180 mm Mak or 8 inch SCT EDGE on planets

[Analysis Paralysis]

Personal experience with side by side viewing? 

Which is the best one if used only on planets?

Thanks

Mark

[Sunshine]

i can say that the "Edge" aspect of the SCT will make diddly difference on planets, thats almost exclusively for imaging providing as flat a field as possible and even then it would only really make a difference on wide field imaging and not planetary imaging.

i am not the authority on this but i have owned several SCT's including an 8 and im willing to bet side by side my 150 Mak may just school my old 8' sct.

[John]

The 180mm mak actually delivers a working aperture of around 170mm. It's a pretty good 170mm but it's worth knowing that it's not 180mm I think.

 

[rocambol]

180mm = 7"

Thus, SCT has larger aperture and I think it wins the contest.

[Galen Gilmore]

2 hours ago, rocambol said:

180mm = 7"

Thus, SCT has larger aperture and I think it wins the contest.

Not necessarily, often the best views on planets are with high quality APO refractors. Therefore the view is highly dependent on quality of optics, and size of central obstruction.

As for which is better, I have never owned either so I can't provide any opinion.

[Pete Presland]

I owned a Mak 180 until 4 years ago, when I "upgraded" to a C9.25 (another 35mm of aperture, compared to the 8" ). The Mak gave some great views of the Mars opposition in 2014, I am expecting a similar performance from the C9.25. 

I do remember my Mak having considerably more mirror slop than the C9.25, but as I fitted a Crayford this wasn't too much of an issue. I bought the C9.25 for its versatility, not because I thought it would be that much better on planets. I never did  side by side, but I wouldn't say there is much difference from memory between the views. I would guess the performances would be similar in the two scopes you are considering.

[dweller25]

I had both of these scopes

The best was the C8 as it cooled quicker

it was eventually replaced with a 7” Intes Micro Mak with active cooling which works really well and is highly recommended

As is a 120ED refractor

 

[Chris]

5 hours ago, Sunshine said:

i can say that the "Edge" aspect of the SCT will make diddly difference on planets, thats almost exclusively for imaging providing as flat a field as possible and even then it would only really make a difference on wide field imaging and not planetary imaging.

i am not the authority on this but i have owned several SCT's including an 8 and im willing to bet side by side my 150 Mak may just school my old 8' sct.

Ah you might be surprised. Take a look at the Celestron white paper for the Edge HD, it compares spot diagrams for the Edge verses the standard and the Edge is tighter on axis due to housing a corrector at the optimum position inside the scope baffle. 

I've owned both Standard C8's from Celestron and Meade, plus the C8 Edge. If money wasn't an object I'd go for the Edge out the two. The mirror locks and vents are also A nice touch with the Edge models. 

Damian Peach, the well known planetary imager uses the Edge variant. 

As to the OP's question. I can't imagine a lot of people have done side by side with these scopes, but I would say go with the faster cooling SCT if you keep the OTA indoors, but if kept outdoors the Mak should be fine. It's the massively thick corrector that's the issue with large Maks, I tend to not get Maks over 5" because of this now days if in a Mak mood.

[chiltonstar]

6 hours ago, John said:

The 180mm mak actually delivers a working aperture of around 170mm. It's a pretty good 170mm but it's worth knowing that it's not 180mm I think.

 

The later ones are 180mm John, I think. The bench test on mine gives the aperture as 179mm without the diagonal in place.

Chris

[Analysis Paralysis]

1 hour ago, Lockie said:

Ah you might be surprised. Take a look at the Celestron white paper for the Edge HD, it compares spot diagrams for the Edge verses the standard and the Edge is tighter on axis due to housing a corrector at the optimum position inside the scope baffle. 

I've owned both Standard C8's from Celestron and Meade, plus the C8 Edge. If money wasn't an object I'd go for the Edge out the two. The mirror locks and vents are also A nice touch with the Edge models. 

Damian Peach, the well known planetary imager uses the Edge variant. 

