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Any success autoguiding an 8se?

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#1 Lord Beowulf

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Posted 22 November 2008 - 11:02 AM

Ok, I finally received my Orion ST-80 and StarShoot Autoguider and at the moment I'm pretty disappointed in the results I've been able to get so far. I do finally have it guiding, but the BEST results I obtained weren't any better than most of the unguided shots I've done to date. I've already been through a lot of the other topics here related to using the 8se with a wedge and/or tracking issues, including Don G.'s alginment thread, cuzimthedaughter's Sliding objects in my FOV, and my own balance efforts. However, I don't see much on actually using an autoguider with the 8se (or any wedge mounted SCT).

It took quite a bit of tweaking to even get to the point where PHD Guiding (provided as the tracking software for the StarShoot) would calibrate and track at all. I'd tried to get PHD to work previously using a cheap webcam and my own serial based ASCOM driver for the 8se HC/mount, but never obtained stable tracking (the sensor was way too small and the reaction time of the serial link was so-so). The 8se definitely won't guide properly without being in equatorial tracking mode. In alt-az, it appears to disable the tracking, causing the tracking star to drift out of field no matter what happens. That of course was a frustrating discovery when I originally tried to test things without having my wedge installed. Initially I'd assumed this was only an issue for the serial commands (it's mentioned in the documentation for the serial command set, which indicates that slewing below a certain speed should NOT affect tracking) but the autoguider port (connected through the StarShoot autoguider port) has the same problem. Unfortunately the location of the autoguider port on the 8se also means the cable prevents clearance of my Motofocus (which already barely cleared the base) when slewing to northern locations.

I was unable to get PHD to calibrate and guide properly at all until I turned up the autoguider slew rate in the 8se from 50% to 99% of the sidereal (maximum supported). While PHD appeared to be able to guide pretty well in R.A. (azimuth axis of the se), the excessive backlash in the elevation gears gave it fits in guiding declination. It took it forever to take up the backlash (the calibration detection in PHD didn't seem to handle that) so that by the time it recovered, it would typically overshoot the other way and then spend forever trying to undo the backlash. Then once the drift carried it out again, it was back to trying to take up the original backlash. It's apparent that I'm going to have to override the declination control to prevent it from oscillating like that.

I'm hoping that one of the many resourceful people here has a good set of parameters for PHD and the Celestron mount for the 8se that they could pass on to get me running a bit better. Any other suggestions for guiding software would be appreciated too. On the other hand I'd hate to learn that no one has been able to get the 8se to do what Celestron has indicated it should be able to do (by providing the autoguide port and wedge)! I know the spur gear design is not the ideal, but given what I've invested so far, I'm not ready to dump it to go for a good EQ mount. It'd be frustrating to waste the cost of the 8se mount too!

I'm including a pic of my current setup just to let everyone see where I'm at for the moment, although I'm expecting to change this again in another week or so!

Beo

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#2 mclewis1

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Posted 22 November 2008 - 11:42 AM

Beo,

I really admire your attempt ... but if I were in your shoes I'd consider taking a different approach. I'd sell some gear (wedge etc.) and buy a used CG-5A or similar GEM and use that for imaging with that nice C8/ST80 combo.

I think you'll spend a lot of valuable time trying to get your SE on a wedge to track and autoguide well, and even then the overall success will likely depend more on the characteristics of your particular SE than your skills in setting it up. I think that time could be better used imaging with the GEM.

#3 rick rian

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Posted 22 November 2008 - 11:50 AM

Beo,

I really admire your attempt ... but if I were in your shoes I'd consider taking a different approach. I'd sell some gear (wedge etc.) and buy a used CG-5A or similar GEM and use that for imaging with that nice C8/ST80 combo.

I think you'll spend a lot of valuable time trying to get your SE on a wedge to track and autoguide well, and even then the overall success will likely depend more on the characteristics of your particular SE than your skills in setting it up. I think that time could be better used imaging with the GEM.


