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Old 31-08-2017, 06:25 PM
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xelasnave
Gravity does not Suck

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Using "cheap" objective and filter.

So I have an old Celeston 150 mm refractor which has a doublet for the main objective.
I have used it with a camera and there were color issues which others would have experienced.
Would using a filter say green basically remove the color problem, which I believe comes from different colors focusing at slightly different points.only the focused part green will be captured.
So being Chanel specific should make a cheap scope usable with a filter wheel?

Another idea.
A friend was over and he asked why I didn't use the 150 mm refractor and I explained how triple is what you need ..he said well just change the lens to a triplet well what can you get...but I would have to change the focuser to something better...yes well do that and you will have a good scope.

I wonder where you could pick up a Triplett lens...must check if Andrews have 150 mm triplet binoculars.
Never thought of such an approach.
Maybe there is some fancy sixtuplet lens army surplus.
Alex
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Old 31-08-2017, 07:18 PM
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cometcatcher (Kevin)
<--- Comet Hale-Bopp

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With an achro refractor you will still get some CA with RGB filters, although it will be less than with one shot colour, I thunk. They do have potential with narrow band as the bandpass is too narrow for CA.

You will also get a bit less with fringe killers, but not enough with a 150mm as that aperture is horrid for CA with a standard achro doublet imo.
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Old 01-09-2017, 06:31 AM
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Atmos (Colin)
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You'd be better off buying a Sky Watcher Esprit 150mm than upgrading yours to a triplet
https://www.astronomyalive.com.au/sk...refractor.html

Certainly not cheap but cheaper than most 6" APOs
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Old 01-09-2017, 12:27 PM
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xelasnave
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Quote:
Originally Posted by Atmos View Post
You'd be better off buying a Sky Watcher Esprit 150mm than upgrading yours to a triplet
https://www.astronomyalive.com.au/sk...refractor.html

Certainly not cheap but cheaper than most 6" APOs
I saw one in Bintel..in the flesh as it were...magnificent I thought.
I didn't see a 100mm but that's what I am thinking to get if I can stick with my program.
But I may be happy with the eight inch, cheap way out.
I think what I get will be better than I have done before, which was primitive by todays standards, for me its like playing the guitar I am not flash but I enjoy it ... Just capturing the stars that were above the other night was exciting...I had an eleven minute run where the mount was perfect. And I recall that if you got it balanced just right it worked well.

What would be nice is a decent mount with the 80mm the 100 mm and the 150 mm each carry cameras but work in a flip mirror in each so you could take a real peak without removing cameras...I am also thinking an 80mm on eq5 to take on short trip up North but first set up eq6 and see if I can make it portable special trolly so I don't carry that sort of thing..

I would like to see what I can get with this cheap 50 to 200 lens that I picked up with the camera. It can be focused from lap top so that could be fun.
Even thought of using the old lxd 55 mount on a cut down tripod carrying just the camera with the 50/200 and as ruff as that mount is with relatively short exposures you are going to get a lot of good captures umong the bad.
but that mount worked good enough for that approach.
Alex
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