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Eq6r vs AZEQ6GT vs Ioptron GEM45 for imaging

Mount Imaging
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#1 Ayaan Hashim

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Posted 13 June 2021 - 10:26 PM

Hi all,

Just a question...for imaging which ranks best? If you push the Skywatcher mounts to their full potential...Like if they were tuned by Darkframe optics(Stellardrive)...they could easily beat the Ioptron, right?

Thanks a lot for replying in advance,

clear skies,

Ayaan



#2 bobzeq25

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Posted 13 June 2021 - 11:13 PM

Performance is comparable.  Mounts in the price range have limited quality control.  No one actually tests each sample at night.  A good example of mount X is likely better than a mediocre example of mount Y.

 

Not familiar with that tuning organization, but tuning by a professional _should_ ensure you've got a good example of whatever.

 

The big difference is weight.  iOptron is a specialist in good, lightweight mounts, and the GEM45 is half the weight.  Not a big deal if you have the mount permanently mounted and/or are strong.  I'm an old man of limited strength, so I like iOptrons.

 

In these parts, the EQ6-R is the best bargain, if that's important.


Edited by bobzeq25, 13 June 2021 - 11:16 PM.


#3 luxo II

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Posted 14 June 2021 - 12:00 AM

Personal experience with an AZEQ6 is that the tracking is excellent both equatorially and in altaz mode - even at 3100mm focal length, although blind pointing with GOTO is not as precise as you might wish.

 

All Darkframe optics are doing is fitting a belt drive (older mounts don't have this, recent ones do), re-greasing the gears and adjusting backlash.

 

Adjusting backlash is a 5-minute DIY job with an Allen key, once you know where the adjustment is (Skywatchers manuals are silent on this).


Edited by luxo II, 14 June 2021 - 12:04 AM.


#4 Ayaan Hashim

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Posted 14 June 2021 - 12:18 AM

Hey all,

Thanks very much for replying!

So essentially:-

1.Best for beginner but heavy-The eq6r pro

2.Lightest mount of the lot-GEM45

3.Best tracking?-AZEQ6?



#5 luxo II

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Posted 14 June 2021 - 12:31 AM

AZEQ6 is the same as EQ6 in most respects apart from (a) it has belt drives and (b) you can use it altazimuth - which is great for most purposes except DSO imaging.


Edited by luxo II, 14 June 2021 - 12:32 AM.


#6 Ayaan Hashim

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Posted 14 June 2021 - 12:35 AM

Which of them is the best for imaging at 0.3arcsec/pixel, 6inch refractor at f8, 12kg riding on top, total imaging train length-<1.3m



#7 Ayaan Hashim

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Posted 14 June 2021 - 12:37 AM

Who wants to use the azeq6 in Alt-Azimuth mode anyway?

Here are the disadvantages-

1.Mount moving in two axes-Possibly more tracking errors

2.Field rotation



#8 Ayaan Hashim

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Posted 14 June 2021 - 12:37 AM

So which mount tracks the best?



#9 bobzeq25

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Posted 14 June 2021 - 12:49 AM

Again, a good example of mount X would track better than a mediocre example of mount Y.  Doesn't matter what X and Y are.

 

Imaging Deep Space Objects at 0.3 arc sec per pixel is going to be way oversampled in just about every sky quality.  That will cost you signal to noise ratio, and image quality.  Tracking at 0.3 arc sec is just about unheard of.  On an ordinary nigt, I'll get about 0.7 with my CEM60, carefully autoguided.  0.6 on an excellent night.  I've seen 0.5.

 

This is a complicated business.

 

Standard image scales (Deep Space Object imaging) are between 1 and 2.  Closer to 1 can theoretically get you more resolution, but a number of other things have to cooperate.  Seeing (atmospheric steadiness), tracking, optical quality.   Otherwise, you've sacrificed signal to noise ratio for no gain.  Closer to 2 gets you better signal to noise ratio, no matter what.

 

Imaging with a 6 inch F8 scope at 0.3 arc sec per pixel would require a camera with 1.8 micron pixels.  As far as I know, none exists.


Edited by bobzeq25, 14 June 2021 - 12:53 AM.


#10 luxo II

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Posted 14 June 2021 - 12:50 AM

Who wants to use the azeq6 in Alt-Azimuth mode anyway?

I do, most nights. You'd be surprised at how well it tracks, about the same as in EQ mode and at club nights others have watched what its doing and even by EQ standards figured its very good - unguided. And my 10" focal length is 3100 mm, the working magnification is not small - 100-900X.

 

No wrestling with finder scopes or star diagonals in awkward positions - always where you want it, though yes at the zenith its a bit low - though no different to an EQ mount.

 

Imaging, there is no need at all for EQ mode for the moon and planets, and even for DSO there is a surprise. According to SharpCap with the ASI533 my optimum exposure is under 1 minute which is so short that field rotation is not an issue. So I shoot lots of frames, around 45 seconds, and use SharpCap to stack them. It de-rotates the frames, automagically.

 

I use a reducer to give f/6.6 or Barlow to achieve f/20 (moon and planets).


Edited by luxo II, 14 June 2021 - 12:59 AM.

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#11 bobzeq25

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Posted 14 June 2021 - 12:57 AM

I do, most nights. You'd be surprised at how well it tracks, about the same as in EQ mode and at club nights others have watched what its doing and even by EQ standards figured its very good - unguided. And my 10" focal length is 3100 mm, the working magnification is not small - 100-900X.

