Quote:
Originally Posted by Heian
Al,
I'm guessing this is a situation where the use of an aperture stop in front of the SA would be an advantage...
What do you think would happen if you just put a mask over the front of the scope? 
cheers
Mark |
I dunno, Mark. A mask in front of the scope will reduce the aperture, so it will change the f/ ratio, reduce resolution and then the exposure time making it longer... a catch 22 I think.
I think maybe it's just something to be aware of when capturing spectra of the dimmer stars. And, it's another reason why a standard camera response curve is a problem
. A standard response curve wouldn't compensate for an increase in scattered blue light from moonshine
. I think I'm starting to realise why it's important to do a camera response curve for each session at least, and maybe each spectral class.
In this case, actually, it's the exposure that's important.
Quote:
Originally Posted by Merlin66
Al,
I think you're getting the hang of this game!! Those spectra are great!
If and when I write "the" book I'll ask your permission to use them!!
|
Thanks Ken. I feel like I'm getting head around it, slowly at least... though sometimes I think I'm doing everything the same but VSpec obviously thinks otherwise and spits me across the room
.
I've come to the conclusion that the filter wheel has got to go! I can get the SA 30 to 40mm further up the light train by not using the filter wheel. That gives me 30 to 40mm more back focus. Hopefully that will allow me to increase dispersion with the f/6.3 reducer with my short barlow body or possibly the star diagonal
. I feel another experiment coming on
.
I think I'll leave my SA in the barlow body if that works out OK. I don't use my 2x barlow much anyway now I have a Powermate
. Will that make it a "SArlow"?
Al.