EQ5 Pro SynScan vs HEQ5 SynTrek Pros and Cons

[stargazerlily]

Hi everyone,

The title of this post should be ... ARGH ... I can't decide what to do .... HELP!!!!

I'm mulling over what mount to buy and have narrowed it down to the two in the title. I currently have a SW 150PL and do a little bit of astro-imaging with a web cam. At some point in the future I would like to try out my Nikon D40 on planetary imaging and also some deep sky images.

At the moment, I only use the scope maybe 2-3 times a month, around quarter to half moon time. I'm not a serious, heavy user in other words. This is making me think that the HEQ5 might be a bit of an overkill. Another problem is that I'm not really sure how far down the astro-photography 'path' I want to go (e.g. do I want to get into auto-guilding etc. I don't know is the simple answer).

There appears to be a consensus that the HEQ5 is the mount of choice for imaging. From what I've read, the EQ5 Pro is also pretty good.

Please, please ... please could someone tell me the pros and cons of each of the mounts. Does anyone have a SW150PL - EQ5 Pro combination? Does it work ok ... any problems etc etc

I'm sorry this this has been covered elsewhere.

Many thanks

Pete

[Cornelius Varley]

The HEQ5 Pro is better, much better.

Peter

[JamesF]

The HEQ5 Pro is better, much better.

I may have misread, but I'm not sure Pete was asking about the HEQ5 Pro.

FLO's website lists an EQ5 Pro, HEQ5 Syntrek and HEQ5 Pro. The latter two appear to be the same apart from the handset. The EQ5 Pro looks to be more lightweight and, IIRC, the maximum quoted payload is about half that of the HEQ5 versions (9kg vs. 18kg?).

I believe Olly quotes a maximum actual load of half to one third of the rated load if you really want to do imaging. I can't find the weight of the 150PL OTA, but I suspect it's about 6kg. With the finder, camera, rings and so on you're going to be getting a bit marginal even on the rated load of the EQ5 Pro, especially when you consider that it's a longer scope and a fair chunk of the mass is some distance from the mount so the turning moment can be quite large.

I suspect that if you want to mostly use it for visual work, never take it out when there's a breeze and just want to drop a webcam in for the occasional bit of imaging then perhaps you'd get away with the EQ5 Pro. Otherwise, one of the HEQ5 variants would seem to be a better choice.

I've read elsewhere in the last few days (from another posting by Olly, I think) that it's very useful to have the Synscan handset if you have the HEQ5 because it helps with diagnostics if you have a problem guiding using a PC. Obviously that pushes the price up even further, but it's possible to buy the handset later and they occasionally come up second hand on AB&S or fleabay.

(I'm in the market for a new mount myself once I've scraped the money together. Can you tell?

James

[NickK]

HEQ5 Pro - the motors have a twice the accuracy and load ability than the basic EQ5 (according to the stepper motor information on the EQMOD pages).

SynScan - GOTO handset/Tracking/slew etc

SynTrek - Tracking/slew handset

Both SynTrek and SynScan mounts can be attached to a computer without the handset for EQMOD connectivity.

I was debating SynTrek vs SynScan for my NEQ6Pro purchase. In the end I went for the SynScan as it allows the option of GOTO if you don't have a laptop around (or don't want to carry it around for visual use).

My laptop died about 3 weeks ago and due to personal circumstances, it means I can't replace it for the short term - hence the SynScan is a lifesaver!

[JamesF]

I get the feeling it won't be useful because he's a fair way from you, but just in case, valleyman has a HEQ5 Pro Synscan on the for sale forum at the moment for pretty much the same price as a new HEQ5 Syntrek.

If I could justify spending the money before next month I'd have had his arm off already

James

[stargazerlily]

Brilliant replies .. thanks Pete, James and Nick.

James ... I can't see the For Sale section as I've not done my 50 posts. Where about is valleyman?

Nick ... when you say 'slew' is that where you move the scope into the general direction of the object? Can this be done manually (ie, unlocking the clutches and moving the scope by hand) as well as using the handset?

