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Author Topic: EQ8 Pro Review  (Read 4883 times)

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Online Nimbus

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EQ8 Pro Review
« on: 11:12:32, 22 September, 2015 »
Introduction

If you search the internet you will find a number of reviews about the EQ8 Pro mount some discussing in glowing terms how happy the owner is with the mount and other reviews which are less positive. Albeit the less positive reviews, in the main, appear to relate to those early mounts which had teething problems and which as far as I can understand have been ironed out in more recently manufactured mounts.
The perspective of this review is from the practical standpoint of ownership the good the bad and the ugly.  I do not intend to cover fairly obvious attributes easily researched elsewhere, but do feel there are practical considerations that I feel are noteworthy and worth sharing.

General Construction

Unlike the EQ6 this mount is far less streamlined in its construction with handles, adjusting jack-screw and various other protrusions and gaps into which cables and alike can easily snag particularly during a dark night with a set of untidy cables just waiting to catch you out.  While the mount is sold with the option to purchase the a polar scope the reality is you either need to buy the polar scope or attach a counter-balance weight to off-set the RA and DEC motors (both mounted close to each other on the same side of the mount) if you are operating the mount with a single scope or scopes piggy-backed on each other (as I do).  Although some owners have said dual mounting scopes eliminates the need for this counter-balance, I have not found a decent off-set of dual mounting scopes could be achieved easily, especially if the scopes being used are heavy and thus difficult to move with precision by sliding the Losmandy plates along the saddle.

Polar Alignment

Adjusting the mount for polar alignment is a fairly straightforward task.  However, the screw jack for altitude would have been better, in my opinion, if the thread were of a finer pitch allowing for a more precise adjustment.  However, the detachable adjustment handle does provide plenty of leverage, unlike the adjustment bolts on an EQ6.  The adjustment knobs for azimuth do not in my view provide for an easy grip and rotation when the mount is fully loaded.  Perhaps a redesign to include a hole through the handle head to allow a screw driver to act as a lever would have been helpful.  In my case I have resorted to using a pair of soft jawed plug pliers to rotate each knob when my fingers found them too difficult to rotate.  In terms of making adjustments to the mount for polar alignment, with respect to locking devices the 2 handles and 2 bolts for altitude and the 2 x M8 bolts either side of the mount base for azimuth - should only be slackened enough (absolute minimum) to allow an adjustment to either altitude or azimuth. The reason being that having got polar alignment spot on, my experience has shown that tightening these locking devices can shift the polar alignment slightly undoing  all that good work – frustrating! Therefore, the minimum you have to tighten these locking devices the better and try to do both sides of the mount together and evenly. That said these flaws do not prevent precise polar alignment and accurate alignment is otherwise straightforward.

Power Supply –Red Diode

Once set up and running with the power on the red diode should glow steadily and you will note from the manual that if the voltage is low the diode will flash and flash more quickly if the voltage is very low, potentially damaging the mount.  However, if you operate the mount in PEC+Sidereal tracking mode the diode will flash quickly in blocks of 3.  My mount has a dedicated 13.8v and 4 amp supply and the handset indicated the mount was receiving 13.8v. Noticing the correlation between the flashing diode and the PEC+Sidereal tracking mode, I concluded the two were connected and no low voltage issues actually existed. This was confirmed by another EQ8 owner on the EQ8 Yahoo forum.

Backlash

EQ8 Backlash is a topic that has been discussed on various forums particularly for DEC. There are a couple of helpful pdf files (with photos) available, which show owners how to strip down (earlier produced mounts) and adjust the backlash is both RA and DEC and I am sure I would not be alone in feeling a little daunted in undertaking these documented procedures. However, Skywatcher appear to have improved the mount through the addition of 3 bung style grub screws (which should be replaced with black short dome or cap-headed bolts to remove the risk of these grub screws falling into the mount head) which give access to the DEC gear meshing adjustment screws.  This modification makes the task of adjusting the DEC backlash a much more simple process, albeit care should be taken NOT to eliminate the backlash completely to allow for high spots in rotation.  I would recommend joining the EQ8 Yahoo user group to explore further research in this area.

