C9.25 - Mushy or Sharp?

[Flame Nebula]

I'm seriously considering this scope, but need to pass a confidence  threshold. 

I need to therefore harvest as many opinions from users, past and present, with regards to their experiences. 

Particularly, with respect to planetary and splitting doubles. 

I've been concerned by reports of mushy views. I like sharp contrasty views, so that would be a deal breaker. But, if a majority of people here have had no issues, that would be enough for me. 

Note, on the CN site, most people there appear to use the word 'sharp' when they refer to this scope.

So, this leaves me confused. 

So, as much help as you can give me, would be greatly appreciated. 

Thanks 

Mark 

 

Edited March 17 by Flame Nebula

[Mr Spock]

Very good on doubles - I split 0.7" with it. Mostly ok on the moon depending on seeing. I've had it up to x294 on a few occasions. On Jupiter I have consistently better views with my 100mm apos (current and previous). I could never really see any belt detail with it. It was always soft and 'mushy' - it doesn't have the MTF 'bite' for belt detail.

It was also very prone to poor seeing conditions. It was stored in a cool place and still left to cool a couple of hours. Often I would just bring it straight back in as the views were too 'mushy' to do planetary.

[johnturley]

My C9.25 gave quite good planetary views, and I personally wouldn't describe them as mushy, unfortunately I never got round to comparing the views side by side with my Esprit 150 when I owned both scopes, but my feeling is that the Esprit 150 gave sharper views. One point bearing in mind however is that my Esprit 150 resides in an observatory shed (piggybacked on top of my 14in Newtonian), whereas my C9.25 (CPC version) was stored in a conservatory (which can get quite hot in summer), and would have suffered from longer cool down times.

Based on several observers comments, it does seem that the optical quality of C9.25's can be quite variable, some suggest that the Edge HD versions are more consistent, but a lot more expensive. I bought my C9.25 from Rother Valley Optics, who are quite local to me so that I was able to pick up the scope in person, and they did check the collimation for for me before I picked it up, and if you purchased from them, you could ask whether they could carry out a Zygo test like they do on Refractors. 

As mentioned in another thread, I would recommend purchasing the OTA and mount separately, rather than getting the CPC version, you would would them be able to mount another scope such as a 4in APO on the same mount.

John 

Edited March 17 by johnturley

[dweller25]

I had a good C6, an excellent C8 and a terrible C9.25. In my opinion SCT optical quality varies.

For the same price as a C9.25 you can buy a Takahashi 180mm Mewlon with 1/20th wave optics which seem to get consistent praise 🙂

Edited March 17 by dweller25

[Roy Foreman]

I only use my C9.25 for lunar and planetary imaging, and for this it excels. Beats Skywatcher's 150ED and 180 Mak hands down.  Can't speak for visual.

Damien Peach has a review of it on his website, and recons it is a real GEM.  Again only considering imaging, but I guess if it does this well, then it is definately not going to be mushy visually.

[Elp]

Don't have that aperture but have a C6, definitely mushy. A larger aperture will only be more affected by seeing.

Want sharp like you're looking through an electronic high megapixel camera viewfinder, refractor or Newtonian. SCT in my experience is near the bottom for clarity, a decent refractor will give sharp views more reliably even during bad seeing.

[Highburymark]

SCTs appear to be very variable in terms of sharpness. I had a decent C8 Edge but a very average C6. Most SCTs will deliver good views of the Moon but almost any telescope or eyepiece will perform well on lunar up to 200x. It’s the planets where differences are clearer, and my TSA-120 is simply in a different league on Jupiter and Mars, even compared with my old C8 Edge. The 9.25 is supposed to be the best SCT, and I’m sure the best C9.25s are excellent. But I’d want to test any SCT before buying.