 

No wrestling with finder scopes or star diagonals in awkward positions - always where you want it, though yes at the zenith its a bit low - though no different to an EQ mount.

I believe he's talking imaging, with is _completely_ different from visual.



#12 Ayaan Hashim

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Posted 14 June 2021 - 01:02 AM

I know I might be asking the most idiotic question CN has ever heard of, but I'm just curious...lol.gif



#13 luxo II

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Posted 14 June 2021 - 01:03 AM

On the contrary, it is not an idiotic question. I can live with imprecise GOTO but good tracking does matter a lot more, even visually.


Edited by luxo II, 14 June 2021 - 01:04 AM.


#14 Ayaan Hashim

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Posted 14 June 2021 - 01:03 AM

luxo ii, the field rotation not being so much on the aggressive is possibly because of your latitude



#15 luxo II

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Posted 14 June 2021 - 01:09 AM

No, field rotation is more complex than just latitude, I did the maths. SharpCap does de-rotate perfectly well. What it can't fix is stars distorted by trailing, which sets an upper limit on exposure and this is a function of altitude, azimuth vs exposure time.

 

What's interesting is the maximum exposure is independent of focal length - it matters not whether you're using  a 60mm f/5 APO, or my monster.


Edited by luxo II, 14 June 2021 - 01:12 AM.


#16 Ayaan Hashim

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Posted 14 June 2021 - 01:13 AM

So if I get the AR152(I prefer the 10" lacerta photonewtongrin.gif ) and an asi 2600mm, I'll be looking at about 0.7 arcsec/pixel



#17 Ayaan Hashim

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Posted 14 June 2021 - 01:20 AM

So can I Image 10 minutes guided at 0.4 arcsec/pixel on the AZEQ6 with 13kg on top Seeing-Average Wind-No wind at all? Or will the eq6r or gem45 beat it? Which is the most affordable mount which has the perormance to image like this-The paramount MYT?


Edited by Ayaan Hashim, 14 June 2021 - 01:24 AM.


#18 luxo II

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Posted 14 June 2021 - 01:28 AM

AZE6 is not in that category. You'd need something from A-P or 10 Micron to do that and even then, only maybe.

 

No-one I know is achieving 0.4 arcsec over 10 minutes - with anything. I think you do not understand what you're asking.


Edited by luxo II, 14 June 2021 - 01:33 AM.


#19 Ayaan Hashim

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Posted 14 June 2021 - 01:45 AM

Put the c14 on an az gti in eq mode-then expect it to successfully image m51 in HaRGB at f11 with an asi183mm lol.gif



#20 bobzeq25

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Posted 14 June 2021 - 02:11 AM

I know I might be asking the most idiotic question CN has ever heard of, but I'm just curious...lol.gif

Not at all.  But it's looking at the wrong things.

 

Those mounts are about the same.

 

Resolution is not usually driven by tracking, but by seeing.

 

Starting out in imaging with a 1200mm F8 scope makes life difficult.  For learning this wonderful, but oh so complicated hobby, a short, light and fast scope makes things much easier.  More fun.  You'll learn faster and better.

 

Some rules of thumb.

 

No more than 600mm, 480 is better.

No more than 10 pounds, 5 is better.

No slower than F6.

 

You'll be using an autoguiding program by Dr. Craig Stark.  PhD scientist, note astrophotographer, who writes and lectures on the subject.  He's seen a lot of beginners, has some advice o0n the best scope to start with.  It's not what he says, it's how he says it.

 

"As light as possible.

 

 

 

Seriously.

 

 

 

 

No, seriously."

 

<smile>



#21 Ayaan Hashim

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Posted 14 June 2021 - 03:07 AM

So if I get an average AZEQ6, clean the gears and belts, re-lubricate everything with lithium grease, I should be looking at about circa 0.5 arcseconds rms in phd2 with pec, right?


Edited by Ayaan Hashim, 14 June 2021 - 03:13 AM.


#22 Ayaan Hashim

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Posted 14 June 2021 - 03:13 AM

I am a beginner. I have been researching on this forum for 1 1/2 years now. I think you should look at the darkframe mounts performance charts...here- https://www.darkfram...rformance-chart .

If I had an Eq6r tuned by David Woods(stellardrive 6), It would probably be a real monster for the total price.



#23 Ayaan Hashim

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Posted 14 June 2021 - 03:17 AM

I understand that a beginner should not get that CGXL and a c14 edge(Alright, putting strain on the mount, make it an 11") with a qhy600,

but instead go for something like an 80mm f5, an asi294mc, and an heq5 for learning...yes, the learning curve is quite steep



#24 Ayaan Hashim

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Posted 14 June 2021 - 03:19 AM

I want to collect scientific data...mostly on discovering comets and asteroids...but with the 2.4" powerseeker here at f15, the chances are virtually nilgrin.gif



#25 Ayaan Hashim

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Posted 14 June 2021 - 03:25 AM

I want to make a setup like the one which astrobiscuit has for 700 pounds(You can see his latest video)...but use that for scientific imaging. He is imaging 0.5 arcsec/pixel with that rig, the mount being an heq5, belt modded, and tuned by David Woods(Darkframe optics)...runs at about 0.6arsec rms...made about a decade and a half ago...he increased the voltage slightly to make the mount track better-but the subs were 5 second exposures. You can check out his video on youtube if you haven't already!


Edited by Ayaan Hashim, 14 June 2021 - 04:38 AM.



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