C9.25 - issues with seeing in uk?

[Flame Nebula]

Hi everyone 

I'm looking for people's experiences with this scope with respect to issues with poor seeing. If I get this scope it would be kept indoors, and I'm concerned it won't provide the performance I'd like unless set up hours before use, which may not be practical. I'm interested in visual and planetary AP, and I understand that seeing won't impact on the latter to any significant degree. So, my question relates to visual. I'm located in the Nottingham area, if that helps. 

Thanks 

Mark

[Stu]

2 hours ago, Flame Nebula said:

Hi everyone 

I'm looking for people's experiences with this scope with respect to issues with poor seeing. If I get this scope it would be kept indoors, and I'm concerned it won't provide the performance I'd like unless set up hours before use, which may not be practical. I'm interested in visual and planetary AP, and I understand that seeing won't impact on the latter to any significant degree. So, my question relates to visual. I'm located in the Nottingham area, if that helps. 

Thanks 

Mark

Hi Mark,

I have had a C925 and would say that from a warm house out on a cold night you do probably need an hour or two to get it cooled down. I did always struggle to get mine cooled, especially if the temperature continued dropping.

Have you considered an open design like the StellaLyra 8” Classic Cassegrain? Or the Tak Mewlon 210 depending on budget. These both have secondary supports so will show diffraction spikes but will cool more easily and don’t suffer from dew problems on the corrector.

Do you have a mount already?

[Flame Nebula]

28 minutes ago, Stu said:

Hi Mark,

I have had a C925 and would say that from a warm house out on a cold night you do probably need an hour or two to get it cooled down. I did always struggle to get mine cooled, especially if the temperature continued dropping.

Have you considered an open design like the StellaLyra 8” Classic Cassegrain? Or the Tak Mewlon 210 depending on budget. These both have secondary supports so will show diffraction spikes but will cool more easily and don’t suffer from dew problems on the corrector.

Do you have a mount already?

Hi Stu, thanks for your reply. I'm currently in the pre purchasing room, and don't have anything yet. Well, I have an ed80 and 127mm mak, but I'm looking for a major step up. I'm conscious that aperture definitely rules for jupiter and saturn AP, so the C9.25 would probably be better than lower aperture options (I think?). 

[JeremyS]

Do you have a (secure) area, dry area that you can store the OTA that is closer to outside temp, eg shed, garage?

[Flame Nebula]

33 minutes ago, JeremyS said:

Do you have a (secure) area, dry area that you can store the OTA that is closer to outside temp, eg shed, garage?

Hi Jeremy, I guess in the autumn and winter, our conservatory would get quite cold. I wouldn't keep it there in summer though 😬

[Cosmic Geoff]

4 hours ago, Flame Nebula said:

I'm interested in visual and planetary AP, and I understand that seeing won't impact on the latter to any significant degree. So, my question relates to visual. I'm located in the Nottingham area, if that helps. 

My experience is that seeing has a marked effect on planetary astrophotography.  From what I have read, C9.25 is a 'sweet spot' for planetary imaging in the UK, in that beyond that aperture you are increasingly unlikely to ever be able to use the scope to its full potential. Allowing time for cooling would be beneficial, but I have never been able to quantify this.  If possible, store it somewhere cool and not high up in a centrally heated room. In any case, storing it indoors will give you half an hour's cooling during the setup time.

[Stu]

One option is a large plastic, sealed contained which you can put the scope into and place outside a few hours before it is needed. I’ve not done this myself but have read that it is effective for similar scopes.

[dweller25]

@Flame Nebula

The trick to getting the best out of a closed tube telescope is to minimise the temperature difference between the optics, the interior air temperature and the exterior air temperature.

Waiting for the scope to come into thermal equilibrium is one way to do this.

Another way is to wrap the scope with two layers of Reflectix from B&Q, this essentially minimises the temperature gradient between the outside air and internal air in the scope giving internal stability.

You will be able to use your scope immediately and an added bonus is the corrector takes much longer to dew up as the air inside the scope stays warm longer.

[davidc135]

Definitely spend a few pounds on a double layer of reflectix.

I'm not sure how much seeing varies from place to place throughout the UK. I suppose it must be influenced by local microclimate but I'd be surprised if the 9.25 sct didn't live up to its potential where you live, at least reasonably often.

David

[dweller25]

My location just North of Manchester is a crossing point for the two major UK flight corridors, so my seeing is not great 🤷🏻

Having tried all the major types of telescopes I find refractors work best in this location.

I live within the Manchester terminal control area 😱

 

Edited February 15 by dweller25

[Dave1]

On 15/02/2024 at 10:53, Flame Nebula said:

Hi everyone 

I'm looking for people's experiences with this scope with respect to issues with poor seeing. If I get this scope it would be kept indoors, and I'm concerned it won't provide the performance I'd like unless set up hours before use, which may not be practical. I'm interested in visual and planetary AP, and I understand that seeing won't impact on the latter to any significant degree. So, my question relates to visual. I'm located in the Nottingham area, if that helps. 

Thanks 

Mark

Hi Mark, 

I haven't had a C9.25 but I have had a Skywatcher Skymax 180 Pro. Out of all telescope designs Maks unfortunately need the longest cool down. Going from warm house to freezing temperatures will take a couple of hours for full acclimatisation to take place. I would recommend a dew shield and dew heating strip. The best thing to do though is to try and keep the telescope in an out building of shed that is closer to ambient outside temperature, this reducings the cool down time.