Backlash Adjustments

In basic terms backlash appears most evident in DEC and RA backlash does not generally manifest its self in mount performance.  The addition of the 3 access holes to the adjustment screws is a real benefit, but adjustments must be done carefully to avoid damage to the mount.  There appear to be two approaches suggested:
•   Method One: An incremental closing of the backlash through adjusting each of the 3 adjustment screws in turn and the incremental checking for binding/sticking through the powered rotation of the DEC axis (preferably unloaded) to ensure a free 360 degrees of rotation.  This iterative process can take as little as 15 minutes, but in reality may take several attempts with ultimately live imaging/tracking/slewing providing the requisite feedback that things are improving if not resolved entirely. Personally, I spent less than one hour making these adjustments over two sessions. The outer screws should be tightened clockwise and the centre screw counter-clockwise to tighten.
•   Method Two: Unlock the DEC clutch and rotate the axis at full powered speed adjusting the 3 adjustment screws very carefully and slowly while listening for any change of tone/sound from the motor.  Once any change in sound is heard, STOP, and then back-off the adjustment slightly.  Reengage the clutch and perform a full 360 degree rotation of the DEC axis under power (NOT full speed).  Assuming no high-spots are found requiring a further release of the adjustment screws you should be good to go. (Note: I preferred to employ method one).
•   RA: If adjustment to the RA axis is required please refer to the other on-line resources in the EQ8 Yahoo forum as this require the mount to be disassembled and thus not easily described in the context of this document as I have no experience of making this adjustment.

GOTO, Guiding and Fine Slewing

In terms of GOTO and tracking performance the mount can perform to an exceptionally high standard particularly for this price range of mount and in comparison with mounts costing 2-3 as much, if not more.  My experience to date is that once properly polar aligned the mount can easily place the target on the central area of the chip of my 383L+ (with FSQ106).  Issues that I have experienced appear to have roots embedded in overly generous backlash, which needed tweaking to resolve fully. Specific issues included:
•   Fine slewing (centring on the chip) can work with great precision, but depending on which side of the chip the backlash appears to exist, the result will either not move the target (or very little) or place the target is slightly the wrong position. Once any backlash is removed I found it necessary to recalibrate the mount characteristics in Maxim DL and then use pinpoint to precisely slew the target to the centre of the chip or to return to a precise point from previous imaging sessions to continue imaging a target.  This resolved the problem.
•   Guiding can be exceptional (in Maxim DL5) with 5 second exposures the error rates have indicated X:0.00 and Y:0.00 for periods of 2-3 minutes with no corrections at all (infrequent corrections that are needed are usually on in the 0.01 to 0.03 range) and RMS errors typically 0.03 or better in RA and 0.04 in DEC.  (This compares with my EQ6 with RMS errors of 0.1/0.2 which I thought was good). However, this guiding performance was only typically this good West of the Meridian.  East of the Meridian the performance can be good, but equally had proven much less satisfactory (again backlash was suspected as being the chief culprit). Typical DEC error rates of 0.4+ have been experienced, but has been known to drift 1.0 to 2.0 thus spoiling images being captured.  Once the backlash was adjusted the error reduced and the mount now performs well both East and West of the Meridian. (e.g. Last night the Maxim DL guiding graph indicated RMS errors in X: 0.002 and Y: 0.001 during 900 second exposures).
•   Dithering is a technique I like to use and did use extensively with my EQ6.  Difficulties have been experienced following the minor slew on dither in my case the mount is commanded to slew 1 pixel, after which the guider should recenter the guidestar and continue guiding.  However, while the guiding in RA recovers quickly to recenter the guide star, DEC is much slower often lagging behind by up to a 1.0+ and often not recovering to recentre the guide star –again backlash appeared to be the issue here.  The solution here appeared to be to extend the Maxim DL guide calibration (Lodestar) from 15 seconds in X and Y axis to 20 and then 25 seconds which appears to have solved the problem. 

Tips

Other tips I would offer:

•   I do not always find the 3 locking handles that secure the Losmandy plate in the saddle easy to tighten, especially when my fingers are cold and the mount is covered in dew. However, try a 13/16” or perhaps 21mm double depth socket (single depth can work) attached to a suitable handle to grip each screw in turn –taking care not to over tighten.
•   Use pair of soft jawed plug pliers to turn the azimuth adjustment knobs taking care not to force the rotation or over tighten against the opposite bolt  ( I had thought of using a large socket perhaps 35-36mm, but I have neither tried it or am confident it would work).

Conclusion and Recommendations

Overall with the backlash issues aside this mount has the shown great promise and offers great value with a very decent load capacity. Had the backlash been properly adjusted prior to delivery I would have been delighted from the outset and much of this review would have gone undocumented. If you are thinking of purchasing a mount in this category then I can highly recommend the EQ8 Pro.  Recommendations to Skywatcher for production of future mounts can be listed as:
•   Ensure backlash is properly adjusted before the mount departs the factory.
•   Change the pitch of thread on the altitude adjuster to a finer pitch to allow more precise polar alignment.
•   Modify the azimuth adjustment bolt handles to include a hole through the handle to allow turning with a small lever such as a screwdriver.
•   Update the manual to indicate the power diode flashes (3 times) when PEC+Sidereal tracking is selected.


