What equipment should I get to start with telescopic astrophotography?

[pipnina]

Hey guys!

I've been doing astrophotography for a while now, but only with a Star Adventurer and my lenses with focal lengths from 18-105mm. I've been thinking about buying into some slightly more serious kit, but obviously there's a lot to consider, not least of all price!

I quite like my dob for observing, and I am also fairly fond of diffraction spikes in images, but the quattro f4 newts seem not just a little pricey (especially when you consider the likely dire need for the £200 coma corrector) but also heavy (I think I would need an EQ6 just for the 200mm?)

I think my budget would end up around £1000~ ish for a telescope and mount, and I think ideally the focal length I'd be after is somewhere in the region of 600mm to 1000mm (if I wanted to do planetary, I could always throw a 3x Barlow in?)

I won't worry about cameras yet, my D3200 might not be ideal but it'll work as a temporary measure and I'll worry about expensive CCDs later.

 

What would people suggest for a first venture into telescopic astrophotography? A small, relatively wide frac? Something like the 130 or 150 PDS? What would I want in a mount? (there are so many versions of the EQ5/EQ6 and I have very little idea what the difference is between them).

 

Thanks

[MARS1960]

My firstish foray into more serious imaging saw the purchase of an Celestron CGEM and  an SW 120ED, i think this could keep you happy for years to come, switch the CGEM for HEQ5/EQ6 if prefered.

[spillage]

There have been some good neq6 mounts on ABS recently. That would be a good start and you would still have money for say a 130pds and cc.

[vlaiv]

Budget is a bit tight.

I would say Heq5 / Eq6 (in any variant, maybe second hand to fit in budget) and any decent scope with FL up to 800mm.

Options would be 130PDS, 6" either F/4 or F/5, and maybe even 8" F/4 but I think skill / learning curve wise that is edge case. Heq5 / Eq6 class mount can handle 8" F/4 scope but all sorts of tweaks and care and attention will be needed to get it to guide good. All of these will need some sort of Coma corrector.

Another option would be frac, but only up to 3". Decent 4" or 5" frac will take you quite a bit out of budget. Will need field flattner

You can also look at RC 6" for example, but that would need reducer as well since those tend to have long focal length.

Don't pay too much attention to aperture of scope, but rather focal length. Play around with field of view calculator to see what focal length would suit you best for majority of intended targets. When you pinpoint focal length (or small range of them) - then look for scope that will provide you with such FL.

All of the above mounts are capable of about same performance (but all need tuning / modding to get to their full potential), with only difference between Heq5 and Eq6 variants is mount weight and load capacity. AZ6 has additional feature of Alt-AZ mod. AZ6 and Eq6-R come with belt drive, and there is belt mod for both Heq5 and Eq6 (that you will probably want to do at some point if you go for any of these two).

[pipnina]

1 minute ago, vlaiv said:

Budget is a bit tight.

I would say Heq5 / Eq6 (in any variant, maybe second hand to fit in budget) and any decent scope with FL up to 800mm.

Options would be 130PDS, 6" either F/4 or F/5, and maybe even 8" F/4 but I think skill / learning curve wise that is edge case. Heq5 / Eq6 class mount can handle 8" F/4 scope but all sorts of tweaks and care and attention will be needed to get it to guide good. All of these will need some sort of Coma corrector.

Another option would be frac, but only up to 3". Decent 4" or 5" frac will take you quite a bit out of budget. Will need field flattner

You can also look at RC 6" for example, but that would need reducer as well since those tend to have long focal length.

Don't pay too much attention to aperture of scope, but rather focal length. Play around with field of view calculator to see what focal length would suit you best for majority of intended targets. When you pinpoint focal length (or small range of them) - then look for scope that will provide you with such FL.

All of the above mounts are capable of about same performance (but all need tuning / modding to get to their full potential), with only difference between Heq5 and Eq6 variants is mount weight and load capacity. AZ6 has additional feature of Alt-AZ mod. AZ6 and Eq6-R come with belt drive, and there is belt mod for both Heq5 and Eq6 (that you will probably want to do at some point if you go for any of these two).

If I got the 130PDS with Baader MK3 coma corrector & EQ5 PRO Synscan it'd cost about £847. But I presume there are other costs to consider as well? Can these mounts connect to mains power through a lead or will I need a battery pack? (I'll probably only ever use it in my back garden, and could plug it in from the cellar). With that specific mount I presume I could input RA/DEC coords into the handset as well as choose known objects?

With a heq5 that goes up to about £1080~ but would I need it for a 130PDS?

What does the belt drive do?

Cheers again.

[carastro]

Quote

If I got the 130PDS with Baader MK3 coma corrector

Good choice, but get an HEQ5 instead of the EQ5, HEQ5 is a capable mount so long as you don't want to put a massive scope on it later on.  I use an HEQ5 with a dual rig and also a 130PDS.  Get a guide camera and put it into the finderscope that comes with the SW130PDS as a finderguider.

This will get you started.  Have a look at my website for recent images I have taken with the 130PDS, also other smallish refractors.

