[Leica] Sensor cleaning tips

[douglas.sharp at gmx.de (Douglas Sharp)]

I posted this a while back, but it really can't hurt to post it again:

The smaller the aperture, the more spots you will find - I regularly 
shoot a predominantly light subject with a very small aperture - shoot a 
cloudless sky, overcast sky or a piece of paper - to check for sensor 
spots.

Blow up the contrast in PS or LR (or whatever software you use) and you 
will very probably get a nasty surprise - there are usually a lot more 
spots than you imagined, most of which are not necessrily visible i a 
shot, but they are there.

But don't get paranoid about it, the tinier ones are almost always 
easier to remove than greasy spots or smears.

Shooting test shots with a Noctilux wide open will NOT help you to find 
sensor spots - don't bother about correct exposure or really precise 
focussing, the spots will show up anyway. The smaller the aperture the 
better.

To avoid having to use swabs and fluid, first shoot 2 to 5 shots before 
and after using a blower and a brush (Arctic Butterfly) on the sensor to 
find out whether the spots are at the same location every time. Don't 
use compressed air cans, they can cause all sorts of damage through 
pressure, low temperature, propellant droplets and the like.

There are compressed air cans that you can pump up yourself, but a 
rubber bulb blower is usually sufficient. Though a warning note here - I 
had one that perished inside and blew sticky blobs of rubber onto a 
focusing screen and I had a hell of a job removing them.

If spots change location or disappear, they were caused by dust, if they 
stay where they were in every shot, they are caused by something 
sticking to the sensor surface. This means you'll have to get out the 
swabs and cleaning fluid.

Never use swabs without having removed loose dust beforehand - you could 
end up scratching your sensor.

Don't expect to be able to see spots on your sensor with the naked eye - 
you'll hardly ever find them.

When viewing a shot with spots, remember that the sensor records the 
image upside down and wrong way round- this means, for instance, that a 
spot at the top of the test shot is at the bottom of the sensor.


First step: use a blower to get off any loose dust. Hold your camera 
with the mount downwards - gravity helps too

Second step: Arctic Butterfly brushes are very good and pick up all 
loose particles and a lot of the more resistant dust.

Third step: if you still have sensor spots, the only remedy left is 
swabs and cleaning fluid.

My experience is that swabs work very well if you follow the 
instructions and do it carefully. It often only gets the sensor really 
clean after 2 or even 3 passes with clean swabs each time. So you may 
have to repeat the procedure starting with test shots gain. This can get 
very frustrating as sometimes the swab may just relocate a stain to 
another part of the sensor.

Do not use excessive pressure on the swab, the cleaning fluid is doing 
the work of dissolving stains caused by grease or condensation.

Not necessarily applicable to digital M users:

if you are using zoom lenses, these often pump dust into the mirror box, 
so blow them out with the blower before use. Also use the blower/arctic 
butterfly brush on focusing screens and the mirror, these are also often 
a source of dust. Be careful not to touch the sides of the mirrorbox or 
parts of the lens mount with the brush, these may be lubricated and your 
brush could pass on this grease to the sensor.

I've found it pays off to clean the sensor with a blower and brush and 
check for spots before you set off anywhere with your camera - it takes 
a lot less time than despotting all your shots when you get back home again.

Here's a series of shots before and after cleaning

Sensor spots to the right of the tower:
http://gallery.leica-users.org/v/DMS/Bits+and+Pieces/Spots.jpg.html

First wipe - this can sometimes move a spot to a different part of the 
sensor - to the right of the tower but closer to it:
http://gallery.leica-users.org/v/DMS/Bits+and+Pieces/First_wipe.jpg.html

Second wipe:
http://gallery.leica-users.org/v/DMS/Bits+and+Pieces/second_wipe.jpg.html

The remaining spots are birds ;-)

Cheers
Douglas