SW120ED or C9.25 for planetary imaging

[Astronutjob]

Hello iv have a SW120ED and C9.25 the SW120ED is mainly used for deep sky imaging and my plan was to use the C9.25 for planetary and lunar imaging, would i be better just selling the C9.25 and just getting say a X3 and X5 barlow with for use with the sw120ED? as i rarely use the C9.25. what are yours thoughts?

[Freddie]

You will be much better off with the focal length of the 925 for planetary. Even with the increased FL, a barlow on the 925 is pretty much a must.

[JamesF]

Loads more aperture, loads more focal length. Can't imagine why you'd not choose the C9.25, to be honest.

James

[earth titan]

9.25, easy choice.

Loads of aperture, long focal length, no false colour problems, portable.

Best scope I've owned - and I've owned a few!

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[michael.h.f.wilkinson]

For planetary imaging and viewing the C9.25 takes any 80mm scope to the cleaners. With a focal reducer you could think about DSO imaging with the C9.25, but that would need a hefty mount I guess.

[Ludd]

Smaller apertures are fine for DSO imaging where resolution is not a primary concern, but as soon as you start observing and imaging planets, you'll need as much resolving power as you can sensibly get, and only aperture can deliver that.

The 9.25 may be a bit more susceptible to bad seeing than a smaller aperture, but I suspect that may be at least partly due to the fact that the 9.25 has the resolving power to show the atmospheric problems that the 120 doesn't show.

Have a look at the sort of planetary images that people are producing with the 9.25 all around the world - it's the ideal scope for this in many ways. I just wish I could afford one!

[ollypenrice]

Refractor nut that I am, for DS imaging it has to be the C9.25. It might not be cut and dried visually on the planets (our TEC 140 usually beats our 10 inch Meade) but for planetary imaing the C9.25 will win easily.

Olly

[hunterknox]

120ED is a brilliant scope, but you need the C9.25.

[Rich MedRev]

C9.25 all day long for planetary imaging, IMHO a total no-brainer!

Sent from my BlackBerry 9800 using Tapatalk

[laser_jock99]

I'm a 120ED owner but would advise you to go for the C9.25. Aperture=resolving power.

[michael.h.f.wilkinson]

Refractor nut that I am, for DS imaging it has to be the C9.25. It might not be cut and dried visually on the planets (our TEC 140 usually beats our 10 inch Meade) but for planetary imaing the C9.25 will win easily.

Olly

I have looked at planets through a couple of APO scopes (including that TEC 140, but alas only under atrocious seeing conditions), and the image is more contrasty than in an SCT, but an SCT with significantly larger aperture should be able to show more detail, albeit at a lower contrast. TheAPO image is more immediately pleasing, but the SCT shows the finer detail once you take your time at the scope. If this is not the case, the SCT is either miscollimated, or the figure of the optics is poor.

The C9.25 is particularly good, because it has an F/3 primary, rather than F/2, which makes control of spherical aberration easier.

[Naemeth]

I have looked at planets through a couple of APO scopes (including that TEC 140, but alas only under atrocious seeing conditions), and the image is more contrasty than in an SCT, but an SCT with significantly larger aperture should be able to show more detail, albeit at a lower contrast. TheAPO image is more immediately pleasing, but the SCT shows the finer detail once you take your time at the scope. If this is not the case, the SCT is either miscollimated, or the figure of the optics is poor.

The C9.25 is particularly good, because it has an F/3 primary, rather than F/2, which makes control of spherical aberration easier.

Reading wikipedia (which may not be the most accurate source), the C9.25 has a F/2.3 primary and a secondary of -F/4.3 (at least I think it's negative).

Regarding the original question, I think everything has already been said, the focal length and aperture of the C9.25 make it a far better choice for planetary imaging, and will have the focal length to be able to get the most of the best conditions.

HTH

[michael.h.f.wilkinson]

You are right, that should be F/2.3. Even that small change allows better control over SA.