Carole 

[vlaiv]

I know that people do image with Eq5 with up to 6" scopes, so it is certainly doable.

Main difference between Eq5 and Heq5 will be mount head mass / carry capacity. Mass is important to dampen any vibrations due to wind or other external influence. Eq6, again has an edge over Heq5 in this, as it is heavier still. I also think that Heq5 (and Eq6 family) offer better tracking, pointing and guiding performance compared to Eq5. With astro imaging you really don't want to put on mount nowhere near it's max carry capacity. Most people recommend to stay somewhere between 1/2 and 2/3 of max stated weight limit of the mount (some even say that 1/2 is upper limit).

Eq5 has 10kg load spec. So you are looking at up to let's say 5-6kg total imaging gear (scope, camera and all accessories), maybe even less if scope is longer. Heq5 has 15/18kg load capacity (depending on source), and I've been imaging with up to 12kg on it. So if you can stretch your budget, then yes, get Heq5 (or second hand eq6) - it will be more accurate and more stable platform (and that is always a good thing).

All of those mounts (I think) run on 12V, 2A max. So you can use either external power tank (even deep cycle battery), or you can get mains adapter (I do that). Just make sure it is 12V, 2A minimum.

With these mounts, you can use hand controller and select target, or you can use laptop with Eqmod - I went the second route, primarily because at the time I was purchasing Heq5 there were also syntrek version which was cheaper than skyscan. Today I don't think you can find syntrek version any more. Difference is that all newer Heq5 mounts include handset with goto functionality so you don't need computer to do goto. Mine just has simple hand controller - no goto, only slewing and speed selection. Skywatcher mounts have good support with EQMod project - it is a way to control mount via special link (serial/usb adapter cable, or there are couple of other options including blue tooth for wireless control) and simple (open source) software. This way you can use software like Stellarium or CDC on your computer and have goto with it - just select target and tell scope to go to it.

With scope, mount, cc and T2 adapter for your camera you are pretty much set for basic imaging. Just check spacing requirements for CC and have appropriate T2 adapter and extension rings (if needed). At some point you will probably want to guide your scope, and that will require either guide scope or OAG (off-axis guider) and guide camera. That will surely be additional costs (somewhere around £250-300 approx depending on what you choose) and you will need computer to do that, or you can get autoguider but that will likely cost more.

Belt is used in some mounts instead of gears - reduction part of mount drive system. Motors need to be reduced (or their speed) in order to hit sidereal rate. By default Eq5, Heq5 and Eq6 come with geared reduction. Az6 and Eq6-R come with belts instead. Gears make more noise and more vibrations. They also tend to produce larger periodic error of the mount. So belts just make things run more smoothly, have less backlash and vibration and give better performance to mount. This is why there are belt mods for Heq5 and Eq6 and why most of the latest mount models use belts instead of gears (unless some other technology like direct drive or friction drive).

 

[pipnina]

59 minutes ago, vlaiv said:

I know that people do image with Eq5 with up to 6" scopes, so it is certainly doable.

Main difference between Eq5 and Heq5 will be mount head mass / carry capacity. Mass is important to dampen any vibrations due to wind or other external influence. Eq6, again has an edge over Heq5 in this, as it is heavier still. I also think that Heq5 (and Eq6 family) offer better tracking, pointing and guiding performance compared to Eq5. With astro imaging you really don't want to put on mount nowhere near it's max carry capacity. Most people recommend to stay somewhere between 1/2 and 2/3 of max stated weight limit of the mount (some even say that 1/2 is upper limit).

Eq5 has 10kg load spec. So you are looking at up to let's say 5-6kg total imaging gear (scope, camera and all accessories), maybe even less if scope is longer. Heq5 has 15/18kg load capacity (depending on source), and I've been imaging with up to 12kg on it. So if you can stretch your budget, then yes, get Heq5 (or second hand eq6) - it will be more accurate and more stable platform (and that is always a good thing).

All of those mounts (I think) run on 12V, 2A max. So you can use either external power tank (even deep cycle battery), or you can get mains adapter (I do that). Just make sure it is 12V, 2A minimum.

With these mounts, you can use hand controller and select target, or you can use laptop with Eqmod - I went the second route, primarily because at the time I was purchasing Heq5 there were also syntrek version which was cheaper than skyscan. Today I don't think you can find syntrek version any more. Difference is that all newer Heq5 mounts include handset with goto functionality so you don't need computer to do goto. Mine just has simple hand controller - no goto, only slewing and speed selection. Skywatcher mounts have good support with EQMod project - it is a way to control mount via special link (serial/usb adapter cable, or there are couple of other options including blue tooth for wireless control) and simple (open source) software. This way you can use software like Stellarium or CDC on your computer and have goto with it - just select target and tell scope to go to it.

With scope, mount, cc and T2 adapter for your camera you are pretty much set for basic imaging. Just check spacing requirements for CC and have appropriate T2 adapter and extension rings (if needed). At some point you will probably want to guide your scope, and that will require either guide scope or OAG (off-axis guider) and guide camera. That will surely be additional costs (somewhere around £250-300 approx depending on what you choose) and you will need computer to do that, or you can get autoguider but that will likely cost more.

