Will this work...... Large load on A NEQ6 Pro

[Whippy]

Enough already.

Quite.

We're well and truly off topic here so can we get back to it please?

Tony..

[themos]

Actually, I stated that a 12" Newt is sub-optimal for planets. That's uncontroversial, surely.

Then I said that 10" is optimal for planets. Those with C14 can argue against that but given that a C14 plus appropriate mount should cost about £10,000 and a C11 can go on a Synta mount for under a 1/3 of that (meaning you can run 3 C11s for the price of one C14), I'm pretty happy with my statement.

[FLO]

Steady Arthur. I think we all know where themos is coming from. His comments are based on a mix of personal experience and acquired knowledge, there is nothing wrong with that.

I for one would like to know more about the effect of atmospheric cells on seeing (in a different thread) but that won't happen if you get all arsey with him.

Be nice, eh

[Catanonia]

Oops what have I started.

Here goes my understanding.

More apature = more light and great for DSO, but maybe not so great for planets.

More light = more chance of LP and hence reduced sub times.

Now I would use this size reflector mainly for DSO imaging work (want to gave as much light as possible) and for some planetary work. The main use would be fuzzy imaging.

I really need to get close and personal to one and take a peek at it's true size. After all, there is nothing stopping me from popping it on and off the mount as and when I want to use it. Just be a pain to re-balance, add guide scope etc.

[GazOC]

Just to reiterate, the point I was making regarding the 12" Newt was over its focal length (1500mm) and its suitability for imaging in the UK.

At the risk of opening a can of worms, generally for extended objects, focal ratio and not aperture governs the duration of the subs needed but you also need the conditions to image at long focal lengths.

[Aza]

Gaz...but does an f5 12inch Newt produce nicer pictures than an f5 8inch Newt?

[GazOC]

Gaz...but does an f5 12inch Newt produce nicer pictures than an f5 8inch Newt?

You'll have to define "nicer"....

I'm no imager but on most objects if they are both f5s, for a given sub length you'll increase the image scale if you use a 12" over a 8" but thats pretty pointless if a) the mount is overloaded and that spoils the subs the conditions arn't suitable to imaging at 1500mm.

[themos]

The main use would be fuzzy imaging.

Then I suggest you look at what kind of equipment was used to shoot the SGL POWs that targetted DSOs. I haven't kept a count but I'd be surprised if you find many shot with a 12" Newt.

[Whippy]

More apature = more light and great for DSO

What you're saying works for visual but for imaging, it's only in relation to focal ratio/length that aperture matters.

Focal ratio = speed, the lower the ratio, the faster the scope and focal length is essentially magnification. The longer the focal length, the smaller the field of view is.

But the problem we have especially here in the UK is we don't get the atmospheric conditions steady enough that will enable us to get that detail or small objects that you're able to do when you image at longer focal lengths. Have a browse through the DSO images, with a few minor exceptions, you won't find hardly any close up images of small objects. Plus imaging with such a big scope and long focal length is a darn sight more challenging than what you're currently using. Learn to walk before you run eh?

Tony..

[Catanonia]

What you're saying works for visual but for imaging, it's only in relation to focal ratio/length that aperture matters.

Focal ratio = speed, the lower the ratio, the faster the scope and focal length is essentially magnification. The longer the focal length, the smaller the field of view is.

But the problem we have especially here in the UK is we don't get the atmospheric conditions steady enough that will enable us to get that detail or small objects that you're able to do when you image at longer focal lengths. Have a browse through the DSO images, with a few minor exceptions, you won't find hardly any close up images of small objects. Plus imaging with such a big scope and long focal length is a darn sight more challenging than what you're currently using. Learn to walk before you run eh?

Tony..

Yes understand that Focal length is an important factor.

Hence the reason to take many many more subs, short enough to ensure that they don't become polluted with LP.

So a Fstop of 3 actually will mean I need to square this and gather 9 times as much light for same image and hence I would 9x as many subs but baring in mind i would need 3x better guidence and LP protection measures

So if you had the time and patience and of course enough clear skies you could take these larger images (more magnification). Of course skies in UK generally stop this.

However, my theory goes, if this large 300m scope is setup and I focus on 1 object for the next 20 times imaging, then I should get the subs needed. Now this would be boring to do. So I would use the ED's for normal imaging... Ah but then I would need 2 mounts for 2 different objects... QED

Either that or I go for the Mil approach and make a 4 way scope that looks like a AA gun on a cruiser

[Whippy]

Hence the reason to take many many more subs, short enough to ensure that they don't become polluted with LP.

