How bad could a achromatic refractor be? [Archive]

View Full Version here: : How bad could a achromatic refractor be?

h0ughy

27-09-2013, 08:23 PM

while getting a mono CCD I was pondering - could one image successfully with large achromatic refractors?:question:

MortonH

27-09-2013, 08:38 PM

Some of the recent comet pics were taken with a 120mm f/5, I believe.

h0ughy

27-09-2013, 08:40 PM

any idea which ones

Wavytone

27-09-2013, 08:56 PM

With a mono camera and colour filters to reduce the secondary spectrum, absolutely yes. The only issue will be choosing a sensor with a pixel size to suit the focal length.

h0ughy

27-09-2013, 08:59 PM

well i bought a morovian g2 8300, was just thinking?

multiweb

27-09-2013, 09:01 PM

You clearly weren't. You're gonna need another trailer. :lol: :P

h0ughy

27-09-2013, 09:03 PM

what do you mean:P

MortonH

27-09-2013, 09:05 PM

http://www.iceinspace.com.au/forum/showthread.php?t=111951

This thread may also be useful

http://www.iceinspace.com.au/forum/showthread.php?t=112207

Lee

27-09-2013, 09:07 PM

You can do narrowband no prob, and RGB less well (focusing in between), but luminance won't be much good....

h0ughy

27-09-2013, 09:12 PM

thanks Lee - was thinking of a wide field type scope but i now see that probably wont work out

h0ughy

27-09-2013, 09:18 PM

thanks for the links morton

cometcatcher

27-09-2013, 09:40 PM

Here's another link.

http://www.iceinspace.com.au/forum/showthread.php?t=112179

I'm still experimenting. Some star fields are more problematic than others. The Orion neb and associated stars are a real test.

DavidU

27-09-2013, 09:52 PM

Dave, here is an interesting thread with our Bert included. Some great inpho
http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Number/2081256/Main/2056336

pluto

27-09-2013, 10:31 PM

I've done a bit of narrowband imaging with my skywatcher 120mm f5 achro and it's pretty good. The only scope I have to compare it to is my SW ED80 and I think for NB it's almost as sharp and with much more light grasp, just let down by the average focuser.
However, while it's been great bang-for-buck, I'm back using my ED80 as I wasn't getting nice looking stars and I figured if I'm going to spend hundreds on a new focuser, in the hope that it'll fix my isssues, I may as well save up and get a bigger ED refractor, an RC, or a newt.

I still find it great for visual observing though :D