As to the OP's question. I can't imagine a lot of people have done side by side with these scopes, but I would say go with the faster cooling SCT if you keep the OTA indoors, but if kept outdoors the Mak should be fine. It's the massively thick corrector that's the issue with large Maks, I tend to not get Maks over 5" because of this now days if in a Mak mood.

Thank you for all your comments. I would keep it outdoors in the garage ( because there's no room in the house, but fortunately that is the best place in terms of cool down time). I have heard too many QC issues, stories of mushy viewing on the SCT. That worries me a lot. You don't hear the same issues from mak owners. I looked through a 11 inch SCT at Saturn- beautiful and sharp. I've looked through an ,8 inch SCT at Jupiter, and was decidedly unimpressed. No sign of N and S belts, that I can even see at 35x mag in a £100 spotting scope! I can't afford an 11 in SCT and it would be bigger than I want anyway. But my only experience with an 8 in SCT ( which was set up by local astronomers for public to look through, so I'd hope it was collimated) has tallied with the ' mushy' comments I've seen.

[alanjgreen]

I've had two Celestron sct and I will not be telling you stories of mushy stars! SCTs are great all round scopes but there a bunch of people who have never owned one and hate them because they are not refractors - these rumours and tales get spread in those parts

For planets, you will need the collimation spot on. Sct are easy to collimate and if done correctly with the screws nice and tight, it will hold for many months. But if the collimation is off then planets will show that in a poor view.

You may have looked through one or two but unless you did a star test at the same time, can you vouch for the state of collimation?

The big planets can also be impacted by their own weather systems making our view quality drop. So beware of forming an opinion after a single viewing!

My c11 (which was correctly collimated) was superb on Jupiter at up to x200 magnifications (usually a little less) and I spent many hours (when the planets were high in the sky) seeing great details and colours within the banding of Jupiter. I got addicted to watching the Great Red Spot  

My C8 was great on planets too but obviously my c11 was better still.

The Celestron C8 had a satisfactory focuser able to get to the sweet spot without issue. The Celestron c11 focuser was unable to cope with the large mirror and had to be replaced with a two speed focuser for more accuracy. Again, with planets focusing precisely will be a top priority.

Neither of my sct were edge versions so I cannot speak to that.

The c11 was a lot more impacted by the seeing so some nights planets were not good when maybe a C8 would still have been ok.

But be sure to do a star test next time you look through an sct to see for yourself the state of the collimation...

[Stu]

53 minutes ago, Analysis Paralysis said:

I've looked through an ,8 inch SCT at Jupiter, and was decidedly unimpressed. No sign of N and S belts, that I can even see at 35x mag in a £100 spotting scope! I can't afford an 11 in SCT and it would be bigger than I want anyway. But my only experience with an 8 in SCT ( which was set up by local astronomers for public to look through, so I'd hope it was collimated) has tallied with the ' mushy' comments I've seen.

I wouldn't take that as a representative level of performance from these scopes. If you couldn't see any belts on Jupiter then something was just plain wrong I should think, either dewed up or badly collimated or poor seeing...or all three!

I have had an 8" Mak (OMC200) and an 8" Edge HD. The Mak did deliver lovely views when everything was right, but was quite a pain to get cooled properly and it often struggled to keep up with falling temps even with active cooling.

The Edge was very nice, would have another. I am not a big fan of the star shapes in compound scopes vs refractors, but the SCT did give very good views of Jupiter, good detail and colour showing in the GRS. Cooling is always something that needs to be right to get the best results, a cat cooler helps, and SCTs need collimation to be spot on for maximum detail and contrast, Maks too.

I have not looked through a non Edge SCT, but at the time I was using Ethos eyepieces and felt that the Edge optics gave a very well corrected, flat field even in such wide afov eyepieces, so there is a benefit for visual too.

[John]

1 hour ago, chiltonstar said:

The later ones are 180mm John, I think. The bench test on mine gives the aperture as 179mm without the diagonal in place.

Chris

Have they increased the size of the primary (and the tube diameter ) in later models then ?

As I understand it, the primary needs to be oversized in the maksutov-cassegrain design for the scope to achieve the full specced aperture.