I hope you find the above useful and it helps with a purchase decision or mount ownership.  Jim
EQ8 Pro
TAK FSQ 106 EDX IV
ATIK 16200 Mono, Atik OAG, Atik EFW3 2" LRGB S2 8.0nm /Ha 3.5nm/O3 8.5nm, Baader Filters, Lodestar Guider, Focusmax4, Robofocus
Maxim DL6.13, CdC & Photoshop CS3E,

Offline ChrisLX200

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Re: EQ8 Pro Review
« Reply #1 on: 12:12:52, 22 September, 2015 »
Thanks for the review Jim, very interesting read!

ChrisH
Chris Heapy - current: 10-Micron GM2000HPS-II U/P, G11/Gemini, TV NP127is, Altair 8" RC, TV Genesis SDF, TV Pronto, SW Equinox 80ED, 10" LX200, 12" f/5.4 Newt, Vixen 90mm.
Atik 490EX, Atik EFW, Baader LRGB filters, Astrodon 3nM NB filters, Lodestar, QHY5L-II all-sky, Canon 70D and 350D
Whirley Obs., MPC Code Z89

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Re: EQ8 Pro Review
« Reply #2 on: 13:42:13, 22 September, 2015 »
No worries Chris, glad you found it interesting.  Regards Jim
EQ8 Pro
TAK FSQ 106 EDX IV
ATIK 16200 Mono, Atik OAG, Atik EFW3 2" LRGB S2 8.0nm /Ha 3.5nm/O3 8.5nm, Baader Filters, Lodestar Guider, Focusmax4, Robofocus
Maxim DL6.13, CdC & Photoshop CS3E,

Offline chris.bailey

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Re: EQ8 Pro Review
« Reply #3 on: 13:45:40, 22 September, 2015 »
Good review Jim. I had a play with one a while back (one of the early ones) and the backlash on that was terrible...nothing-nothing-nothing-shoot past but as you say it guided very well.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
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Re: EQ8 Pro Review
« Reply #4 on: 14:17:27, 22 September, 2015 »
Thanks Chris, I have no experience of the early mounts, I didn't even see one in the flesh until I got mine.  However, Ian King gave me some good advice, which guided my purchase decision over other mounts available in this price range. 

I think Skywatcher now have a good product and certainly at this stage I have no regrets plumping for the EQ8.

Regards Jim
EQ8 Pro
TAK FSQ 106 EDX IV
ATIK 16200 Mono, Atik OAG, Atik EFW3 2" LRGB S2 8.0nm /Ha 3.5nm/O3 8.5nm, Baader Filters, Lodestar Guider, Focusmax4, Robofocus
Maxim DL6.13, CdC & Photoshop CS3E,

Offline psjshep

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Re: EQ8 Pro Review
« Reply #5 on: 23:45:03, 22 September, 2015 »
Very good review - top notch...

I must get some opinions some time from our Astro society ex-chairman... I know he has had one for about 2 or 3 yrs now.. would be interesting to see his comments back-to-back on yours...

Phil
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Re: EQ8 Pro Review
« Reply #6 on: 07:06:50, 23 September, 2015 »
Thanks Phil regards Jim
EQ8 Pro
TAK FSQ 106 EDX IV
ATIK 16200 Mono, Atik OAG, Atik EFW3 2" LRGB S2 8.0nm /Ha 3.5nm/O3 8.5nm, Baader Filters, Lodestar Guider, Focusmax4, Robofocus
Maxim DL6.13, CdC & Photoshop CS3E,

Offline Eccoskies

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Re: EQ8 Pro Review
« Reply #7 on: 20:28:10, 23 September, 2015 »
Jim,

Excellent review, thanks!
There is nothing in there thay puts me off purchasing an EQ8 despite the niggles  :thumbup:

Cheers
Mark
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Online Nimbus

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Re: EQ8 Pro Review
« Reply #8 on: 20:35:30, 23 September, 2015 »
No worries Mark. Good luck with your future purchase. Jim
EQ8 Pro
TAK FSQ 106 EDX IV
ATIK 16200 Mono, Atik OAG, Atik EFW3 2" LRGB S2 8.0nm /Ha 3.5nm/O3 8.5nm, Baader Filters, Lodestar Guider, Focusmax4, Robofocus
Maxim DL6.13, CdC & Photoshop CS3E,

 

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