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Best scope under £300 for planetary imaging

scottphillips

By scottphillips
in Imaging - Planetary

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hobsey

hobsey

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Personally, I would stick with the webcam for planetary imaging and go for the Skywatcher scope you put the link up to in another post.

Reasons for this? Because of the size of the sensor on a DSLR, the images will be quite small where as the webcam has a smaller sensor meaning the images would be larger than on a DSLR.

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hobsey

hobsey

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Will my webcam be able to take multiple frames per second like DSLR's can so I can stack to improve image ?

Yes, pretty much most of the planetary images you see a round the forums are done with a webcam of some sort.

Planetary imaging camera are just high speed webcams in the end with better sensors.

You record in video mode using something like sharpcap and then stack the frames together in registax.

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michael.h.f.wilkinson

michael.h.f.wilkinson

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+1 for the webcam rather than DSLR. For planetary imaging, aperture is king, so a tracking Newtonian of significantly larger aperture than the 127mm Mak listed above will be better. You will need a quality Barlow or PowerMate to extend focus to about F15-F30 depending on the physical pixel size of the webcam used. Eyepiece projection also works well. The SkyMax 127 does punch well above its weight in planetary AP, I must say. There are some very nice images taken with these little scope about on SGL and elsewhere

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JamesF

JamesF

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+1 for the webcam rather than DSLR. For planetary imaging, aperture is king, so a tracking Newtonian of significantly larger aperture than the 127mm Mak listed above will be better. You will need a quality Barlow or PowerMate to extend focus to about F15-F30 depending on the physical pixel size of the webcam used. Eyepiece projection also works well. The SkyMax 127 does punch well above its weight in planetary AP, I must say. There are some very nice images taken with these little scope about on SGL and elsewhere

Whilst I do agree with what Michael says about newts here, I'm not sure the newt can be done in the budget you have unless you can find something used.  Once you get above 130mm aperture the prices jump a fair bit (the 150P on an EQ3-2 comes in just under £300, but then you'd need to motorise it as well to get tracking).  And given a choice between, say, a 130mm newt and a 127 Mak I think I'd personally have the Mak every time for planetary imaging because it's more compact and has a greater focal length.

The newt may still be a better choice if you'd also like to use it for wide field visual though.  The Mak is a bit more limited in that respect.

James

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Alien 13

Alien 13

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I agree with James the two realistic choices at the £300 mark are the 127Mak on the supertrack mount or the 150P on the EQ3-2 both are great starter scopes and each has its good points.

The 150P with EQ3-2 will ultimately cost a little more if you factor in the purchase of a polar scope and RA motor but would give you more options i.e. scope with webcam for planets/lunar and mount with DSLR for wide field AP.

Alan

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JamesF

JamesF

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It's probably also worth mentioning that whatever scope you buy, you'll probably also need a barlow of some sort to get a good size image.  What exactly you need depends on the camera however, and practising without one first is probably sensible.

You should also know that not all webcams are particularly good for astro imaging.  Many just don't have the sensitivity or the degree of control required.  You can't just throw any old webcam in and expect good results.

James

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Kokatha man

Kokatha man

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There are only a few things to consider but first is how much you can afford to spend - and here a second-hand scope probably comes into its own as a consideration - they don't "wear out" per se and if it is a reputable make and the mirrored surfaces etc look fine and the mount runs properly then it's as good as a new'un for all intents...."shiny new" is a bit of a suck-in in many instances!

Aperture is always first followed almost as much by a motorised (preferably EQ) mount. (although there are some fantastic planetary images taken with non-driven dobs, but that is a specialised, acquired capability imo)

Forget the dslr if you wish to concentrate on planetary imaging and probably the ASI or QHY cameras are the ones to choose between...and I'd presume that at this stage a colour unit is the way to go...

Probably little difference between a 5" or a 6" but if you look around at second-hand prices I'm sure that an 8" scope of whatever optical system is within you financial constraints (although being in Oz I obviously don't know the UK market...but being a more populated country I'd imagine you can do far better deals than over here where my appraisals are based...maybe like motorbike prices! ;) )

If you can spring an 8" newt etc on a driven mount you'll be infinitely better off than the other 2 suggestions... ;)

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Space Cowboy

Space Cowboy

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Planetary imaging is rather limited for the next few years in the UK all apart from Jupiter being very low elevations. The skymax 127 is very much limited to planetary and lunar imaging so a newtonian on an eq mount would be the most flexible option which you could use a webcam and DSLR with. The Philips spc900 webcam is still the best cheap option for planetary imaging I.e under £50. A 2nd hand canon EPs 1000d body can be picked up for £50 on ebay for imaging dsos.

