Small APO or Large ACHRO

Red_Dog (Rod) · #1 26-09-2016, 01:01 AM

Hi folks

Located southern suburbs of Perth Western Aust wanting to view planets mostly for that quick fix but also looking to search out some DSO's.
I am going to purchase a refractor and this cannot be swayed. I will not be getting a reflector of any form on any mount.
Dillema l have is.....

Would a 70 to 80 mm apo be any better than a 127 f9.7 achro apart from the CA and colour fringing, which is why l went for the 127L @f9.7.
Unfortunately l don't have time to join a club, go to a star party, hire or anything else.
Just looking for confirmation that the larger achro will see more than a small apo? Happy to put whatever filter on the achro to improve things.
Planning on getting the BRESSER 127mm x 1200mm f/9.4 achromatic refractor with EXOS (EQ5) mount and steel tripod. Package includes 9mm, 15mm and 25mm Plossls plus a 2" adaptor, 2x Barlow. This should keep me happy for a long time.
Convinced myself to not get the 152L as it is a bit heavy for the exos mount/tripod l think but happy to be told otherwise plus it's only f7.
Budget is maxed at $1500.
Hope to be part of the Perth astronomy scene soon.

Your thoughts?

Cheers.
Red_Dog

silv (Annette) · #2 26-09-2016, 01:56 AM

The 127/1200 on that mount is a good decision for your observing goals.

However, there is no scope growth left in that mount, refractor-wise.
But you said you have set the firm budget so your choice is really good for now.

While astrophotography is neither on of your goals nor is it comparable with visual results, a search on Astrobin for that particular scope brings up these:
Astrobin Bresser 127/1200

And the 152/1200 on AStrobin Astrobin Bresser 152/1200

Have fun!

glend (Glen) · #3 26-09-2016, 01:58 AM

I have a Bresser 152mm f5 which i use for narrowband imaging and its a great scope, but you can't buy them in Australia, have to import them from europe (Teleskop-Express). Your suggested 127mm scope is nearly identical to the Explore Scientific AR127L, and should be as they are made in the same factory. Plenty of reviews online for that 127mm ES.
Btw, Andrews (Sydney), has the Bresser 127mm AR127L, plus that mount and package for $1069, but i think you have to order it (not usually stocked), talk to Luke at Andrews..

Red_Dog (Rod) · #4 26-09-2016, 02:48 AM

Wish I'd come to this forum 6 moths ago.
Thanks for the quick replies guys, just what l wanted to hear.
Not only that l got the link to Andrews of here the other day and saw the 127L package, best deal in Oz for this scope and thanks for the heads up on Teleskop Express. I do like supporting our Aust shops though where ever l can.
I really do want the 152 but it's just to heavy for that tripod and mount l think, despite what websites say.
Looks like it's nearly time to pull the trigger on a new toy.
Thanks guys.

Tinderboxsky (Steve) · #5 26-09-2016, 10:47 AM

It sounds as though you have come to best solution for yourself.
Speaking from experience, you would find an 80 mm scope quite limiting as your only one, no matter the quality of the optics. At the other end of the refractor size scale, 152mm scopes are large and quite heavy. There is one for sale in the classifieds with the owner saying he is selling for this very reason.
In my view, 120 to 140 mm hits a sweet spot for refractors. These open a whole world of observable deep sky objects, probably more that you can chase down in a lifetime. They are of a manageable size and do not give away much noticeable light gathering power compared with the 152mm.
It is unlikely you will see any CA for deep sky. I get a small amount of blue fringing on the bright planets, but not enough in my opinion to affect the view. The blue CA on the moon softens the focus at medium to high power in my 140mm achro, but this is easily solved with a Baadar Semi APO filter and stopping the scope down to 120mm wth a simple cardboard ring (CA becomes more difficult to control in achro lenses over 120mm). The CA is removed and the focus nice and sharp.
Enjoy and remember the best scope is the one you use the most.

Cheers

Steve

glend (Glen) · #6 26-09-2016, 11:11 AM

Quote:

Originally Posted by Tinderboxsky

It sounds as though you have come to best solution for yourself. .......At the other end of the refractor size scale, 152mm scopes are large and quite heavy. ......

....... and stopping the scope down to 120mm wth a simple cardboard ring (CA becomes more difficult to control in achro lenses over 120mm).

Well i would disagree with some of that. I have a 152mm refractor and compared to a newt it is not heavy at all - it depends on the design. A triplet or quad APO will be heavier than say a simple ED doublet, or even a Achro with a Petzval corrector at the rear. I have a Bresser 152mm f5 Achro with a Petzval corrector and its a great scope, visually ok but i use it for narrowband imaging mainly (where CA is never an issue).

Red_Dog (Rod) · #7 26-09-2016, 01:01 PM

Thanks Steve. Glad to know my research was not all in vain and l was mostly on the right track.
Obviously there's not one perfect scope for everything, or at least not that l can afford
edit. Andrews and supplier out of stock damn it that was a well priced package. Have to go off shore to get it now.
Thanks again.
Red_Dog.

skysurfer · #8 27-09-2016, 05:09 AM

Indeed, CA is overrated.

