Couple of shots from Monday night (M13 & M31)

The CCD is looking very superior to the DSLR and the fact that you DONT have to make long exposures is a real help for tracking, which is why I'm going to ditch the canon next year for DSOs.

Dave I would disagree to a point on that. There is no doubt that a dedicated CCD has it's upsides, TEC cooling being not least of them. However there are downsides to. Typically the chip sizes in CCDs are *MUCH* smaller than DSLR's Take the SAC-10 for example. I've seen Jed Glovers up close and the chip is really tiny this is gonna limit what you can do with it. Even my ATIK chip is of an order of magnitude smaller than the dslr.

Having used both the ATIK and the dslr for some time now, I can see a niche for both. Certainly the ATIK allows me to go much deeper much quicker. However for large nebula shots etc the only substitute for the dslr would be a large format CCD camera costing more than most can afford to shell out.

So in short I'd say go get the CCD camera but dont throw away your DSLR just yet!

If you have any doubt just check out some of the images here;

www.cloudynights.com/ubbthreads/showflat.../1035790/Main/398564

Is it possible to take just one shot after framing, and then reviewing it before carrying on? Then you'll know if you have your target correctly framed or not.

Thats pretty much how I do it.

The three star alignment (TSA) gives you goto, it DOES NOT polar align your mount.

oops. You're right of course. My bad.

polar scope alignment is way off

The Polar Scope should be aligned fine; I aligned and tested it during the day & if I move the scope while looking through the polarscope there is only a very tiny movement.

This is why the issue is so weird. It should track best when accurately aligned to Polaris, BUT, in my case a drift align always pushes Polaris away from the polarscope field of view. Incidentally, the same occurs if I just eyeball Polaris through the polarscope holder with the polarscope removed & at the end of a drift Polaris isn't anywhere to be seen.

I've done this before loads of times on a cheap EQ3 with no issue so there is something wrong in here.

It really looks like the mount is tracking slightly off axis, but I can't figure out why. Mechanically it should be sound.

BTW the Polar Align utility will alway cause the SCT to turn upside down with the counterweights pointing straight up towards the south. This is definitely a malfunction as that used not happen + it only gives about 1cm clearance from the tripod even with the diagonal removed.

Anyway, it's no biggy at the moment as the autoguiding is working. It has to work very hard though.

How long does the 'Calibration' take?

Most of the time I guess it's between 10 & 30 seconds. Sometimes it will hang & never get there. If it takes longer than a minute the gotos are even worse than normal as you mention, but it doesn't happen often.

I made the dd/mm/yy mistake a couple of times before after a factory reset & it does make gotos go way off. It's in american format at the moment though.

The CCD is looking very superior to the DSLR

That's for sure for suitable objects and a matched scope, but with the chip is tiny as DaveG mentioned so it really only is useful @ a very short focal length, e.g. the SCT would give me .56 arcsec/pixel @f6.3 which is way below optimum for seeing here. It wouldn't compete with the DSLR for wide field.

Cheers,

Trev

Trevor

it would be pretty much impossible to tell (without specialist equipment) that your polarscope is misaligned to the mount. The polar scope must be orthogonal to the RA axis. Presumably, since you have had good perfomance in the past, this is the case. That is what is so worrying and odd about Polaris being out of the field of view when you believe you are polar aligned.

When you say you tested the polascope alignment, how did you do that? And do you mean tested its alignment with respect to the mount?

Also, I'm not sure how your polarscope works, but the one I use has a centre point with a circle around it. The circle represents the movement of Polaris whilst the centre-point indicates the celestial north pole. So, when you look through my polarscope, Polaris is positioned on the circle. The circle would be positionaed about one third of the FOV from the centre point.

If your drift alignment is pushing Polaris away from the FOV I can only think that you are drift aligning incorrectly... If the polarscope is orthogonal to the mount, drift alignment will bring Polaris closer and closer to its correct motion arounf the celestial north pole...

Yopu must be really way off polar alignment if you can't even see Polaris through the RA bore!

This state of affairs will also have a significant impact on your GOTO's.

The upside down OTA is indicative of incorrect time/date and/or daylight saving corrections or possibly the way the mount is initialised.

In the case of the AP, it can be parked in one of three positions. When I resume from a parked position, if I insert incorrect time/date/daylight savings data to keypad, this is exactly the behaviour I can expect. I can also expect this behaviour if I have the mount's location set incorrectly.

Check the time and date, the mount location (your local co-ordinates) and daylight savings options plus time-zone.

Also, when you do a drift align, when you are pointing to a star in the East, make sure the OTA is on the West side of the mount (or the counterweight shaft is on the East side of the mount). If its on the East, your counterweight shaft will be pointing in the air!

As far as autoguiding goes, I hear what you say in that it corrects for these issues. But that's at the expense of making the mount motors and gears work serious overtime that they don;t need to. Conceivably, this will result in worn motors/gears/worms... And that's a biggy

Here's what I'd do in your shoes:

1. Check out the keypad settings. Ensure all dates/times/daylight savings are correct, allowing for non-EU date formats. Ensure your co-ordinates are accurate (Google Earth will get you close) and input them in the format the manual tells you to.

2. Do a manual polar align without the polar scope - get Polaris in the centre of the RA bore.

3. Insert the polar scope and see where Polar is - if its in the FOV, you're probably ok.

4. Do a drift align - if you need to make massive adjustments to the RA or DEC, you're not drift aligning properly - either choice of star or incorrect adjustments.

5. Do not use the polar align routine or three star align routine until you are successful with the above.

This must be driving you mad! But hopefully this will help you out.

By the way, in order to get the best out of your mount, and therefore your images, you really need to solve this issue. Relying on autoguiding I fear will be storing up trouble for the future.

Cheers

Dave

Hi Dave,

When installing the polarscope it's necessary to align it with the ra axis on this mount.

The best way to check the alignment of a Polarscope is to put the mount down to it's lowest altitude mark until you can view something distant through it, then releasing the RA clutch you can rotate the scope and counterweights.
Usually, when you have just installed the polarscope the target will move around due to the misalignment. Then it's possible to adjust the three setscrews on the polarscope holder to get rid of any movement.

Those were the steps I followed. Seems the exact same as I was used to with the EQ3 as per www.skywatchertelescope.net/Downloads/Polarscope.pdf

From you description of drift alignment I think it was done correctly, so I'm baffled. I think I'll give Astronomy Ireland a call and see what they think as I hadn't thought of the gears wearing down and you're right that really would be a biggy!!!

I forgot another symptom. Sometimes when I switch the mount on and place it at the index mounts it thinks it's at crazy co-ordinates rather than 90 degrees and 12 hours, e.g. the other day it thought it was at 97 degrees and 22 hours! Thinking more on this it sounds like a software problem as all of the date and regional settings are correclty entered.

All these problems started happening after a runaway slew a couple of months ago that caused the mount to crash into the tripod. In fact, the mount sometimes gets confused and will crash to a halt because it tries to slew beyond it's limit in one direction - another indication of a software problem.

Sound like getting onto Celestron & Astronomy Ireland again is the way to go.

Sorry, I must be driving ye crazy with all this :oops:

Thanks,

Trev

Sorry, I must be driving ye crazy with all this :oops:

Nah