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JamesF

JamesF

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The skymax 127 is very much limited to planetary and lunar imaging

*cough* :D

m27-2013-08-31.png

Stuart's point is quite fair though, in all honesty.  You do need a certain level of masochism to want to attempt the above :)

James

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Alien 13

Alien 13

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Ok so based on your comments could you provide me with a link to purchase the best two options you have suggested please ? And also possible a webcam that would suit

I think these are the two main contenders

http://www.firstlightoptics.com/maksutov/skywatcher-skymax-127-supatrak.html

http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-eq3-2.html

Alan

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JamesF

JamesF

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Ok so what about the skywatcher explorer 130p SynScan ?? It says I can track objects with with GoTo and take images using webcam ?

The desire with planetary imaging is to match the focal ratio of the optical system to the pixel size of the camera.  Taking the SPC900 as an example, the ideal is to have a focal ratio somewhere around f/35.  With a 127 Mak and a well-chosen barlow that's not actually too difficult at all.  I used to use a 2.5x Revelation Astro barlow and an extension to get there.  With the 130P the shorter focal length means you need a much higher power barlow to achieve the same focal ratio.  That can lead to a world more pain.  Get a target lined up without, say, a 5x barlow, then drop the barlow in and you may well not find  the planet at all.  Put in something with a 1/4" camera sensor in and you'll probably end up very frustrated.  It's far from impossible and you'll find plenty of experienced planetary imagers here who do it, but mostly using much more expensive kit.  Not to mention that the 2.5x barlow can be in your hot little hand for less than forty of your Earth pounds.  A decent 5x barlow will cost a lot more.

James

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Space Cowboy

Space Cowboy

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Very nice image with the skymax James. What mount was that on? The problem as I see it is the slower the scope the better the mount needs to be to take longer exposures on those deep sky objects. I don't agree with your comment on barlows and newts.  All you need is a 3x barlow and extension tube which is not that expensive. :smiley:

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JamesF

JamesF

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Very nice image with the skymax James. What mount was that on? The problem as I see it is the slower the scope the better the mount needs to be to take longer exposures on those deep sky objects. I don't agree with your comment on barlows and newts.  All you need is a 3x barlow and extension tube which is not that expensive. :smiley:

I'm fairly sure that was on a HEQ5 Pro, so not something even remotely within the OPs budget :)  I had quite a few attempts at it on my EQ3-2 and whilst it was possible to get good subs there were far too many thrown away due to trailing.  My EQ3-2 is quite old and well-(ab)used though.  That said, I'm really pleased with the image scale and I will be giving it another go with either the 127 Mak or even the C9,.25 on the NEQ6 to see how much longer I can get the exposures.  It is a bit of a masochist's game and something of an experiment just to see how far I could push things contrary to generally accepted wisdom.  I spent an awful lot of time on it and threw away shedloads of data that wasn't good enough :(

I'm genuinely surprised you can get the necessary increase in focal length with a 3x barlow and extension.  I'd estimated that the extension would be hideously long if you wanted to get out towards f/30 using an OTA with a native f/5 focal ratio.  Different game for the QHY5L-II though, as the pixel size is so much smaller.  It's one of the really nice things about the newer CMOS cameras with the smaller pixels.  I actually quite liked using a barlow and extension to get a sufficiently large multiplier because it meant I could take several steps before I fitted the camera and re-centre each time.  These days with the C9.25, ASI120MM and filter wheel I'm struggling to get a decent barlow with a small enough multiplier, which is an odd place to be in really :)

James

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riklaunim

riklaunim

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5x Barlows aren't that scary as well as Newtonians - although they quickly get long and heavy. SCT or on middle sizes Maks will be shorter, lighter, but more expensive aperture.

GoTo is not intended for imaging - it's just for finding objects. Webcam won't handle those DS objects.

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