[mikeDnight]

Over 45 years Ive only once seen a SCT give a great view of Jupiter and that was an old orange 1980's C8. Other than that, and no matter what the aperture, I've found them to be consistently disappointing as regards planetary sharpness. Schmidt's original design was to be used as a camera and that's where they seem to shine, though how much of that is down to stacking and computer jiggery pokery I've no idea!  Maksutov's on the other hand, despite being similar in design other than the corrector plate, give very pleasing views, and once thermally stable, are probably as close to refractor like as it gets. So the issue with SCT's would appear to be down to the Schmidt corrector which is a thin mass produced lens made by sucking a optically flat plate onto a figured master plate. Once ground and polished it takes on the figure of the original. So the Schmidt plate is not an individually figured item, it's pot luck! 

[Flame Nebula]

3 hours ago, johnturley said:

My C9.25 gave quite good planetary views, and I personally wouldn't describe them as mushy, unfortunately I never got round to comparing the views side by side with my Esprit 150 when I owned both scopes, but my feeling is that the Esprit 150 gave sharper views. One point bearing in mind however is that my Esprit 150 resides in an observatory shed (piggybacked on top of my 14in Newtonian), whereas my C9.25 (CPC version) was stored in a conservatory (which can get quite hot in summer), and would have suffered from longer cool down times.

Based on several observers comments, it does seem that the optical quality of C9.25's can be quite variable, some suggest that the Edge HD versions are more consistent, but a lot more expensive. I bought my C9.25 from Rother Valley Optics, who are quite local to me so that I was able to pick up the scope in person, and they did check the collimation for for me before I picked it up, and if you purchased from them, you could ask whether they could carry out a Zygo test like they do on Refractors. 

As mentioned in another thread, I would recommend purchasing the OTA and mount separately, rather than getting the CPC version, you would would them be able to mount another scope such as a 4in APO on the same mount.

John 

Thanks John, 

The plan, all being well, is to get a AZ-EQ6. I like the idea of a good zygo test result, prior to agreeing to purchase. I also wondered if FLO may also be prepared to do that. 

[Flame Nebula]

3 hours ago, dweller25 said:

I had a good C6, an excellent C8 and a terrible C9.25. In my opinion SCT optical quality varies.

For the same price as a C9.25 you can buy a Takahashi 180mm Mewlon with 1/20th wave optics which seem to get consistent praise 🙂

Thanks Dweller, 

Since I'm also planning on planetary AP, I need ideally to have more aperture. Unless of course the Tak can produce high quality planet images.... 

[Flame Nebula]

3 hours ago, Roy Foreman said:

I only use my C9.25 for lunar and planetary imaging, and for this it excels. Beats Skywatcher's 150ED and 180 Mak hands down.  Can't speak for visual.

Damien Peach has a review of it on his website, and recons it is a real GEM.  Again only considering imaging, but I guess if it does this well, then it is definately not going to be mushy visually.

Hi Roy, 

You'd think so wouldn't you. I know imaging selects best frames for stacking, but if all the frames were mushy, so would the final image? Unless my logic is flawed. 

[dweller25]

Just now, Flame Nebula said:

Hi Roy, 

You'd think so wouldn't you. I know imaging selects best frames for stacking, but if all the frames were mushy, so would the final image? Unless my logic is flawed. 

Correct, “you cannot make a silk purse out of a sows ear” 🤣

[Flame Nebula]

2 hours ago, Elp said:

Don't have that aperture but have a C6, definitely mushy. A larger aperture will only be more affected by seeing.

Want sharp like you're looking through an electronic high megapixel camera viewfinder, refractor or Newtonian. SCT in my experience is near the bottom for clarity, a decent refractor will give sharp views more reliably even during bad seeing.

Hi Elp, 

Well, I'm thinking of getting a used SW 120ED, after compiling lots of opinions here, but that would be for visual only. It would be nice to think that for the cost of a new C9.25, it would be of some visual use too, once cooled down, not just AP. 

 

[Flame Nebula]

1 hour ago, Highburymark said:

SCTs appear to be very variable in terms of sharpness. I had a decent C8 Edge but a very average C6. Most SCTs will deliver good views of the Moon but almost any telescope or eyepiece will perform well on lunar up to 200x. It’s the planets where differences are clearer, and my TSA-120 is simply in a different league on Jupiter and Mars, even compared with my old C8 Edge. The 9.25 is supposed to be the best SCT, and I’m sure the best C9.25s are excellent. But I’d want to test any SCT before buying.

