200PDs an age old question

[Simon Dunsmore]

Hi Folks, 

It's been quite a journey, plenty of mistakes made along the way. Finally I've almost assembled a rig that I'm happy with. 

I started with a Skywatcher 130p on an EQ3/2 mount, sold the mount when it just wasn't cutting it. 

Next I purchased a used eq5 pro goto. Much better! This is where I goofed, I developed  a fatal case of aperture fever sold the 130p and purchased a 200PDs. I then started down the road of astrophotography, so far so good. Until I realised the EQ5 pro wasn't man enough to take the 200PDs. This whole process took 8 years! 

Just recently after much saving and reading a hundred different articles I found a still boxed and unused second hand Heq5 pro goto mount (which I collect next weekend)  I have since read that the 200PDs is too heavy for astrophotography on the Heq5. 

Here's the question, is the 200pds really too heavy? I have thought about selling this, it's in perfect condition and boxed but no one seems too interested, do I keep trying to sell it and buy a 130PDs or just ignore the negative reports and go for it with the 200PDs? 

BTW I'm imaging DSO using a Canon 60D and qhy5l-ii guide camera 

Thanks from a confused but enthusiastic star glazer. 

PS I read somewhere that even the neq6 isn't man enough for the 200PDs...really??? 

[Johns22]

Hi Simon,

I've only been doing this for the past couple of months - not the 8 years you have, so my comments may be worth little. I've got the 200P on an EQ5 mount that I've upgraded with a Synscan goto kit. I'm using a Canon 600D DSLR for my astrophotography. Like you I have read lots on the internet that basically tell me the kit I have isn't the best for the job. However, I'm enjoying learning and have had reasonable success to date considering the scope had not been collimated since I purchased it. I don't yet have a guidescope fitted and everything I have has been bought second hand. I want to find the limitations of my kit and better understand what I need as I go along. Whilst advice on the internet can be helpful, I think you can miss the appreciation of why you need some of the gear along the way.

I've just had my scope collimated (and a lesson at the same time) at my local Astronomy club and I can't wait to get on with capturing images of the night sky with it. I won't be changing it anytime soon (if ever!) but I'll be adding some accessories like a guidescope. I've seen some people on Facebook posting in the groups who use the same setup as me and the photo's are incredible.

The only thing I have noticed whilst imaging is anything more than a breeze causes star trails but I can live with that for now. I'm going to get on with it and learn myself!

 

[alacant]

Hi

If you've an observatory to protect from the wind, I'd try the 200 on the new mount but I'd volunteer you'd have a lot more success and fun with the 130 on the same.

SW 200s don't seem to have much resale value and come up frequently on the used market so -guessing- your price would have to be competitive. Or keep it and get an eq6 and a 130. Best of all worlds?

JTOL, but HTH.

 

Edited March 8, 2020 by alacant

[Stu]

Hi Simon,

I'm a visual astronomer, not an image, so feel free to disregard these comments. I've been around this forum for a while, and you get to know what works, and what people struggle with. My 'advice' would be to get a 130PDS and avoid lots of hassle and disappointment. An under mounted, longer focal length scope will just give you constant challenges, and lighter, properly mounted scope with a shorter focal length will see you progress much faster.

[Simon Dunsmore]

Hi Folks, 

Thanks for all your replies. I figured that go with the 130PDs would be the general opinion. 

I if that's the way to go, I'll use my 200pds until I can sell it and then go for the 130. 

I've got it listed at £195 does this sound about right? 

Thanks again 

Simon 

[Spaced Out]

I use both 130 PDS and 200 PDS on a HEQ5. I have a permanent pier which is outdoors (not inside the walls of an obs) and I only use the 200PDS on calm nights because it is like a big sail in the wind. Having said that the 200PDS works fine on my HEQ5 and with guiding I get 10 minute subs no probs. The 130 PDS is perhaps better matched to a HEQ5 and slightly less prone to getting blown about by the wind too.

[bottletopburly]

52 minutes ago, Simon Dunsmore said:

I've got it listed at £195 does this sound about right? 

 

I sold my 200p for £125 , flocked , handle , bobs knobs 

[ollypenrice]

3 hours ago, Simon Dunsmore said:

Hi Folks, 

It's been quite a journey, plenty of mistakes made along the way. Finally I've almost assembled a rig that I'm happy with. 

