GoTo scope for long exposure imaging?

[Mizar]

I've done very little imaging thus far. But my understanding is for imaging on an equatorial, you have to use an extra accurate method when polar aligning. Also, auto guider scopes are often used. I've been looking at the Orion StarSeeker II 130mm GoTo Reflector http://www.telescope...roductId=102293 and noticing it has some rather substantial advantages over the equivalent equatorial scope (Orion SpaceProbe 130ST Equatorial Reflector http://www.telescope...?productId=9007) plus tracking drive, in lightweight and portability characteristics due to the alt-az mount, for barely any greater cost.

So, I have three questions: 1. Would this scope already polar align accurately enough for even long exposure imaging, or would it require some special technique as well? 2. Would it require an auto guider? 3. Would the StarSeeker indeed be a better/easier imaging scope than the SpaceProbe?

[ronin]

The first is not equitorial so not suited for long exposures.

The second one needs a much better equitorial mount for imaging, especially long exposure, the EQ5 or similar at least as I do not think the mount supplied would take any more then a single RA motor - I am sure that is all that can be fitted to an EQ2 mount so you cannot have goto on it and no chance later of guiding.

Imaging is a different aspect to viewing, the requirements are in a way swapped.

For visual you want big scope on a mount that will handle it within reason, for imaging you want a solid mount that will easily the scope you are intending to use. So it tends to be a big mount and small scope.

Over here something like an EQ5 or HEQ5 is often used with a WO 70-72mm refractor. Many pick the ED 80 scopes not often do people go bigger on the scopes and the mount is if possible an EQ6 = BIG, SOLID, HEAVY.

What retailers display and sell are visual systems not imaging systems and one of the first mistakes is looking at a visual system while thinking of doing imaging.

[swag72]

Mount, mount, mount - DSO astrophotography is all about the mount. The minimum recommended is the HEQ5 and I can say with experience that this mount is very good value indeed. It satisfies my need for 30 minute subs with little or no problem. Coupled with that a short focal length refractor and it churns out good data night after night. You need stability and predictability. It will place minimum stress on the mount for guiding purposes and with nothing more than a finder / guider it does me proud.

Do not try an scrimp and save on AP, it will cost you more in the long run. You can not avoid things such as polar alignment and good balance if you want to produce good images. People on here that produce the goods have data that run into many hours and believe me they will not have taken any short cuts with regards polar alignment or any thing else for that matter.

If you can get hold of the book 'Making Every Photon Count' available in the book section of the FLO website, it is a definitive read for those in AP. There's no short cuts!!

[VigdisVZ]

Yeah what Ronin and Sara said. Long exposure is an expensive hobby to start. You should definetly have a look at Steve Richards book "Making Every Photon Count" if you're serious about going into DSO AP.

The scopes you've linked are purely visual setups. You need an equatorial mount first (the alt-az one introduces field rotation). And it needs to be sturdy and have good motor drive. The recommendation is always a HEQ-5 to start out with. You can do it cheaper like the EQ3-2, but then you risk hitting a wall pretty soon and you might be tempted to upgrade.

Also could be worth noting that some newtonian focusers dont have enough focuser movement to reach focus with a DSLR, therefore the Skywatcher Explorer PDS range of scopes are good newtonians to start imaging with, but dont forget looking at the excellent ED that Ronin mentions above.

Hope this gives you a bit of perspective, just come back with any questions you might have. It's a super-rewarding hobby, but make sure you arm yourself with as much knowledge as you can before investing as it's a lot of money at stake.

[Jannis]

Do you have any scope allready? Or at least a camera with some decent lenses?

If so, i would focus mainly on the mount, and mount only if money is an issue to begin with - and use only the mount + camera with a camera lens.

I personally wouldn't go for anything less then a HEQ5 mount if you intend to use it for imaging. Others have got good results with smaller mounts too though, but the one you linked to with EQ2 is simply way to small for any imaging with probably teh moon as teh only exeption.

You'd need at least an EQ3-2 as an absolute minimum, but i'd strongly recommend to throw more money into the mount, as chances are you'll very soon feel the need to upgrade.

