First Scope Decision - Opinions?

Outcast (Carlton) · #1 22-07-2013, 10:10 PM

Now, I know that this question is going to throw up a lot of opinions but, I would like some advice before I spend my hard earned.

Fairly new to stargazing although, thanks to the advice on this forum, I purchased some good binoculars (10x50) a few years ago & have spent some time enjoying night sky views (between clouds & rain storms) up here in Cairns.

I have read a large number of articles & posts on first scope purchases. After careful consideration of what is important to me, I have decided that a short tube refractor on an Az/Alt mount is the scope that I am likely to use often due to simplicity & portability. I know this might not open up the entire heavens to my eyes but, no point in having a large aperture scope, if it never gets used.

So, my question is this: I have a budge of approximately $1000 (dependant upon wife mood at any given time) & have been looking at two refractors:

Scope A: Skywatcher SW120 Achromatic on Az/Alt mount

Scope B: Stellarvue SV80ED with an Az/Alt mount to be purchased

Post Script: Scope C: Meade 5000 series 80mm APO that just popped up in the classifieds

I have read about Chromatic Aberration associated with Achromatic scopes but, how bad is it likely to be? Should I go for the larger aperture, lower quality scope or for a little bit more money (but within budget) go for the smaller aperture but, better quality?

Thoughts, opinions, advice please

Logieberra (Logan) · #2 22-07-2013, 10:30 PM

Have you looked into the North Group 127 apos? They were running hot for a while, and great value by most accounts. The ED series from Skywatcher are great performers too. I'd steer clear of achromats if possible. Good luck.

Outcast (Carlton) · #3 22-07-2013, 10:40 PM

Quote:

Originally Posted by Logieberra

Have you looked into the North Group 127 apos? They were running hot for a while, and great value by most accounts. The ED series from Skywatcher are great performers too. I'd steer clear of achromats if possible. Good luck.

Thanks,

Unfortunately the larger APOs are out of my price range.

Noting your comment on Achromats, do you think I would get more satisfaction from the smaller aperture APO then?

Logieberra (Logan) · #4 22-07-2013, 11:02 PM

I'd do some serious googling on apo vs achro if I was you. There is loads of data out there. I'm no optical expert. From my limited knowledge on achros, the purple haze around bright objects is quite off-putting for some observers...

Outcast (Carlton) · #5 22-07-2013, 11:17 PM

Quote:

Originally Posted by Logieberra

I'd do some serious googling on apo vs achro if I was you. There is loads of data out there. I'm no optical expert. From my limited knowledge on achros, the purple haze around bright objects is quite off-putting for some observers...

Cheers Logan,

I have had a look at a great deal of data on that issue..

Guess I'm just curious on how much I will be able to see with an 80mm APO; don't want to spend the coin & end up going 'is that all'...

That said, I can't afford larger in an APO & I don't want to go down the large reflector as I think it just won't get used.

ZeroID (Brent) · #6 23-07-2013, 09:28 AM

If you're dead set on a Refractor for visual I'd suggest the biggest aperture you can afford, in that case the 120. Remember though, a short focal length will aggravate chromatic effects, ie more false colours around bright objects.
I have a 102 f7 Lunt doublet which is not quite an APO but does damn well visualy and phtographically. I also have an 80mm f5 Achro which is my grab&go and I admit it does quite well but for any faint objects it is a bit under specced.
80mm APO's seem to be 'reserved' for photography mainly. Compensate for aperture with longer exposure times and high quality lenses.
Planets need longer focal lengths but are not so dependent on aperture being brighter than DSOs.
Basically if you want to see more than just planets and the moon the bigger aperture is required. Chromatic aberration is not so critical here anyway.

Kunama · #7 23-07-2013, 01:47 PM

If I was again setting up for visual only with a $1000 budget

I would buy a Bintel or similar 8"F4 or 5 reflector ($449 new) and mount it on an secondhand Alt Az manual mount. 8" aperture, very light ota, on an alt az mount you don't end up with the eyepiece at unreachable
angles either.

