Why and when would you adjust the autoguiding speed?

[Tim]

On my HEQ5 mount, on the synscan controller, it is possible to adjust the auto guide speed.

Default is set to 0.5X.

What is this speed, and what is it half of?

Why and when would you need it to be different?

My mother never told me ANY of this stuff. It's a wonder I've made it as far as I have in life with the limited instruction I recieved.

Sorry for all the questions, thanks for all the answers!!

TJ

[cygnusx1]

0.5x refers to sidereal rate.

Personally i wouldn't recommend changing it, 0.5x is sufficient for 99% of guide setups.

It is the rate at which the mount will move to correct for guide star position, too high and overcorrection qand chasing could result, too low and the mount may play catch up continuoysly.

Leave it at 0.5 unless you have good cause play with it.

[Kaptain Klevtsov]

An example where you would want to change it is doing autoguiding on a planet with a 4X Barlow on a 200mm f/10 'scope. The guiding is too much then and even a tiny guide pulse will chuck the planet off the chip.

Other than that, I'd leave it alone. You can set the guiding parameters in your guide software (or let PHD do it for you) so you don't need to change it.

Kaptain Klevtsov

[Astroman]

Another time you may need to change it is if you are imaging something very close to the horizon and have to take atmospheric refraction into account. This would only become a factor if it was something time sensitive, like an occultation or shadow transit or GRB or something. Otherwise, wait an hour and it'll be better. 8)

[Tim]

Right, those are the answers I was looking for.

Thanks very much

TJ

PS, KK, did you mean 2000mm scope? ? ?

[Kaptain Klevtsov]

The Tal, and C8 SCT are f/10 'scopes. This means that the aperture is 200mm, but the focal length is 2000mm. The Tal is better for high magnification than my 200mm Newt. because the focal length is double that of the Newt. If I were to use the Newt. for planet imaging, I'd need the 4X Barlow AND a 2X Barlow to get the same image scale. With the TAL its only the 4X one that's necessary, so its better.

Anyhoo, when the guide 'scope has a very long focal length, like in this case, anything to calm down the guiding helps. If the planet goes off by a few pixels, the last thing you want to do is fling a big correction pulse at the thing as it will fly off your screen very rapidly. Slowing down the guiding software and the guide speed is fairly necessary.

When I do planets, I guide using the imaging camera, as it will do both jobs if you talk nicely to K3CCD Tools. Saves having to stand and watch it while the beer is in the fridge staying cold.

HTH

Kaptain Klevtsov

[Tim]

Hmm, havent noticed that trick. I'd like to watch that in progress.

To be honest, the HEQ5 is pretty good at tracking the planets, even with all that weight on.

I use my C9.25 (2350mm) with a 2X + 3X barlow, and if the planet is near the zenith, the mount will keep it centre screen for many minutes. Even if it does start to wander, with the manual adjusting set to 0 speed, its easy to keep it central.

I havent tried k3ccd with my webcams yet, is it useful with them?

Cheers

TJ