Are any of these telescopes good for Astrophography?

[AlanP_]

Sorry to still be asking questions about this, but I just realised the F5 and the F6 are available. Would I be better off with the F6 as im a beginner? Would this offer a decrease in results? Both are the same price so thats not an issue.

Edited December 30, 2020 by AlanP_

[vlaiv]

5 minutes ago, AlanP_ said:

Sorry to still be asking questions about this, but I just realised the F5 and the F6 are available. Would I be better off with the F6 as im a beginner? Would this offer a decrease in results? Both are the same price so thats not an issue.

No unless you specifically want F/6 for specific reason.

We could say that 150mm F/4 Newtonian is too fast for a beginner and similarly we could say that 150mm F/6 is too slow for a beginner.

That telescope has 900mm of focal length and that is a bit too much for general astrophotography. It is good for high resolution work or if you know advanced processing techniques like binning and such. Issue with long focal length is that you are imaging at high sampling rates which makes every error in mount performance much more obvious as things are zoomed in.

Depending on camera used with the scope - you could well end up at resolutions not supported by your sky and mount. This reduces your signal to noise ratio in image (light spread over more pixels) and increases blur (again too zoomed in).

I would recommend F/6 version for someone wanting to split telescope use between visual and photographic with more emphasis on planetary work and EEVA then on long exposure DSO.

F/6 scope will not need coma corrector with small sensor camera (like planetary type camera) as it has 4.2mm diameter coma free field (and then it slowly increases). You can even use focal reducer with small sensor. This image was recorded with F/6 newtonian (8" one) and x0.5 reducer with camera very similar to ASI120:

But F/6 scope has smaller secondary and hence smaller fully illuminated field and is not as suitable for work with larger sensors like APS-C - in any case you still need to use coma corrector for it.

[AlanP_]

9 minutes ago, vlaiv said:

No unless you specifically want F/6 for specific reason.

We could say that 150mm F/4 Newtonian is too fast for a beginner and similarly we could say that 150mm F/6 is too slow for a beginner.

That telescope has 900mm of focal length and that is a bit too much for general astrophotography. It is good for high resolution work or if you know advanced processing techniques like binning and such. Issue with long focal length is that you are imaging at high sampling rates which makes every error in mount performance much more obvious as things are zoomed in.

Depending on camera used with the scope - you could well end up at resolutions not supported by your sky and mount. This reduces your signal to noise ratio in image (light spread over more pixels) and increases blur (again too zoomed in).

I would recommend F/6 version for someone wanting to split telescope use between visual and photographic with more emphasis on planetary work and EEVA then on long exposure DSO.

F/6 scope will not need coma corrector with small sensor camera (like planetary type camera) as it has 4.2mm diameter coma free field (and then it slowly increases). You can even use focal reducer with small sensor. This image was recorded with F/6 newtonian (8" one) and x0.5 reducer with camera very similar to ASI120:

But F/6 scope has smaller secondary and hence smaller fully illuminated field and is not as suitable for work with larger sensors like APS-C - in any case you still need to use coma corrector for it.

Ok perfect, thanks for clearing that up. I'll stick with the F/5 for now then. In regards to a coma corrector, would this one work? - https://www.firstlightoptics.com/coma-correctors/baader-mark-iii-mpcc-coma-corrector-photographic.html

Although, it is a bit expensive. I thought it was going to be cheaper than that! Is there a cheaper one than this or would I be best off going for that one? My bank account is wheeping!

Another question, My HEQ5 mount only came with 1 counterweight, will I need to buy another one to properly balance with the TS-Photon F5 and a 600d?

I've added a T-ring adapter for my 600D to my cart, I hope thats everything to get started...

[malc-c]

Alan, define "better results".  An f5 isn't better than an f6, or f8.... it all depends on what you want you want from a scope.  The higher the focal ratio the more magnification you can get for a given eyepiece.  But in imaging terms it has an effect on exposure times.  It's not an exact relationship, but an 8" f10 will be "slower" than an 8" f5.  Think of the telescope as a lens for the camera rather than a visual device.  As Vlaiv mentioned, for a given aperture a longer focal length (and thus higher focal ratio) reduces coma, but if you have a large sensor a corrector will probably still be needed.  - Again, to the average amature, if an image of the same target was taken through an 8" f5 and an 8" f6, and then processed through software, would they be able to notice any real difference.... probably not.

