180 mm Mak or 8 inch SCT EDGE

[Analysis Paralysis]

I know this has been discussed in the past,but I would like an update from members who have much more experience. Without consideration of price difference at this point, it comes down to observing.

I don't plan on using either for astrophotography, as I have recently bought a second hand ED80. I plan to buy an heq5 pro to go with it and from what I have read, that is a good combo.

However, i know this will not scratch my planetary itch. Hence I am here. I'm not particularly bothered by looking for dim DSOs, and I'm much more interested in seeing astrophotographs of them where details are more obvious. But I must have sharp contrasty and detailed views as possible for Jupiter. Anything less would annoy me. I've read lots about seeing and how a 10 inch Dob will blow a 180 mak or 8 inch SCT out of the water, but I want something that can be used on the heq5 and track automatically whilst providing pleasing views. Plus I am interested in double stars, Orion nebula and other similarly bright DSO. I only have ONE chance to finance this dream, so it has to be the right scope for me. As an aside, in the future I know I can cheaply add a Newtonian 6 in f5 to look at dimmer DSO and even photograph them( I've seen very impressive dim DSO taken with this scope on eq3-2!).

Thank you for your comments in advance.

Mark

[Peter Drew]

As a 8se owner I would prefer currently to favour the SCT over the Mak. Despite the potential more contrasty view from the Mak and better star images, the cool down time of the Mak and the low position of the planets if you are in the UK are going to offset these advantages. The slightly shorter focal length and larger aperture of the SCT should show a benefit on DSO's. It is a moot point as to whether you need the more expensive Edge version for visual use.   

[Chris]

7 minutes ago, Peter Drew said:

It is a moot point as to whether you need the more expensive Edge version for visual use.

If you use wide angle Ep's the Edge variant gives more aesthetically pleasing stars towards the edge, plus I believe it shows tighter stars on axis. I've owned the C8 Edge plus several standard SCT's from Meade and Celestron, this is where I'm drawing my opinion from.  

[dweller25]

Hello Mark ans welcome to SGL,

I have had both of these scopes - primarily for Planetary observation.

If you are thinking about a Skywatcher 180mm Mak then think carefully about cool down times and when you observe. I had this Mak and it took a long time to cool and could not keep up with dropping temperatures in the evening.

The C8 I had was better in that it did cool down faster.

I ended up with an Intes Micro 715 Mak that has active ventilation from an internal fan - it makes a world of difference to the views.

BUT - I would not use the Mak at the moment as the planets are quite low and I find this combined with the ever present jetstream seems to affect scopes with a central obstruction more than those without in terms of image stability.

In my honest opinion a 120ED refractor would be a much better choice for the objects you want to look at.

Also Binoviewers bring a lot to the party if you can get on with them.

[Owmuchonomy]

Aside from the technical question just bear in mind the positions of the planets over the next few years.  If you are at UK latitudes then we will all be waiting a few years for sharp views of the giant planets.  Only Mars presents a decent target in the next couple of years.  Therefore, I wouldn't invest in any planetary specific gear for a while.

[Chris]

4 minutes ago, dweller25 said:

I find this combined with the ever present jetstream seems to affect scopes with a central obstruction more than those without in terms of image stability.

Is this definitely central obstruction related and not just a function of aperture?

[dweller25]

Good point Chris - I forget to mention that.

[Analysis Paralysis]

33 minutes ago, dweller25 said:

Hello Mark ans welcome to SGL,

I have had both of these scopes - primarily for Planetary observation.

If you are thinking about a Skywatcher 180mm Mak then think carefully about cool down times and when you observe. I had this Mak and it took a long time to cool and could not keep up with dropping temperatures in the evening.

The C8 I had was better in that it did cool down faster.

I ended up with an Intes Micro 715 Mak that has active ventilation from an internal fan - it makes a world of difference to the views.

BUT - I would not use the Mak at the moment as the planets are quite low and I find this combined with the ever present jetstream seems to affect scopes with a central obstruction more than those without in terms of image stability.

In my honest opinion a 120ED refractor would be a much better choice for the objects you want to look at.

Also Binoviewers bring a lot to the party if you can get on with them.

