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Originally Posted by troypiggo
Interested in gathering some thoughts on the above scopes, primarily for planterary and DSO imaging with DSLR and/or CCD. As a side-comment, also interested in how they'd go for viewing occasionally as well (planetary and DSO).
They all seem to fall within the same ballpark of price. I know their focal lengths differ. I'd be trying to mount them on my HEQ5PRO for the moment with ED80 as a guidescope. Pushing the limits of the mount, I know, but if I can get away with it I will.
Celestron C9.25 - this has consistently been recommended in many reviews as a great imaging scope. 2350mm focal length, with barlow/powermate certainly capable of planetary imaging. f/10 - too dark for observation?
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Never used one or even looked through one. But as it's an SCT it will have coma at the edge of field unless a Focal Reducer/Field Flattner is used. Should be great for planetary work (Bigger aperture means shorter exposure time, longer FL for image scale. For DSO's will be difficult to get effective guiding at long FL, even with a FR in the image train. Will need a better mount. Visually f-ratio is less important than aperture.
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Originally Posted by troypiggo
GSO RC 8" - newish on market. Good first impressions, but read that you need to spend a bit more money on it to improve/correct some distortions or optical errors?
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See ongoing threads on this scope. Seems to be good for DSO's. Visual and planetary may suffer due to large central obstruction and smaller aperture. Only available in 8" ATM. Light, so won't overtax your mount. Focusser needs upgrading, requires FR for flat field, several have been tried, but none are made specifically for this scope.
Quote:
Originally Posted by troypiggo
VC200L (or is VMC200L better) - heard this one highly recommended as well.
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Flat field is great for DSO's, not seen too much planetary work done with these, again may suffer from larger CO. Very fat spider so large diffraction spikes and square stars if you don't oversample. Reasonably light so mount should be up to it.
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Originally Posted by troypiggo
LX200-ACF - read good reviews on these too.
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Assume you mean the 10"er OTA. Same arguments as for C9.25" regarding f-ratio and FL. Flat field, so FR shouldn't be a FF as well, although in practice the f6.3 has been used. I would reccomend the AP0.75 FR as it's great on my RCX, Optec 0.5 induces coma at edge of field so off-axis or self guided cameras have problems with this FR. Great visual scope.
Quote:
Originally Posted by troypiggo
Can I please have your 2 cents' worth? If you have one of them and were faced with the same dilemma, what made you choose X over Y etc?  |
In general, one scope can't do all of these things, as usual there will have to be a compromise between uses. Pick which one you are going to concentrate on and pick the best scope for that, then put up with the limitations of the other uses.
For planetary, aperture is king, it gives better image scale as it usually comes with longer focal length. Mount is unimportant, you can even use an Alt/Az fork mount. Collimation of the optics is essential.
For DSO's, the optics are relatively unimportant, the mount is King. You need low PE or consistent PE, other than that f-ratio is important if imaging under light polluted skies. Collimation of the optics is essential.
Visually, the optics are important, aperture rules, image scale is defined by your eyepiece, larger aperture allows more magnification. Again mount is not very important, but pointing accuracy and ease of setup become factors.
Hope this helps, of course other may have different opinions.
Cheers
Stuart