A zygo test could be an option if new. Perhaps this might help to avoid an lemon. 

[Elp]

Imaging and visual are two different things. With imaging you can stack, reject the images where seeing was poor so are left with the "good" images, you can then denoise, sharpen, sharpen with wavelets and deconvolution to recover even more detail. Even derotate the planet.

When doing visual you can't do any of that and are at the mercy of atmospheric seeing.

Edited March 17 by Elp

[johnturley]

19 minutes ago, Flame Nebula said:

Thanks John, 

The plan, all being well, is to get a AZ-EQ6. I like the idea of a good zygo test result, prior to agreeing to purchase. I also wondered if FLO may also be prepared to do that. 

That sounds like a good plan, if just for visual with a C9.25, you could get away with an AZ-EQ5 or HEQ5 mount, but for imaging I agree that you would probably need an AZ-EQ6 or EQ6-R or equivalent.

John 

Edited March 17 by johnturley

[Flame Nebula]

1 hour ago, mikeDnight said:

Over 45 years Ive only once seen a SCT give a great view of Jupiter and that was an old orange 1980's C8. Other than that, and no matter what the aperture, I've found them to be consistently disappointing as regards planetary sharpness. Schmidt's original design was to be used as a camera and that's where they seem to shine, though how much of that is down to stacking and computer jiggery pokery I've no idea!  Maksutov's on the other hand, despite being similar in design other than the corrector plate, give very pleasing views, and once thermally stable, are probably as close to refractor like as it gets. So the issue with SCT's would appear to be down to the Schmidt corrector which is a thin mass produced lens made by sucking a optically flat plate onto a figured master plate. Once ground and polished it takes on the figure of the original. So the Schmidt plate is not an individually figured item, it's pot luck! 

Hi Mike, 

So, a bit like pulling the handle on a fruit machine and hoping three lemons don't come up? 

I'm pretty much planning on going with the used SW 120ED, based on several opinions( including yours) and my own Internet review searches, but the C9.25 is making me nervous. Potentially a lot of money and disappointment. Not my preferred option. 

[Flame Nebula]

5 minutes ago, Elp said:

Imaging and visual are two different things. With imaging you can stack, reject the images where seeing was poor so are left with the "good" images, you can then denoise, sharpen, sharpen with wavelets and deconvolution to recover even more detail. Even derotate the planet.

When doing visual you can't do any of that and are at the mercy of atmospheric seeing.

All true, but a lemon is a lemon, and if the image is mushy even in good seeing, I guess the stacked image would be too. One user on this forum, Mr Spock, reports good views through a newt and mushy views in C9.25 even after cooling. So seeing presumably wasn't the issue then. 

[Elp]

You do have cooling time to contend with also with an SCT (IE internal air). A Newtonian is open, and from what I've read as you go larger and larger with SCTs the cooling takes significantly longer as you go larger.

Edited March 17 by Elp

[RT65CB-SWL]

Maybe the views are ‘mushy’ because it has not had long enough to acclimatise. I have a C6 and give it a minimum of thirty minutes before I start observing.

The other thing I don’t get, why are Bob’s Knobs so damn expensive?

[Flame Nebula]

8 minutes ago, johnturley said:

That sounds like a good plan, if just for visual, you could get away with an AZ-EQ5 or HEQ5 mount, but for imaging I agree that you would probably need an AZ-EQ6 or EQ6-R or equivalent.

John 

I think for planetary I might get away with the heq5, but if I ever felt the urge for more difficult small dso imaging or wanted a bigger scope, the az-eq6 would allow more flexibility. I haven't purchased anything yet, so I'm open to alternatives. 🙂

[paulastro]

2 hours ago, mikeDnight said:

Over 45 years Ive only once seen a SCT give a great view of Jupiter and that was an old orange 1980's C8. Other than that, and no matter what the aperture, I've found them to be consistently disappointing as regards planetary sharpness. Schmidt's original design was to be used as a camera and that's where they seem to shine, though how much of that is down to stacking and computer jiggery pokery I've no idea!  Maksutov's on the other hand, despite being similar in design other than the corrector plate, give very pleasing views, and once thermally stable, are probably as close to refractor like as it gets. So the issue with SCT's would appear to be down to the Schmidt corrector which is a thin mass produced lens made by sucking a optically flat plate onto a figured master plate. Once ground and polished it takes on the figure of the original. So the Schmidt plate is not an individually figured item, it's pot luck! 