Hi dweller25, thank you. You and others make a good point on the planets. I'm also interested in double star splitting as well which I think the 180 mak should, in theory, better the 5 inch refractor.

[dweller25]

Hi Mark,

The 180mm aperture will have better resolution which will give an advantage as long as thermal and seeing conditions do not interfere.

 

[Paz]

Either scope would be very good but the sct would cover more bases and be easier to use (lighter, faster cool down, can do wider fields).

Another advantage of a C8 is they are much easier to get hold of second hand so you don't have to take a big depreciation hit buying from new. In any given month a few C8's will come and go (not necessarily the edge version though) but you could be waiting months for a 180 mak to come up... only to then find someone else buys it who is faster on the trigger putting you back to square one.

Having said all that if it's brighter high contrast targets your after I'd go for the 180 mak personally with the main factor to be wary of is making sure you have arrangements to cover cool down ok (who said these decisions have to be rational!?).

 

[Chris]

Another positive for the SCT's is the ability to use a reducer to give a wider FOV and faster f/6.3. 

[25585]

1 hour ago, Lockie said:

Another positive for the SCT's is the ability to use a reducer to give a wider FOV and faster f/6.3. 

That is a deal maker IMO. 

The reducer is also protecting the inside of an OTA, it's lens being a barrier. Useful when changing eps. 

[LukeSkywatcher]

I have an 8" SCT so i'm bias. 

[RobertI]

I find the low power views when using the 0.63 reducer on my C8 are really wonderful; the stars look much ‘tighter’ and more ‘refractor like’, due I guess to the lower power. The larger open clusters and nebulae look amazing. The reducer makes it a very versatile option IMO. I have also had some breathtaking views of Jupiter under the right conditions, with very fine detail visible. The main downside is the slightly ‘bloaty’ stars when using high powers for viewing doubles. I have never owned a 180 Mak btw....I would love to try one but don’t feel it would give me anything significant over the C8 apart from potentially sharper stars at high powers. I may be wrong though.

[Chris]

Totally agree with Rob, the reducer really sharpens things up with SCT's. This is despite the reducer/corrector being placed at the back of the scope which is slightly sub optimal. The Edge version places the corrector at the optimal position inside the scopes baffle tube which really sharpens things up, even natively at f/10. 

With this in mind I think it's partly the corrector of the 0.63 reducer/corrector that sharpens stars up with the standard SCT, not just the lower mag. A standard SCT with a 0.63 corrector reducer is a very good alternative to the Edge, just not quite as good. 

One more noteworthy thing about SCT's is the weight per aperture. An 8" SCT is barely over 5kg! By contract I once briefly owned a 6" Mak which felt very heavy for the aperture.

[chiltonstar]

A couple of additional points:-

Maks don't generally need collimation, SCTs do - most of the C8s I've looked through have been out of collimation.

Storing the 180 Mak outside will reduce cooling times considerably, but obviously if the air is cooling fast, the thermal inertia may prevent stable viewing.

There are said to be a fair number of C8s around that are not the best examples of the breed! I suppose these turn up on the secondhand market, more often than not.

120EDs provide wonderful views of doubles and planets, but as well as only having 2/3 of the resolution of a 180 Mak (at optimum) they pass a lot less light; planetary moons and faint companions of doubles will be harder to spot with only ca. 50% of the light.

Really, you need to try them all at a local astronomy society observing evening.......

Chris

 

[25585]

Of all the eye pieces made, which would give the largest TFOV in a 180 Mak?

[chiltonstar]

22 minutes ago, 25585 said:

Of all the eye pieces made, which would give the largest TFOV in a 180 Mak?

I use a SW Panaview 38mm which gives theoretically 59 arcmin - (slightly more than that in practice, depending on how much extension I use at the rear of the scope). With a 1 1/4" adaptor, the limit is about 47 arcmin. The field of a Mak is flat, so these are sharp across the field, whereas a non-Edge SCT will not be of course.

With such a long FL, the 180 Mak is very tolerant of EP quality: I find even a cheapo 8-24mm zoom works well, even a 1 1/4" 40mm Plossl (I can hear the purists shrieking in horror!) gives a nice view with a good exit pupil, even if the EP is slightly "tunnel-like" for those used to superwide EPs.

