There's nothing like...

[Westmoorland]

...Upgrading to a £3000 set up to discover you probably had more success with a £400 one. The clouds are threatening to spoil another night but I'd like to know how to get the most out of a C9.25 AVX. 

[Stu]

3 hours ago, Westmoorland said:

...Upgrading to a £3000 set up to discover you probably had more success with a £400 one. The clouds are threatening to spoil another night but I'd like to know how to get the most out of a C9.25 AVX. 

Can you give a bit more detail on the problems you are having, and what is causing the disappointment? What was your previous setup and what was better about it?

[Mr Spock]

As a former C9.25 user I can understand your frustration. On a good night they can be very detailed. They do need a long cool down though to get the best out of them as they can suffer from strong tube currents. Also, they seem susceptible to poor seeing more than other scopes. A good, long, dew shield is also essential. 

I have, on occasions, used mine at x392 (6mm eyepiece). I had an easy split of a 0.7" double with it. So, the quality is there, you just need to be patient.

[Westmoorland]

7 hours ago, Stu said:

Can you give a bit more detail on the problems you are having, and what is causing the disappointment? What was your previous setup and what was better about it?

It's early yet, as I only picked it up from the seller late last month. The only other scope I owned was a SW Mak127 alt-az, bought in late 2013. I stopped using around it 2015 as I felt I'd done all I could with it and knew there was better, 'bigger', stuff out there.  The dew was not too bad, even without a dew shield, unlike with the c9.25 with a dew shield on now. It wasn't great at tracking objects and keeping them in the eyepiece for long periods but at least I could align it easily: (I've only managed 1 accurate alignment with the 9.25 so far). The 1500 focal length of the Mak made it worth pointing at objects like the Pleiades and the Orion nebula but it seems low power is impossible now even with a 25mm eyepiece. I was lucky on my first night with it and got a good look at Jupiter: The improved brightness and detail satisfied me but both Jupiter and Saturn have seemed over turbulent ever since. The ring nebula looked great from what I remember years ago but I found it by luck as I slewed randomly knowing my scope was not aligned properly, so it seems pointless looking for deep sky stuff until I know I can reliably align it. 

Optically I know it can perform but I never know whether it's down to the atmosphere or the scopes readiness that the seeing goes bad. I had some naive idea I was at the 'intermediate' stage of the hobby, having been able to handle a small Mak and name a few stars, and the upgrade would be a piece of cake if I read about bigger scopes. This is not the case and I've probably jumped the gun. There's no question I won't keep the scope as I know it's got a great reputation and I feel lucky to own it and the mount, but it seems expensive diagonals, eyepieces, power supplies were not the most essential upgrades I should have gone for. 

[Westmoorland]

2 hours ago, Mr Spock said:

As a former C9.25 user I can understand your frustration. On a good night they can be very detailed. They do need a long cool down though to get the best out of them as they can suffer from strong tube currents. Also, they seem susceptible to poor seeing more than other scopes. A good, long, dew shield is also essential. 

I have, on occasions, used mine at x392 (6mm eyepiece). I had an easy split of a 0.7" double with it. So, the quality is there, you just need to be patient.

I don't know the quality of this shield the seller threw in with the scope and mount.

 

[PeterCPC]

I don't think that dew shield is heated. My experience with my C9.25 made a heated dew shield a necessity. Also, have you checked the collimation yet? They hold collimation well but you have to get it right first.

[Mr Spock]

That dew shield is similar to the Astrozap I used they work just fine.

A C9.25 is never going to be wide field. But I did find with a 2" diagonal and my 42mm eyepiece the Pleiades just fit the view. It was tight - 1.28° field of view which is as big as you can get with the C9.25. Something like a 25mm Plössl will only get you 0.53°...

Collimation is best done with a star test, so you'll need good seeing. Once done it hold for ages; mine didn't change in 18 months or more. Unlike my Newt which needs collimating every session. It is critical though and the C9.25 can't perform without the collimation being spot on.

