Artifacts?

[John0z (John)]

Hi,

I have been trying out my Sony Nex5 camera with the GSO 32mm camera projection lens and have a few issues. The GSO has a T2 thread, so I use a T2 adapter for my Nex5. I shot a few photos of the Sun this morning - and I thought there were more spots than before, so moved the image a little and shot again - a lot of artifacts are showing in the same places, where do these come from?

I took another photo of the Sun with a different camera and eyepiece - Nikon Coolpix 4300 coupled to Williams Optics DC-28 - the Nikon set distance for focusing. This is much cleaner and shows the right number of sunspots.

Any ideas on what I can do?

-John

[seeker372011 (Narayan)]

As a guess, I'd suggest a sensor clean

[Steffen]

Yes, I too reckon those are dust bunnies.

Cheers
Steffen.

[John0z (John)]

Thanks everyone for the comments. I had a look at the sensor but cannot see anything on it. The camera does have a cleaning mode, but when I tried it - it said it had insufficient power, battery was at 25%. I am charging the battery now, and will try it again later. Then see if it makes a difference.

-John

[trent_julie]

Hi John,
I agree with the previous posters, there is some dust in your optical chain near or on your sensor. The "self clean" most likely won't be enough to get rid of this dust. Often this dust can be too small to see by naked eye easily.

Here is a short video I have found to get you started
http://www.youtube.com/watch?v=SqmJx...eature=related

Trent

[John0z (John)]

Hi,

Ok - I tried the cleaning mode - this is basically like a mirror lockup, except there is no mirror. I used a blower to blow onto the sensor. It still looks very clean. I tried Sony's suggestion of taking a photo at f/11 of a plain white wall and can see no artifacts as such.

I looked at other photos I had made and found that the artifacts were in a slightly different position on some photos. Then I checked the camera projection lens, and sure enough on the eyepiece side, there is a bit of lint. It appears that when projecting to give a higher magnification, the focus point changes until the lint started to get close to focus - does this make sense? I will have to wait a couple of days to try it out again since I am busy tomorrow most of the day.

Thanks Trent for your suggestion to check the optical chain. My eyes are not as good as they used to be, so using an illuminated magnifying glass helped to see the lint.

-John