Chris

[Chris]

38 minutes ago, chiltonstar said:

Maks don't generally need collimation, SCTs do

This is true, SCT's need collimating once, well unless you drop it. All the SCT's I've owned held collimation surprisingly well, and I think this is because it's only the secondary you need to collimate with an SCT and not the primary plus seconary as with a Newtonian. True that there are a lot of out of collimation SCT's out there which don't show their potential, you do need to get the collimation spot on to unleash an SCT's full potential, I've heard this time and time again. 

I think Mak's hold collimation really well, but I personally have no idea how to collimate one if it does go out? I remember a forum member saying that he/she hoped to get there Mak collimated this year so they could use it which shows I'm not alone in not knowing. 

This is how simple an SCT is to collimate, not as scary as you'd think using an eyepiece and an star:

I will add that I personally feel safer with Bob's knobs than having a screw driver near the corrector, but you so rarely have to do this that I guess it's a small risk.

 

[Analysis Paralysis]

On 31/12/2017 at 09:48, chiltonstar said:

I use a SW Panaview 38mm which gives theoretically 59 arcmin - (slightly more than that in practice, depending on how much extension I use at the rear of the scope). With a 1 1/4" adaptor, the limit is about 47 arcmin. The field of a Mak is flat, so these are sharp across the field, whereas a non-Edge SCT will not be of course.

With such a long FL, the 180 Mak is very tolerant of EP quality: I find even a cheapo 8-24mm zoom works well, even a 1 1/4" 40mm Plossl (I can hear the purists shrieking in horror!) gives a nice view with a good exit pupil, even if the EP is slightly "tunnel-like" for those used to superwide EPs.

Chris

Hi Chris, by cheapo do you mean celestron 8-24?

[chiltonstar]

12 minutes ago, Analysis Paralysis said:

Hi Chris, by cheapo do you mean celestron 8-24?

Marketed in the UK by Seben, a generic type I think.

Chris

 

[Analysis Paralysis]

2 minutes ago, chiltonstar said:

Marketed in the UK by Seben, a generic type I think.

Chris

 

Even cheaper than the celestron one then. That's useful to know. I was going to get the baader zoom, but this would get used in a 80 mm ed frac, so perhaps more important to have higher quality in that case to get best out of the frac?

[Louis D]

13 minutes ago, Analysis Paralysis said:

Even cheaper than the celestron one then. That's useful to know. I was going to get the baader zoom, but this would get used in a 80 mm ed frac, so perhaps more important to have higher quality in that case to get best out of the frac?

Watch for the Celestron Regal M2 zoom to come up for cheap when people sell them from their spotting scope.  They are very close to Baader zoom and regularly come up for $60 to $80 here in the states.  They also come up for sale from the Olivon T-800 scope (but with a rubber grip instead of metal ribbing).

[Analysis Paralysis]

5 minutes ago, Louis D said:

Watch for the Celestron Regal M2 zoom to come up for cheap when people sell them from their spotting scope.  They are very close to Baader zoom and regularly come up for $60 to $80 here in the states.  They also come up for sale from the Olivon T-800 scope (but with a rubber grip instead of metal ribbing).

Thanks for the tip. I'm based in UK, so hopefully something could come up on eBay here.

[Luna-tic]

I'd go for the Edge over the Mak. You may not think you'll use it for AP, but if you're imaging with the frac, eventually you'll want to try the SCT, and it will open up more possibilities. The reducer for the Edge is .7,  and is specific for each size of Edge (also much more expensive than the .63 for standard SCT's).  I don't know how fast your ED80 is, f/6?, but having both a widefield and narrower field scope to image with is a grand slam, IMO. Plus, if you go completely AP bonkers, you can go the Hyperstar route and image at f/2 with the Edge. Whatever you give up in increased contrast with the Mak, you'll get back in greater versatility with the Edge.

I started with a C6, added the .63 reducer, then added the Edge HD 8", then got the .7 reducer. I still wanted something extra wide-field, so I just recently got an 80 APO at f/5.9, with a reducer that takes it to f/4.7. That's pretty much a full spectrum of possible field sizes and exposures. You won't regret the Edge.