I started with a Skywatcher 130p on an EQ3/2 mount, sold the mount when it just wasn't cutting it. 

Next I purchased a used eq5 pro goto. Much better! This is where I goofed, I developed  a fatal case of aperture fever sold the 130p and purchased a 200PDs. I then started down the road of astrophotography, so far so good. Until I realised the EQ5 pro wasn't man enough to take the 200PDs. This whole process took 8 years! 

Just recently after much saving and reading a hundred different articles I found a still boxed and unused second hand Heq5 pro goto mount (which I collect next weekend)  I have since read that the 200PDs is too heavy for astrophotography on the Heq5. 

Here's the question, is the 200pds really too heavy? I have thought about selling this, it's in perfect condition and boxed but no one seems too interested, do I keep trying to sell it and buy a 130PDs or just ignore the negative reports and go for it with the 200PDs? 

BTW I'm imaging DSO using a Canon 60D and qhy5l-ii guide camera 

Thanks from a confused but enthusiastic star glazer. 

PS I read somewhere that even the neq6 isn't man enough for the 200PDs...really??? 

I think you're concerning yourself with the wrong numbers. It's an error to think that a mount's main concern is to carry the required weight. Yes, it does have to do that but what it must also do is deliver a tracking accuracy which supports the pixel scale of the setup.  If you are imaging at 2.0 arcseconds per pixel the mount, roughly speaking, must deliver an accuracy of about twice that - so 1 arcsecond RMS. This is certainly going to be the figure under guiding since the Skywatcher mounts, good as they are, have periodic errors twenty or thirty times that, unguided.

So... I think your 200PDS/Canon will be working at 0.89"PP. This is a realistic scale on nights of exceptional seeing and with a mount which can deliver an RMS under guiding of 0.45 arcseconds or better. This guiding figure is at the absolute limit of what's normally possible with your mount and the demands on the seeing are very unlikely to be met in the UK. This means you would do just as well, or better, with a considerably shorter focal length. Essentially you are chasing the impossible. You would probably catch just as much detail, and have a vastly increased field of view, if you went for a far shorter focal length. Aperture fever belongs in visual observing. It is a snare and a delusion in imaging.

Olly

[Simon Dunsmore]

4 minutes ago, ollypenrice said:

I think you're concerning yourself with the wrong numbers. It's an error to think that a mount's main concern is to carry the required weight. Yes, it does have to do that but what it must also do is deliver a tracking accuracy which supports the pixel scale of the setup.  If you are imaging at 2.0 arcseconds per pixel the mount, roughly speaking, must deliver an accuracy of about twice that - so 1 arcsecond RMS. This is certainly going to be the figure under guiding since the Skywatcher mounts, good as they are, have periodic errors twenty or thirty times that, unguided.

So... I think your 200PDS/Canon will be working at 0.89"PP. This is a realistic scale on nights of exceptional seeing and with a mount which can deliver an RMS under guiding of 0.45 arcseconds or better. This guiding figure is at the absolute limit of what's normally possible with your mount and the demands on the seeing are very unlikely to be met in the UK. This means you would do just as well, or better, with a considerably shorter focal length. Essentially you are chasing the impossible. You would probably catch just as much detail, and have a vastly increased field of view, if you went for a far shorter focal length. Aperture fever belongs in visual observing. It is a snare and a delusion in imaging.

Olly

Thanks Olly fit your explanation, much appreciated. I also have a 72ed whi ch which is a lovely little scope for wide field. I was looking for something with a little more focal length which is why I was leaning towards the 130. If you have any suggestions that may be more appropriate, I'd welcome your thoughts.

I just need to move the 200pds.

20 minutes ago, Spaced Out said:

I use both 130 PDS and 200 PDS on a HEQ5. I have a permanent pier which is outdoors (not inside the walls of an obs) and I only use the 200PDS on calm nights because it is like a big sail in the wind. Having said that the 200PDS works fine on my HEQ5 and with guiding I get 10 minute subs no probs. The 130 PDS is perhaps better matched to a HEQ5 and slightly less prone to getting blown about by the wind too.

Thanks for your reply. 

As I mentioned, I will try the 200pds until I can sell it. Do you find much difference when imaging with the two with regards to image quality? 