Mike, I can understand you saying this , to some degree,  as your experiences are  in the Lancashire/Yorkshire area - which have generally rather poor seeing - even when compared to most other parts of Britain. 

Add to this that most SCs in use are 8inches or more in aperture and the fact that SCs have suffered from varying quality control issues at various times, and what you say is understandable.

However, in places where the seeing is consisteantly much better than in the UK (parts of the USA etc),  the SCs have a much better reputation - including for planetary.  Peter Drew, who used his 8inch SC from his property in Tenerife over many years, told me many times how he was frequently able to get excellent results on the planets using magnifications between x400 and x600. This would be almost impossible in the UK.

Though I agree in the UK an SC would not be many peoples first choice as a mainly visual planetary telescope - I don't think it deserves its sometimes poor reputation.

My best view of Mars was many years ago through a 16 inch Meade 16 inch SC at Kelling Heath.  The view as dawn broke over the heath was outstanding.  This particular SCs  had been taken to Kelling from The Astronomy Centre by Peter .Drew and some other members.

 

 

 

 

Edited March 17 by paulastro

[Paz]

I can't comment on variations in scope quality but owning a C8 I can say it relies on good conditions, being cooled down, and being collimated. Occasionally I've had some great views but more often it's disappointing. (I'm visual only).

[Flame Nebula]

4 minutes ago, paulastro said:

Mike, I can understand you saying this , to some degree,  as your experiences are  in the Lancashire/Yorkshire area - which are generally rather poor - even when compared to most other parts of Britain. 

Add to this that most SCs in use are 8inches or more in aperture and the fact that SCs have suffered from varying quality control issues at various times, and what you say is understandable.

However, in places where the seeing is consisteantly much better than in the UK (parts of the USA etc),  the SCs have a much better reputation - including for planetary.  Peter Drew, who used his 8inch SC from his property in Tenerife over many years, told me many times how he was frequently able to get excellent results on the planets using magnifications between x400 and x600. This would be almost impossible in the UK.

Though I agree in the UK an SC would not be many peoples first choice as a mainly visual planetary telescope - I don't think it deserves its sometimes poor reputation.

My best view of Mars was many years ago through a 16 inch Meade 16 inch SC at Kelling Heath.  The view as dawn broke over the heath was outstanding.  This particular SCs  had been taken to Kelling from The Astronomy Centre by Peter .Drew and some other members.

 

 

 

 

Hi Paul, 

Indeed, as noted in my original post, there does seem to be a larger percentage of people on the CN site(which may or may not mean predominantly American based users) who reported sharp C9.25. But, then I see evidence from one user at least, who said their newt had no issues with the seeing on the same night the C9.25 gave mushy views. Logic seems to vanish then. Clearly, this could be one of those nightmare situations, where multiple factors are at play. So, a mushy view could be due to the OTA and/or seeing and/or collimation and/or thermals. 😬😬

 

[paulastro]

2 minutes ago, Flame Nebula said:

Hi Paul, 

Indeed, as noted in my original post, there does seem to be a larger percentage of people on the CN site(which may or may not mean predominantly American based users) who reported sharp C9.25. But, then I see evidence from one user at least, who said their newt had no issues with the seeing on the same night the C9.25 gave mushy views. Logic seems to vanish then. Clearly, this could be one of those nightmare situations, where multiple factors are at play. So, a mushy view could be due to the OTA and/or seeing and/or collimation and/or thermals. 😬😬

 

Yes, you're right about the collimation issue.  Strange for SCs since they are about the easiest type of telescope to collimate in my view.  As you can imagine, with Peter Drew present, the SC I mentioned at Kelling all those years ago would have been spot on! 😊