, is that a job for Superman? Is it even possible for an owner to clean behind the OLPH? A follow up to that is does the OLPH come off with the PL mount when changing to the Nikon mount? Not having a camera yet, I'm having to guess what the arrangement is. Thanks in advance for the help.
02-22-2008, 07:45 AM
If you are shooting at small apertures you will see the dust on the sensor.
Shooting at F4 or closer to WFO will make any dust very difficult to see. Unless it is really big.
02-22-2008, 07:54 AM
So how do you practice safe cleaning?
Electro magnetic loupe cleaner?
What are you guys doing or using?
02-22-2008, 10:30 AM
See this thread (search is your friend):
People seem to like the Visible Dust loupe and brush combo (though, like all cine gear, it's arguably overpriced). There's also a recommendation for fluid further down the thread.