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#51 alpal

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Posted 02 July 2013 - 12:41 AM

Hi alpal.

As a big admirer of the direct drive mounts of ASA and other European manufacturers, I have to say those should not be used in any comparison with Synta's/Sky-Watcher's EQ8.

The latter is for people unwilling or unable to invest the kind of capital required to possess a DDM-85 or similar, so criticising the EQ8 for not being a super high-end ASA, Astelco, or Planewave direct drive mount is more than a little unfair, in my opinion.

And at any rate the first reports are very positive from the growing number of EQ8 owners in Australia. It appears to be yet another bargain from Synta and will likely be as successful as its little brothers.


I agree & I can't wait to see some images & some FWHM values
that were obtained for long exposures.

#52 alpal

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Posted 02 July 2013 - 12:49 AM

I wouldn't say that it's not good. The resolution of the steppers seems to be more than adequate for precise gotos. At least it was fine on my old EQ6.
The absolute encoders are nice, however it is my understanding that if you want to shoot unguided you need to build a pointing model. That might be fine for those lucky ones that have a permanent setup. For the rest of us who have to travel to dark spots it seems that building a pointing model at the beginning of every session would be a waste of precious imaging time.
I can tell you that both my mounts have a guaranteed PE that is higher than what I read on this forum and each one of them cost at least about twice what the EQ8 costs plus they have a lower payload. I think that even without the Renishaw encoders The EQ8 looks pretty good.
I don't see a built in polarscope tho.



True but when they talked about encoders it was misleading -
I thought they meant a cut down version of a Renishaw encoder -
maybe not as accurate as a Renishaw but still a dual axis closed loop
control system based on optical encoders attached to the axes -
which it appears that it's not but to be honest -
I'm still not sure as the spec sheets really don't go into
that sort of technical detail.


Another thing:
I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)

The only reason I can think of is that the mount is not square -
not orthogonal.

I hope the EQ8 is a bit better in this regard?

#53 andysea

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Posted 02 July 2013 - 01:22 AM

Another thing:
I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)

The only reason I can think of is that the mount is not square -
not orthogonal.

I hope the EQ8 is a bit better in this regard?


That is quite peculiar. I have never heard of that. You might want to start a new thread about it. I'm sure a lot of people will chime in. Your assessment makes perfect sense tho. I've only had the Atlas/EQ6 for a few months and I never drift aligned it so I can't provide any useful feedback.

#54 alpal

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Posted 02 July 2013 - 01:30 AM

Hi Andy,
I don't think we need a new thread on it.
I would be interested to see what others have found & to see what the EQ8 does.

#55 rmollise

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Posted 02 July 2013 - 09:06 AM

Probably just for general pointing, and not used for tracking at all.


No "probably" about it. The encoders are there to let you move the OTA by hand without losing alignment.

#56 rmollise

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Posted 02 July 2013 - 09:09 AM

I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)


Something is wrong with your mount or with your procedure. I would guess your procedure, since there's little way for non-orthogonality to cause different polar alignments in different parts of the sky. All that would cause that would be for the RA axis itself to move. ;)

#57 rigel123

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Posted 02 July 2013 - 09:48 AM


I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)


Something is wrong with your mount or with your procedure. I would guess your procedure, since there's little way for non-orthogonality to cause different polar alignments in different parts of the sky. All that would cause that would be for the RA axis itself to move. ;)


I would agree with Rod here, I don't have that issue with my Atlas. Maybe a balance issue?

#58 telfish

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Posted 02 July 2013 - 01:32 PM

I wouldn't say that it's not good. The resolution of the steppers seems to be more than adequate for precise gotos. At least it was fine on my old EQ6.
The absolute encoders are nice, however it is my understanding that if you want to shoot unguided you need to build a pointing model. That might be fine for those lucky ones that have a permanent setup. For the rest of us who have to travel to dark spots it seems that building a pointing model at the beginning of every session would be a waste of precious imaging time.
I can tell you that both my mounts have a guaranteed PE that is higher than what I read on this forum and each one of them cost at least about twice what the EQ8 costs plus they have a lower payload. I think that even without the Renishaw encoders The EQ8 looks pretty good.
I don't see a built in polarscope tho.


The polar scope is a separate item supplied with the scope. It sits on it's own bracket and is not part of the central axis like the eq6 scope.

#59 alpal

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Posted 02 July 2013 - 05:53 PM


I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)


Something is wrong with your mount or with your procedure. I would guess your procedure, since there's little way for non-orthogonality to cause different polar alignments in different parts of the sky. All that would cause that would be for the RA axis itself to move. ;)


I would agree with Rod here, I don't have that issue with my Atlas. Maybe a balance issue?


Don't think so.
I am surprised that no one else has noticed this.

#60 Coastal

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Posted 02 July 2013 - 06:06 PM


I notice with my EQ6 that it can be polar aligned & drift aligned for one part of the sky
- then when I turn the mount to a different target -
say from North to South - that it's no longer drift aligned.
The stars will be moving across the frame where as they were stationary before.
(I do level the mount with a carpenters level)


Something is wrong with your mount or with your procedure. I would guess your procedure, since there's little way for non-orthogonality to cause different polar alignments in different parts of the sky. All that would cause that would be for the RA axis itself to move. ;)


I would agree with Rod here, I don't have that issue with my Atlas. Maybe a balance issue?