There is no one scope suits all.... If you want to do planetary work, long focal lengths are better, but then in order to compensate for the lower levels of light and to get resolution you also need aperture.  That's why some of the best Mars images I've seen this year have come from guys with 14" schmidt-cassegrain with focal lengths of several metres.... You can still use such a scope for DSO's but you need to use focal reducers etc and thus it gets more complicated.    It's a poor analogy, but it's like an f1 race car attempting the RAC rally... it would probably make it round the track, but not as well as a 4x4 scooby

By comparison to Vlaiv's Orion Nebula image, here's an early image I took with my 200P (f5) -   I grosley over exposed for the trapezium ...  

 

 

Edited December 30, 2020 by malc-c

[vlaiv]

2 minutes ago, AlanP_ said:

Ok perfect, thanks for clearing that up. I'll stick with the F/5 for now then. In regards to a coma corrector, would this one work? - https://www.firstlightoptics.com/coma-correctors/baader-mark-iii-mpcc-coma-corrector-photographic.html

Although, it is a bit expensive. I thought it was going to be cheaper than that! Is there a cheaper one than this or would I be best off going for that one? My bank account is wheeping!

Another question, My HEQ5 mount only came with 1 counterweight, will I need to buy another one to properly balance with the TS-Photon F5 and a 600d?

I've added a T-ring adapter for my 600D to my cart, I hope thats everything to get started...

I know very little about coma correctors from practical point of view. I know some theory like 2 element ones introducing spherical aberration and making stars a bit bloated in center of the field and 4 element ones being the best - but I can't really be certain. I'm not sure I would be able to select coma corrector for myself if (or rather when ) I needed one.

 

[malc-c]

11 minutes ago, AlanP_ said:

 

Another question, My HEQ5 mount only came with 1 counterweight, will I need to buy another one to properly balance with the TS-Photon F5 and a 600d?

 

Hard to say IMO, but if you are placing a large order and the additional weight is not that expensive, and you can afford to do so, then it makes sense to add it to the order and save on postage....  If you find you don't need it, even with both weights all the way up the shaft you can always keep it should you add additional equipment or change the OTA for something larger and heavier

[AlanP_]

13 minutes ago, malc-c said:

Alan, define "better results".  An f5 isn't better than an f6, or f8.... it all depends on what you want you want from a scope.  The higher the focal ratio the more magnification you can get for a given eyepiece.  But in imaging terms it has an effect on exposure times.  It's not an exact relationship, but an 8" f10 will be "slower" than an 8" f5.  Think of the telescope as a lens for the camera rather than a visual device.  As Vlaiv mentioned, for a given aperture a longer focal length (and thus higher focal ratio) reduces coma, but if you have a large sensor a corrector will probably still be needed.  - Again, to the average amature, if an image of the same target was taken through an 8" f5 and an 8" f6, and then processed through software, would they be able to notice any real difference.... probably not.

There is no one scope suits all.... If you want to do planetary work, long focal lengths are better, but then in order to compensate for the lower levels of light and to get resolution you also need aperture.  That's why some of the best Mars images I've seen this year have come from guys with 14" schmidt-cassegrain with focal lengths of several metres.... You can still use such a scope for DSO's but you need to use focal reducers etc and thus it gets more complicated.    It's a poor analogy, but it's like an f1 race car attempting the RAC rally... it would probably make it round the track, but not as well as a 4x4 scooby

By comparison to Vlaiv's Orion Nebula image, here's an early image I took with my 200P (f5) -   I grosley over exposed for the trapezium ...  

 

Thats a good way of putting it, thanks! I guess it just shows my lack of knowledge when it comes to all this. I'll get it with time and begin to understand it, its just quite overwhelming. There's a lot of different things to know!

3 minutes ago, vlaiv said:

I know very little about coma correctors from practical point of view. I know some theory like 2 element ones introducing spherical aberration and making stars a bit bloated in center of the field and 4 element ones being the best - but I can't really be certain. I'm not sure I would be able to select coma corrector for myself if (or rather when ) I needed one.

