Budget EQ mount for 6" SCT?

[Martyn87]

Afternoon all! First off, I know I know, SCTs are not recommended for newbie astrophotographers. However I bought the scope for looking at planets, double stars etc with my 7 year old daughter, and she hardly has the patience to wait for me to line it up with the moon, let alone sit in the cold for hours on end while imaging nebulae 

 

On the other hand, I am a glutton for punishment, and I'd love to be able to capture some nice DSOs with this thing at some point. However, I'm on a bit of a tight budget and trying to pick up as much gear as I can on the second hand market. 

 

With that in mind, I figured the best first upgrade would be to replace the manual ALT-AZ mount with a motorised (potentially goto?) EQ mount. Are there any good value options out there that might come in a bit under the ~£450 mark that the HEQ5 Pro seems to go for second hand? I have access to a 3D printer and am handy-ish with a soldering iron if there are good DIY options available? I'm guessing payload support is going to be the biggest issue here? 

 

Also up for any other suggestions that might be a better place to start with upgrades!

[Cosmic Geoff]

If you want to use the 6" SCT for taking images of small deep-space objects, I would suggest that the minimum mount is an EQ-5 Synscan. A HEQ5 might be better, more future-proofing, etc.  It is possible to upgrade the manual EQ-5 to GoTo either by buying the official Synscan upgrade (now about £350) or by assembling one of the DIY kits available.   Note that if you go the latter route, you don't get a handset and are relying on computer control. Unless you really like to tinker, IMHO the best use of your time and money would to buy a used Synscan mount in good order.

You will probably also need a f6.3 focal reducer (around £150 new) and if you want to shoot nebulae, a dual narrow-band filter (around £100 or more).

If you don't have a good mount then beware, you could spend a good deal of time and money pursuing images that you could have just as well produced with a £550 Seestar S50 which has the mount, the GoTo, the optics, the filter, and the stacking all built in.

 

[vlaiv]

I guess cheapest option would be to hunt down second hand manual EQ5 mount and then tune it up and perform DIY goto upgrade in form of AstroEQ or OnStep or something similar

(basically 2 stepper motors + controller and firmware).

[Martyn87]

Thanks Geoff. I think for imaging I would likely be looking at computer control anyway, but the handset would definitely be a lot easier for visual. I think the primary difference between the EQ5 and HEQ5 would be payload capacity? Maybe the extra would be handy if I ever go down the Hyperstar route, as I'm assuming I'd have to use a secondary guide scope... (planning to use off-axis guiding at the moment). 

 

I'd been looking at the f6.3 reducers, I will definitely be keeping an eye out for one in the next couple of months. I think I need a camera upgrade before I start doing any serious imaging though. I have no idea what filters are used for what so that's something I really need to do more research on, thanks for that. 

 

I'm aware that getting something like the Seestar is probably easier and cheaper, but if it does all the work for you and just displays stuff on the screen, I might as well just search through Astrobin! 

[Cosmic Geoff]

1 minute ago, Martyn87 said:

I'm aware that getting something like the Seestar is probably easier and cheaper, but if it does all the work for you and just displays stuff on the screen, I might as well just search through Astrobin! 

The Seestar has the option of saving all the subs internally so you can spend hours post-processing them if that's your thing.

[vlaiv]

2 minutes ago, Martyn87 said:

I think the primary difference between the EQ5 and HEQ5 would be payload capacity?

HEQ5 is a bit more serious mount than EQ5.

There are mechanical differences between the two that are responsible for HEQ5 performing better for imaging - like use of bearings on axis and such.

[Martyn87]

Thanks vlaiv, for both responses! Seems like the cheapest way to get a manual EQ5 is to buy it with a scope attached, there are a few going for £250 - £300ish but then by the time I bought materials, motors, arduino etc, the HEQ5 Pro are going for £400-£450 on ebay, seems a bit of a no brainer if they're significantly better. 

