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First light with EQ3 Pro guided - it is possible!

Welrod50

By Welrod50
in Imaging - Deep Sky

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Welrod50

Welrod50

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All,

Ventured out last night for the first time to try my shiny new Orion Starshoot autoguide scope/camera. Started at 23:00hrs and finished at 03:00 today.

Rig as follows:

EQ3 Pro with calibrated/adjusted polar scope and spot-on polar alignment.

SW130 PDS, correctly balanced. Whole OTA/DSLR/Guide rig weighs exactly 5.5kg all in.

Orion 50mm guidescope and Starshoot guide cam through PHD on laptop ( guidescope slightly defocused to bloom stars a little).

Unmodded Pentax Kr.

Did three star align first, slewed to M51, PHD took about 10 minutes to calibrate itself, then off and guiding first time no mither. I never touched it after that and it guided faultlessly all night. I've imaged before unguided with maximum of 1 minute subs and then with a 50% loss due to tracking error.

I know it's early days yet, but a very promising start. I have read that EQ3 isn't the best for autoguiding, albeit I have seen a few folks who've successfully done it on Astrobin. I therefore went out ready to be frustrated, but have spent a lot of time adjusting the polarscope and balancing the OTA on the mount and after the solid polar align, gave the guide camera the best foundations to work with and it did work very well. I'm chuffed!

Lots more to do and more/longer subs to try now, but for a first attempt last night I'm very happy. M51 with Kr at iso 1600, via PK Tether through laptop. Took x10 300 sec subs with long cool down times between each one. No darks, flats,offset (yet) stacked with DSS and finished with PS Elements 8.

C & C most welcome :)

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Welrod50

Welrod50

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And just ordered a Baader MPCC coma corrector which should deal with that obvious coma. Hopefully with the weather this week, it should arrive and be set up for next outing where I intend to try some longer subs. Anyone know if a coma corrector will interfere with my initial star focus with the Bahtinov?? I can't see how it would, but will the optical path be altered at all dead centre? Still chuffed with the EQ3 guiding :hello2:

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alpal

alpal

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Good first result.

PHD guiding should not take 10 minutes to calibrate - something is wrong -

it normally takes only 20 seconds on my EQ6 -

maybe you have too much backlash in your mount? -

which can be adjusted out on the EQ6 but I don't know about the EQ3.

cheers

Allan

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Welrod50

Welrod50

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Mmmm maybe, although it says in the instructions for the autoguider that it can take up to 15 minutes to calibrate with PHD, so I thought it was pretty quick! Probably does have some backlash compared to yours and the stepper motor resolution is also half that of your mount. I could do a PEC training but with the results I got I'm not sure I will bother. To be fair, it could take 20 minutes to start guiding and I would still be happy, as it never missed a beat all night thereafter. :smiley:

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malc-c

malc-c

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Alan, I think Scott is using the stock finder as a guidescope, which due to the short focal length may take longer to register the movement of the guide star, hence the longer calibration run.

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badgerchap

badgerchap

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Mmmm maybe, although it says in the instructions for the autoguider that it can take up to 15 minutes to calibrate with PHD, so I thought it was pretty quick! Probably does have some backlash compared to yours and the stepper motor resolution is also half that of your mount. I could do a PEC training but with the results I got I'm not sure I will bother. To be fair, it could take 20 minutes to start guiding and I would still be happy, as it never missed a beat all night thereafter. :smiley:

To be fair, if it ain't broke, don't fix it! I do concur though, 10 mins does seem a lot. When I was using the EQ5 with guideport mod, it was only taking a minute at most to calibrate. But like you say, it works, so it works!

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Welrod50

Welrod50

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Alan, I think Scott is using the stock finder as a guidescope, which due to the short focal length may take longer to register the movement of the guide star, hence the longer calibration run.

Not using a finderscope - I purchased the Orion Mini Guider package from IAS last weekend, so the guidescope is the Orion 50mm mini guide scope. Although it is a similar size to a large finderscope I suppose. The camera gain was set to 95% with 2 second exposure and I used a brighter guide star although there were quite a few visible on the screen. This was a first test run and I would've been happy with getting the guider all set up and the mount tracking accurately. The fact I was then able to then capture some subs was the icing on the cake! ;)
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Richie092

Richie092

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You might need to increase the calibrattion step value in phd as your using a short fl guidescope try somewhere around 1500-2000..

Peter...

Sent from my GT-P7300 using Tapatalk HD

Might try that too. I'm using finder guider and PHD also takes between 5 and 10 mins to calibrate but once up and running is faultless.

Doesn't look like there will be much opportunity this week though!

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Welrod50

Welrod50

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Cheers for that, I will have a look at the calibration step value next off. To be quite honest I am not too bothered by how long it took, as long as it tracks and the mount plays ball that's all that matters. I set the guide speed to 50x also to lessen the aggressiveness of the adjustments due to the limitations of the EQ3. All in all, my meticulous preparations seem to have paid off. The OTA/camera assembly is also perhaps a tad overweight, but it is balanced perfectly and given the tracking accuracy all night, I can't see why I couldn't go for longer subs. I think the limiting factor now might be the camera and sensor noise! Thanks for the input! All advice/observations most welcome!! :)

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Gonzo

Gonzo

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Quite a few members have great success with the EQ3 :)

If you stay well within the maximum payload, do take care of the backlash and a very good polar alignement, I don't see why you couldn't use this mount and take great pictures.

After all, myself and Themos use a modded auto-guided EQ1.... with good results ;)

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alpal

alpal

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Quite a few members have great success with the EQ3 :)

If you stay well within the maximum payload, do take care of the backlash and a very good polar alignement, I don't see why you couldn't use this mount and take great pictures.

After all, myself and Themos use a modded auto-guided EQ1.... with good results ;)

So you can adjust the backlash - just like the EQ6?

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Welrod50

Welrod50

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Thanks guys. Of note, you can also adjust the backlash settings on the handset, although I haven't played with my settings as it all seems to be pretty smooth so far.

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alpal

alpal

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Hi Scott,

looking at those 3 links above - it would be worth adjusting your mount for mechanical backlash.

It made a huge difference on my EQ6.

It was unusable as delivered new from the factory until an expert adjusted it - now it's great.

He used a 2 meter long bar attached to the head & actually measured the backlash before & after.

Luckily there was an expert in Melbourne Australia but there should be someone in the UK? -

if you don't want to take the risk of doing it yourself.

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Gonzo

Gonzo

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Hi Scott,

looking at those 3 links above - it would be worth adjusting your mount for mechanical backlash.

It made a huge difference on my EQ6.

It was unusable as delivered new from the factory until an expert adjusted it - now it's great.

He used a 2 meter long bar attached to the head & actually measured the backlash before & after.

Luckily there was an expert in Melbourne Australia but there should be someone in the UK? -

if you don't want to take the risk of doing it yourself.

How was it done exactly? Do you remember?

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alpal

alpal

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How was it done exactly? Do you remember?

No - I wasn't there but I was told that he used a simple cigarette paper placed between

the worm gear & the drive gear. He adjusted it until the paper jammed & then backed it off till

he could just slip the paper out.

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