[ollypenrice]

1 minute ago, Simon Dunsmore said:

Thanks Olly fit your explanation, much appreciated. I also have a 72ed whi ch which is a lovely little scope for wide field. I was looking for something with a little more focal length which is why I was leaning towards the 130. If you have any suggestions that may be more appropriate, I'd welcome your thoughts.

I just need to move the 200pds.

Thanks for your reply. 

As I mentioned, I will try the 200pds until I can sell it. Do you find much difference when imaging with the two with regards to image quality? 

OK, the place to start is your achievable guiding accuracy. Tell PHD your guide scope pixel size and focal length and it will give you your average guide error in arcseconds. Whatever this is, you need to double it and that is the finest pixel scale at which it is worth imaging. What is the longest focal length, with your camera, which does not exceed this limit? You'll find this calculator useful. http://www.12dstring.me.uk/fovcalc.php

If your focal length takes you to a pixel scale below 2x your guide RMS in arcseconds you are wasting your time. You may get a bigger image of a small galaxy but that image will contain no more detail than a smaller one. This may be darned annoying but the truth often is darned annoying! I've imaged with a 14 inch reflector with an FL of about 2.4 metres and a 5.5 inch refractor with a FL of 1 metre. The big one was working at about 0.6"PP and the small one at 0.9"PP. The seeing, however, said '0.9"PP, over and out.' There is no significant difference between the results in my view.

Olly

[Spaced Out]

2 minutes ago, Simon Dunsmore said:

 Do you find much difference when imaging with the two with regards to image quality? 

 

Very little difference apart from focal length, I actually like the 200 PDS. My original plan was to buy 2nd hand HEQ5 and 130 PDS to get started but then a HEQ5 and 200 PDS came up near me and I couldn't resist. I had planned to just sell the 200 PDS but ended up keeping it while I learnt with the 130 PDS.

Some pics with DSLR and both telescopes here, not the best because I am learning, rubbish at processing and I didn't use any calibration frames but it'll give you some idea.

https://www.flickr.com/photos/132427272@N04/albums/72157663479649980/with/44093130860/

 

[Simon Dunsmore]

5 minutes ago, Spaced Out said:

 

 

Very little difference apart from focal length, I actually like the 200 PDS. My original plan was to buy 2nd hand HEQ5 and 130 PDS to get started but then a HEQ5 and 200 PDS came up near me and I couldn't resist. I had planned to just sell the 200 PDS but ended up keeping it while I learnt with the 130 PDS.

Some pics with DSLR and both telescopes here, not the best because I am learning, rubbish at processing and I didn't use any calibration frames but it'll give you some idea.

https://www.flickr.com/photos/132427272@N04/albums/72157663479649980/with/44093130860/

 

Hi, 

Wow! Love these. 

So these were taken with a DSLR through a 200pds on a Heq5? 

Maybe ill give it a whirl! 

[Spaced Out]

6 minutes ago, Simon Dunsmore said:

So these were taken with a DSLR through a 200pds on a Heq5?

Most were 130 PDS but a couple were 200 PDS, M33 was 200 PDS. Yes crop sensor DSLR.

Edited March 8, 2020 by Spaced Out

[Erling G-P]

I posted some of my images with a 200PDS on an unguided HEQ5Pro in this thread:

 

[jimjam11]

Best bet is to test it and see, the bayer matrix on your dslr will effectively halve your resolution to 1.8"/px so you might get away with it sometimes.

Having said that I wouldn't dream of putting my 200pds on a heq 5. My heq5 averages 1.2" rms and any hint of wind makes it worse. 

 

[Whistlin Bob]

On 08/03/2020 at 21:44, Simon Dunsmore said:

Maybe ill give it a whirl! 

Yes- definitely do. Especially for small targets or tight framing of larger ones.

I use a 200p on an HEQ5 and it usually guides at around 1-1.2 rms, I get slightly better figures with my 130pds (hard to tell definitively because the seeing impacts this). This means I'm losing potential resolution, but I'm still collecting more than double the photons with the eight inch. Sure- it would be better if I had a bigger mount but I don't and that's that.

M51 image below was taken with a Canon 600d on the 200p / HEQ5.

 

 

[alacant]

On 08/03/2020 at 18:42, Simon Dunsmore said:

one seems too interested

If you can ship to Spain, I have someone who may bite. Do you have details/photos/prices?

Cheers