The 8" F4 OTA would be about 230mm diameter and 700mm long easily carried on a medium alt az mount.
The alt az mount and tripod will be easier to move and more compact that a Dobsonian (which is also an Alt Az)

Edit: These can also be used on an Eq for astropics if the mood strikes.

MattT · #8 23-07-2013, 03:30 PM

Hi Carlton,
1: I admit to being a refractorholic.
2: I admit to being an achro fan too.
3: I have zero interest in astro photography.
So with that in mind I can tell you from my perspective that a 5-6" achro at f8 makes a good visual scope.
I use a 6" frac and love it. It gives a tiny bit of violet wash on Jupiter and a fringe on the Moon but a semi-apo filter from Baader fixes that.
Only on bright stars does violet show up.
It is only 6" though and won't show everything.
In the past I had a 4" f9 ED Saxon scope which was great on bright planets, but I found 4" not enough....globs remained blobs, not so with the 6". Also had an 8" f5 Newt which was pretty similar to the 6" achro (minus the violet colour of course) so being a refractorholic it got sold.
If you can get a 5" ED then go for it.
Just my thoughts
Matt

AstroJunk (Jonathan) · #9 23-07-2013, 11:27 PM

Quote:

Originally Posted by Outcast

... no point in having a large aperture scope, if it never gets used.

And equally, there is no point having a small telescope that doesn't show anything.

Ignore the others*, nothing less than 8 inches

*Except for Kunama, whose wise words you should listen to

The Mekon (John Briggs) · #10 24-07-2013, 05:44 PM

Carlton,

Go for the best ED or Apo you can get for your money. If that means an 80mm ED then do it. You will be amazed at what you can see with these scopes. With dark skies there are plenty of galaxies, planetary nebula and globulars that an 80mm will reach. Double stars will be resolved down to 1.2" with steady seeing. Not to mention open clusters and the wonderful wide fields you will enjoy.
Observing with a small scope can be real fun.
(you may get a William Optics 90mm for the money you are looking at)

Outcast (Carlton) · #11 05-08-2013, 08:25 PM

Thanks for the input from those that contributed, everyone made extremely valid points & it gave me pause for thought in terms of what I was trying to achieve.

I ended up purchasing a Meade 5000 80mm APO from the IIS classifieds & have a skyview Az/Alt mount on the way together with some eyepieces from Andrews.

Whilst I know that an 80mm APO will not capture everything that is out there, after considerable research, I am satisfied that it will capture enough things to keep me busy for the next few years at least & it will be a very handy rig for an extended trip we have coming at Christmas which will include some time in very dark skies between Cairns & Adelaide. Much to my wife's chagrin, there will be room for the golf clubs, the scope, our luggage and the teenager

I have been reading through 'Turn Left at Orion' & whilst aimed predominantly at the Northern Hemisphere it does contain information about the Southern Hemisphere skies; most importantly to me, it's aimed at small scope users. The section on Southern skies will be my starting point for observations.

Should have it all together by the end of this week; salivating at the thought of first light... of course it will probably be overcast & raining

Logieberra (Logan) · #12 05-08-2013, 08:50 PM

Good choice. If you get a bigger mirrored scope in years to come, that nifty triplet will ride above very comfortably, and will also make a very nice guide scope too. It will also be a pleasure to image with if you do long exposure guiding with an equatorial mount. Most people start out imaging with 80mm, so you're in good company

noeyedeer (Matt) · #13 05-08-2013, 10:24 PM

Quote:

Originally Posted by Outcast

I have been reading through 'Turn Left at Orion' & whilst aimed predominantly at the Northern Hemisphere it does contain information about the Southern Hemisphere skies; most importantly to me, it's aimed at small scope users. The section on Southern skies will be my starting point for observations

being in Cairns, a fair bit of that book will be relevant. when they talk about summer months, its winter for us (just invert the images) etc. its a great book.

there are limiting latitude factors but most are visable given a good nothern horizon.

the main thing is our southern skies are usually always redily available unlike the northern skies which come and go...

btw nice scope choice, and clear skies.
matt