GTD - Gemini vs MESU 200e vs Fast linear buying advice?

[RayD]

34 minutes ago, Zakalwe said:

The DDM85 is a £12k mount. For that I'd expect it to wake me in the morning with a cup of tea and a cooked breakfast! 😄

And without moaning about it!

[RayD]

31 minutes ago, Gorr_77 said:

Defo- and only from commercial point of view it is not possible to adjust production line and get to the mentioned precision, within price buget - i am sure they can, but it would be very marginal market. I wouldn't mind to see " a special edition" mount:  CEM 120 SLR  - let say, same how AMG is working with Merc...

The encoders would need to be changed for something with far higher precision, such as renishaw, and then you are getting in to serious money and serious mechanical precision to deal with it.  The encoders fitted are high definition, but only sufficiently so to provide an extremely low PE.

As quite rightly pointed out by @Zakalwe, guiding is pretty simple if done correctly and is definitely the way to go unless you have big bucks to spend on a mount (tens of thousands) as it takes in to account for what is actually going on, rather than what is theoretically going on.

Edited April 30, 2020 by RayD

[Gorr_77]

3 hours ago, Skipper Billy said:

If you planning to set up and break down every session juts be aware that the Mesu is heavy.  With the c/wshaft and cw weights mine is approaching 45kgs. 

 

Ufff- i have thought its 19kg+the wedge+shaft... = i see.... 

[Gorr_77]

1 hour ago, andrew s said:

There is no such thing as perfect polar alignment. The position of the refracted pole varies with where you are pointing in the sky. Without some form of model to compensate for this you will get drift.

The best you can do is aim for the mean refracted pole. 

Regards Andrew 

Don't get me wrong in here,

I respect everyone in here as all of you have a  vast knowledge about AP and happily willing to share with all , but,... Are we not getting too detail in here?

Sorry, what i am trying to say is: where do we stop? is there a limit? theoretically there is a line where guiding will make no difference to your pictures? 

Finding working platform it is very hard - i think that a friction drive it is possible to be build without NASA scientific research what that has been proofed,

Can worm drive can be developed more without encoders?, to see a difference? Astro P, SB ? 

 

 

[Gorr_77]

14 hours ago, Northernlight said:

I think the old rule applies - get the best you can afford. Of the mounts you listed I would get the mesu if I had the money.

 

I think that will happen.... but i will hang on there few more days - trying to evaluate everything... as you know it is a lot and in the end of day i didn't win this, and i do travel a lot - lakes, Peaks, Cornwall and Durham side... - i might have to get a trailer

I was fine with CEM60...

Positives - too many for all mounts, 

"Cons" (with everyone's help)  - remaining:

....and please don't hate me for this:

1. MESU  - 100kg load is not for AP- who tested? were you there?

i ve heard several times that is more - 65kg - but i wasn't there....( i will travel and do few tests after the Covid-19),

, also chopping off half the mount and attaching wedge to the leg, isn't really slimming, is it! - 200e

2. Gemini - no controller - open source - can be added - OneStep controller ?  not sure- someone 've said that with sky model -  will guide better than anything else - but i wasn't there... 

or any other controller - SITech 1/2?

30kg AP SWL - i wasn't there....

3. JTW - nobody knows anything - yet  

- did they abandon the Trident idea? and working now on something else?

4. ASA - no more smaller models only ASA100 and up - for me too big - and still too expensive for me 

[Skipper Billy]

Mesu - 75kgs for imaging.

http://www.modernastronomy.com/images/products/Sky_firstlightmesu.pdf

[Northernlight]

Gorr - General rule of thumb to safely calculate AP imaging loads is generally 3/4 of the stated payload, and as Skipper Billy has pointed out - it is rated at 75gk for imaging which will take pretty much most monster scope setups

[Gorr_77]

.... and more than i will ever use......:)

Lottery - def my own planetarium with few tickets for everyone ...:) 

[Gorr_77]

In the meantime, Would one of you be so kind as to forward a copy off S.Richards setup guide for Mesu and Sitech?.... i cannot find it anywhere....much appreciated.....

[tooth_dr]

31 minutes ago, Gorr_77 said:

In the meantime, Would one of you be so kind as to forward a copy off S.Richards setup guide for Mesu and Sitech?.... i cannot find it anywhere....much appreciated.....

I googled ‘mesu Steve Richards’ and it is the first result 👍🏼
https://stargazerslounge.com/applications/core/interface/file/attachment.php?id=235759

Edited April 30, 2020 by tooth_dr

[Gorr_77]

4 minutes ago, tooth_dr said:

I googled ‘mesu Steve Richards

hahahaha - sometimes i just make things to complicated....

Thanks

Greg

[andrew s]

2 hours ago, Gorr_77 said:

Don't get me wrong in here,

I respect everyone in here as all of you have a  vast knowledge about AP and happily willing to share with all , but,... Are we not getting too detail in here?

Sorry, what i am trying to say is: where do we stop? is there a limit? theoretically there is a line where guiding will make no difference to your pictures? 

Finding working platform it is very hard - i think that a friction drive it is possible to be build without NASA scientific research what that has been proofed,

Can worm drive can be developed more without encoders?, to see a difference? Astro P, SB ? 

 

 

No problem,  I will refrain from contributing to this thread further.

Regards Andrew 

[Gorr_77]

Hi Andrew,

Why not?  🙌

I am grateful that you are here, I dint have a go at anybody - sorry if you feel that way - i was only trying to ask, if there will be a time, when we could simply say to our self that: we don't need  better  or more equipment , would it make a difference if, let say MESU, had better encoders? i always find everybody's pictures better than mine...and blaming everything but myself....

