Question about sensor cleaning...

[AlwaysOnAuto]

I just dealt with my first spot on a sensor problem on my NEX 7, which is fairly new to me (bought it used).
I'm wondering what the best test shot is to see if the sensor is really clean.
The spot showed up in the sky of some photos I took at the beach yesterday.
Is a clear blue sky the best image to use or is there some other way of doing it?
If shooting a 'white card' or some such surface, how do you know you haven't blown the high lights out such that the spot wouldn't appear if still there?
Sorry if all this sounds like an amateur talking, but it is. I've never had any 'dust bunnies' in my Nikon D7000 because I've never changed the lens on it much until recently.
The NEX cleaning mode didn't do anything for removing the particle, I had to resort to the blower to get it off.
Any help on what to shoot as test shot would be appreciated. I like to keep my gear fastidiously clean if at all possible.

[purplehaze]

Oh, glad you were able to get it off. I hesitate to use the blower on the sensor, as I figure I am just as likely to blow dust on as off.

As to your question, I just shoot a blank wall, and then push the contrast slider all the way in PP to make them show.

[AlwaysOnAuto]

Thanks Janis. At first I didn't think I even had one on the sensor as it looked 'clean' to my old eyes. I almost resorted to taking a macro shot of it just to really check it out closely, but then I got a flashlight and shed some light on it and there it was. It must have been electrostatically charged since the cleaning mode didn't seem to phase it at all. We've been having some really dry days here lately so it doesn't surprise me. I'm just glad I was able to get it off.
What color wall do you shoot your picture of?
I don't suppose a dark wall would work too well would it?

[Shadowman]

I just dealt with my first spot on a sensor problem on my NEX 7, which is fairly new to me (bought it used).
I'm wondering what the best test shot is to see if the sensor is really clean.
The spot showed up in the sky of some photos I took at the beach yesterday.
Is a clear blue sky the best image to use or is there some other way of doing it?
If shooting a 'white card' or some such surface, how do you know you haven't blown the high lights out such that the spot wouldn't appear if still there?
Sorry if all this sounds like an amateur talking, but it is. I've never had any 'dust bunnies' in my Nikon D7000 because I've never changed the lens on it much until recently.
The NEX cleaning mode didn't do anything for removing the particle, I had to resort to the blower to get it off.
Any help on what to shoot as test shot would be appreciated. I like to keep my gear fastidiously clean if at all possible.

Unless you have a light shining on the wall you shouldn't overexpose your whites.

[Stagecoach]

I simply take an image of a clear sky (exposed roughly right) at f/22.

Another option that works well is to produce a white screen on your monitor and shoot that, saves the walk outside.

[AlwaysOnAuto]

I suppose that would work too IF I can assure myself all the pixels of the monitor are working as they should be.
The sun has gone down or is about to, right now it's actually clouding up as there's a 20% chance of RAIN here tonight.
Guess I'll give the monitor a try. I took a picture of a diffused LED flashlight to use on my laptop as a light box for copying slides with my macro lens. Maybe I can use it to some effect here.
Thanks for the idea!

[Stagecoach]

I suppose that would work too IF I can assure myself all the pixels of the monitor are working as they should be.
The sun has gone down or is about to, right now it's actually clouding up as there's a 20% chance of RAIN here tonight.
Guess I'll give the monitor a try. I took a picture of a diffused LED flashlight to use on my laptop as a light box for copying slides with my macro lens. Maybe I can use it to some effect here.
Thanks for the idea!

I think that after a little bit of experience you will very soon be able to differentiate between a pixel missing on the screen and a mark on the sensor. If concerned, simply take two shots of the monitor, framing each slightly differently.

On my sensor I have two spots, at f/22 one shows up in the image as a fairly sharp small black circle, the other as a lighter larger circle so beware they do not all look identical.

[AlwaysOnAuto]

I'll need to work on this some more. I took a shot of my monitor with my 'light' picture on the screen.
It turned out a perfect shade of grey for some reason, operator error would be my first guess.
I was able to see a spot though up at the center top of the image so I think the dust bunny may have relocated a bit north but not off the sensor completely.
I'll update this thread as I delve into the realm of how to shoot a white screen and get it to turn out actually white.

[Stagecoach]

+2 Stops but it really is not critical, light grey or a blue sky is fine for evaluation.

Hold camera pointing downwards with mirror up, gently blow in with the hope that dust will fall downwards due to it's mass. Take another picture and assess.

Sometimes I use my blower to also suck out rather than blow in.

[pnodrog]

I'll need to work on this some more. I took a shot of my monitor with my 'light' picture on the screen.
It turned out a perfect shade of grey for some reason, operator error would be my first guess.
I was able to see a spot though up at the center top of the image so I think the dust bunny may have relocated a bit north but not off the sensor completely.
I'll update this thread as I delve into the realm of how to shoot a white screen and get it to turn out actually white.

If the photo of your screen turns out at about 18% grey it just means your exposure is correct. Even snow should be grey....

[NorthernFocus]

Dude, you think too much. Where do dust bunnies show up on photos? Just go shoot that

Speaking of dust bunnies and monitors. Here's an embarrassing confession. This morning I was processing an older image of a coastal scene including some sky that had more than its fair share of dust bunnies. In LR I was using the spot removal tool and it was working well except for one particular spot. I increased the size of the brush I was using a couple of times trying to get rid of this one particular spot with no noticable effect. I finally got rid of it by using my thumb and wiping it off the screen

[NorthernFocus]

If the photo of your screen turns out at about 18% grey it just means your exposure is correct...

Or at least technically accurate

[Mike Buckley]

I finally got rid of it by using my thumb and wiping it off the screen

That's how I get rid of almost all of my dust bunnies. It works every time.

[DanK]

AOA (can you please add your name to your profile--we use real names here),

Just take a picture of this http://www.pbase.com/copperhill/image/95174363/original at f/22. If you have a reasonable exposure, it will show the dust bunnies. There is no reason to worry about bad pixels on the monitor; they would look nothing like dust bunnies.

No harm in using a blower, as long as it does not have a propellant that can leave crud on the sensor. I use a rocket blower. My proceedure is this:

1. Start with the blower, with the lens mount facing down.
2. If that doesn't work, I gently use a static brush. You can get one from Copper Hill. That often is enough.
3. If that doesn't work, I do a wet cleaning, using copper hill stuff again.

Dan

[pnodrog]

Rather than use the blower to blast the dust around the camera innards. Squeeze it first and then try and get it to suck the dust off.

[loosecanon]

Surely the test is to photograph something with a light continuous tone, but not to focus on the target so any image is due to dirt. It just happens that it is easier to see dirt on a light blue background than anything else, and the sky is blue and tends not to have static blobs in it.

[CBImages]

if you use a blower press it several times well away from your camera just to clean out any dust that might have settled inside it since you used it last.

Don't worry about damaging your sensor as most cameras have a filter over the actual sensor and it is this filter you are cleaning and not the actual sensor itself. Obviously you still need to take a certain amount of care but there is no need to be overly worried.

Use a blower in the first instance, for more stubborn dirt I use a LensPen http://www.wexphotographic.com/buy-l...-tool/p1529777

For really stubborn dirt I use one of these, they are amazing http://www.amazon.co.uk/Eyelead-Dust...ensor+cleaning

It's a gel pad on a stick, the gel is sticky enough to pick all dirt off you sensor or lenses yet doesn't leave any residue whatsoever.

Hope this helps.