Cheers

Pete

[Gina]

Yes, I too decided the extra for the SynScan was worth the investment. Now I've got it I'm glad I did. I'm not yet ready for computer control and my experience of many years of computer use has told me NOT to rely on them. And there are other useful functions on the SynScan handset not on the SynTrek I gather.

[Parus major]

I'm in the same boat but I'm gettinig an NEQ6 next week.

For the record the 150PL with the stock finder is 5.8Kg.

[JamesF]

Where about is valleyman?

South Wales.

James

[Gina]

I should have said - it's the NEQ6 Pro SynScan that I bought.

[stargazerlily]

South Wales.

James

Anywhere near Cardiff???

Pete

[RogerTheDodger]

I'll pm the details to you Pete

[stargazerlily]

Thanks mate. Got the details.

Pete

[NickK]

Nick ... when you say 'slew' is that where you move the scope into the general direction of the object? Can this be done manually (ie, unlocking the clutches and moving the scope by hand) as well as using the handset?

From memory the mount detects the position by the feedback from the motor encoders. It doesn't detect the position of the mount body itself. This means if you undo the clutches and move the axes then mount handset/EQMOD will lose it's understanding of position.

Slew is just making the mount point to a different location by using the motors to move. You can set the rate of slew from just getting a small reposition to centre the object, to 8 or 9 times the speed when the mount moves quickly. Both SynScan and SynTrek have this ability.

Tracking is where the mount just turns the RA axis at a predefined rate. With correct Polar alignment this means the objects in the field of view appear to remain stationary. Both SynScan and SynTrek have this ability.

GOTO (SynScan) is simply control over slewing accurately to a target location. So once you have Polar aligned, a second alignment is required for the GOTO feature (it slews to a target and you then correct it's positioning, after a couple of targets it knows the corrections needed automatically). You can then use the pre-programmed objects (DSOs, Planets etc) or enter the RA/DEC locations for targets it doesn't know.

I've used the NEQ6Pro without power before - just undo the clutches and manually move the scope (you'll not have any tracking if you don't have power). Due to the way the axes move, you'll still want rough Polar alignment.

It's possible to just unlock move then lock with the mount still providing tracking through sidereal tracking movement. This means you can use it manually to star hop without using the controller to slew. You'll need some form of polar alignment or the tracking will be out and you'll need to make some corrections. Note - as soon as you undo the clutches and make a move without using the motors to slew, the mount will lose it's bearings and hence GOTO will need realignment (you could just do a single star align or align on a star you know using a goto to that star, unlock locate the star and then lock).

[RogerTheDodger]

I'm pretty sure there are no encoders in the HEQ 5/6.

[NickK]

I'm pretty sure there are no encoders in the HEQ 5/6.

True, although the encode implied by the stepper motor shaft - not a seperate encoder attached to the mount itself.

It's a mod I'd be tempted todo - weld 4" diameter disk to the mount axis with high accuracy encoders.. or possibly make my own Forked-EQ mount in future.

[RogerTheDodger]

Have a look at the note at the bottom of this page of the eqmod docs EQMOD ASCOM DRIVER [EQMOD] there is no feedback from the motors, just ring-counters to count the steps issued.

[NickK]

Ok, we're getting into detailed schematics which aren't really relevant for the OP... but...

A pulse counter will not track the motor shaft movement - true, if a pulse fails to turn the shaft then it will still be seen as 'movement' whereas an encoder would detect that - both still will not detect the multitude of error causes in the drive train that cause issues with the mount's actual pointing. Currently this is done with optical feed back by PEC as feedback mechanism.

The reason you see large geared discs on larger mounts are down to (a) accuracy of the manipulation - teeth, turns etc and ( an encoder attached on the high end mounts needs the radius to magnify the movement as you want a factor of ten to be accurate.

Given that a mount is usually only loaded at a fraction of it's stated visual payload capacity for AP, means that the chance of pulses resulting in a failure of movement is very very low (lower than the chance of error from the drive chain) - means you can imply that a pulse is as good as an encoder in this instance.

I hope that clears up my reasoning - however you're correct there's no distinct encoder providing positional feedback.

[stargazerlily]

Thanks Nick for your explanation of Tracking, Slewing and GoTo. Finally got my head around all the different terminology.