The mount may seem very expencive, and you might feel that a bigger scope is what you want. But concider it like this; the mount is an investment. If you put money into buying a decent one to begin with, you'll be happy with it for many many years to come. If you save on the mount, you can buy any scope you want, and they will be all equally useless for imaging.

[lensman57]

I've done very little imaging thus far. But my understanding is for imaging on an equatorial, you have to use an extra accurate method when polar aligning. Also, auto guider scopes are often used. I've been looking at the Orion StarSeeker II 130mm GoTo Reflector http://www.telescope...roductId=102293 and noticing it has some rather substantial advantages over the equivalent equatorial scope (Orion SpaceProbe 130ST Equatorial Reflector http://www.telescope...?productId=9007) plus tracking drive, in lightweight and portability characteristics due to the alt-az mount, for barely any greater cost.

So, I have three questions: 1. Would this scope already polar align accurately enough for even long exposure imaging, or would it require some special technique as well? 2. Would it require an auto guider? 3. Would the StarSeeker indeed be a better/easier imaging scope than the SpaceProbe?

Hi Friend,

The mount in the photo is an AltAz mount, it can track the planets and deep sky objects for a short period for observation only, it is not an equitorial mount, for imaging deep sky objects you need a solid equitorial mount so that it could be polar aligned you can not polar align an AltAz mount unless you have one of the big Meade or Celestron SCTs with their auxilary equitorial wedge, these are big, heavy and very expensive and IMHO not suitable for widefield DSO imaging. The EQ5 pro, HEQ5 Pro and NEQ6 from Skywatcher are decent mounts with reasonable prices and are very popular here in the UK. You really need to look at a choice of a mount first, the bigger the better but less portable, when you get to NEQ6 then a sort of permanent place (obsy ) becomes appealing, you really do not want to carry the beast around everytime you come to set up, that is why EQ5 and HEQ5 are popular here because of portability. As for the scope the fashion seems to be short focus fast EDs and Apos at the moment, anything in the 65~100 mm and F5 ~F7.5, aperture range will do depending on the type of objects to wish to image and how wide you want to go. Hope this helps.

A.G

[Mizar]

Thanks for the replies and the great info.  I feel kind of naive to have started out thinking those top-heavy scopes could work for photography  .  It logically fits how you all are describing AP equipment.

Do not try an scrimp and save on AP, it will cost you more in the long run. You can not avoid things such as polar alignment and good balance if you want to produce good images. People on here that produce the goods have data that run into many hours and believe me they will not have taken any short cuts with regards polar alignment or any thing else for that matter.

I wasn't looking for short cuts.  I was asking about the precision alignment needed for AP.  Hey, I'm all about precision- I have to try not to be too much a perfectionist .  Just for visual use I've polar aligned my scope in the finder plenty of times, or even the eyepiece, instead of just pointing the mount.  I was asking about the computer controlled alignment of an otherwise visual-use appealing scope, because it seemed it might happen to be more accurate and/or easier to set up.  But computer controlled alt-az mounts apparently aren't the way to go for AP in the first place.  I'm guessing the reason is they're not near as smooth mechanically as equatorial drives?

Yeah what Ronin and Sara said. Long exposure is an expensive hobby to start. You should definetly have a look at Steve Richards book "Making Every Photon Count" if you're serious about going into DSO AP.

The scopes you've linked are purely visual setups. You need an equatorial mount first (the alt-az one introduces field rotation). And it needs to be sturdy and have good motor drive. The recommendation is always a HEQ-5 to start out with. You can do it cheaper like the EQ3-2, but then you risk hitting a wall pretty soon and you might be tempted to upgrade.

Hope this gives you a bit of perspective, just come back with any questions you might have. It's a super-rewarding hobby, but make sure you arm yourself with as much knowledge as you can before investing as it's a lot of money at stake.

Yep, I'll check out some AP book.  Computerized GoTo alt-az isn't supposed to have field rotation since it tracks.  So, is it that it isn't smooth enough for AP, or just the fundamental lack of a sufficiently heavy sturdy mount?

Honestly, I would be inclined to go with something like the EQ-3, not only because of not having loads of money for it but because of needing it to be more amply portable.  And then one of the smallest/lightest scopes, such as an 80mm f/5 achromatic or a 114mm f/4 Newtonian.