Most of what you are saying comes with practise. It will come 

[Knighty2112]

What mount are you using with the scope? I find with my heq5 pro that I get excellent results after a 3 star align. Also I own a Celestron 6/8SE goto mount too which also performs much better with a 3 star alignment.

[Westmoorland]

1 hour ago, Knighty2112 said:

What mount are you using with the scope? I find with my heq5 pro that I get excellent results after a 3 star align. Also I own a Celestron 6/8SE goto mount too which also performs much better with a 3 star alignment.

Celestron AVX

[Westmoorland]

1 hour ago, Mr Spock said:

That dew shield is similar to the Astrozap I used they work just fine.

A C9.25 is never going to be wide field. But I did find with a 2" diagonal and my 42mm eyepiece the Pleiades just fit the view. It was tight - 1.28° field of view which is as big as you can get with the C9.25. Something like a 25mm Plössl will only get you 0.53°...

Collimation is best done with a star test, so you'll need good seeing. Once done it hold for ages; mine didn't change in 18 months or more. Unlike my Newt which needs collimating every session. It is critical though and the C9.25 can't perform without the collimation being spot on.

Most of what you are saying comes with practise. It will come 

De-focused stars, I noticed, have the hole central to the ring, so I'm hoping that's enough collimation for casual viewing.

[Westmoorland]

2 hours ago, PeterCPC said:

I don't think that dew shield is heated. My experience with my C9.25 made a heated dew shield a necessity. Also, have you checked the collimation yet? They hold collimation well but you have to get it right first.

Makes me wonder why sell dew shields in that size if they won't even work.

[Westmoorland]

Items.

[Mr Spock]

33 minutes ago, Westmoorland said:

Makes me wonder why sell dew shields in that size if they won't even work.

Mine worked just fine 

[Tomatobro]

There is a big performance difference between a dew heater strap and a dew shield (heated or not) I find

[PeterCPC]

58 minutes ago, Westmoorland said:

Makes me wonder why sell dew shields in that size if they won't even work.

It works but you need a heater as well.

[Gfamily]

You can reduce the effects of tube currents by lagging the outside of the OTA with radiator foil.  It sounds anomalous because it increases the time for the internal temperature to reduce, but it seems to be the speed of temperature adjustment that causes the internal currents that affect the seeing.

Also, when observing the planets in the summer, they will be at low altitude and more affected by atmospheric conditions. Of course, if we were observing them in the winter we could well be affected by the Jetstream - you just can't win!

In principle, you might consider getting a focal reducer to increase the field of view - to be honest, my biggest bugbear of SCT and Maks is the narrow field of view, which means that many open clusters lose their impact. 

As for dew, yes, a heated shield or a 12v hair dryer could be of value. 

[Westmoorland]

1 hour ago, Mr Spock said:

Mine worked just fine 

I was under the impression the shield alone might be an advantage. Apparently not.

[Westmoorland]

19 minutes ago, Gfamily said:

You can reduce the effects of tube currents by lagging the outside of the OTA with radiator foil.  It sounds anomalous because it increases the time for the internal temperature to reduce, but it seems to be the speed of temperature adjustment that causes the internal currents that affect the seeing.

Also, when observing the planets in the summer, they will be at low altitude and more affected by atmospheric conditions. Of course, if we were observing them in the winter we could well be affected by the Jetstream - you just can't win!

In principle, you might consider getting a focal reducer to increase the field of view - to be honest, my biggest bugbear of SCT and Maks is the narrow field of view, which means that many open clusters lose their impact. 

As for dew, yes, a heated shield or a 12v hair dryer could be of value. 

Focal reducer. More money to spend, but helps if you look at it as an investment.

[bemak187]

For larger SCT focal reducer is a worthwhile item.  Never going to have a massive field but it gives more flexibility with FOV.

[Westmoorland]

On 25/09/2022 at 17:10, bemak187 said:

For larger SCT focal reducer is a worthwhile item.  Never going to have a massive field but it gives more flexibility with FOV.

I got a look at the Orion nebula this morning. So much more vivid than in the old 5'' Mak. A focal reducer will help for views like that until I can afford a good refractor.