Skywatcher 16" (400P) on a EQ6 PRO Mount

[simon84]

Nice comeback Olly and a point very well proven.

The first thing you need to ask yourself before going down the imaging route is what field of view do you want.

Do you want to get all of Hydra in your image? Do you want to be able to frame M31 nicely or do you want a real nice close up of M27?

Before you answer that question there really is little point in looking at scopes and cameras.

In an ideal world a couple of apo refractors on a solid mount would be nice, I always planned to have the Equinox 120 and an Equinox 80, and then use the Atik 4000 for a nice tight fov with say a modded Canon 1000D for a nice wide fov and then for constellation imaging the Canon with a 20mm lens on it.

Until you know what it is you want to image you cant really decide on what scope your going to use. If you plan to go with a 14" or 16" scope on an NEQ6 I think the only thing you will image is the floor.

[E621Keith]

If the 16" weights 52kg, then there is a good chance even the EQ7 won't handle it. Remember, Synta's American subsidiary makes the GCE Pro and that's only rated for 40kg. I can't imagine they will try and kill the sales of their own mount by making EQ7 better.

At 52kg, the only options left are the very expensive $$$ Paramount, AP1200 or Planewave's Ascension.

[lukebl]

Great image Olly, but think how much better it would have been if you'd taken it with a 14" on an EQ6.

.... runs for cover

[Astrokev]

Great image Olly, but think how much better it would have been if you'd taken it with a 14" on an EQ6.

.... runs for cover

Brave man !

Really interesting and quite entertaining thread.

As someone contemplating an EQ6 for my 10" f6.3, very informative too.

Thanks to all.

Kev

[Moonshane]

QUOTE

c. Despite all the advice regarding focal length and aperture, I still cannot see how a comparatively small refractor can yield better (or even comparative) resolution images to a images taken through a large reflector.

Now I cannot let my little Tak FSQ85 be spoken about like this!! Honour is at stake!!

Olly

that's rubbish Olly.

I've seen better than this in my life.

it's awful.

oh, and a happy 'opposites day' to all!

seriously, this image is like all the others I have seen of this subject but with the cobwebs blown off. it's just totally clean and stunning in detail. my reaction cannot be printed but part of it was an excited giggle. I totally get why imagers image I just don't really have time presently.

[sixela]

Great image Olly, but think how much better it would have been if you'd taken it with a 14" on an EQ6.

He'll pay for the scope if you pay for the focuser and sensor to get it all on the picture .

[ollypenrice]

I have said this before but what do you want to image?

Answer this and choose your focal length.

Now at that FL, how much aperture can you afford?

Next, can you afford a mount that can carry the weight AND guide at the FL in question?

With an EQ6 and a realistic metre of FL you can do something like this very reliably and reliability in imaging is a scarce commodity to be treasured.

Olly

[step_hen]

Olly your just showing off now! Great image- what scope and camera is that one with?

[ollypenrice]

Heh heh, I hope I am not showing off. This was done on an EQ6, that is the point, but at the kind of FL an EQ6 can handle.

TEC 140 apo and Atik 4000 mono.

No 16 inch scopes on the scene.

Olly

[MichaelBruno]

OK, and once again thanks for all the feedback on this thread.

As per my last reply, I had pretty much resigned myself to getting a 150+mm APO refractor for that EQ6, so I set about trying to find the best bang for buck in terms of lightweight large aperture refractors.

Predictably I ended up in the SCT domain instead and started looking hard at the EdgeHD's from Celestron.

They start at 8" and go all the way up to the 14".

The OTA's alone are reported as weighing in as follows:

EdgeHD 9.25" 9.5kg

EdgeHD 11" 12.7kg

EdgeHD 14" 20.9kg

The attractive thing about the EdgeHD is that the Focal Length issue, which everyone in the know here has been cautioning me about, is elegantly addressed with these EdgeHD scopes.

For example, you can use the 14" EdgeHD at a focal length of F11 for visual and astrophotography at the rear of the OTA. F11 means that the 2800mm focal length gives excellent magnification on a 35mm format DSLR, but of course at a very narrow field of view - requiring very accurate and stable mount performance.

If you want to go wide field, you can mount your imager (CCD or DSLR) at the prime focus location on the front of the OTA. This is called Faststar or HyperStar configuration, on account of the faster equivalent photon capture times when compared to longer focal length work.

This allows you to use the scope at F2, or as I understand it, approximately 500mm Focal Length.

Now we're in that "happy place" when it comes to astrophotography and focal length.

My understanding is that with a small focal length, tracking accuracy and mount stability are less critical due to the large field of view - I get this loud and clear now!

