Absolute newbie's guide to powered mount upgrades

[Caelus]

I'm contemplating the feasability, practicalities and potential costs involved in converting my 200p skyliner Dob to something that could serve as a gateway to astrophotography, initially with webcams but perhaps later using a DSLR. Aside from knowing that I'd need to fit scope rings and a dovetail to my OTA, I'm ashamed to admit that I have almost no idea what hardware I would need to achieve this, or if it is really practical with this scope at all.

So aside from a mount, I presume there would be gizmos to consider like power tanks and various cables? Anything else I'm overlooking?

[Keiran]

To start you would need to convert the scope from a dob mount to rings and dovetail. This isnt difficult. A set of tube rings... http://www.firstlightoptics.com/tube-rings/skywatcher-telescope-tube-rings.html

Then you will need a dovetail bar... http://www.firstlightoptics.com/skywatcher-mounts/skywatcher-dovetail-mounting-plates.html

The rings secure around the tube, and the dovetail will be connected to the rings. Its then a case of mounting your scope on an EQ mount. For that scope you would ideally be looking at a HEQ5. A power supply, like a 110Ah leisure battery works very well. You will need a 12V cigar socket to battery clamps, and a 12v cigar plug to mount connector. This will be the mount and scope ready to go. As for connecting a DSLR, you will be looking at getting a T thread ring to DSLR connector and then a t thread nose adaptor (either 2" or 1.25" depending on what you want to use) This is the basics, that will get you started.

Kerian

[90mm]

As far as the power pack goes you may want to look into Celestrons deep cycle power packs. Not too exspensive and 17 Ahs. As Keiran mentioned the HEQ5 should do fine but I like to have a little more mount then telescope so I use something like the HEQ6. It think it's a little steadier.

[JamesM]

As part of your initial investment in imaging kit goes, I would certainly recommend that you get yourself a copy of Steve Richards' "Making Every Photon Count" (FLO £19.95) in order to work out what kit you need and why you need it. Using a webcam is great for solar system objects (moon and planets) but you wouldn't necessarily need an expensive mount to track these objects, as their relative brightness allows you to make short exposures from your existing set up. Using this method of creating in effect a short film, allows you to choose the best 'frames' to then stack on top of each other to produce the final composite image. The mount really comes in when you are wanting to image deep sky objects (DSO's) such as galaxies and nebulae where you will need to take longer exposures because these objects are so faint. Here a webcam is not the most appropriate means of recording the data (except on the very brightest of DSO's such as Orion's Belt - M42) and a DSLR is a more realistic starting point. Accuracy of the mount can be influenced by the load that it is carrying and the general rule of thumb is that any imaging setup (camera, scope etc) should not exceed half the maximum payload of any given mount and explains one of the reasons why many imaging 'rigs' normally use refractors. The above book will discuss comprehensively some of these considerations in more depth and having this overview before buying or changing existing kit is really important in order for you to decide on how deep you want to go and whether there is a big enough budget to get you there. Many conversations on starting out in imaging naturally discuss concerns around the data collection side of imaging which is only half of the equation when generating a final image - processing the collected data being the remaining half. Thankfully there are many great software programs out there are free and fairly straightforward to use but as you might imagine there are going to be one or two others that are also very useful but regrettably need to be paid for out of the start up budget. Reading the above book which is both comprehensive and well written, will certainly provide you with all you need to know to enable you to take good consistent images that will make astrophotography an activity that is fun rather frustrating to accomplish. You have done the right thing in coming here to enquire for more information, the above book will certainly go a long way in answering many of your concerns.

Clear skies

James

[Caelus]

Thanks for your responses guys, they've all been informative

rule of thumb is that any imaging setup (camera, scope etc) should not exceed half the maximum payload of any given mount and explains one of the reasons why many imaging 'rigs' normally use refractors.

This makes me wonder about the practicality of using my newt, both with size and weight. If I want to pursue the AP route would I be better investing in a smaller, lighter, refractor or should I be able to make a useful setup using my existing 'scope without too much trouble?

[Caelus]

Using a webcam is great for solar system objects (moon and planets) but you wouldn't necessarily need an expensive mount to track these objects, as their relative brightness allows you to make short exposures from your existing set up

I have tried turning my hand to this with my current setup, but the biggest probem I have is reliably keeping my target in the frame. Adjusting on the fly has led to some very jumpy and seemingly useless clips that didn't want to stack. However, If I do plunge into AP my main interest would be DSOs.

[ollypenrice]

This may seem odd but in creating an imaging setup the least difficult and least expensive part is the telescope. Mount first, camera second. (Some might reverse optics and camera but I wouldn't.)

The 200P will work fairly well on an HEQ5. The H is important because it brings the finer stepper motors which make the autoguider work properly. If you go for a lesser mount and stick with AP you will certainly replace it and buy twice with attendant losses. A better mount for your scope would be the NEQ6 simply because it will cope better with wind and the weight of the 8 inch Newt. However, if you went for a small imaging refractor instead then the HEQ5 would be just as good as the NEQ6. There is no consistent difference in accuracy between these mounts.

