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markclaire50

Probability of new/used C9.25 being a duff one?

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I hear many stories of people getting poor performance from various SCT scopes. Comments related to mushy viewing for example.

Then I hear other stories of them being superb. ????

Has anyone had experience of buying this C9.25 scope new or old and finding it less than you hoped? By less, I mean less than it should perform, as opposed to hubble-like views. ??

Thank you 

Mark 

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I bought my C9.25 new but the collimation still needed tweeking to get it right. Mushy views are normally down to collimation. It is a superb scope.

Peter

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3 minutes ago, PeterCPC said:

I bought my C9.25 new but the collimation still needed tweeking to get it right. Mushy views are normally down to collimation. It is a superb scope.

Peter

Thanks Peter. Sometimes I've read people say they still don't think the scope performs even when they've collimated. Why do you think that might happen? Dodgy mirror? How easy was collimation for you? 

Edited by markclaire50

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I've never bought a C9.25 but I've bought several others from 8" to 16". Never had a duff one, most that are, are ones that have not been collimated or cooled correctly. A used one should have a track record and probably a safer bet.   ?

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1 minute ago, markclaire50 said:

Thanks Peter. Sometimes I've read people say they still don't think the scope performs even when they've collimated. Why do you think that might happen? Dodgy mirror? How easy was collimation for you? 

Collimation is easy with an SCT - particularly if you have fitted Bob's knobs.

Peter

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Here are a few factors...

You have to let SCTs cool down, this used to take up to an hour with my c11.

You have to have the scope well collimation.

I believe c925 and definitely c11 benefit from a two speed micro focuser as fine focus is difficult with the standard focuser, my c8 focuser was fine as the mirror is much lighter. A decent focuser makes all the difference to sharp images. My c11 was a [removed word] to get focused until I got a feathtouch microfocuser fitted.

Many folks use way too much magnification and expect sharp views, you need the right magnification for the chosen target.

The bigger aperture is more atmosphere dependant, a c11 can give shaky moon views when a small refractor has no issue on the same night. My big dob is the same.

However, the longer focal length of SCTs can make those DSOs grow in size and get more that just a grey fuzzy at the eyepiece.

Oh, and invest in a FLO dual fit desiccant cap to keep it all dry inside when not in use. 

Alan

Edited by alanjgreen
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I've only ever bought C8's C6's and a C5. I had doubt's about the first one I ever bought, but in hindsight I'm not sure I had it collimated good enough. All the proceeding ones I've owned have been superb for what they are. 

You need to let them cool too to get the most out of them. If you're keeping the scope indoors bear this in mind. 

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32 minutes ago, Peter Drew said:

I've never bought a C9.25 but I've bought several others from 8" to 16". Never had a duff one, most that are, are ones that have not been collimated or cooled correctly. A used one should have a track record and probably a safer bet.   ?

Thanks. Obviously with used, you are trusting what the seller says, with no protection if it turns out to be 'duff'. With new, you can get it replaced once you're sure it's not performing even if collimated. I suppose this is always the issue, but given these scopes cost nearly a £1000 even secondhand from what I've seen, I worry about the risk of used. 

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As all above....in bad seeing,as with most scopes,it can give mushy views,but when collimated and cooled with good seeing my one is superb.

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I currently have 6, none of them new but all good.   ?

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There is no such thing as a do it all scope but in my view my SCT 9.25" comes quite close.  Fit Bob's knobs and it is easy to collimate.  I have had to collimate mine twice in 12 years.  I also added a second hand Moonlite focuser which helps precise adjustment and a dew shield is a must have accessory.  I can't really see what there is to go wrong with them.  You can look through the 'front window' and see if it is in good shape.

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Thanks for everyone's replies do far. The general consensus appears to remove a lot of concern with buying used. And making sure collimated! 

I'm thinking of going with the C9.25, seeing how it performs, particularly on double stars and planets, and if I think I need to get a secondhand 180mm mak to give me what I want on those, so be it. The latter scopes are a lot cheaper too, so it will be relatively low outlay compared to the combined cost of heq5 and C9.25. But, if the latter is as good as I'm told it can be, I won't need to get the 180. I hope this is the better strategy. 

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Many of the active observers in my society own 8 or 10 inch SCT's. My ED120 refractor usually provides better views of doubles and the planets but I suspect the SCT's collimation is the reason for that - the image delivered by an SCT goes down hill quite fast if the collimation is a little off. I think a good proportion of SCT owners don't realise that the scopes do need collimation now and then:

http://www.astrophoto.fr/collim.html

 

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26 minutes ago, John said:

Many of the active observers in my society own 8 or 10 inch SCT's. My ED120 refractor usually provides better views of doubles and the planets but I suspect the SCT's collimation is the reason for that - the image delivered by an SCT goes down hill quite fast if the collimation is a little off. I think a good proportion of SCT owners don't realise that the scopes do need collimation now and then:

http://www.astrophoto.fr/collim.html

 

Hi John

Yes, I'm starting to get the feeling that a well collimated and cooled C9.25 would be a capable instrument. Emphasis on these. 