Greg

[andrew s]

13 minutes ago, Gorr_77 said:

Hi Andrew,

Why not?  🙌

I am grateful that you are here, I dint have a go at anybody - sorry if you feel that way - i was only trying to ask, if there will be a time, when we could simply say to our self that: we don't need  better  or more equipment , would it make a difference if, let say MESU, had better encoders? i always find everybody's pictures better than mine...and blaming everything but myself....

Greg

Maybe I misunderstood you. My view is simple, if your equipment doesn't add to the FWHM of your stars beyond that determined by your local seeing then you can't  do better. 

I believe several mount/software technologies can do this, some with some without guiding. It does not matter to me which technology you chose if it works reliably and achieves the goal stated above. 

Regards Andrew

PS Unless you can afford pro level adaptive optics.

Edited April 30, 2020 by andrew s

[iapa]

5 hours ago, DaveS said:

I use an ASA DDM60 and am in the process of commissioning an ASA DDM85, and would never willingly go back to any form of guiding. In fact, to get either mount off me it would have to be prised from my cold dead hands.

You finally really did it. You maniacs! You blew it up!

[Gorr_77]

Thanks,

Regarding AO - as it helpling to straighten up  seeing distortions / light wave distortion -  would the cheap mirror (reflector) generate a problem with reading - affecting guiding?

[iapa]

3 hours ago, Gorr_77 said:

Don't get me wrong in here,

I respect everyone in here as all of you have a  vast knowledge about AP and happily willing to share with all , but,... Are we not getting too detail in here?

Sorry, what i am trying to say is: where do we stop? is there a limit? theoretically there is a line where guiding will make no difference to your pictures? 

Finding working platform it is very hard - i think that a friction drive it is possible to be build without NASA scientific research what that has been proofed,

Can worm drive can be developed more without encoders?, to see a difference? Astro P, SB ? 

 

 

As with anything, law of diminishing returns.

For example, long exposure images have less noise than short, but, you need to balance taking a 3600s exposure, with probability of having the throw it away because an aircraft flew through, versus 600 x 60 exposures and stack them.More noise in any image, bur as your stack them noise reduces.

Same with mounts, some will allow you to take these 60 images without guiding as their gearing is so accurate - at a cost.

Or, a, less expensive, mount with less precision, but that can still take your 60s images albeit with guiding.

As long as the cost for guiding is less than the difference between the cost of the two mounts - it's a cost saving for more or less the same result.

The bass principle I have seen expressed over past few years is determine your budget, and ad 10%.

Then get the best performing mount with in that budget, but allow for at least a 10% increase in payload - you will go for better OTA eventually, so, build that capacity in from the start.

HTH

 

 

[Gorr_77]

Hi HTH,

Done: Mesu and Gemini remaining 👍

JTW and ASA DD100 on the way out - too big! and monies (⊙_⊙;)

[DaveS]

2 hours ago, Northernlight said:

Gorr - General rule of thumb to safely calculate AP imaging loads is generally 3/4 of the stated payload, and as Skipper Billy has pointed out - it is rated at 75gk for imaging which will take pretty much most monster scope setups

ASA payloads are quoted for imaging as the ASA ecosystem is heavily skewed toward professional remote imaging. Visual is barely an afterthought.

But yes, ASA have gone off the scale unless you can find someone upgrading to the new DDM 100, and that's unlikely.

[Gorr_77]

6 hours ago, Zakalwe said:

Personally, I'd take the JTW vapourware off the list.

 

Off - it is

[Gorr_77]

Hi Dave S,

I was just about to email you  -  about if you know why ASA stopped making gear for - small people.... !!!

No focuser as well?

Greg

[Zakalwe]

22 minutes ago, Gorr_77 said:

Hi HTH,

Done: Mesu and Gemini remaining 👍

JTW and ASA DD100 on the way out - too big! and monies (⊙_⊙;)

If it was my decision, then I'd go for the Mesu as it is more of a "known" quantity. I was in a similar position when I was choosing my mount and I went through a similar thought process. I short-listed a Gemini, but decided on the Mesu as I couldn't find many user experiences of the Gemini.

[DaveS]

From speaking to Rupert Smith at Astrograph (The UK dealer / distributor) I think ASA were moving away from "small" mounts in general. There was a development of the DDM 60 called the DDM 60 Revolution, that had the computer in a box on the mount, for imaging on the go, but I think they ran into so many problems that they just gave up, and now are concentrating on the big stuff. Their projected DDM mounts go up to the DDM 500, with yes, you guessed it, 500 kg payload. the mind boggles.

ASA do a focuser, Here, but as expected, it ain't cheap!

Edited April 30, 2020 by DaveS

[Northernlight]

Yeah ASA i think is the best that money can buy if you've just robbed a bank, but the performance will the Stella due to the direct drive - but not usually in the grasp of the average working man.

So i think it's a dimple decision - How much imaging payload do you need ?  

If you're fine with 25kg - then get the Gemini E.Fric and save some money  -  If you need more than 25kg get the Mesu

I think the performance of the E.Fric and the Mesu will be extremly close  -  Granted you dont get any encoders with the E.Fric - but do you really need them ?  I turned mine off on my EQ8 as it was messing up the guiding and i just use plate solving all the time without any issues. I'm just not sure how the E.Fric handles the Home position. 

The most important thing about any mount is it's Stiffness and ability to track accurately with Low PE and no backlash.  - So i would pay serious consideration to the E.Fric.  Apparently  you can get a stepper controller for 180 Euro.

 

Rich.

 

[Gorr_77]

Hmm - i couldn't see on their website... Looks good !! i will open new post..

Thanks