Planetary imaging telescope....

[wavydavy]

Hi all..........ok so here goes, ive now got my ASI120MM mono camera, EQ5 equatorial mount, however I don't think my mobile set with regards to the telescope is any good for planetary imaging, im getting reasonable images but the image scale and detail isn't quiet there I feel, im currently using a 6 inch newt, its about an F5........I feel I need more aperture, poss more focal length. Im on a serious tight budget so poss gonna sell my 6 inch to fund another.........ive been looking at 8 inch newts, id like to go for a Schmidt, but doubt budget will allow........whats peoples opinions? Any ideas of makes/models what would be well suited. Ive added the best pic so far with the 6 inch, used a x5 barlow.....

[Leveye]

Personally i think that's a great image that could be processed even a bit further. How did you achieve this just a Barlow and camera?

[Pete Presland]

i think thats a pretty good image as well. planetary imaging is not all about focal length and aperture, the seeing conditions will dictate your quality of image far more. most SCT or MAKS make good planetary imagers, due to thier long focal length. this image was taken with a MAK127 by an SGL member http://stargazerslounge.com/topic/208387-jupiter-15th-feb-on-the-c8-127-mak/

you are using the ASI120MM mono camera, are also using RGB filters?

[Space Cowboy]

An 8" Newt will beat a 5" Mak every day of the week. Newts are the best value for money aperture wise and a good barlow will up the focal length. If you can afford it go for a 10" Newt then you will see a real difference over your 6" scope.

[DrRobin]

Hi,

Nice image that. A lot of imagers use SCTs as they give you a long focal length in a short tube, but they are a lot harder to collimate than a newt, require longer cool down times and are generally a lot more expensive. A 10" newt and decent Barlow will give just as good results as a 10" SCT, but will be physically a lot bigger, probably the main reason why a lot of the large aperture scopes are SCTs.

An SCT due to its size is easier to mount on an EQ mount, but a dob is fine for the planets.

Robin

[wavydavy]

Sorry it's taken so long to reply.....my internets been down all day......thanks for the nice comments. I've also got an 12" scope at my old observatory, however it's badly outa collimation and I rarely get the chance to venture over there, it's f4 again hardly a planetary scope! But a bit bigger image scale.....think I may get better results over there.

[wavydavy]

As far as colour is concerned I've got a filter wheel but can't reach focus with it......

[todd8137]

Keep at it condition are not great at the min time and patience is all it take keep at it

Pat

[JamesF]

If you really want to keep costs under control then I'd be tempted to look at a second hand 127 Mak or C6 and combine it with a Revelation 2.5x barlow, or perhaps a decent 2x barlow if you can find one.  You might even get to keep the 6" newt for wide field that way?

I don't disagree at all with Stuart, but I think for planetary imaging an 8" newt on an EQ5 is going to be a serious handful.  At a focal length of 5m or so even the slightest wobble is going to have the image all over the camera sensor and I think you could really struggle to keep that under control with a 200P on an EQ5.  That's probably a cue for someone to say "It's fine.  I've done it and it worked beautifully at f/25"

You'd also have no problem reaching focus with the filter wheel with the Mak or SCT.  You might need something like the 200PDS were you to want to do that with an 8" newt.  It's possible the barlow might push the focal plane out far enough for that not to be a problem but I honestly don't know.  Something to check before you buy.

If you really wanted to go down the 8" newt route then perhaps selling everything and replacing it with something like the 200P flextube GOTO dob would be the way to go (assuming reaching focus isn't a problem or you're happy just to work in mono).  In fact even if focus were a problem you could just not open the trusses fully.

James

[wavydavy]

Cheers James........

[DannyHarvey]

Nice capture!

[catman161]

I use an 8 inch Newt (200P) mounted on an NEQ6 and it is great for planetary imaging and observing of the fainter fuzzies. It's a great all rounder-I highly recommend.To give an example of what can be achieved with one in okay seeing conditions I have attached an image that I took with the ASI120MC (colour version of your camera) through the newt with a 2x televue powermate and 3.5 inch extension tube.

[Space Cowboy]

Unless your 6" Newt is of poor quality I don't see a 5" Mak making any improvement. Focal length is governed by aperture, the more light you have the more you can increase image scale. My 10" Dob is only 1200mm fl compared to my 5" Mak at 1500mm but I can image at twice the focal length with the Dob simply by using a 4 or 5x barlow.

As James mentions Auto tracking/GOTO Dobs are great but the GOTO Dobs are not cheap and the Auto trackers are no longer sold so unless you can get one second hand you are looking at over £700 for an 8" GOTO Dob.

[SnakeyJ]

Excellent advice throughout this thread, and I think a very good image in your opening post - I think your best result for little budget would be to tune that 12" F4 Newt up, with a 5x barlow and a filter wheel to provide some additional extension, you can probably push F25 on this which will give you a nice image scale and plenty of light grasp.    

Collimation will need to be accurate to get the best results, but start with cheshire or laser and then star test for initial tuneing with  a 2x barlow, the camera and Metaguide might be a good initial step and then hone with the full image (5x barlow, filter wheel and camera) in place on a star close to Jupiter Eps Gemini works for me.     I do find a red filter helps to stabilise the image when star testing in Metaguide.

You'll also need to let things cool down properly to get best results at long focal lengths - if not already fitted a fan can help to speed cooling and eliminate tube currents.    I also try to avoid dew heaters, but use a hair dryer if the secondary gets dewed up. 

[wavydavy]

All great advise.....lots for me to take in.....gonna give the 12 a go......in the near future.