From: "milton_aupperle" <milton@outcastsoft.com>

Date: August 29, 2010 4:28:56 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: guiding last night...

Hi Mark;

After zeroing the internal backlash with the Hand Controller, I'm pretty sure your going to find out the mount is loose on the RA and probably Dec axis.

You can see if the mount is got slop just with your hand by rocking the scope gently back and forth on both axis. If you can feel the scope shifting, then you will have backlash.

To measure it visually, all you need to do is put a camera or an eyepiece on the scope (prime focus is best with the C 9.25 at 2350 mm), center it on a bright star and then use the hand controller Left / Right or Up / Down buttons. Press a button and count how long it takes for the object to start moving. Then release the button and see if it keeps moving after being released. The Reticule in Astro IIDC works really well for checking this.

If the mount is perfectly in synch with no backlash it starts when you press and stops when you release, no delay at all. If there is any delay in either case, then you have backlash.

I've also done that test in daylight if you have a distant object say 500 m to 1+ kilometers away. You just turn of the sidereal tracking and move the scope with the hand controller. Things should stop / starts immediately - just as I described before.

HTH..

PS: Also check to make sure that Periodic Error correction is not being performed and is off by default.

Milton Aupperle

--- In Astro_IIDC@yahoogroups.com, Mark Gaffney <markgaffney@...> wrote:

Milton,

Attached is the backlash adjustment section from my Manual (It`s for a  

C9.25 SGT scope, which mine is effectively with the C9.25 OTA & CG-5  

mount..)

I`ll try tomorrow, weather permitting to set these backlash settings  

to zero as you suggest..

As for testing whether this has any effect we`ll see..

Mark.

On 30/08/2010, at 3:44 AM, milton_aupperle wrote:

Mark;

--- In Astro_IIDC@yahoogroups.com, Mark Gaffney <markgaffney@>  

wrote:

Milton,

Some of those fluctuations in the guiding graph may be accounted for

by my turning on the desklamp I have at the site so I can add  

items to

& from the scope without balancing a torch in one hand.

I seriously doubt that has any affect unless the light is pointing  

in the guide scope.

The

callibrations were done in the dark though (I`m pretty sure..?).

Would the settings you described for your 1100 mm FL (with an f6.3

reducer I presume) be OK..i.e. 7 seconds for start time & min

distances of 25 for RA & 20 for Dec..? Or should I be trying  

something

a little different?

I can tell you all the settings in the world mark, but it will not  

make a bit of difference. You have mechanical issues with the mount  

and nothing will fix that until you resolve them.

You`ve got to realise I`m yet to familiarise myself with the

significance of the figures in the log..! These pixel distances  

etc.,

measurements, I take it are how far Astro IIDC is moving the mount

when guiding..

Read the previous message I sent about the Log results wher eI  

describe in detail what they measn.

I may try to adjust the backlash settings on the HC & mount using

power from my battery tank (it`s not much chop running for long  

times

though, especially running just a dew strap which I usually use it

for)..

My readings for the FL etc. of the Kwiq & the Scorpion combination,

seem to tally with yours..as far as I can see..?!

Why not read what I wrote and think about it. Both the last message  

and the other one described in detail how to interpret the  

calibration log and what it is telling you.

Your ignoring the actual problem that your mount is mechanically out  

of whack. Until you solve that problem, which is screwing up not  

only the guiding but your GOTO repeatability, your wasting your time  

imaging DSO's.

Best of luck..

Milton Aupperle