[vlaiv]

50 minutes ago, Martyn87 said:

Thanks vlaiv, for both responses! Seems like the cheapest way to get a manual EQ5 is to buy it with a scope attached, there are a few going for £250 - £300ish but then by the time I bought materials, motors, arduino etc, the HEQ5 Pro are going for £400-£450 on ebay, seems a bit of a no brainer if they're significantly better. 

Not sure if you can access classifieds section of SGL (there is some limit given the number of posts / relative new signup - but not sure if that is just for posting or browsing as well):

Here you have EQ5 for £150 with motors fitted. Apparently it is ready to be guided for astrophotography. Probably the cheapest option.

In any case, yes, HEQ5 is certainly better option - just depends on how much you are willing to spend (and £450 for HEQ5 is a good deal).

[Martyn87]

26 minutes ago, vlaiv said:

Not sure if you can access classifieds section of SGL (there is some limit given the number of posts / relative new signup - but not sure if that is just for posting or browsing as well):

Here you have EQ5 for £150 with motors fitted. Apparently it is ready to be guided for astrophotography. Probably the cheapest option.

In any case, yes, HEQ5 is certainly better option - just depends on how much you are willing to spend (and £450 for HEQ5 is a good deal).

 

Thanks Vlaiv, unfortunately can't access the classifieds at all at the moment, but I'll check it out once I've been here a bit longer 

[vlaiv]

39 minutes ago, Martyn87 said:

 

Thanks Vlaiv, unfortunately can't access the classifieds at all at the moment, but I'll check it out once I've been here a bit longer 

I think it is 10 "astro related" posts (those in lounge don't count).

[Elp]

Heq5 is the general goto recommended. I've never used one, I had a manual eq3-2 which I felt was quite solid so further up the range can only be a good thing.

I now use my C6 (native, reduced or HS) mostly with my Hem15, bit up the price range but I didn't want counterweights anymore, and I can use the mount on any photographic tripod (don't worry ive got solid ones, not the typical spindly variety), and I can also pack the mount in the same bag as the scope and all AP gear barring the tripod. Works well, haven't done a long project at 1000mm yet, it's next on my list, but it handles the Starfield 102 at 714mm perfectly fine. I am autoguiding.

Gem28 handles the C6 fine too, the ioptrons are whisper quiet in operation.

Edited June 11 by Elp

[bosun21]

2 hours ago, vlaiv said:

There are mechanical differences between the two that are responsible for HEQ5 performing better for imaging - like use of bearings on axis and such.

The EQ5 actually uses bearings as well.

[radiofm74]

Hi there! I have an HEQ5 Pro and have tried to take some shots with my C6, although that is not my main imaging scope. Some thoughts

1. An HEQ5 Pro is a good platform for imaging, it will hold your C6 without a problem, and it's also fun to use for visual. 

2. An HEQ5 Pro is not a top-notch EQ mount and for decent accuracy you will need guiding from the get go, especially at those focal lengths, or your exposure time will be severely limited and you'll have a lot of throwaways. So you need to consider the added expense of a small guide camera (a used ZWO 120 mini might be your best bet) and a small guidescope or off-axis guider (OAG). An OAG is considered the standard with SCTs, because a small guide scope might have insufficient focal length + may suffer from differential flexure. With all that, I'd still suggest that you get one of those mini-guidescopes because an OAG is more difficult to operate and it may prove especially challenging to find a guide star with a C6. (I am about to go into tests about this so… but first experiences were that a guide scope is easier).

3. The 6.3 reducer is a sine qua non. Do not even consider shooting at f/10 with 1500mm focal length. It's going to be challenging enough at 945mm focal length and f/6.3! No need to stress that a small ED refractor would make your entry in the imaging world a lot easier… think about it because getting a used small ED doublet is not going to cost you a lot, especially not if you consider the whole package you have to buy (mount, main camera, guide camera, guide scope, ……)

Just to give you an idea: these are a couple shots I took one summer with the C6 just for kicks. I'm not terribly proud of them, but they give you an idea of what can be achieved with a C6 on and HEQ5, with a ZWO mini guide scope and ZWO ASI120 mini, a stock Canon 60D and a UHC filter, using an old PC and free software + elaboration in Photoshop. I was not very experienced when I took these but I have no more recent results as I've focused more on using my ED refractors.