You will get lots of advice regarding the weight of the telescope and the mount payload such as I've offered above. What is under-discussed is always focal length. Why is this so critical? Because the longer the focal length the better your guiding has to be. This is an absolute rule. If you use a 50mm FL camera lens unguided on a polar aligned EQ3 you will probably be able to take 5 minute subs and keep the lot without an autoguider. By the time you are up to 500mm FL you will want a better mount. To keep most of your subs of over a couple of minutes on an HEQ5 you will need an autoguider.

So what about taking your first imaging steps through a camera lens? Nice short FL, no need for super accurate guiding. Just a driven EQ mount.

AP shortlist; decent driven mount. Optics. Camera. Autoguide setup of camera and small guidescope. PC. Power tank. (Caravan/boat batteries are good and better than most powertanks.) Probably dewheater.

Preprocessing software. (DSS is free.) Post processing software. GIMP (free) or Ps CS3 (often available at huge discounts) or Pixinsight. Nearby soup kitchen to feed you while you are paying for this lot .

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=1793797527&k=WMbNhhG

[brantuk]

Great advice above - just a thought - once you have the mount then you have the flexibility of choosing any ota to put on it. So a refractor would be good for imaging, and all you'd need is the tube rings and dovetail to mount the 200P for observing. Sell the current mount to offset the cost. An HEQ5 in good nick and perfect working order under two years old, generally fetches circa £500. HTH

[Caelus]

Once again, thank you both for your input. Olly, your reponse has covered pretty much everything but has also given me pause for thought. I would say that the NEQ6 is outside of what I can forsee my budget would be. Given your remarks about focal length I am now wondering if my 200p would realistically be suitable given that I'd likely be looking at a HEQ5. Of these models would the Syntrek suffice or would I need the Synscan?

Either way, I'm now wondering if settling for either variety of HEQ5 would just result in an expensive compromise that could well be unsatisfactory for astrophotography.

[ollypenrice]

I've never tried a 200mm Newt on an HEQ5 but, in discussions in the past, the folks have done so offer different views ranging from 'Fine' through 'Only just' to 'Never again.' I've used quite a lot of kit and my instinct would be to say 'only just,' I reckon. Having recently manhandled one into our loft for storage I think it's quite a lot for the smaller mount!

As Brantuk says, HEQ5s come up second hand and more often than NEQ sixes because people moving to larger scopes need more capacity. If using an 80mm refractor I wouldn't care less whether I were using an 5 or a 6. It would make not a jot of difference. If I were a mobile imager give me the 5 any day. I would not consider the Syntrek without GoTo. In AP GoTo is not just about finding objects at the start. It has lots of other functions which save time and time is the great obstacle in imaging. You often want to image things you will never see in any telescope, things that no one has ever seen. You may want to slew to a bright star to re focus, then slew back to just the same position. You may lose a guide star to a passing cloud and want to reframe quickly. Without GoTo you'd lose a staggering amount of data capturing time. You certainly do not want to be taking your camera out to put in an EP. The camera goes in, you find critical focus, it stays in, you don't turn it, you don't touch it!! (I bang on a lot about this when helping beginners.) If you do you risk mucking up your flats and wasting further time refocusing (which you will have to do after using the EP to find your object in an EP. But then you may need to slew to a star you can focus on. AAARRRGGGHHH!!!)

See the problems? GoTo and imaging are bedfellows.

Olly

[andyboy1970]

I use my 200p with ST80 piggy-back on my pier mounted HEQ5 and as long as its well balanced it works a treat.

On focal length the 200p from a dob is F6 (1200mm) a 200p from an EQ mount is F5 (1000mm) so guiding would be necessary unless your happy throwing away 50-60% of your subs.

Andy

[Caelus]

I've never tried a 200mm Newt on an HEQ5 but, in discussions in the past, the folks have done so offer different views ranging from 'Fine' through 'Only just' to 'Never again.' I've used quite a lot of kit and my instinct would be to say 'only just,'

I would not consider the Syntrek without GoTo. In AP GoTo is not just about finding objects at the start.

Olly, thanks again for your input. Given your experience I'm inclined to accept that it would be wildly optimistic to mount my 200 on a HEQ5 and that I will either need to reconsider my next move or find the extra pennies for a six . As for Goto, thanks for clearing that up... I had presumed in my ignorance that goto was still more of a luxury than something that was particularly useful or necessary. I really should get hold of "Making every photon count", if only to confirm how little I know!

I use my 200p with ST80 piggy-back on my pier mounted HEQ5 and as long as its well balanced it works a treat.

Andy, is it possible that stability and success you enjoy comes more from using a pier? Whenever I see anyone buying or building a pier on here I get envious, however it's not something that will be an option for me in the forseeable future.

[andyboy1970]

The pier is obviously a lot more solid than a tripod but I no problems with it tripod mounted either.