I'm with Mark on this one too, Beo ... the NexStar 'one armed' mount can only do so much and visual observing with a few attachments seems to be it's "sweet spot". Kudos to you for doing what you've done, but I don't think you'll have a lot of luck with what you're attempting.

(I must say, your setup looks awesome, I only wish it were mechanically suited for your wants)

#4 Tel

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Posted 22 November 2008 - 12:02 PM

Hi Beo,

Sorry, but I agree wholeheartedly with Mark.

Although I never ventured into the realms of autoguiding, I tried many other conceivable ways to improve my long(er) exposure imaging with the my Nexstar 8i / DSI combination, (i.e. wedge mounting, off axis guider, flip mirror, drizzling, and various post capture field derotation software programs etc.) but finally came to the expensive conclusion that the mount's spur gearing with its inherent backlash is just not up to the task. As a result I invested in a HEQ5-Pro GEM. The difference in the two drive systems is incomparable and provides the ideal platform for more advanced imaging.

Best Regards,
Tel

#5 Lord Beowulf

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Posted 23 November 2008 - 01:04 AM

Yeah, I know the drive sucks for this application, but I'm not quite ready to admit defeat yet. It doesn't seem right for Celestron to be selling a wedge and providing a guide port on a scope that can't be guided! Not that I put it past them (or anyone else) to do so, but it would be interesting to see what they have to say about it.

The HEQ5 Pro looks pretty good, but if I DO go ahead and spring for a new mount, I'll probably try for the EQ6 Pro, so that I'll be guaranteed to be able to use it for a larger OTA in the future if I ever decide to upgrade. The only problem there is that it's a HEAVY son of a gun! Unfortunately it also appears that the Sky-Watcher mounts aren't sold here in the US (Orion has an OEM version of it). However, it looks like I can get it considerably cheaper from Canada than buying the Orion version, assuming they have the same accessories. Comparing these to some of the other units out there, though, I wonder how they can justify the excessive cost for those others!

Beo

#6 Tel

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Posted 23 November 2008 - 05:24 AM

Hi Beo,

I'm certainly all for pushing this one as far as it will go: it's only that my own long term struggle with this issue resulted in my conclusion that wedges, spur gears, CCD units and I, just didn't go together !

However, from what I have read, Don G., Reggie and your goodself have certainly solved some of the problems particularly attached to balance when wedge mounting the OTA which is a lot more than ever I achieved. Nevertheless, unless the inherent backlash in that spur gear drive can be overcome, I still hold the view that long exposure times are out.

I do hope someone proves me wrong but until then, I think a good GEM really is the only recourse; be it an HEQ5, HEQ6 or something similar.

I'd also be very interested to learn what Celestron have to say on the subject of wedge mounting but I guess we'd be lucky if we got a definitive answer !

Best regards,
Tel

#7 Midnight Dan

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Posted 23 November 2008 - 12:01 PM

Beo:

I'm looking into the same option of buying an Orion Sirius or HEQ5 Pro. The Atlas/HEQ6 Pro is too heavy for my old bones. In any case, where can you get it in Canada and for what price?

-Dan

#8 Pete GLA

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Posted 23 November 2008 - 03:08 PM

Beo:

I'm looking into the same option of buying an Orion Sirius or HEQ5 Pro. The Atlas/HEQ6 Pro is too heavy for my old bones. In any case, where can you get it in Canada and for what price?

-Dan


Hi Dan,

I don't know if there's an advantage in buying from Canada. When the Can $ was @ par with the US $, I ordered from Orion some products, and would you believe me that I would've paid the same regardless if FedEx'd to me or taking a 4 hour trip to Toronto and personally picking it up. So to me there was no advantage...

Anyways, right now at Efston's website, the HEQ-5 PRO is $1,200 Canadian. The HEQ-6 PRO is $1,641 Canadian.

Clear Skies Please...