Good luck!

 

[Martyn87]

4 minutes ago, radiofm74 said:

Hi there! I have an HEQ5 Pro and have tried to take some shots with my C6, although that is not my main imaging scope. Some thoughts

1. An HEQ5 Pro is a good platform for imaging, it will hold your C6 without a problem, and it's also fun to use for visual. 

2. An HEQ5 Pro is not a top-notch EQ mount and for decent accuracy you will need guiding from the get go, especially at those focal lengths, or your exposure time will be severely limited and you'll have a lot of throwaways. So you need to consider the added expense of a small guide camera (a used ZWO 120 mini might be your best bet) and a small guidescope or off-axis guider (OAG). An OAG is considered the standard with SCTs, because a small guide scope might have insufficient focal length + may suffer from differential flexure. With all that, I'd still suggest that you get one of those mini-guidescopes because an OAG is more difficult to operate and it may prove especially challenging to find a guide star with a C6. (I am about to go into tests about this so… but first experiences were that a guide scope is easier).

3. The 6.3 reducer is a sine qua non. Do not even consider shooting at f/10 with 1500mm focal length. It's going to be challenging enough at 945mm focal length and f/6.3! No need to stress that a small ED refractor would make your entry in the imaging world a lot easier… think about it because getting a used small ED doublet is not going to cost you a lot, especially not if you consider the whole package you have to buy (mount, main camera, guide camera, guide scope, ……)

Just to give you an idea: these are a couple shots I took one summer with the C6 just for kicks. I'm not terribly proud of them, but they give you an idea of what can be achieved with a C6 on and HEQ5, with a ZWO mini guide scope and ZWO ASI120 mini, a stock Canon 60D and a UHC filter, using an old PC and free software + elaboration in Photoshop. I was not very experienced when I took these but I have no more recent results as I've focused more on using my ED refractors.

Good luck!

 

 

If I ever get photos as good as these, I'll be over the moon!!

 

Off axis guiding was the plan, as you mentioned, most of what I've read mentions it as the preferred option for SCTs, although I'm yet to try either for myself of course. On the up side, a guide scope isn't particularly expensive compared to an OAG so worth a go in the first instance maybe. I'm looking at ASI EAF for autofocusing too, in fact the bracket for it is almost done on the 3D printer as we speak. 

 

If you've been able to shoot those with a DSLR (albeit a much better one than my old Finepix S3 Pro...) maybe the next spend needs to be on the reducer rather than a camera. At least this would give me change to get my head around back focus too.  

 

[Elp]

I'd take baby steps, don't buy everything at once. You can image DSO native but it takes a long time to saturate those camera pixels, and your guiding needs to be better than at shorter focal length, seeing also need to support the imaging per pixel+guiding resolution.

For the F6.3 reduced, I'd say an OAG is essential, not all are built the same. I didn't get on with the ZWO one, but bought the old Celestron Radial Guider and that works very well, it's easy to setup and adjust also. You can save money by getting the reducer from AE. Your imaging train from the back of the reducer will need to be around 105-120mm to the camera sensor so you may need a few m42 or m48 extension/spacer rings. I found with the OAG, filter drawer, adaptor then camera most of that was eaten up.

You really don't need an autofocuser if you're going to be with the scope at setup, it's a personal preference, I've also never refocused during an imaging session and haven't seen much of an issue with any optical setup be it sct, refractor, newtonian or camera lens. It's an added expense, added power requirement and technical "burden", and unless you have an automated obsy setup I believe an unnecessary one.

Edited June 11 by Elp

[radiofm74]

7 minutes ago, Martyn87 said:

 

If I ever get photos as good as these, I'll be over the moon!!

 

Off axis guiding was the plan, as you mentioned, most of what I've read mentions it as the preferred option for SCTs, although I'm yet to try either for myself of course. On the up side, a guide scope isn't particularly expensive compared to an OAG so worth a go in the first instance maybe. I'm looking at ASI EAF for autofocusing too, in fact the bracket for it is almost done on the 3D printer as we speak. 