I hear enough positive comments to suspect this. I would hope this scope would be my largest aperture with respect to my likely interests. 

Thanks

Mark 

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There are few planetary opportunities for a few years so if that is your objective just bear that in mind.  The SCT fitted with a 0.63 reducer provides a great match up with the basic staranalyser S100 grating to give very good simple spectroscopy results. It’s a nice distraction whilst waiting for the planets to get better over the next few years. SCTs are very accommodating in back focus.

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8 minutes ago, Owmuchonomy said:

There are few planetary opportunities for a few years so if that is your objective just bear that in mind.  The SCT fitted with a 0.63 reducer provides a great match up with the basic staranalyser S100 grating to give very good simple spectroscopy results. It’s a nice distraction whilst waiting for the planets to get better over the next few years. SCTs are very accommodating in back focus.

Hi. Planets are definitely at the top of my list. But I've developed an interest in double stars too. In that respect I'm hopeful the C9.25 can match a 180mak. Posts I've read suggest it can. Plus I believe it may be better for dso and planetary imaging. What do you think? 

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My SW ED 150 gives 'sharper' views of double stars than my (collimated) SCT 9.25" but I have not stretched either to the limit when splitting multiples.  It's not really my thing.  Both scopes can show 6 stars in the trapezium.  I did look very recently through a MAK 180 but it didn't seem any better than my scopes and it was quite a 'turbulent' view.  The 9.25" is not a DSO imaging tool in my mind.  For planetary imaging you need to match your scope to your intended camera, that's very important so look at camera options first but both scopes have sufficient focal length.  

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Just to add, the C9.25 is a superb planetary imaging scope. You can image DSOs but it's not easy due to the focal length. What you can do is lots of short exposure imaging which can provide reasonable results.

Peter

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Here is an example of a DSO with the C9.25 with short exposures. 72 subs at 20 secs with Canon 1200d.

Peter

M57b.png

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3 hours ago, Owmuchonomy said:

My SW ED 150 gives 'sharper' views of double stars than my (collimated) SCT 9.25" but I have not stretched either to the limit when splitting multiples.  It's not really my thing.  Both scopes can show 6 stars in the trapezium.  I did look very recently through a MAK 180 but it didn't seem any better than my scopes and it was quite a 'turbulent' view.  The 9.25" is not a DSO imaging tool in my mind.  For planetary imaging you need to match your scope to your intended camera, that's very important so look at camera options first but both scopes have sufficient focal length.  

Thanks. For dso I didn't mean for imaging, just visual compared to 180mak. Whereas, I think it may be better for planetary imaging than the mak, especially Saturn based on images I have seen. I've noted your comment on the camera and I will see what other people use with it on the image details. 

You have the SW 150ed. What's your opinion of it overall. Being a refractor, I'm not surprised it can give tighter star images than the sct, although I suspect the C9.25 can resolve tighter doubles simply by its 50% greater aperture and I've read posts from people who have split stars near to its theoretical limit. 

Thanks 

Mark 

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2 hours ago, PeterCPC said:

Here is an example of a DSO with the C9.25 with short exposures. 72 subs at 20 secs with Canon 1200d.

Peter

M57b.png

Nice! My main (actually only) scope I intend using for dso is my 80ed and was the main reason I bought it, in addition to wide field views. I've also had half an eye on the 130pds f5, which I've seen a lot of good images. 

I really want a scope that I will be satisfied with with respect to doubles and planets and imaging of the latter, with decent enough aperture for light gathering and resolution. The C9.25 seems to be that scope... ?

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The ED80 is great for DSO imaging. I am sure that you will love the C9.25.

Peter

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I've never tried my C9.25 close to it's limit but 0.7" is a wide split. It is well collimated though and produces sharp stars in good seeing conditions.

As others have said, get it well collimated and it's unbeatable; have the collimation off and you'll get mush. Good news is they do hold collimation well and once done you may not need to touch it for some time.

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55 minutes ago, Mr Spock said:

I've never tried my C9.25 close to it's limit but 0.7" is a wide split. It is well collimated though and produces sharp stars in good seeing conditions.

As others have said, get it well collimated and it's unbeatable; have the collimation off and you'll get mush. Good news is they do hold collimation well and once done you may not need to touch it for some time.

Thank you Mr Spock

So you have bobs knobs? 

 

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