 

Would that coma corrector work for my setup? I did some research and I would probably benefit from using it. 

3 minutes ago, malc-c said:

Hard to say IMO, but if you are placing a large order and the additional weight is not that expensive, and you can afford to do so, then it makes sense to add it to the order and save on postage....  If you find you don't need it, even with both weights all the way up the shaft you can always keep it should you add additional equipment or change the OTA for something larger and heavier

I'll see if I can pick one up second hand. I'll be more annoyed if I dont get it and it turns out I need it to balance!

[AlanP_]

Would this adapter work for connecting my Canon camera to the telescope?

Edited December 30, 2020 by AlanP_

[vlaiv]

1 minute ago, AlanP_ said:

Would that coma corrector work for my setup? I did some research and I would probably benefit from using it. 

I think it certainly will work.

Most of coma correctors work rather good with parabolic mirrors - it is subtle differences in the image - like edge star correction or if stars in center of the frame are sharp enough (like without coma corrector).

From a quick search that I did on topic - I think that Baader MPCC III is probably best CC in that price range.

[malc-c]

It can be overwhelming, and whilst posting on forums for advice seems the logical thing to do, it can often lead to more confusion as we all give differing advice. 

 

[vlaiv]

1 minute ago, AlanP_ said:

Would this adapter work for connecting my Canon camera to the telescope?

Yes, that looks like standard T2 / EOS adapter.

[AlanP_]

1 minute ago, vlaiv said:

I think it certainly will work.

Most of coma correctors work rather good with parabolic mirrors - it is subtle differences in the image - like edge star correction or if stars in center of the frame are sharp enough (like without coma corrector).

From a quick search that I did on topic - I think that Baader MPCC III is probably best CC in that price range.

Perfect, I googled it myself but I got a bit confused. Thanks for that, I may aswell get the best in the price range while im here!

 

1 minute ago, malc-c said:

It can be overwhelming, and whilst posting on forums for advice seems the logical thing to do, it can often lead to more confusion as we all give differing advice. 

 

Definitely. Which is why I really appreciate everyones help here. This forum is great, i'd struggle without everyones help!

1 minute ago, vlaiv said:

Yes, that looks like standard T2 / EOS adapter.

Brilliant! I was about to pay 35 euro for one! 

So im trying to create a picture in my head of what my setup will look like, or how it will connect to each other. Am I correct in saying Camera > T2 adapter > coma corrector > telescope? 

[Whistlin Bob]

1 hour ago, AlanP_ said:

Would I be better off with the F6 as im a beginner?

To agree with Vlaiv, I bought an f5 Newtonian to get started in AP a couple of years ago, it was perfect for me then and remains perfect for me now. It's a sweet spot for all the reasons stated, just a really good place to start. If you use it with a Skywatcher coma corrector then you're down to f4.5 anyway, which is pretty quick.

Also- your HEQ5 will be fine. I also image with a 200p on mine, which I think is right on the limit (slightly over?), but it'll handle a 150mm with no problems. 

[AlanP_]

1 minute ago, Whistlin Bob said:

To agree with Vlaiv, I bought an f5 Newtonian to get started in AP a couple of years ago, it was perfect for me then and remains perfect for me now. It's a sweet spot for all the reasons stated, just a really good place to start. If you use it with a Skywatcher coma corrector then you're down to f4.5 anyway, which is pretty quick.

Also- your HEQ5 will be fine. I also image with a 200p on mine, which I think is right on the limit (slightly over?), but it'll handle a 150mm with no problems. 

Great stuff! Thats reassuring. 

You mention the Skywatcher coma brings it down to a 4.5, is that because it has a built in reducer? Do you find you need a coma corrector with an F5?

[Whistlin Bob]

23 minutes ago, AlanP_ said:

You mention the Skywatcher coma brings it down to a 4.5, is that because it has a built in reducer? Do you find you need a coma corrector with an F5?

Very much yes and yes. The coma without the corrector is pretty awful. The SW corrector is also a 0.9 reducer hence the slightly lower f ratio. I bought it with the correct adaptor for my Canon and it just worked with no faffing about with spacers and the like.