Belt is used in some mounts instead of gears - reduction part of mount drive system. Motors need to be reduced (or their speed) in order to hit sidereal rate. By default Eq5, Heq5 and Eq6 come with geared reduction. Az6 and Eq6-R come with belts instead. Gears make more noise and more vibrations. They also tend to produce larger periodic error of the mount. So belts just make things run more smoothly, have less backlash and vibration and give better performance to mount. This is why there are belt mods for Heq5 and Eq6 and why most of the latest mount models use belts instead of gears (unless some other technology like direct drive or friction drive).

 

Lots of good information cheers!

Both the Baader MK3 and the skywatcher CC they designed for the F5 PDS range say they need 55mm of backfocus, I would presume (since the skywatcher CC is bade for the PDS) that it would fit on the 130pds, but I don't see any specifications for that metric for the scope by any retailer. (Although, it's possibly camera-specific?)

12v/2a sounds a lot like one of my phone chargers! I'd presume that as long as the adapter I use is exactly 12v but supplies 2a upwards it's fine?

[vlaiv]

4 minutes ago, pipnina said:

Lots of good information cheers!

Both the Baader MK3 and the skywatcher CC they designed for the F5 PDS range say they need 55mm of backfocus, I would presume (since the skywatcher CC is bade for the PDS) that it would fit on the 130pds, but I don't see any specifications for that metric for the scope by any retailer. (Although, it's possibly camera-specific?)

12v/2a sounds a lot like one of my phone chargers! I'd presume that as long as the adapter I use is exactly 12v but supplies 2a upwards it's fine?

55mm of backfocus means that camera sensor surface needs to be 55mm away from the end of CC (Or if you look at it the other way around if sensor is where it usually sits, there needs to be 55mm room on focuser side to account for CC-sensor distance, so focuser needs to move 55mm forward in normal operation - hence backfocus, yes I know, it hardly makes sense ). If you are using Nikon D3200 sensor, first thing to look up is flange distance

According to various sources, this distance is 46.5 mm (https://en.wikipedia.org/wiki/Lens_mount#List_of_lens_mounts and http://imaging.nikon.com/lineup/dslr/d3200/spec.htm)

This means that your T2 adapter has to be at most 8.5mm of optical path length (this means that it can be longer than 8.5 with threads and all parts, but when put together with other things in front and behind, it needs to separate them by 8.5mm). I've just had a look at few T2 adapters for Nikon F but I can't find specs for optical length on any of them. You will probably need to measure it somehow and if it is less than 8.5mm you will need to add suitable T2 extension ring.

Yep, any charger 12v and 2A or more, make sure it has 5.5mm tip positive jack (at least for Heq5).

 

[pipnina]

59 minutes ago, vlaiv said:

55mm of backfocus means that camera sensor surface needs to be 55mm away from the end of CC (Or if you look at it the other way around if sensor is where it usually sits, there needs to be 55mm room on focuser side to account for CC-sensor distance, so focuser needs to move 55mm forward in normal operation - hence backfocus, yes I know, it hardly makes sense ). If you are using Nikon D3200 sensor, first thing to look up is flange distance

According to various sources, this distance is 46.5 mm (https://en.wikipedia.org/wiki/Lens_mount#List_of_lens_mounts and http://imaging.nikon.com/lineup/dslr/d3200/spec.htm)

This means that your T2 adapter has to be at most 8.5mm of optical path length (this means that it can be longer than 8.5 with threads and all parts, but when put together with other things in front and behind, it needs to separate them by 8.5mm). I've just had a look at few T2 adapters for Nikon F but I can't find specs for optical length on any of them. You will probably need to measure it somehow and if it is less than 8.5mm you will need to add suitable T2 extension ring.

Yep, any charger 12v and 2A or more, make sure it has 5.5mm tip positive jack (at least for Heq5).

 

I just got out the micrometer and found the T2 adds 8.02mm of optically relevant height, but with the adapter which connects the T2 to the telescope (on my 250PX, it's the bottom half of the 2" to 1.25" adapter) included it comes to 10.16mm of added height.

[vlaiv]

2 hours ago, pipnina said:

I just got out the micrometer and found the T2 adds 8.02mm of optically relevant height, but with the adapter which connects the T2 to the telescope (on my 250PX, it's the bottom half of the 2" to 1.25" adapter) included it comes to 10.16mm of added height.

Ah, I guess you are sorted then, Baader MPCC III has t2 connection, so you don't need adapter from T2 to 2" as body of MPCC is 2" and will fit nicely in focuser of 130PDS. Just get simple T2 0.5mm spacer (or couple of those like 0.2, 0.3, 0.5mm so you can dial in optimum distance if there is need, those are really cheap)

It will be connected like this:

2" Focuser on PDS - Baader MPCC III - T2 spacer 0.5mm - T2 Nikon F adapter (8mm) - Nikon D3200 (flange distance 46.5mm)

Giving total of 55 backfocus distance

[spillage]

There is a neq6 with wedge on here for sale at a very good price and you will appreciate the added wedge.