Since I plan to use a DSLR Canon EOS550D (Rebel in the US) I need to use either the 11" or the 14", since the physical size of the DSLR at prime focus would obstruct too much of the primary on the 9.25" or smaller.

The Celestron guys on-line go "on and on" about the 3x image flatness of these EdgeHD's and fancy coated optics for pin point stars etc. It looks like these OTAs were designed especially for DSLR and the more expensive larger format CCD imagers.

I am looking to take advantage of the superb 18Mpixel CMOS sensor in the Canon 550D. It's probably worth mentioning that the camera body weight is les that 0.6kg. A lightweight 18Mpixel camera on a large aperture F2 OTA sure sounds like a perfect state of the amateur art imaging system to me.

So, sold on the F11/F2 versatility & FLAT performance of the EdgeHD, I am back where I started in selecting the best aperture option for my already purchased EQ6 Pro...

The 11" OTA is precisely half the weight of the EQ6 25kg payload rating. Many astrophotographers suggest that you should never load your mount at more than half the max payload rating for serious astrophotography. I can't help but ask myself whether these words of wisdom are relevant to F2 OTA setups. Surely a widefield F2 high pixel count (high resolution DSLR) system could

tolerate a little more jitter or tracking error?

So my greedy thoughts turn back to that oh so desirable 14" aperture EdgeHD, which still weighs in at 4kg less that the EQ6 mount published max capacity...

(OK, OK, I realize that published capacity means "It won't break capacity", and not "It will work well" capacity, but not breaking of stripping gears is OK for me at this point)

Many would caution me about the additional weight of the guide scope, eye pieces & imager. I plan to add only the 0.6kg of the Canon DSLR, and possibly an LVI autoguider camera with a light weight refractor to plug into the EQ6 ST4 port.

I'll probably end up at the 25kg full mount capacity, due to the weight of the autoguider optics (3kg) and 0.15kg LVI Smartguider camera.

Surely I'm not the first person to try and mount an EdgeHD 14" on an EQ6 Pro mount. Has anyone out there tried this already?

All said and nothing done, that's where my thoughts as regards the best possible OTA for an EQ6 Pro mount are at, at least at this moment. I'll keep updating this thread until I have images to demonstrate the capability of my ultimate decision on what to do with an EQ6 Pro mount....

[MichaelBruno]

I'm going to continue this thread as :

"Celestron EdgeHD 14" on an EQ6 Pro mount"

Kindly post any answers there, thank you.

[SiriusB]

At the prices your looking at for even an eq6 i'd be tempted to find a local engineer, buy him LOTS of beer

& convince him while he's merry to build you a beefy mount! Just a thought.

[sixela]

I'd rather you had posted "Celestron Edge HD 9.25 on EQ6"...C14 is, again, (future) EQ7 class, not EQ6 class.

BTW, f/11 is not a nice ratio to image many things. It'll take ages before your sub is actually well it (3.36x longer than on an f/6) when you're imaging extended objects.

But there's an Edge-HD compatible reducer "coming soon" from Celestron for just that reason.

[blackparticle]

I found this thread while searching for information about my little 130P and was most impressed by the pictures of the monster tubes.

One thing sprang to mind about the question of mounting these things.

Has anyone ever tried to build their mount onto a small flatbed truck? Given the right enclosure and canopy that would make an amazing portable observatory.

It would even be something you could then take out into the dark sky areas and probably above the clouds as well.

Just an idea.

[michael.h.f.wilkinson]

I found this thread while searching for information about my little 130P and was most impressed by the pictures of the monster tubes.

One thing sprang to mind about the question of mounting these things.

Has anyone ever tried to build their mount onto a small flatbed truck? Given the right enclosure and canopy that would make an amazing portable observatory.

It would even be something you could then take out into the dark sky areas and probably above the clouds as well.

Just an idea.

I have heard of such constructions, though never used one. I would think you need some way to immobilize the car when using the scope (like a set of posts you can wind down onto the ground). I would also think you need to recollimate your scope after each bump in the road , unless your suspension is super smooth.

[RobH]

The 14" would be impossible on an EQ6 pro, it's far too big (I have both)

Ben and John......John H produces some fantastic long exposure deep space images using an Orion Optics(UK) SPX 14 and an EQ6.

As far as I know, he hasn't done major surgery on the mount.

I must admit, if someone suggested it to me, I'd be dubious, but John has walked the walk, and talked the talk

[NeutrinoWave]

I recently purchased an Skywatcher EQ6 PRO Equatorial Mount.

At the moment I have an 8" Orion on the mount.