[AlanP_]

Just now, Whistlin Bob said:

Very much yes and yes. The coma without the corrector is pretty awful. The SW corrector is also a 0.9 reducer hence the slightly lower f ratio. I bought it with the correct adaptor for my Canon and it just worked with no faffing about with spacers and the like.

Brilliant. I may go for that so. My poor, poor bank. Its barely recovered from Christmas and now im picking up one of the more expensive hobbies! I'm sure I wont regret it  

[AlanP_]

So, i've ordered my first telescope! I went ahead and got the TS Photon 6" F/5. I also ordered a T2 adapter for my camera and an extra counterweight for my mount as it only has one.

Just a few (MORE!!) questions. 

1. So my HEQ5 mount came with the power cable and the synscan controller. How do I connect it to the computer? Do I need to buy this cable?
2. Does my telescope come with a dovetail mount to mount it to my HEQ5? Or is that something I need to buy seperately? The guy I purchased off couldn't find it the vixen dovetail that he had!
3. Am I missing anything else like a cable, adapter, connnector? 

Thanks in advance!

[vlaiv]

2 minutes ago, AlanP_ said:

So my HEQ5 mount came with the power cable and the synscan controller. How do I connect it to the computer? Do I need to buy this cable?

Yes, either buy that one or DIY one. It is really just a FTDI chip (that costs something like $6-$7 on eBay and RJ45 cable connection). If you want to DIY - look at EQMod project EQDirect cable:

http://eq-mod.sourceforge.net/eqdirect2.htm

(usb version - note that for Heq5 you need 5V signaling, so take care to get exact FTDI chip).

6 minutes ago, AlanP_ said:

Does my telescope come with a dovetail mount to mount it to my HEQ5? Or is that something I need to buy seperately? The guy I purchased off couldn't find it the vixen dovetail that he had!

You'll need to get one unless one is delivered with the scope.

TS website is a bit confusing with respect to that:

They have image showing what is included and dovetail bar is there. They have description of item and last point remarks that you get Generous equipment (that is sort of true for OTA only version - usually one just gets rings with OTA) - including dovetail, but section In the Box does not list it for some reason but it does list 2" 35mm extension used for visual to reach focus - which is not mentioned nor depicted above.

12 minutes ago, AlanP_ said:

Am I missing anything else like a cable, adapter, connnector? 

There is huge chance that you'll be missing something, but unfortunately - you'll only know at the moment you realize you are missing it

 

[AlanP_]

10 minutes ago, vlaiv said:

Yes, either buy that one or DIY one. It is really just a FTDI chip (that costs something like $6-$7 on eBay and RJ45 cable connection). If you want to DIY - look at EQMod project EQDirect cable:

http://eq-mod.sourceforge.net/eqdirect2.htm

(usb version - note that for Heq5 you need 5V signaling, so take care to get exact FTDI chip).

I think i'll just order that cable to be on the safe side. 

I've messaged telescop-express about the dovetail, hopefully they can clear things up for me.

Thanks for your help again!

[malc-c]

28 minutes ago, AlanP_ said:

So, i've ordered my first telescope! I went ahead and got the TS Photon 6" F/5. I also ordered a T2 adapter for my camera and an extra counterweight for my mount as it only has one.

Just a few (MORE!!) questions. 

1. So my HEQ5 mount came with the power cable and the synscan controller. How do I connect it to the computer? Do I need to buy this cable?
2. Does my telescope come with a dovetail mount to mount it to my HEQ5? Or is that something I need to buy seperately? The guy I purchased off couldn't find it the vixen dovetail that he had!
3. Am I missing anything else like a cable, adapter, connnector? 

Thanks in advance!

 

That link was for a 5m EQDIR cable, do you intend to have the PC that far away ?  If so then you may need 5m USB cables for the connection to the guide camera and for your main camera (assuming the manual exposure is controlled via USB and not a cable release socket as in the case with my 400D).  Most people tend to have one long active USB cable between the PC and the mount, where it connects to something like a 4,5, or 6 port USB hub.  Then the EQDIR cable, the USB cable for the guide camera, and the USB cable for the main imaging camera is connected to the hub.