You can buy LP filters which help enormously but do add on exposure time. The idea of grabbing as much data as possible is to reduce noise in the final image.

So a Fstop of 3 actually will mean I need to square this and gather 9 times as much light for same image and hence I would 9x as many subs but baring in mind i would need 3x better guidence and LP protection measures

If by Fstop you mean focal ratio (sorry, I'm not a photographer. All I know about the technical side is through astro imaging) then my understanding is you square it if you're making comparisons. The way I look at it is that it takes a f5 scope 25 minutes to get the same data as it takes 49 minutes for an f7 scope, so the f5 is twice as fast. Again, I'm no photographer so I've probably got this wrong.

So if you had the time and patience and of course enough clear skies you could take these larger images (more magnification). Of course skies in UK generally stop this.

Sort of. The atmopsheric conditions affect more the level of detail rather than exposure time (although it does to an extent). If you really want to image at long focal lengths, buy a big SCT or Mak-Cass and use a reducer. Much more sensible than using a huge Newt.

However, my theory goes, if this large 300m scope is setup and I focus on 1 object for the next 20 times imaging, then I should get the subs needed. Now this would be boring to do. So I would use the ED's for normal imaging... Ah but then I would need 2 mounts for 2 different objects... QED

Boring it maybe but if you want to get really nice images, you have to get the exposure time in. My current exposure time 'record' is 6 hours on M81 & 82 with an f6 scope and I still wasn't overly happy with the result. Unfortunately, time and a bit of patience is necessary.

Either that or I go for the Mil approach and make a 4 way scope that looks like a AA gun on a cruiser

Indeed. The way I see Arthur's setup is you have 4 cameras each doing the L, R, G & B all at the same time therefore saving time.

Tony..

[Catanonia]

If you really want to image at long focal lengths, buy a big SCT or Mak-Cass and use a reducer. Much more sensible than using a huge Newt.

Tony..

mmmm, ok why would this work ?? Is it because of the reduced focal length, but big mirror. What type would you suggest, link, name ?

I don't know much about SCT scopes so a bit new.

Thanks for your patience, the way I work, ask and ask and then use the advice so as not to throw money away

[FLO]

.... ask and ask and then use the advice so as not to throw money away

Then get your existing saddle/dovetail situation sorted.

You aren't going to be happy if both your scopes drop onto the patio. Seriously, it wouldn't be funny

[Catanonia]

Then get your existing saddle/dovetail situation sorted.

You aren't going to be happy if both your scopes drop onto the patio. Seriously, it wouldn't be funny

Point taken already and looking into it now. I am surprised that Peter at OpticStar didn't mention it when I bought the new ED120 and NEQ6 off him at the time. I spent well over an hour discussing everything with him.

I will double check and take some photos to see exactly what my mount plate is. I am more than likely wrong saying it is the other type, but need to check. Peter surely would have said something.

Actually come to think of it, I didn't use the mount plate that came with the NEQ6, just used the one already on the ED120... Naturally in newbie state assumed they were the same... mmm, need to check.

[FLO]

Actually come to think of it, I didn't use the mount plate that came with the NEQ6, just used the one already on the ED120... Naturally in newbie state assumed they were the same... mmm, need to check.

Aaaah, there's your answer

[beamish]

well this thread has certainly had it's moments !

[Whippy]

mmmm, ok why would this work ?? Is it because of the reduced focal length, but big mirror. What type would you suggest, link, name ?

I don't know much about SCT scopes so a bit new.

Thanks for your patience, the way I work, ask and ask and then use the advice so as not to throw money away

SCT is short for Schmidt Cassegrain Telescope. SCT's fold the lightpath up inside the scope so you get a long focal length scope (typically f10) in a short scope. As it stands normally, f10 is a little slow for imaging but using a reducer makes the scope much quicker. Another point is you can also use an off-axis guider to help with the weight and flexture issues. There's a few members using SCT's this way.

Here's a 9.25" SCT: Optical Tube Assemblies - Celestron C9.25 XLT Optical Tube Assembly

And the reducer: Reducers/Flatteners - Celestron f6.3 Focal Reducer

That scope plus the reducer will give you a focal length almost the same as the Newtonian and without half the hassle but I'll reiterate what I said in an earlier post, stick with what you've got for now, master what you have and then think about changing stuff about, you're only going to make life difficult for yourself.

Tony..

