NOTICE:
This was not an scientific experiment.
I was curious and had the opportunity (isn't both mars rovers by the way?).
I tried to achieve the best possible focus with both scopes.
SHORT STORY:
Well I'm not new to astrophotography (as started back in the 70ies) but the equipment today is different and so much more interesting.
I've owned small achromats, apochromats and newtons but no catadioptric scopes and never anything larger than 6 inch.
As with many of my hobbies I try to have keep a low budget but still keep sort of quality aspect to it.
So when it was time to switch my main-OTA I did not searched for the most advanced triplet or quadruplet design but instead planned to go for the cheapest semi-APO that matched my criterias; Skywatcher Evostar 80ED.
I did at the time use a pretty slow 4,5 inch Newton (!) and as almost everyone told me that even semi-APOs like SW doubles would beat all Newton designs.
But the strange thing was that I did not really find many comparative tests between these optical designs.
I mean everyone can search in astrobin but what about a test where you have tried to really compare i.e. 80ED semi-APO against a 150PDS Newton?
So I did exactly that
I did select these two as they as similar as I could manage.
And It didn't seem realistic to compare an 6 inch Newt with a 6 inch frac.
I did manage to lend a second Heq5 and could place the 80ED and 150PDS just 2 meters from each other.
The 80ED hade the Skywatcher 0,85x flattner och the 150PDS did use Baaders MPCC (1x) coma corrector.
I did use 40x180sec but as you notice I did have different cameras.
The guiding went well (<1" RMS on both) and I could use all light frames.
I haven't done anything fancy with the images more than stretch and zoooom.
This is not an conclusive test, more like fun, but I did notice that the contrast problems and soft stars that I was expecting to see in the Newts image wasn't there.
And the semi-APO did not match the images I had manage to get with my (lent) Esprit 100.
I did not keep the 80ED as my 150PDS did (almost) do the same thing (and this would be even more true when compared with a 130PDS).
Instead I went for a wide field frac that is now about to be upgraded to a true APO (quadruple)
My conslusion:
The Skywatcher ED-serie is very good (budget) semi-APO:s and the PDS-serie is quite nice as well if you manage the hassle with Newts.
The weight and smaller size of the ED:s is nice but apperture of a Newt it hard to beat (even for some real APO:s).
Question:
Have I done anything wrong and are there any other tests out there contradicting these results?
This was not an scientific experiment.
I was curious and had the opportunity (isn't both mars rovers by the way?).
I tried to achieve the best possible focus with both scopes.
SHORT STORY:
Well I'm not new to astrophotography (as started back in the 70ies) but the equipment today is different and so much more interesting.
I've owned small achromats, apochromats and newtons but no catadioptric scopes and never anything larger than 6 inch.
As with many of my hobbies I try to have keep a low budget but still keep sort of quality aspect to it.
So when it was time to switch my main-OTA I did not searched for the most advanced triplet or quadruplet design but instead planned to go for the cheapest semi-APO that matched my criterias; Skywatcher Evostar 80ED.
I did at the time use a pretty slow 4,5 inch Newton (!) and as almost everyone told me that even semi-APOs like SW doubles would beat all Newton designs.
But the strange thing was that I did not really find many comparative tests between these optical designs.
I mean everyone can search in astrobin but what about a test where you have tried to really compare i.e. 80ED semi-APO against a 150PDS Newton?
So I did exactly that
I did select these two as they as similar as I could manage.
And It didn't seem realistic to compare an 6 inch Newt with a 6 inch frac.
I did manage to lend a second Heq5 and could place the 80ED and 150PDS just 2 meters from each other.
The 80ED hade the Skywatcher 0,85x flattner och the 150PDS did use Baaders MPCC (1x) coma corrector.
I did use 40x180sec but as you notice I did have different cameras.
The guiding went well (<1" RMS on both) and I could use all light frames.
I haven't done anything fancy with the images more than stretch and zoooom.
This is not an conclusive test, more like fun, but I did notice that the contrast problems and soft stars that I was expecting to see in the Newts image wasn't there.
And the semi-APO did not match the images I had manage to get with my (lent) Esprit 100.
I did not keep the 80ED as my 150PDS did (almost) do the same thing (and this would be even more true when compared with a 130PDS).
Instead I went for a wide field frac that is now about to be upgraded to a true APO (quadruple)
My conslusion:
The Skywatcher ED-serie is very good (budget) semi-APO:s and the PDS-serie is quite nice as well if you manage the hassle with Newts.
The weight and smaller size of the ED:s is nice but apperture of a Newt it hard to beat (even for some real APO:s).
Question:
Have I done anything wrong and are there any other tests out there contradicting these results?
)
so I might wait until I naturally get to that point where I have enough parts to do that.