Pete :praying:

#9 Pete GLA

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Posted 23 November 2008 - 10:29 PM

I may be out of line here, but speaking of the HEQ-5 PRO,
HOW LONG WOULD IT TAKE TO MASTER THE BASICS OF PROPERLY ALIGNING THE MOUNT TO TRUE NORTH? And once mastered, how long in minutes does it take to align the mount. I'm not including StarAlign the scope, just Align the mount to True North.

I've yet to own/use an equatorial mount, and as some of you speak highly of the HEQ-5 PRO over the CG-5...I'm looking at early spring for this to happen (I should've bought it a month ago, that's where the prices bottomed out).

The use of the equatorial mount would be as where I'd want to observe from rather than a permanent observing site, this is why the hesitation of acquiring one...

Thanks for reading

Clear Skies Please And Thank You,

Pete

#10 steveoid

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Posted 24 November 2008 - 04:30 AM

Pete, I use the HEQ5 pro and can get it up and running within 15-20 minutes, and this is while the tube is cooling down so there is no problem really. Just mark out on the lawn or floor where you observe and thats it. Steve

#11 Tel

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Posted 24 November 2008 - 05:02 AM

Hi Pete,

First and foremost, I'm not sure that an EQ mount provides any advantage at all over our standard Alt./Az. system if you merely use your 'scope for viewing rather than for imaging. In fact I would regard my HEQ5-Pro as no real advantage at all in this respect, mainly because of the sometimes awkward positions in which it places the OTA and additionally, it does take a significant while longer to set up (mine not being permanently sited). Once set up however, it does have a much superior driftless drive which is a real joy to use.

I don't know if you would intend moving yours (if you were to buy one), from one site to another so I can only explain my own set up. As I said, my HEQ5-Pro is not permanently sited but I do virtually use the same spot from which to use it.

To explain, the first thing I did, (and this may be a little OTT), was mark out a meridian line on my patio, (having allowed the sun to cast a shadow from a tall vertical pole at midday).

I then marked two other lines either side and parallel to my meridian line at a spaced distance between the two outer lines equal to that between two legs of the tripod. This allows me to place the "North" leg of the tripod on the meridian line and the other two on the parellel lines. This, in turn, also allows me to move the position of the tripod along the lines to vary my position on the patio should I require to do so.

Having established this permanent position for my mount, all I do is transport it, prior to each session, to the chosen spot, add which ever OTA I want to use, balance the axes with the counterweights and then use the built in polar 'scope to align on Polaris and hence bring the mount very close to the NCP. If I were to want even more accuracy, then the drift method of alignment is the next step but, being a very tedious process and the fact that my mount is not permanently sited, I find the use of the polar 'scope accurate enough for my purposes.

I hope this gives you a basic introduction to what's involved. It's not at all difficult and reasonably quick once you get used to it.

Best Regards,
Tel
BTW -- There is no Skyalign alignment option with the HEQ5-Pro, but then it's not on offer if your Nexstar is EQ wedge mounted. The HEQ5-Pro does however offer a three star, two star and one star align.

#12 Tel

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Posted 24 November 2008 - 06:37 AM

Hi Pete,

Here's a couple of links which may be of additional interest to you concerning the HEQ5 -Pro. The first is a review of the HEQ5 and HEQ6 Pros : the second, details on how to use the HEQ's polar 'scope to achieve good NCP alignment.

http://www.pulsar-op...dHeq5EQ6Pro.pdf

&

http://www.adur-astr...HEQ5/HEQ5-1.htm

(Excuse the title of the second link) ! :lol:

Hope this helps a little further,

Best regards,
Tel

#13 Pete GLA

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Posted 24 November 2008 - 11:53 AM

Hello Tel, Steve...

Thanks for the input and the sites directed to.

Tel,
This is just the predicament, equatorial mount would be mainly for imaging. Thanks to the Royal Astronomical Society of Canada, we have a permanent site open to its members and the general public to use...We also have a Celestron 14" on an equatorial mount completely computer controlled, with a dome at our disposal.