[Catanonia]

SCT is short for Schmidt Cassegrain Telescope. SCT's fold the lightpath up inside the scope so you get a long focal length scope (typically f10) in a short scope. As it stands normally, f10 is a little slow for imaging but using a reducer makes the scope much quicker. Another point is you can also use an off-axis guider to help with the weight and flexture issues. There's a few members using SCT's this way.

Here's a 9.25" SCT: Optical Tube Assemblies - Celestron C9.25 XLT Optical Tube Assembly

And the reducer: Reducers/Flatteners - Celestron f6.3 Focal Reducer

That scope plus the reducer will give you a focal length almost the same as the Newtonian and without half the hassle but I'll reiterate what I said in an earlier post, stick with what you've got for now, master what you have and then think about changing stuff about, you're only going to make life difficult for yourself.

Tony..

Many thanks mate. I am looking around Christmas time as an idea for the missus to get me a pressie At my rate I will have bid on the hubble and built a platform for it in the garden by then

I checked the mount plate and the one on the ED120 is exactly the same as the one shipped with the NEQ6 Pro mount, just about 2/3rds the length. Therefore logic would assume if this type was shipped with the NEQ I got, then it must be correct ?

Trying to find a picture of it on the web, but struggling.

Edit :

A bit of browsing and the mount plate of Skywatcher is the same as a Vixen and CG5 type according to that SCT Celestron site. The mount plate supplied with my NEQ6 Pro is the same as the one supplied with my SW ED120 one. Are the NEQ's branded by SW to have thier plates ? It all seems very secure with the 2 locking nuts and has never budged one mm

[FLO]

Which picture most closely resembles your dovetails?

[MartinB]

So many threads within a thread, I'm dizzy! Going back to the start, if you can manage to hoik that scope onto your mount consistently without it falling off you will be doing well. I struggle with a 10" SCT.

Having got everything mounted your problems will begin, they come down to weight, windage and leverage.

The rating of 25kg is meaningless. The mount is a clone of the Tak EM200 which is rated by Tak at 16kg. Now an EM 200 is definitely able to carry as much as an NEQ6.

Weight - you can balance everything out with counterweights but pressure is being applied to the gear and the more the mass of the set up the greater the inertia. The motors and gears are designed for the size of mount and the load it is likely to be carrying. Expecting those little motors speed up the scope then slow it down then speed it up every 2 or 3 seconds and to do it with the accuracy required for a 1500-2000mm f/l scope is unrealistic. Not such a problem for visual use.

Windage - that newt will catch every puff of wind. A modest little gust will put a few pounds of sideways pressure on the mount. By the time this is translated to the camera you image will be shaking around like jitterbug with a bad itch.

Leverage - weight isn't everything. Your heavy imaging gear will be stuck out a long way from the mount as will that heavy primary mirror at the other end. They will have a happy time playing see saw on your mount.

As for focal length, obviously with higher magnification it isn't just the focal length that is magnified, it's every little shake and tracking error so long focal lengths make great demands on the gear.

Are our conditions up to it, rarely for DSO work.

If your heart is set on it then go for it, don't let us killjoys spoil your fun but be aware of the problems.

[Catanonia]

Closest match is the 2nd picture

[FLO]

The second picture shows a Losmandy-type dovetail which would be correct for an NEQ6 mount. If the dovetail supplied with your 120ED is the same width then you have nothing to worry about

[Catanonia]

The second picture shows a Losmandy-type dovetail which would be correct for an NEQ6 mount. If the dovetail supplied with your 120ED is the same width then you have nothing to worry about

Excellent, was a bit worried then

[MartinB]

On a NEQ6 Pro mount.

I have heard the rule, always go 1/2 of the load spec of the mount for imaging, but no one gives reasons.

Do you want any further clarification after the points I made above? I put a bit of time into my post, it would be nice to have some acknowledgement as to whether you feel it made sense.

[Catanonia]

Do you want any further clarification after the points I made above? I put a bit of time into my post, it would be nice to have some acknowledgement as to whether you feel it made sense.

Apologies mate, didn't mean to offend, but I too got a bit lost in the thread.

Yes everything you say about loading the mount makes sense and I can understand the reasoning. I currently have my mount probably loaded to about 1/2 of its max load with the 2 ED's I have on it at the moment. I need to weigh them to be sure.

I think I will take the advice and not overload the mount any more as it seems to be fine at the moment with smooth tracking for 20 mins or more with guiding.

When I get a tube reflector, I will have to make do with swapping tubes over.

Thanks again.