Starter scope for narrowband?

morls (Stephen) · #1 02-11-2019, 12:10 PM

I'm starting to think a little more about trying some narrowband imaging from suburban Melbourne. I wonder if I could ask for a few pointers? I have an NEQ6, and I'm just looking for info on suitable OTA's, not cameras.

I'm thinking about a Saxon/skywatcher level refractor.

1. What aperture/focal length is recommended for beginners?
2. Is it true that an achromatic refractor is adequate for narrowband?
3. Are there any "tried and true" options?

Cheers
Stephen

casstony · #2 02-11-2019, 01:37 PM

You probably need to look at ED scopes in order to get a decent focuser, not to mention better optics.
Any 4" f/7 or smaller ED doublet or triplet that turns up in the classifieds should be ok to start with.

With a reducer/flattener on the 4" f/7 scope you're at 560mm focal length; anything under 600mm is easier for beginners to learn with.

morls (Stephen) · #3 02-11-2019, 01:49 PM

Thanks Tony.

Merlin66 (Ken) · #4 02-11-2019, 04:09 PM

Stephen,
+1 for the ED refractors. They are very good performers and will satisfy you for a long time. Most of them are keepers!

I have three ED80 - two used for solar imaging (CaK and Ha) -doesn't come much more narrow band than that

The other is used for grating/ prism spectroscopy.
Hope that helps.

morls (Stephen) · #5 02-11-2019, 05:55 PM

Thanks Ken.

xelasnave · #6 03-11-2019, 06:47 PM

I am very impressed with my 80mm espirit.
I had purchased an eight ,f5 which I thought would be it...but I haven't used it since I got the ,80mm sure things to come etc..but if you got an 80 mm and nothing else you would be years extracting its potential..in my view..
It's sortta like moto cross..who would ride a 125???
Go for a 250...if you can really ride a 125 you will be better than everyone when you go 250...80 mm is a great to start and never leave...I have a 115mm now but I think it will be down hill for a long time.
Alex

Nikolas (Nik) · #7 03-11-2019, 07:05 PM

I have an Orion ED80 Refractor which is the same as the skywatcher I've upgraded the focuser Front element is Fpl53 glass etc. Same as the Skywatcher Saxon Brands as they are all Synta scopes, You can't go wrong with these if you want to do Narrow (or Broadband)

morls (Stephen) · #8 05-11-2019, 01:57 PM

Thanks Alex and Nik. ED80 it is!

morls (Stephen) · #9 05-11-2019, 07:26 PM

I think my budget will be too tight for an ED80 any time soon...

I've read somewhere that an achromatic scope is OK for narrowband, as the aberrations aren't an issue. Can anyone confirm or otherwise?
Cheers
Stephen