 

If you've been able to shoot those with a DSLR (albeit a much better one than my old Finepix S3 Pro...) maybe the next spend needs to be on the reducer rather than a camera. At least this would give me change to get my head around back focus too.  

 

Thank you for your kind words. If you start imaging you'll start pixel-peeping and you'll find a myriad little problems with those shots ;D;D;D;D

Backfocus is pretty easy. You need to get spacers enough to put 105mm between the optical surface of the reducer and the plane of the sensor of whatever camera you're going to use. If memory serves, Celestron's own adapter for the SCT thread provides 55mm. The rest might very well be provided by your T-ring. 

The problem with C6 and OAG is that your image circle is small as it is, so the OAG might not be getting any sky to show to your guide camera, or a very small portion. 

I agree on the EAF. A Bahtinov mask for a few quids is what you actually need ;D

But you do need the reducer, and some form of guiding imho. 

[Elp]

Don't forget the computer controller, all cables and any potential mounting solutions and power...

[Martyn87]

Thanks both for your input on the EAF, I'd figured this would come in handy and I was going to DIY it so wouldn't cost too much, but that money will be better spent on the reducer it seems. At least I have the brackets printed if I decide to add it later 

 

I think focus is pretty good as is with the Celestron SCT adapter and T ring, but I think adding the reducer would affect this, would it not? 

 

If my printer was big enough I'd have the Bahtinov mask already haha. I have checked a couple out out of focus stars and my doughnuts look pretty good to me, so I think collimation is good, need to read up on how to use the mask for focusing though. 

[Martyn87]

3 minutes ago, Elp said:

Don't forget the computer controller, all cables and any potential mounting solutions and power...

I'll mostly be imaging from the garden for now, so power and computer won't be an issue until I maybe venture off to some dark sites. I'll probably look at something like Astroberry eventually. 

[vlaiv]

35 minutes ago, bosun21 said:

The EQ5 actually uses bearings as well.

I've found some references that DEC axis uses bushings instead. Did quick search on youtube and strip down / servicing video does indeed seem to show DEC axis using bushings of sorts.

I might be wrong though.

[radiofm74]

12 minutes ago, Martyn87 said:

Thanks both for your input on the EAF, I'd figured this would come in handy and I was going to DIY it so wouldn't cost too much, but that money will be better spent on the reducer it seems. At least I have the brackets printed if I decide to add it later 

 

I think focus is pretty good as is with the Celestron SCT adapter and T ring, but I think adding the reducer would affect this, would it not? 

 

If my printer was big enough I'd have the Bahtinov mask already haha. I have checked a couple out out of focus stars and my doughnuts look pretty good to me, so I think collimation is good, need to read up on how to use the mask for focusing though. 

Yes, the reducer introduces the back focus requirement (requirement is perhaps too strong a word… wrong back focus will degrade performance at the edges).

Using a Bahtinov mask is easy, don’t worry about that

As for PCs and suchlike: an AsiAir might be a good idea. Some love ‘em some hate ‘em. One thing that is sure is that they make acquisition much easier. The polar alignment routine is easy and pretty accurate, plate solving instantaneous, guiding is also much simplified…. You can do all this on a traditional PC and there’s value in learning it the “traditional” way, but AsiAir makes it all much easier. 
 

Anyhoo, let’s not get ahead of ourselves … snatch that mount and reducer first. They’ll be great accessories also just for observing at ease in your garden! 

[bosun21]

2 hours ago, vlaiv said:

I've found some references that DEC axis uses bushings instead. Did quick search on youtube and strip down / servicing video does indeed seem to show DEC axis using bushings of sorts.

I might be wrong though.

The RA axis most definitely uses bearings as I have replaced them on an EQ5 I previously owned. The RA bearing is generally tightly fitted in the housing and I had to tap it out as I didn't have an extractor. It also has a slim thrust bearing at the polar scope end of the RA. You are probably correct regarding the Dec axis using bushes though.