I'm a lot clearer now on the differences between the EQ5 Pro SynScan and the HEQ5 SynTrek mounts.

Many thanks

Pete

[RikM]

I tried my 150P out on an EQ5 a little while ago and felt that it didn't give me much of an upgrade from my current EQ3-2. HEQ5 is a different animal alltogether, really a much better mount.

[malc-c]

Even if the mounts had some form of digital encoders it wouldn't get over the issue of losing its place when the clutches are released, mainly as most encoders work when attached to part of the gearing, and to have one attached to the axis shaft would require something quite large to give the required resolution.

[stargazerlily]

I tried my 150P out on an EQ5 a little while ago and felt that it didn't give me much of an upgrade from my current EQ3-2. HEQ5 is a different animal alltogether, really a much better mount.

Thanks for this Rik. Was it because you felt the mount wasn't sturdy enough ... or something else?

TBH, I was thinking that the EQ5 might be 'similar' to a EQ3/2 mount based on ... well ... nothing really.

Pete

[NickK]

Even if the mounts had some form of digital encoders it wouldn't get over the issue of losing its place when the clutches are released, mainly as most encoders work when attached to part of the gearing, and to have one attached to the axis shaft would require something quite large to give the required resolution.

Yup, there are some high accuracy encoders (used by the likes of Bisque and AP) that offer large diameter rings to attach to large diameter shafts. It would be straight forward to utilise one of these on the large diameter seconds of the axis - for example if you look at the AP1200 the axes are supported by large circular plates - the outter diameter is perfect for such an encoder.

I should have been more specific in my previous statement - 'mount' ment to be the actual physical part of the mount axis. I'd weld large diameter metal circles directly onto the mount so as the axis turns a set of mouse sensors could be used to measure the movement of the mount. I bought a mouse to test this - a laser optical mouse that gives 5000 ticks/inch, although just using one at 4" (could have been 8") gives an accuracy of 40 arcseconds IIRC my calculations. Given a couple of spaced sensors the number of ticks per inch could be doubled or quadrupled although total cost of sensors increases though (£50 per mouse..). Ten sensors could get you to 4 arcseconds absolute position sensing but at a cost of £500- at which point it may be better looking at the cost of a high accuracy encoder..

I've been thinking ways to increase the sensitivity, perhaps using reflected beams to double the sensitivity.

Remembered that Renshaw do the encoders: http://www.renishaw.com/en/ultra-high-accuracy-rotary-angle-encoder-systems--6476

[RikM]

Thanks for this Rik. Was it because you felt the mount wasn't sturdy enough ... or something else?

TBH, I was thinking that the EQ5 might be 'similar' to a EQ3/2 mount based on ... well ... nothing really.

Pete

I use the EQ3-2 / 150P combo for DSO visual and unguided imaging. I use the same mount with a 127mm refractor for higher magnification lunar / planetary observing so I was looking for something that would be more stable for high magnification observing and with better tracking accuracy and higher load capacity for longer subs for unguided imaging. The EQ5 I borrowed gave me neither of those. It still took a while to settle when moved during observing and the tracking on 90sec subs was not even as good as I get with my current mount. I felt it would not give me £300 worth of an upgrade. It could always have been just that particular mount rather than the model generally, but the chap I borrowed it from knows which end of a scope to look through and I am confident it hadn't been mistreated.

I thought about going for an HEQ5 (standard version) but after discussing with the Mrs. (and NickK) decided not to compromise on the mount but to save for an NEQ6 with all the bells and whistles and autoguiding. That way it is only painful once and I really want 5 minute subs.

[ollypenrice]

Certainly one of the HEQ variants for imaging. That is a cert. The cheaper one is fine if you want to use EQmod and some love it. I'm sure it is great software and am absolutely not knocking it. BUT I like to have a handset because when we have problems (like last night!!) it is always at the PC end of things. GRRRR.....

But I may be in a minority here. I don't use our electric filterwheel much either because twice it has given me Device Not Recognized and while I am jackassing around rebooting and re-installing I am letting people down.

The mount is the number one bit of kit in any imaging system. Don't skimp on it.

Olly