I have owned a couple of non-Edge 8" Celestron SCT's and a 180mm Skywatcher Mak-Cass but not at the same time so I didn't have the chance to compare them "back to back". I seem to recall getting great planetary views from both types though, when the conditions were good and the collimation on the nail.

The cool down time of both designs is more than I prefer but the 7" mak-cass did seem to tak a really long time to be ready for high powers.

like David, if I went for another mak-cass I think I'd go Russian now.

Neil English enjoyed his time with the 180mm mak-cass though (his was branded Orion but the same as the Skywatcher):

https://neilenglish.net/the-joy-of-the-maksutov-telescope/

 

 

[Analysis Paralysis]

9 minutes ago, John said:

Have they increased the size of the primary in later models then ?

As I understand it, the primary needs to be oversized in the maksutov-cassegrain design for the scope to achieve the full specced aperture.

I have owned a couple of non-Edge 8" Celestron SCT's and a 180mm Skywatcher Mak-Cass but not at the same time so I didn't have the chance to compare them "back to back". I seem to recall getting great planetary views from both types though, when the conditions were good and the collimation on the nail.

The cool down time of both designs is more than I prefer but the 7" mak-cass did seem to tak a really long time to be ready for high powers.

like David, if I went for another mak-cass I think I'd go Russian now.

 

 

Thanks John. More food for thought.

Mark

[neil phillips]

l think the MAK will work better on both planets and lunar. Less optical aberrations at F15 it will be easier to get those really high powers with the MAK. Spot size is slightly smaller. Needs good cooling. If its planets your after the Mak is better suited 

[parallaxerr]

I've owned a Bresser 152 Mak and a non-edge C8.

With the 152 Mak, on cold nights the scope was always chasing thermal equilibrium, preventing the highest power views. At that time, my ED80 kept up no problem due to the Mak being held back. The Mak didn't hang around long.

I had some outstanding planetary views with the C8 though. Cool down was faster and the scope settled even during very cold weather, having been brought outside from a warm house. I used widefield EPs because it was mounted on a manual alt/az so required "dob nudging", I saw no significant aberrations at the edge of the FoV, so the Edge isn't required for planetary observation in my opinion.

Ultimately the C8 made way for an Apo though, whose planetary performance I have yet to test but one thing's for sure, cool-down is a non-issue.

[neil phillips]

4 minutes ago, parallaxerr said:

I've owned a Bresser 152 Mak and a non-edge C8.

With the 152 Mak, on cold nights the scope was always chasing thermal equilibrium, preventing the highest power views. At that time, my ED80 kept up no problem due to the Mak being held back. The Mak didn't hang around long.

I had some outstanding planetary views with the C8 though. Cool down was faster and the scope settled even during very cold weather, having been brought outside from a warm house. I used widefield EPs because it was mounted on a manual alt/az so required "dob nudging", I saw no significant aberrations at the edge of the FoV, so the Edge isn't required for planetary observation in my opinion.

Ultimately the C8 made way for an Apo though, whose planetary performance I have yet to test but one thing's for sure, cool-down is a non-issue.

I mentioned cool down, falling temps is a problem. But under ideal conditions personally I think a Mak would win. But I was a imager so maybe that is a different consideration to viewing. For imaging A 152 mak would kill a 80mm apo stone dead. 

[parallaxerr]

4 minutes ago, neil phillips said:

For imaging A 152 mak would kill a 80mm apo stone dead. 

No doubt, that's why I bought a much bigger Apo

[neil phillips]

2 minutes ago, parallaxerr said:

No doubt, that's why a bought a much bigger Apo

Lovely scopes agreed but not cheap. I would love to image with a very large apo for sure.  I took my lunar images with a 300 quid scope 12 newt. If the guy ever wanted to image and doesn't have the dosh a 10 newt is a good option. But now I am changing the question a bit. I am biased after using two meade f15 maks for years I sold it and got another after I missed it lol. Sorry guys Mak all the way for me 

[25585]

There is a "mint" SW 150 Mak for sale at ENS Optics for £450. 