Of course, an APO or even an ED shows less CA, but, as said earlier, deep sky does not show CA.
I have an 80mm f/6.5 achromat, but is shows crisp images, even from the planets at 130x.
Admitted, a faint purple halo is visible at Jupiter, but not annoying at all. And bright (+2 or brighter) stars show blue halos, but that is all.
I have a 110mm ED which indeed shoes less CA, but the 80mm on tabletop tripod is a super G&G scope for quick viewing planets or deepskies.

And, indeed I prefer a short scope (even when it is just an achro) than a long rainpipe of 80mm f/12 which required a heavy tripod.

In the latter case, I pull my 400mm Dob outside within the same time.

dannat (Daniel) · #9 27-09-2016, 08:02 AM

Yes to the 127 over 152 or 80mm, 5" achro is most you want to manage.

A light yellow #8 filter will help with most of the CA without cutting ou to much light

Red_Dog (Rod) · #10 27-09-2016, 07:38 PM

Once again thanks for the replies.
They all help and are all appreciated.

Would you believe l may even get the 152L. Will be ordering something next week.
Coupled with a set of 5 vixen EP's and filters l will be as happy as a pig in muck.

152L only because of future astro photog possibilities.
You can all blame Silv for this decision.

dannat (Daniel) · #11 27-09-2016, 08:39 PM

stick with the 5" f9, CA will be better on planets, & the mount won't have to struggle -

Red_Dog (Rod) · #12 27-09-2016, 09:19 PM

Quote:

Originally Posted by dannat

stick with the 5" f9, CA will be better on planets, & the mount won't have to struggle -

I know you are right and you exposed my greatest fear that the mount won't be strong enough.
I owe you a beer.

barx1963 (Malcolm) · #13 27-09-2016, 11:43 PM

Rod
I know that you said you will not be swayed away from a refractor, but do mind me asking how you came to that position? I am certainly not a refractor OR a reflector guy (looking over my current crop of scopes in my house I have exactly 3 of each) but always curious about how people make decisions.

Cheers

Malcolm

Red_Dog (Rod) · #14 28-09-2016, 12:52 AM

Hi Malcolm.
The reasoning behind a refractor was based on a few very simple reasons which in themselves are not negative against reflectors but rather just lie on the refractor side of the fence. (and only "just" at that).
This will be a lifetime investment for me. I don't plan on being able to afford much more in the next ten years.
Having closed optics l won't have to clean a mirror, ever. Not that newtonians need cleaning that much, but fracs just don't have that need.
Collumnation. Very, very little versus a reflector.
Form over function. I prefer the look of fracs over any other scope. It won't be sitting out for public view as a "look at me" statement but rather tucked away in the corner of a cupboard or room staying crisp and fresh for the next clear night. It looks like a scope should look though. I won't be looking at a big frac wishing l had a big reflector. I would however wish l had a big frac if there was anything else perched on the mount.
Transport. Fits my campervan better than a big newt.
These are very personal choices. I nearly got a 250 newt but decided it would be to unwieldy on a eq mount.
I want an eq mount so in future l can add motor drives for tracking. Don't like the idea of goto electronics. All electronics will fail eventually, especially if left outside for hours in the cold night. So the less elecs the better.
Dobs are ugly, don't track of one axis and need flat ground. Where l travel to does not always have flat ground and a frac, even a 10kg one, would be way more portable than anything else in my budget.
So, a rather holistic approach to my decision. One that ticks all my boxes and not someone elses.
I know it's not the best scope but l do know it will make me smile for a long time to come and that's got to be worth something.

Cheers.

Red_Dog.

edit. I see you're in Colac, l was born in Colac.

brian nordstrom (As avatar) · #15 28-09-2016, 12:42 PM

PM sent.
Brian.

silv (Annette) · #16 28-09-2016, 07:10 PM

for astrophotography there is a rule of thumb for the mount:
never load more than half (or for some mount-scope setups 3/4) of the advertised load capacity.

believe me, it's just not fun at all noticing the motor and gears dying under the load while you're desperately trying to image with exposures longer than 2 seconds...

Red_Dog (Rod) · #17 30-09-2016, 09:58 PM

Just about to pull the trigger on the Bresser 127.
May have to upgrade focuser in the short term.

With your years of experience would you buy this or a smaller 70-80mm apo of the same budget range. Or some other scope?

Steffen · #18 30-09-2016, 10:14 PM

Between the 80mm Apo and the 127mm Achro I'd choose the... 127mm Mak.

There is a Celestron package at Andrews for $999 at the moment.

SkyWatch (Dean) · #19 01-10-2016, 12:48 AM

Just a thought if you want to buy in Oz: Andrews have the Skywatcher "Black Diamond" 120x1000 refractor on an EQ5 for $1199, or with motor drives for $1449. This is "in stock" according to their website.
There is not much difference between a 120mm and a 127mm aperture in terms of image brightness and resolution...

- Dean

doug mc · #20 01-10-2016, 10:50 AM

The 127 L achromat receives good reviews,but being a long tube you may find you will need to extend the height when viewing near the zenith. I have gone the refractor route with scopes from 80 mm to 150 mm. I thought that the 150 f/8 would be best, but have now returned to aGSO eight inch ASDX dob. I have a eq5 to mount it on for those stable nights. The 127L is a scope I would like to have myself as it would be a great all-rounder. I recommend the Badder fringe killer as it has the best light through put and minimum yellowing of the image. Versatile, good reviews scope, it should be a keeper.