Dust or Central Obs

[hayju01]

Hi guys,

Something that has been bugging my imaging for a while is 'a round artifact', I usually try and align the imaging object away from it and it gets processed out just rather not have it in the first place.

Left of centre and down.

I have managed to discount a few things.

It's not

1. the camera (at not unless both SPC's have the same 'dust')

2. The barlow (I have cleaned and used 3 different one)

3. The Star Diag (I removed this and put the SPC straight into VB)

So the only two things I can think it can be is

A. Dust/Dirt on OTA lense

B. An artefact created by the Central Obstruction

I have my suspicion that it could be A. as the lense is a bit dirty but having read alot about 'Don't clean unless you have too' I want to be sure first. I have my doubts about B as the 'artefact' doesn't seem to be slap bang in the middle of the image.

All thoughts and comments most welcome.

Thanks,

Justin

[roundycat]

I think it is most likely dirt somewhere. Why are you using a diagonal with a camera?

Dennis

[brantuk]

Well - it could be atmosphere magnified - but it's only a guess. The focal length is over 2300mm so your pushing it close to 400x magnification - 200x to 250x ought to be more than enough for tight and crisp images. Much over that is when the image starts to go fainter and grainier

[hayju01]

Thanks roundycat. So i can swap the camera out for a EP and when I started i big probs getting image target onto chip so there was a lot of swapping :-)

[hayju01]

Well - it could be atmosphere magnified - but it's only a guess. The focal length is over 2300mm so your pushing it close to 400x magnification - 200x to 250x ought to be more than enough for tight and crisp images. Much over that is when the image starts to go fainter and grainier

Thank you. The unprocessed frame was taken last night with a 2.5 and tube extension so probably close to x4 which judging by your comments is way over the top

Next chance I get I'll bring it down a bit well ok a lot

Thank you both for your assistance. Should take delivery of Len brush any day so can look at tackling that.