Flats

[AlistairW]

Hello,

My imagining train is static and I rarely have to take it apart. So, I tend to take a set of flats and use them for a few months. 

However, I was wondering, - if I were to clean my Objective lens (whilst leaving everything else - as is), - do I then need to take a new set of Flats. Or put another way, does the dust on the Objective make any difference to Flats (as I though the dust particles nearer the sensor were the only contaninents of concern) ?

Thanks

Alistair

[wimvb]

Dust on the objective shouldn't affect your flats. Dust is moving there all the time anyway. Any surface further away than a flattener/reducer/coma corrector is probably too far from the sensor to matter much. I would take new flats only if a problem shows up.

(For a mobile setup it's an entirely different story of course. The bouncing around during assembly and disassembly can knock dust off any surface.)

[ollypenrice]

Here's your answer!

Try as I might I can't wipe that black thing off the front of my SCT but it seems to have no effect on the view...

Dust on the objective has no perceptible effect on the flats, I promise.

lly

 

[wimvb]

3 hours ago, ollypenrice said:

Try as I might I can't wipe that black thing off the front of my SCT but it seems to have no effect on the view...

Not on the view maybe, but certainly on the image. Are there dso images around with pinpoint stars from scts and/or other reflectors? Legitimate question, because I haven't looked around. Time to fire up the Google engine, methinks.