10 & 12 " dobsonians, goto and tracking

[Flame Nebula]

Hi Everyone, 

Anyone used both of these? I'm thinking mainly about the goto and tracking ones, but also I'd be interested in people's experiences with non goto too. If I get one, it would be goto, as I never got on with a dobsonian (8") I had 35 years ago, and it was impossible, at least for me, to track planets at high mag. 

I'd be interested in knowing the following :

If you knew then what you know now, which one would you get, and why? 

This is an all encompassing question relating to handling, reliability(specifically relating to the goto and tracking platform), ease of use, any planetary AP success, and of course visual observation, particularly what have you seen easily in the 12" that you've failed in the 10". For the latter, I'm particularly interested in planets, splitting doubles, planetary nebulae, and orion nebula, but any of your comparisons would be interesting. 

Looking forward to this! 🙂

 

Thanks 

Mark

[Paz]

I've not had a Dob with built in goto or tracking but I do use an equatorial platform with my dobsonian for tracking sometimes.

I'll use it when viewing things at higher magnifications in the faster parts of the sky and it makes observing much easier amd more enjoyable and I'll see more because I can concentrate more.

However it is another contraption to manage so I don't use it unless the targets mean it is worthwhile.

If I was getting a dobsonian now I'd be content with just having a tracking facility.

Edited February 24 by Paz

[Mr Spock]

I had a goto Skywatcher Flextube which didn't work out. My current 12" Dob has an EQ platform which tracks perfectly.

[Saganite]

1 hour ago, Paz said:

I've not had a Dob with built in goto or tracking but I do use an equatorial platform with my dobsonian for tracking sometimes.

I'll use it when viewing things at higher magnifications in the faster parts of the sky and it makes observing much easier amd more enjoyable and I'll see more because I can concentrate more.

However it is another contraption to manage so I don't use it unless the targets mean it is worthwhile.

If I was getting a dobsonian now I'd be content with just having a tracking facility.

Hi Paz,

I had a tracking platform for a short while but sold it, because for me , it was just something else to 'faff' with and I felt it simply introduces another layer of  potential wobble.  This is just my view of course and others will no doubt disagree.

I use my 12" dob for deep sky and so low powers are adequate, and it suits me that way.  I have tracking on my ED152 and that telescope is quite adequate for deep sky and excels at Lunar ,planetary, and double stars.

Edited February 24 by Saganite

[AstroKeith]

My own view, is that the 'popular' Dobsonians have been cost engineered down too far. The mirrors are generally of good quality, but the mounts let them down. The non-Goto/tracking variants suffer from poor motion and altitude balance issues. The GoTo versions have drives that are borderline adequate, and often fail to perform. I've seen very few budget Dobsonians that can hold good collimation for a whole night. The solid tube versions are best, but again the mirror supports and focusers are 'basic'.

I even had to rebuke a popular vendor who tried to justify poor mounts by saying it was the optics that are important. What good are optics if you cant get a stable image.

The step up to a 'premium' Dobsonian comes with a significant increase in price and weight. A good solid basic Dobsonian on an EQ platform can be a good solution for some.

[Flame Nebula]

1 hour ago, Mr Spock said:

I had a goto Skywatcher Flextube which didn't work out. My current 12" Dob has an EQ platform which tracks perfectly.

Hi Mr Spock, is this your stellalyra 12"?Did the equatorial platform come built in? 

[Flame Nebula]

52 minutes ago, Saganite said:

Hi Paz,

I had a tracking platform for a short while but sold it, because for me , it was just something else to 'faff' with and I felt it simply introduces another layer of  potential wobble.  This is just my view of course and others will no doubt disagree.

I use my 12" dob for deep sky and so low powers are adequate, and it suits me that way.  I have tracking on my ED152 and that telescope is quite adequate for deep sky and excels at Lunar ,planetary, and double stars.

Hi Paz. Is that a skywatcher ed152? 

[Flame Nebula]

47 minutes ago, AstroKeith said:

My own view, is that the 'popular' Dobsonians have been cost engineered down too far. The mirrors are generally of good quality, but the mounts let them down. The non-Goto/tracking variants suffer from poor motion and altitude balance issues. The GoTo versions have drives that are borderline adequate, and often fail to perform. I've seen very few budget Dobsonians that can hold good collimation for a whole night. The solid tube versions are best, but again the mirror supports and focusers are 'basic'.