[chiltonstar]

5 hours ago, John said:

Have they increased the size of the primary (and the tube diameter ) in later models then ?

As I understand it, the primary needs to be oversized in the maksutov-cassegrain design for the scope to achieve the full specced aperture.

 

 

In later models like mine, the mirror said to be larger, therefore using the full aperture. There is quite a discussion on this subject on CN.

Chris

[Analysis Paralysis]

5 hours ago, neil phillips said:

I mentioned cool down, falling temps is a problem. But under ideal conditions personally I think a Mak would win. But I was a imager so maybe that is a different consideration to viewing. For imaging A 152 mak would kill a 80mm apo stone dead. 

But not on DSO where the f ratio is important. Just thought I would ask, even though this thread is planets. ?

[RT65CB-SWL]

My C6 (SCT)* & 're-modded' ETX105 (Mak)** give me about the same magnification despite being different focal lengths and focal ratios, (see below). 

Between them I think the ETX105 gives me the better view and contrast on lunar and planets.

Not in the same league as requested in the original post, but something to mull over if nothing else.

 

* C6 = 1000mm @ f/10

** ETX105 = 1470mm @ f/14 (and 're-modded' to accept my SCT accessories).

[Analysis Paralysis]

43 minutes ago, Philip R said:

My C6 (SCT)* & 're-modded' ETX105 (Mak)** give me about the same magnification despite being different focal lengths and focal ratios, (see below). 

Between them I think the ETX105 gives me the better view and contrast on lunar and planets.

Not in the same league as requested in the original post, but something to mull over if nothing else.

 

* C6 = 1000mm @ f/10

** ETX105 = 1470mm @ f/14 (and 're-modded to accept my SCT accessories).

Thanks Phil.

Mark

[Chris]

14 hours ago, Analysis Paralysis said:

Thank you for all your comments. I would keep it outdoors in the garage ( because there's no room in the house, but fortunately that is the best place in terms of cool down time). I have heard too many QC issues, stories of mushy viewing on the SCT. That worries me a lot. You don't hear the same issues from mak owners. I looked through a 11 inch SCT at Saturn- beautiful and sharp. I've looked through an ,8 inch SCT at Jupiter, and was decidedly unimpressed. No sign of N and S belts, that I can even see at 35x mag in a £100 spotting scope! I can't afford an 11 in SCT and it would be bigger than I want anyway. But my only experience with an 8 in SCT ( which was set up by local astronomers for public to look through, so I'd hope it was collimated) has tallied with the ' mushy' comments I've seen.

How were the seeing conditions when you looked through the 8" ? It seems that as scopes increase in aperture, they become more dependant on good seeing. I looked into this a while ago, from memory it's to do with larger apertures straddling more air cells thus showing more turbulence, but I'm sure there might be a more exact answer out there?

for the 11" to perform well I'm guessing you had some pretty good seeing which is great, and maybe the seeing was a bit pants when you looked through the 8"? Or the corrector had dewed up a bit, or the owner didn't have collimation spot on, or maybe it hadn't cooled, or a mixture of several of these....Or as you say it could just have been a Friday afternoon scope in the factory, or one made during the Halley comet era (an era in the late 80's where QC was bad as they were trying to keep up with demand).

I agree that Chinese Maks have got really good and consistent. Maybe they are just easier to manufacture, and if you're keeping the scope outside might be a better bet.

Yeah, so to recap, maybe bigger isn't always better in a land of often bad seeing. I think this is why the, 127mak, ED100 and ED120 does so well in blighty! 

Going back to C8's, I as mentioned I've had I think 4 over the years of different types, plus a C6 xlt. I think one was possibly a bit sub par, but this was my first one so looking back I'm not convinced I got collimation spot on enough for it to really sharpen up? Or maybe it was just bad? Certainly my more recent Meade 8", C6 xlt, and the Edge HD were very good indeed, especially the the Edge which gave me my best ever view of Jupiter (staggering detail), the other two got close to the Edge with the 0.63 corrector, but obviously didn't have the sharpness then at native focal length.