What's the best planetary imaging scope these days?

[Camelopardalis (Dunk)]

I like my ZWO ASI224MC, very sensitive and low read noise. Experts with mono versions of ZWO ASI290 have been putting out some absolutely cracking results IMO.

[Rac (Raymond)]

For colour I like the ASI224MC with an ADC and for mono I like the ASI290MM.
I have both but haven't had a good night with the ASI290 yet. I find it more fun using the colour camera and you can get some really good results with it!
I use my DIY 20" goto dob.
Here's a link to my flickr page. All this years images are with the asi224 and the 20" and a few with my 18" f3.3 newtonian.
https://www.flickr.com/photos/46302893@N02/

[Paul Haese]

It's been a couple of years since I have produced a top class planetary image, but I have been keeping tabs and planning my return to planetary imaging albeit in a remote capacity. Staying up all night has knobs on it so my plans center around removing that problem.

Part of the above plan is to replace my peltier cooled C14. Its diameter is limiting but Damian Peach and Darryl Pfitzner are still producing the best images with these scopes. Darryl images in the SA Mallee not far from my site. That said, the corrector dewing will not meet my plans. So I am contemplating a radical change. Most likely an RC despite the seconday size and mass I am inclined to experiment and that Greg is what I think you should. Experimentation will give you good data. Seeing is always king in planetary imaging and no matter which scope you use, it will dictate your results. In the 10 years I was doing planetary I can count probaby 15 nights when the seeing was exceptional and most of them were from my current imaging site.

As to cameras. The 224MC and 174MC are highly touted. I have recently bought the 174MC but have not yet been able to test it in vain. My last camera was a 120m and will still use that until I find a new mono camera. I also have seen good results from a 290m too. Given how hard planetary imaging really is, I would recommend going with a colour camera first.

[Stefan Buda]

Raymond,

Top notch images but I'm even more impressed by those sets of extra focal images. I don't think I have seen better.

Can't advise on cameras as I'm behind in that department. I deliberately picked an older version for my current camera because of its 3.75 micron pixel size that allows me to do high resolution lunar imaging without a focal extender, at 6.5m focal length. For planetary I only need to use a 1.4x teleconverter.

Paul,

Planetary stacking software is so damn good these days that you can reach the theoretical limit of your scope in moderately good seeing. I have not experienced anything that I could call excellent seeing and yet I've been able to go down to bellow 0.2" quite often.

[ags_ (Phil)]

My 14"SCT coupled to a ZWO174mono with astrodon filters produced many very good planetary images, however nothing beats a correctly built Newt for contrast that's why I changed. A secondary around 20% diameter of a top end main mirror is best, but anything will work especially if you have great seeing! The best camera I have ever used is my current GS3-U3-32S4M-C a newer version CM3-U3-31S4M-CS is now much lower priced.

[clive milne]

Greg, we have a 16"DK up at the dark sky site (which often has excellent seeing) It performs beautifully on planetary, certainly better than any C14 I have ever looked through (and I have actually owned one with good optics)... fwiw) The difference in secondary ratios between these scopes is not that great (35% vs 40%)

I would not recommend the TEC Mak... you will no doubt find the aperture to be limiting.

As others have intimated, thermal management is everything.
The way the pro's do it is to house the telescope in an insulated enclosure
which is refrigerated during the day. Interestingly, telescope performance
is significantly less affected by having optics below ambient as compared to when they are warmer. The boundary layer tends to just slide off rather
than sending plumes up in to the OTA. When I visited the Max Planck observatory on Calar Alto (some years ago) the 3.5m was basically kept just above the anticipated dew point, or minimum night time temperature, which ever was greater... food for thought.

Two other things the pro's do that (most) amateurs don't are:
* Elevate the telescope above the ground... most of the seeing is within the first 10m or so. It's worth noting that often when potential observing sites are evaluated for seeing, they'll build an elevated platform for the small aperture test telescope.
* Secondly, (according to the professional literature) the boundary layer
can be disrupted by blowing air horizontally across the optics at a velocity of a couple of m/s. (Wilson et al)

The fact that massive telescopes with substrates 20cm thick or greater (like at the ESO) can perform so well even with tens of tonnes of thermal mass is testament to the fact that the strategy outlined above genuinely works.

If the scope is going to be a dedicated planetary instrument, you only need a diffraction limited field of a minute of arc (or there abouts) so a simple Newtonian would actually be the best bang for the buck. Also, being as exposures are going to be no more than a fraction of a second then the highest performance per dollar will be a large aperture Newtonian on a driven, Alt Az mount in an elevated, insulated, air conditioned observatory.

2c

~c

edit}

fwiw, here's a direct image of a planet orbiting the star CVSO 30 taken with the Astralux camera on the 2.2m on Calar Alto... separation is approximately 2 arc seconds.
Obviously, they are doing something right.
image:
http://www.caha.es/images/prel/cvso30/portada.png
info:
http://www.caha.es/the-weird-system-...distances.html

best
~c

[gregbradley]

Thanks for the answers. There's a fair bit to it.

I'll start with putting one of those recommended cameras on the CDK and see how it goes.

I have a portable air conditioner I could rig up to blow colder air onto it if needed.

Thanks to all who responded.

Greg.