Like I said imaging is the main reason, and I would've to pick a spot at the RASC site and do what you have suggested...But I think I would still use the Alt/Azm mount over the equatorial mount without hesitation. :question:

Still, how often do I get a chance let alone the weather co-operating, to go out there and do some imaging (~ 6 times per year at most). I know once is enough, spend an entire night just imaging and it is worth buying the HEQ-5 PRO or any other equatorial mount. Like I said Early spring would be the time to really think about buying one.

It's raining here maybe changing to snow later on with ~ 3" of snow accumulation possible.

Thanks Again,

Clear Skies To The Rest Of Us...

Pete

#14 Lord Beowulf

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Posted 24 November 2008 - 12:23 PM

Actually, I found the EQ6 Pro at All-Star Telescopes for quite a bit less (about the same as the HEQ5/Sirius elsewhere) and only $100 more for the GPS option. While I am a bit worried about the extra weight, I really don't want to have to invest in another mount should I decide to upgrade to something larger than my 8" scope in the future! Now I just have to wait for them to get it in stock!

Beo

#15 Tel

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Posted 24 November 2008 - 01:40 PM

Hi Pete,

OK, thanks, I now understand where you are coming from on this in your intention to set up at the RASC site when that rare occasion for imaging presents itself !

It shouldn't give you any significant problem though.

If you can see Polaris you need only to make a rough alignment on it with a HEQ5-Pro and once you have it in your polar 'scope, merely refine it to bring the mount axis very close to the NCP. This should be good enough to give you reasonable unguided exposure times when imaging and you can always take the accuracy further by using the drift alignment procedure should you so wish.

Hope this helps,
Best Regards,
Tel

#16 Midnight Dan

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Posted 24 November 2008 - 01:42 PM

Thanks Beo!

Here's what it looks like to me for the Atlas/HEQ6 Pro (this is with shipping to my location near Rochester, NY):

All-Star Telescopes: $1205 USD + $104 shipping = $1309
Orion: $1499 + $0 shipping = $1499
SAVINGS = $190 --- pretty good!

for the Sirius/HeQ5 Pro:

All-Star Telescopes: $1071 USD + $98 shipping = $1169
Orion: $1199 + $0 shipping = $1199
SAVINGS = $30 --- marginal

The 6 does seem like a good deal, but since I'm going for the 5, I'll probably stick with Orion. Mostly just because it's a place I've done business with and they have good customer support. $30 savings isn't worth the risk of a company I've never dealt with.

If weight is not an issue for you, then you're right to go with the HEQ6. It has a 40 pound capacity vs. the HEQ5's 30 pounds. It's a significantly better mount.
-Dan

#17 Pete GLA

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Posted 24 November 2008 - 04:49 PM

Thanks Beo!

Here's what it looks like to me for the Atlas/HEQ6 Pro (this is with shipping to my location near Rochester, NY):

All-Star Telescopes: $1205 USD + $104 shipping = $1309
Orion: $1499 + $0 shipping = $1499
SAVINGS = $190 --- pretty good!

for the Sirius/HeQ5 Pro:

All-Star Telescopes: $1071 USD + $98 shipping = $1169
Orion: $1199 + $0 shipping = $1199
SAVINGS = $30 --- marginal

-Dan


Hi Dan,

Have you ever purchased a product that came from another country?

When I order from USA, Besides the S/H I MUST PAY brokerage and customs fees, :bawling:which I'ven't figured it out, but I'd guess that amounts to an additional 15%-25% on top of what I pay the company that I dealt with... :shocked:

Just a caution, heads-up!!!:getem:

Pete

#18 Pete GLA

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Posted 24 November 2008 - 05:05 PM

Hi Pete,

OK, thanks, I now understand where you are coming from on this in your intention to set up at the RASC site when that rare occasion for imaging presents itself !

It shouldn't give you any significant problem though.

