Spots 'n stuff

We had a visitor to our kitchen last night, a centipede, much to my wife's fear and annoyance. So i grabbed my Pentax A 50mm and put it on the tubes and started snapping away, I then reversed the lens holding it with my fingers as the adapter hasn't shown up yet. Got some really close up shots. I then imported them using Lightroom 2 to tweak them up a bit and was horrified to find a shed load of spots all over the photos, I've done a dust alert and it's clean and as hard as I've tried I cannot see any dust on the lens. What am I doing wrong?

Dust.jpg


Drying off after falling in wet sink.


Dry and back on the move.

I can't see anything in your first shot

Nice shots of a horrible insect! When I was about 12 I was bitten on the neck while asleep in my bed by a 10" one! Now I'm not a fan

Those dust spots on the centipede shots don't appear to be in the same place?

Perhaps you should post a shot of a white wall?

Yes, they are in a different place.I wonder if you were almost in focus on spots on the rear element of the lens?

Confession they were cropped, differently. Please take a look at the next two.

1st. with Sigma105



2nd. with a Pentax 50 on tubes



BTW Tim I'm really glad we don't have any of those really big creepy crawlies in GB. If this thing was 10 inches I certainly wouldn't be getting this close and personal.

Oh well, no doubt about that then, you have a lot of muck

I foresee an arctic butterfly in your future

"Arctic butterfly?" you'll have to excuse my ignorance I've only recently crossed over from a bridge camera so my next question is why does it not appear on the dust alert (Dust.jpg) picture earlier?

Confused

Do you mean one of these?
link

He means one of these. Brilliant things. Worth the money.

Found it on SRS £44.95 cheers for your help guys... although I'm still wondering why the dust alert still says my sensor is clean?

You could try a rocket blower first (plenty of inexpensive perfectly decent ones on ebay), that will probably shift most of the dust, but any really sticky bits (e.g. flower pollen) will probably need something more direct like the arctic butterfly.

Personally I don't have much faith in the dust alert system. It does occasionally work but it often misses specks that are visible in photos.

Dont use the blower....just the butterfly!....the blower puts bits into all kinds of wierd places!

When using the dust alert, try it with the aperture as small as your lens will allow. The dust is not on the sensor itself, but on the AA filter in front of the sensor. Shutting down the aperture will allow the light that reaches the sensor to "focus" slightly in front of it, helping to show anything that could be there. I used to take a long exposure of a white wall with the aperture at f:22 with my K10D to check for dust.

The Arctic Butterfly will also throw "big chunks" (relatively speaking) in weird places. There is no free lunch anywhere.

Noobody has yet mentioned using the sensor cleaning system of the camera itself. Not once, but several times to see if the dust can be dislodged.

If not, with the camera pointing downwards, the rocket blower to remove more stubborn dirt.

I have yet to use any contact method for cleaning.

Yves said
The Arctic Butterfly will also throw "big chunks" (relatively speaking) in weird places. There is no free lunch anywhere.

Yves, do you use the Arctic Butterfly whilst it's spinning

Greg