Don't think so.
I am surprised that no one else has noticed this.


The only time I've had a situation somewhat similar I was able to track it down to mirror shift on an old 10" Meade SCT.

#61 BPO

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Posted 02 July 2013 - 06:49 PM

Speaking of Meade and the EQ8, an Australian owner (Jonathon, on the iceinspace forum) just posted this video to You Tube demonstrating the grippiness of the clutches and the excellent damping of his EQ8 with 14" Meade LX200. (2,200mm fl.)

#62 alpal

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Posted 02 July 2013 - 09:48 PM

Good video.

I would still like to know more about those encoders.

#63 Per Frejvall

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Posted 02 July 2013 - 11:57 PM

If this baby delivers with guiding it will be a top product. The discussion about the encoders is correct; they have 1.2 arcmin of resolution and the rest of the accuracy comes from just counting stepper motor steps.

The payload and the price sets it in a class by itself, me thinks. It will be very interesting to see the AP performance!

/per

#64 alpal

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Posted 03 July 2013 - 12:21 AM

If this baby delivers with guiding it will be a top product. The discussion about the encoders is correct; they have 1.2 arcmin of resolution and the rest of the accuracy comes from just counting stepper motor steps.

The payload and the price sets it in a class by itself, me thinks. It will be very interesting to see the AP performance!

/per


Oh dear - I though I could buy one & get Renishaw encoders
just like an ASA mount for 1/4 of the cost.

I was only dreaming. :foreheadslap:

#65 rob288

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Posted 03 July 2013 - 05:03 AM

EQ8 mounts have arrived in New Zealand, just need to set up on permanent pier and test.

Attached Files



#66 alpal

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Posted 03 July 2013 - 05:10 AM

Great news - please post the imaging results.

#67 lafo0100

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Posted 03 July 2013 - 07:26 AM

Rob, I see that you've got the 2 counterweights right down to the bottom. Are they enough to balance your 12"? Looks like 3 or 4 weights will be needed depending on the users setup.

#68 rmollise

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Posted 03 July 2013 - 08:07 AM


Don't think so.
I am surprised that no one else has noticed this.


There's a reason for it: There's no way this will be the result of a non-orthogonal mount. It's your set up. Check that everything on your mount (like the tripod to head attachment) is secure. Make sure the latitude adjustment bolts are locked down. Check that the telescope or its mirror are not moving. Check that you are not moving or bumping the polar axis at some time.

#69 alpal

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Posted 03 July 2013 - 08:10 AM



Don't think so.
I am surprised that no one else has noticed this.


There's a reason for it: There's no way this will be the result of a non-orthogonal mount. It's your set up. Check that everything on your mount (like the tripod to head attachment) is secure. Make sure the latitude adjustment bolts are locked down. Check that the telescope or its mirror are not moving. Check that you are not moving or bumping the polar axis at some time.



I have checked all that.
I have always noticed this problem.

#70 rmollise

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Posted 03 July 2013 - 08:15 AM

Well, sorry about that. You might have an experienced amateur from your local club have a look at your mount.

#71 jrcrilly

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Posted 03 July 2013 - 08:22 AM



Don't think so.
I am surprised that no one else has noticed this.


There's a reason for it: There's no way this will be the result of a non-orthogonal mount.


Yup. Polar alignment is polar alignment. The RA axis doesn't know or care where the telescope is pointed - and isn't affected by moving the telescope unless something is wrong. If you get drift after moving the telescope then either the polar alignment is worse than you think or the RA axis is physically shifting due to some mechanical problem.

#72 alpal

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Posted 03 July 2013 - 08:51 AM

OK thanks guys - I thought what I was seeing was normal.

#73 pubquiz

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Posted 03 July 2013 - 09:31 AM

Am closely following all the EQ8 threads and results with great interest.

I was (still am ) desperately saving for a Mesu 200 as after doing lots of research here in the UK it seems the best reviewed (Olly Penrice's reviews of Yves's and Steve Richards review in Sky at night mag) and best bang for buck feature for feature.

However with weights and saddle it comes to £5274 which is well over twice the price of the EQ8 at £2465 without tripod.

Out of the 2 I prefer the friction drive and higher capacity of the Mesu 200 but am coming to the conclusion that the EQ8 will easily match my requirements and save me £2809!...that would get me a nice new refractor to put on it :)

Due date in the UK seems to Sept/Oct?

Tom

#74 Sunspot

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Posted 03 July 2013 - 09:36 AM

Must be getting blind in my old age...I can't find the price.

Paul

at that price it should wash dishes, fix the car, take out the trash, and cook too.........


I assume you haven't priced mounts with similar payload capacity recently. ;)



#75 ghataa

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Posted 03 July 2013 - 03:51 PM

The blindness must be contagious! I can't any reference to the price either!

George






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