[AlanP_]

2 minutes ago, malc-c said:

 

That link was for a 5m EQDIR cable, do you intend to have the PC that far away ?  If so then you may need 5m USB cables for the connection to the guide camera and for your main camera (assuming the manual exposure is controlled via USB and not a cable release socket as in the case with my 400D).  Most people tend to have one long active USB cable between the PC and the mount, where it connects to something like a 4,5, or 6 port USB hub.  Then the EQDIR cable, the USB cable for the guide camera, and the USB cable for the main imaging camera is connected to the hub.

Thats actually a really good idea. I think i'll use that method using the really long usb cable connecting to a usb hub. Is there one thats recommended on this forum or would any one suffice?

[AlanP_]

Also, does my telescope need to have polaris in sight for polar alignment? I can do it, it just means i'll need to put my mount a bit further back in my garden than i'd like.

[malc-c]

Being able to Polar Align on Polaris makes things a lot easier.  Personally I would pay the £10 for Sharpcap Pro, and use the built in tool to set the mount up using the guide camera / guidescope.  It's a lot easier than peering through the polar scope with the mount set to the polar HA position....

As for the hub... can't say really... I stuck to branded hubs rather than a cheap no name off e-bay.  

One other thing.. I can't recall if you mentioned how you intend to power the mount... The HEQ5 likes to have a decent 12v supply, capable of delivering 2A with ease.  In slewing tests mine draws 1.9 amps with both motors running.  It's not really advisable to have  mains outside, so running a standard mains extension lead to the mount and plugging in the power supply in the exposed damp cold air is not recommended.  Ideally, look for a 13.8v regulated supply rated at 5 amps and then run some nice thick multi-stand cable to a  weatherproof box (screwfix / toolstation) and then take the feed to the mount off that.  Have a search of the DIY section to see how others have done their power distribution.

Or you can look at a powerbank...https://www.rothervalleyoptics.co.uk/telescope-power-supplies.html  The SW 7amp hour powerbank is around £50 and should give you a decent nights imaging  run

[KP82]

26 minutes ago, AlanP_ said:

Also, does my telescope need to have polaris in sight for polar alignment? I can do it, it just means i'll need to put my mount a bit further back in my garden than i'd like.

If the North Celestial Pole region is visible, it will make polar alignment a lot easier. With tools like sharpcap or polemaster, precise polar alignment can be achieved in just a few minutes.

Otherwise you will need to rely on drift align which can take over 30 minutes and you will first need to learn this technique. There are software designed to help with this also (e.g. PHD2 drift align tool), but they won't speed up the process. You will simply be staring at your computer screen instead of peeking through an eyepiece.

[AlanP_]

7 minutes ago, malc-c said:

Being able to Polar Align on Polaris makes things a lot easier.  Personally I would pay the £10 for Sharpcap Pro, and use the built in tool to set the mount up using the guide camera / guidescope.  It's a lot easier than peering through the polar scope with the mount set to the polar HA position....

As for the hub... can't say really... I stuck to branded hubs rather than a cheap no name off e-bay.  

One other thing.. I can't recall if you mentioned how you intend to power the mount... The HEQ5 likes to have a decent 12v supply, capable of delivering 2A with ease.  In slewing tests mine draws 1.9 amps with both motors running.  It's not really advisable to have  mains outside, so running a standard mains extension lead to the mount and plugging in the power supply in the exposed damp cold air is not recommended.  Ideally, look for a 13.8v regulated supply rated at 5 amps and then run some nice thick multi-stand cable to a  weatherproof box (screwfix / toolstation) and then take the feed to the mount off that.  Have a search of the DIY section to see how others have done their power distribution.

Or you can look at a powerbank...https://www.rothervalleyoptics.co.uk/telescope-power-supplies.html  The SW 7amp hour powerbank is around £50 and should give you a decent nights imaging  run

Ok, I can use polaris. I dont need to make it more difficult for myself as a beginner! I dont have a guide camera yet though, can I still use that?

Yeah, I was just going to run an extension cable outside. Im not sure what the voltage is on it though. Maybe im better off going for that SW powerbank. I've emailed them to see if its in stock. God, this is really racking up in cash