I even had to rebuke a popular vendor who tried to justify poor mounts by saying it was the optics that are important. What good are optics if you cant get a stable image.

The step up to a 'premium' Dobsonian comes with a significant increase in price and weight. A good solid basic Dobsonian on an EQ platform can be a good solution for some.

Hi Astrokeith, when you say equatorial platform, do you mean equatorial mount on tripod? Or the flat type that comes with goto dobs? 

[Saganite]

Hi Flame Nebula,

The post you have quoted is my reply to Paz.

My telescope is an APM ED152mm.......

Edited February 24 by Saganite

[Mr Spock]

13 minutes ago, Flame Nebula said:

Did the equatorial platform come built in? 

No, it was something I got used. I don't know who makes them now.

[AstroKeith]

5 hours ago, Flame Nebula said:

Hi Astrokeith, when you say equatorial platform, do you mean equatorial mount on tripod? Or the flat type that comes with goto dobs? 

Definitely not the first, and not quite the second! EQ platforms are the 'flat types' used under Dobsonians, but not goto's - they dont need one. EQ platforms are used with push-to dobsonians that dont have any drive at all. They provide about an hour of tracking before they need 'winding back' to start again.

[John]

I had a good UK made EQ platform which I used with my 12 inch dob for a while but eventually found that I preferred using the scope undriven and that the additional height that the EQ platform added just put the eyepiece a little higher than I wanted.

My 12 inch dob was based on an Orion Optics optical tube mounted on a bespoke plywood dob mount. I owned it for a decade and got loads of enjoyment from that scope on a wide range of targets. 

Posted a thread on the scope and EQ platform setup way back in 2013:

My 12" Orion Optics Dob with Equatorial Platform - Members Equipment Gallery - Stargazers Lounge

 

[Zermelo]

6 hours ago, Flame Nebula said:

when you say equatorial platform, do you mean equatorial mount on tripod?

 

Some nice DIY work here:

 

[Mr Spock]

38 minutes ago, John said:

I had a good UK made EQ platform which I used with my 12 inch dob

Oh, look what I've got 

Height is fine for me. Must be a different focal length.

[rl]

I've owned both 12" and 14" Dobs made by OOUK. Both have been excellent optically and the OO mounts have been expensive but well-made. They are possibly not the smoothest, but certainly smooth enough. The mount components are all milled from solid plate and would last a lifetime. The friction brake works well but needs the occasional adjustment. Personally I've had no problems tracking planets at *200 and above, but I use widefield eyepieces which helps. It's a bit more difficult with an orthoscopic in the focuser but not a showstopper.

Using a cats-perch astro chair helps a lot; you can adjust the height to suit the eyepiece and it's much easier sat down to concentrate on the planet and to tweak the scope's position. 

I've never tried a platform or go-to with a Dob. Something about it gets away from the beautiful simplicity of the Dob concept for me...

[John]

5 minutes ago, rl said:

....I've never tried a platform or go-to with a Dob. Something about it gets away from the beautiful simplicity of the Dob concept for me...

Yes, I came to that point of view as well.

 

[John]

6 minutes ago, Mr Spock said:

...Height is fine for me. Must be a different focal length.

My dob was F5.3. The base was designed to put the eyepiece at the height that I wanted - I prefer to stand while observing. The EQ platform added around 7.5cm to that which just put the eyepiece too high when observing objects high in the sky.

Otherwise it was an excellent EQ platform, sadly out of production now though.

 

[Flame Nebula]

40 minutes ago, Mr Spock said:

Oh, look what I've got 

Height is fine for me. Must be a different focal length.

Nice. 👍

[Stu]

44 minutes ago, John said:

The EQ platform added around 7.5cm to that which just put the eyepiece too high when observing objects high in the sky

Simples…..🤣

[Stu]

I often put my 8” f8 dob on an EQ platform, particularly for lunar or planetary sessions at high power. It is quite tall and spindly (hence his name, Basil…) and prone to wobbles because of the narrow base. I fitted a dual speed focuser (Moonlite) to help reduce vibrations but the EQ platform makes the biggest difference, giving long periods with no need to touch the scope. Generally the planets aren’t too high, so sitting on my Catsperch chair works well. At the zenith it is more of a challenge obviously but that is rarely needed.