Yes, definitely I'll research it thoroughly before buying.

Do you have any scope allready? Or at least a camera with some decent lenses?
If so, i would focus mainly on the mount, and mount only if money is an issue to begin with - and use only the mount + camera with a camera lens.

I personally wouldn't go for anything less then a HEQ5 mount if you intend to use it for imaging. Others have got good results with smaller mounts too though, but the one you linked to with EQ2 is simply way to small for any imaging with probably teh moon as teh only exeption.
You'd need at least an EQ3-2 as an absolute minimum, but i'd strongly recommend to throw more money into the mount, as chances are you'll very soon feel the need to upgrade.

The mount may seem very expencive, and you might feel that a bigger scope is what you want. But concider it like this; the mount is an investment. If you put money into buying a decent one to begin with, you'll be happy with it for many many years to come. If you save on the mount, you can buy any scope you want, and they will be all equally useless for imaging.

Yes, I have a couple scopes, but not any massive mount that would work for AP with them.  I only have a 1.9 MP phone camera currently, and it doesn't look like it would have the needed options such as longer exposure times.  That sounds like a good idea to first start long exposure AP with just a digital camera on my existing EQ-1.  I'll look into a good digital camera, and a clock drive for the mount.

Then next will be AP with a scope.  But I don't think I can get that serious into AP anytime soon, to spend more than for an EQ-3.  Plus I have transportation and storage limitations that would make the weight and size prohibitive.  Perhaps a particularly small and lightweight scope on an EQ-3 will serve adequately, like a scope I mentioned above.

Hi Friend,

The mount in the photo is an AltAz mount, it can track the planets and deep sky objects for a short period for observation only, it is not an equitorial mount, for imaging deep sky objects you need a solid equitorial mount so that it could be polar aligned you can not polar align an AltAz mount unless you have one of the big Meade or Celestron SCTs with their auxilary equitorial wedge, these are big, heavy and very expensive and IMHO not suitable for widefield DSO imaging. The EQ5 pro, HEQ5 Pro and NEQ6 from Skywatcher are decent mounts with reasonable prices and are very popular here in the UK. You really need to look at a choice of a mount first, the bigger the better but less portable, when you get to NEQ6 then a sort of permanent place (obsy ) becomes appealing, you really do not want to carry the beast around everytime you come to set up, that is why EQ5 and HEQ5 are popular here because of portability. As for the scope the fashion seems to be short focus fast EDs and Apos at the moment, anything in the 65~100 mm and F5 ~F7.5, aperture range will do depending on the type of objects to wish to image and how wide you want to go. Hope this helps.

A.G

I'm aware of the difference between alt-az and equatorial, I have both types for my scopes.  It sounds like I'm hearing the only type of GoTo scope good for long exposure AP is the particularly expensive EQ GoTo.  I'd be doing well to get an EQ-3 mounted scope moved around anywhere much  .  Hopefully it could handle an 80mm f/5 achromatic or a 114mm f/4 Newtonian.  The OTAs weigh 3.0 lbs. and 3.7 lbs., respectively, plus accessories.  Does that sound realistic?  I suppose I could go even smaller if need be, for it to work well enough on the mount, like a 60-70 some mm OTA.

Thanks again, everyone, for all the advice.

[gkec]

Any Alt-Az mount will have field rotation regardless of the accuracy of tracking.  Large observatories are Alt-Az because it is cheaper to build a de-rotator than the extra cost of a  building for an Eq mount.

BTW de-rotators are expensive before you get your hopes up

[daverave83]

I know this thread is quite old.

But don't be put off by the SLT 102 as they are good scopes.

Yes there are limitations however it's about testing the boundary of what you can get.

This image was taken with 30 sec subs, on a Skywatcher SLT 102 Goto, and after preliminary testing i can get up-to 1.10 min exposures without trailing. on a Unmodded Canon 1100D.

Polar Alignment is a Key with GOTO and counter weight, i have a tube ring and dove tail bar so the weight is closer to me, this puts more strain on the gears of the Altz Mount so field rotation is less.

I am going to see if i can push it to 2 min exposures.

Goto Mount are not the greatest but good if you want to dip your feet into it without spending £500 + on AP.