Edited June 11 by bosun21

[Martyn87]

6 hours ago, radiofm74 said:

Yes, the reducer introduces the back focus requirement (requirement is perhaps too strong a word… wrong back focus will degrade performance at the edges).

Using a Bahtinov mask is easy, don’t worry about that

As for PCs and suchlike: an AsiAir might be a good idea. Some love ‘em some hate ‘em. One thing that is sure is that they make acquisition much easier. The polar alignment routine is easy and pretty accurate, plate solving instantaneous, guiding is also much simplified…. You can do all this on a traditional PC and there’s value in learning it the “traditional” way, but AsiAir makes it all much easier. 
 

Anyhoo, let’s not get ahead of ourselves … snatch that mount and reducer first. They’ll be great accessories also just for observing at ease in your garden! 

 

Bahtinov mask is now printing  I'll do some googling and see how I get on but it looks simple enough!

I had considered ASIAIR, but am I right in thinking that it only works with their cameras? Might not be a huge issue as I know they have a pretty good reputation, but I was thinking something a bit more open would give me more options. I work in IT so would like to think that the computer side if things won't trip me up too much, although the sheer amount of software options for everything, from controlling to processing, is just mind boggling! 

 

[GrumpiusMaximus]

24 minutes ago, Martyn87 said:

 

Bahtinov mask is now printing  I'll do some googling and see how I get on but it looks simple enough!

I had considered ASIAIR, but am I right in thinking that it only works with their cameras? Might not be a huge issue as I know they have a pretty good reputation, but I was thinking something a bit more open would give me more options. I work in IT so would like to think that the computer side if things won't trip me up too much, although the sheer amount of software options for everything, from controlling to processing, is just mind boggling! 

 

The ASIAir does only work with their hardware.  The first generation was just a Raspberry Pi with their own OS on it.  The newer versions are much the same.

I have an 'Astroberry', which is a Raspberry Pi with the Astroberry OS on it.  It has all of the software that you need for imaging and can be accessed via your home network in the browser by IP or host name.  You can theoretically set it up to run over the Internet too obviously.  It's effectively an open-source Raspberry Pi-style solution that works with a variety of devices and has drivers, etc. loaded by default.  It's not difficult to get set up - but I work in IT too.  It's just an ARM Linux distro with some applications and drivers installed.

The main issue I've had with mine was getting Polar Alignment but that's a skill in and of itself and I find the routines a bit tricky.  The ASIAir's Polar Alignment options are incredibly slick by comparison.

I'd also definitely recommend getting a real-time clock installed on any Raspberry Pi you use if you go down the Astroberry route.  My WiFi doesn't extend well into my garden, so I control mine via a laptop connected directly to the Astroberry's own hotspot but without direct Internet access, it can't reference an NTP server and without the RTC installed you have to set the time manually each boot, which is a pain in the rear.  And you absolutely need it to have an accurate time.

Setting up cameras and sequences is very easy, as is setting up GOTO.  I haven't tried any guiding with mine (I don't have a guidescope) but I gather it's similarly straightforward.  You can choose a save location of images, too.  Plus it will do platesolving, etc. etc.

If you have Raspberry Pi kicking around (who doesn't?!) and source a 5-Quid CMOS-style RTC from eBay you can give it a go.  I'm using a Pi4 with 8GB of RAM but a Pi3 should run it OK too.  The more RAM the better, obviously.

Edited June 11 by GrumpiusMaximus

[Martyn87]

Thanks Grumpius, I was reading up on astroberry a bit last night (as well as stellar mate and a couple of other pi/mini pc options) and I do think it's probably the way to go. I have a couple of Pis around the house already doing various jobs, so I'm pretty familiar with them and I'm not a complete Linux noob, although faaaar from an expert too. 

Interesting point on the RTC! I don't have a spare Pi at the moment, but interestingly, the Pi 5 has a built in RTC, so I might have to grab one, for testing purposes of course! 

Edited June 11 by Martyn87