It looks like mine is the same brand as Michael’s, which is WatchHouse, sadly not made any more. I believe Sumerian and TS make good ones, and it looks like FLO stock one too.

[Flame Nebula]

12 hours ago, Stu said:

I often put my 8” f8 dob on an EQ platform, particularly for lunar or planetary sessions at high power. It is quite tall and spindly (hence his name, Basil…) and prone to wobbles because of the narrow base. I fitted a dual speed focuser (Moonlite) to help reduce vibrations but the EQ platform makes the biggest difference, giving long periods with no need to touch the scope. Generally the planets aren’t too high, so sitting on my Catsperch chair works well. At the zenith it is more of a challenge obviously but that is rarely needed.

It looks like mine is the same brand as Michael’s, which is WatchHouse, sadly not made any more. I believe Sumerian and TS make good ones, and it looks like FLO stock one too.

Hi Stu, what kind of view do you get with the planets with the extra focal ratio, compared to say an F6? 

[Stu]

13 hours ago, Flame Nebula said:

Hi Stu, what kind of view do you get with the planets with the extra focal ratio, compared to say an F6? 

I honestly don’t know as I haven’t compared it with an f6, but theoretically the smaller central obstruction and 1/10th wave hilux mirror should give better contrast and detail.

These may be of interest. First a report I made after a really good session on Mars at opposition:

Secondly a review of a similar scope by Roger Vine:

http://www.scopeviews.co.uk/OrionOptics200Dob.htm
 

I often use mine on an EQ platform (as pictured in previous post) which alleviates some of the problems Roger identified with nudging and missing the moments of best seeing. I also have a dual speed Moonlite on it so focusing is much more accurate and with a lighter touch.

[Flame Nebula]

2 hours ago, Stu said:

I honestly don’t know as I haven’t compared it with an f6, but theoretically the smaller central obstruction and 1/10th wave hilux mirror should give better contrast and detail.

These may be of interest. First a report I made after a really good session on are at opposition:

Secondly a review of a similar scope by Roger Vine:

http://www.scopeviews.co.uk/OrionOptics200Dob.htm
 

I often use mine on an EQ platform (as pictured in previous post) which alleviates some of the problems Roger identified with nudging and missing the moments of best seeing. I also have a dual speed Moonlite on it so focusing is much more accurate and with a lighter touch.

I read Roger's review, with interest. One thought that came to mind. Do you think the az-eq6 in alt az mode could handle this in terms of stability AND avoiding the use of rotating rings? And could you look through the eyepiece without a ladder? 😀

Edited February 25 by Flame Nebula

[Stu]

29 minutes ago, Flame Nebula said:

I read Roger's review, with interest. One thought that came to mind. Do you think the az-eq6 in alt az mode could handle this in terms of stability AND avoiding the use of rotating rings? And could you look through the eyepiece without a ladder? 😀

I think the mount would cope with it, my concern would be whether the tube would flex too much a you still end up with vibrations. That could be alleviated by a couple of long Losmandy dovetails to space the tube rings out further along the tube I guess.

The eyepiece height can end up as a problem, but @Captain Scarlet (Magnus) uses a 12” of similar focal length on an AZ-EQ6 so may have some insight, particularly on eyepiece positioning. Magnus uses a CF tube which I’m sure helps with stiffness.

[Captain Scarlet]

Yes indeed I do mount my 12” on my az-eq6 in alt-az mode. As Stu says, my current set-up is a carbon fibre tube and all-in including rings eyepieces CC etc it comes to around 23kg. Before, I had a SW 300p with blue steel tube, that was 28kg! They were both fine on the mount. I’ve never had problems I might associate with being undermounted. It seems to tolerate being slightly out of balance very well. I’m strictly visual.

As for eye height, I use a Planet on its lowest setting, and anything above 50 degrees does need a step, I use a small set of 3 steps.

To mount it, I mount the rings/dovetail first, then place the tube into the rings, very easy, avoiding trying to place the dovetail into the mount “blind”. I have an ADM dovetail replacing the stock one.

@StuartT I believe also mounts his 300p on an az-eq6.

Cheers, Magnus

 

Edited February 25 by Captain Scarlet