I was waiting patiently for the Skywatcher 14" 350P tube to come to South Africa, but upon querying the local supplier I found out that Skywatcher have now also launched a 16" 400P tube!

My interest in long exposure astrophotography, so the equatorial mount (as opposed to ALT-AZI) is a must.

I am very curious as to whether anyone has considered, or better yet, tried mounting a Skywatcher 16" 400P on an EQ6 PRO mount.

I would think that to be a dream amateur astrophotographers setup?

Long Exposure? Surely the 16in will reduce the exposure time, and you are limited by the alt-az design ... so the EQ mount does not equate with the Dob

[ollypenrice]

A C14 needs an accurate mount. Think native PE of +/- 2 arcsecs. The native PE of an NEQ6 is from here to Tokyo, to borrow a gag from a dealer I know. It is around 20-30 arcsecs, ten times the sort of error you are looking for. OK it guides out... up to a point. You reach that point somewhere around 1.5 to 2 metres. You would never ever get a round star at native FL in a C14 and probably not in a C11.

The Hyperstar solution is a good one but I would stay well away from the giant 14 inch on the NEQ6. The 11 would be better. You need to be aware that F2 is staggeringly fast, which is good, but brings issues of its own. Think of the angle of the light cone approaching the chip; the focal plane is microns deep so focus has to be perfect as in perfect. So does collimation and othogonality. You are going to try to achieve this focus using a Celestron moving mirror focuser. Uh-oh. Reality time.

You're making another error, quite honestly, in thinking millions of tiny pixels are good for astronomy. They're not. They sample at the wrong rate and with a one shot colour camera you can't bin to redress this. The best astro cameras have quite large pixels.

If you want a fast system that woks buy a Takahshi Epsilon. Not cheap but it will work, and will work with your small pixels and your EQ6.

Olly

[ollypenrice]

Long Exposure? Surely the 16in will reduce the exposure time, and you are limited by the alt-az design ... so the EQ mount does not equate with the Dob

No no no! It is F ratio, not aperture, that determines exposure time. Hard to believe but true. Honestly.

Olly

[Moonshane]

it always amazes me how complex the issues concerning imaging are. the mount, the focal length and ratio, the optical quality, the camera the chip, the leads....oh....the leads and then of course the imaging.

visual for me always!

[dph1nm]

No no no! It is F ratio, not aperture, that determines exposure time. Hard to believe but true. Honestly.

Oh no - don't get me started on that one again!

NigelM

[ollypenrice]

Oh no - don't get me started on that one again!

NigelM

Heh heh, no, it's an old one! The caveats are point sources being excepted and the need to compare fast and slow only at the same focal length.

Olly

[michael.h.f.wilkinson]

Quite apart from imaging issues, I have this image in my mind of the 16" scope just tipping over the NEQ6 mount and crashing to the ground :eek:, about 10 seconds into the first sub.

When I first started out in amateur astronomy, one of the heroes of the day was Dany Cardoen, with his 16" monster Newtonian (F/4 I think). It was mounted on a HUGE EQ mount way more solid that an NEQ6. As I recall, he had a plate camera at prime focus and made some awesome shots. He is still at it, in Puimichel, with an even more awesome scope.

The bottom line is that you can do imaging with a 16" newt, but you will need a really serious mount.

[Merlin66]

Stumbling upon this thread made me reminisce about some of the fork mounts which I've made and used over the years all the way up to 29" f5.

We should seriously look at a split rings/ fork and disk solution for reflectors. The reason the GEM has become so popular is the Dovetail connection.....

If we could come up with a standard set of "disks" where the arms could be adjusted in or out to match the size of the OTA then there some economies of scale.

Much more robust than the GEM, greater weight carrying capacity and with a suitable drive system probably better (PE) than the small worm and wheels on the current series of amateur sized GEM's......

[michael.h.f.wilkinson]

Stumbling upon this thread made me reminisce about some of the fork mounts which I've made and used over the years all the way up to 29" f5.

We should seriously look at a split rings/ fork and disk solution for reflectors. The reason the GEM has become so popular is the Dovetail connection.....

If we could come up with a standard set of "disks" where the arms could be adjusted in or out to match the size of the OTA then there some economies of scale.

Much more robust than the GEM, greater weight carrying capacity and with a suitable drive system probably better (PE) than the small worm and wheels on the current series of amateur sized GEM's......

Most really big scopes have a fork mount of some sort. The main problem of the fork mount is that the size of the fork poses bounds on the scope it can handle. It should be possible to make a drive system (polar axis only) that attaches to a variety of forks. If the forks can be made in a modular way, this might provide some economies of scale, although the stiffness might suffer.