If you can see Polaris you need only to make a rough alignment on it with a HEQ5-Pro and once you have it in your polar 'scope, merely refine it to bring the mount axis very close to the NCP. This should be good enough to give you reasonable unguided exposure times when imaging and you can always take the accuracy further by using the drift alignment procedure should you so wish.

Hope this helps,
Best Regards,
Tel


Hi Tel,

Yes, the info that you've provided would greatly save time and frustration in setting up at RASC's site or any other foreign site. :bow:

Hopefully, I'll try taking some Prime Focus and Piggy Back photos just for practise and curiosity.

Recently I purchased a Radial Guider and a Micro Guide IPC, no sense hiding them in the closet...

Best Regards,
Pete

#19 Midnight Dan

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Posted 24 November 2008 - 07:37 PM

Hi Pete:

>> Have you ever purchased a product that came from another country?

No, but I assumed there would be the potential for additional fees. That's why I'm sticking with Orion, especially since I'm aiming at the Sirius/HEQ5. The $30 savings isn't worth the hassle.

Thanks for the heads up!
-Dan

#20 Lord Beowulf

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Posted 24 November 2008 - 11:35 PM

Dan,

Yeah, for the difference in price, the EQ6 was easy to justify over the HEQ5. However, I went ahead and canceled my order after hearing about the new Celestron CGEM, which is believed to be the next generation of the EQ6! Given I think I'd rather have the NexStar type goto and that it's lighter, etc. I think I'll wait until it comes out and a few people can review it. The dealer I was talking to also indicated that Sky-Watcher has a new MEQ6 coming out that he thinks is their version of the CGEM. See this thread for more info.

Beo

#21 Lord Beowulf

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Posted 24 November 2008 - 11:38 PM

When I order from USA, Besides the S/H I MUST PAY brokerage and customs fees, :bawling:which I'ven't figured it out, but I'd guess that amounts to an additional 15%-25% on top of what I pay the company that I dealt with... :shocked:


Pete,

I don't think that should be an issue for buying from Canada to the US (NAFTA and all that) but I could be mistaken. I've only bought small $$ items from amazon.ca in the past.

Beo

#22 Midnight Dan

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Posted 25 November 2008 - 10:37 AM

Hi Beo:

>>Celestron CGEM ... NexStar type goto and that it's lighter

From what I can determine, it doesn't appear to be lighter. The total weight of each mount is about 75 pounds, but that includes the counterweights. Since the Celestron only includes a 17 pound CW and the HEQ 6 Pro include 22 pounds of CW, that means the mount part of the CGEM is a few pounds heavier.

Not that that's a big issue. I agree with you - if the weight was within my personal limits, I'd go with the CGEM over the HEQ 6.

-Dan

#23 Lord Beowulf

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Posted 25 November 2008 - 12:52 PM

Well last night I finally got some good clear skies and was able to try out my autoguider again and tweak some settings and lo and behold! PICTURES! With stars as DOTS instead of DASHES! Granted things aren't perfect and I'm sure a better mount will make all the difference, but after spending some time tweaking the settings on the 8se (backlash correction actually works pretty well for declination) and in PHD, as well as spending some time doing drift alignment (a pain with the wedge) I was able to get some really good two minute shots. My five minute shots still had a bit of problems, but I think a few more tweaks would help them as well. I think every so often PHD starts oscillating for a bit and then settles back down.

The pics below are a quick stack of twenty one-minute shots (no darks or flats applied) and the second is a single two-minute shot. Now I just have my work cut out for me to get the 300 10 MB raw images I took last night processed into something pretty!

Beo

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#24 skyler

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Posted 25 November 2008 - 01:01 PM

Thats a BIG improvement (Good Job) and bet there is more data in there to pull out if you play with it.

What ASA were you using on the D90?

S

#25 rick rian

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Posted 25 November 2008 - 01:43 PM

Way cool, Beo ... nicely done sir! :waytogo:


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