Orion SSAG and PHD - can these settings be improved??

[Welrod50]

All,

Having posted a couple of weeks back about my relative success autoguiding my EQ3 pro, I am now looking for some advice to see if I can stretch my 5 minute subs out any further.

I always polar align accurately each time and set up the SSAG the same way. I can consistently obtain 300 sec subs, but much more begins to show evidence of trailing - not much admittedly, but it is visible. I will list here my kit and PHD settings and if anyone can suggest any tweaks, I'm eagerly waiting to try them before the rain comes back again

Thanks in advance!!!

OK, here it all is :

SW 130 PDS f650 mounted on EQ3pro (collimated and polar scope centred accurately, mounted ever so slightly East heavy)

Mount tracking in Sidereal only at 1.0x rate (I found 0.50x default to give slight trailing)

3 star align and no PEC correction (Orion instructions suggest this is not required)

Laptop running Windows XP Pro (SP3)

SSAG camera through Orion 50mm autoguide scope (f160 ish)

PHD settings:

RA Aggressiveness = 85 Dec Guide mode= Auto

RA Hysteresis = 10 Dec Algorithm = Resist switching

Max RA Duration = 1000ms Dec slope weight = 5.00

Search region pixels= 15 Max Dec duration = 150ms

Min motion pixels= 0.15 Star mass tolerance= 0.50

Calibration steps = 750ms Noise Reduction = Off

Time lapse = 0ms Camera gain = 95%

Force calibration ticked - all else unticked.

To be honest, to be able to guide for 5 minutes consistently now is a real achievement, but I am greedy and to be able to capture 10 minutes subs would be the icing on the cake. I cannot fathom how, if it will track spot on for five minutes, why it will not do much more as surely the guider is working and the mount is receiving its corrections?

Any and all input gratefully received peeps

Scott.

[wxsatuser]

Try......

RA Aggressiveness = 100

RA Hysteresis = 20

Max RA Duration = 350ms

Calibration steps = 2500ms

Max Dec duration = 350ms

Star mass tolerance= 1.00

Noise Reduction = None

Dither Scale 1.00

Got these settings here, this guy uses it successfully with a NEQ6

http://lightvortexastronomy.blogspot.co.uk/2013/03/tutorial-imaging-setting-up-orion.html

Make 100% sure your polar alignment is spot on.

[Scott]

Sorry Scott, can't help you but five minute subs on a eq3..... now thats pretty impressive. I know who to come and see when I finally get a guide camera .

[Freddie]

One key bit of info. I don't see is the guide cam exposure. You don't want that to be too short chasing the seeing.

[Welrod50]

OK, update: Last night I tried altered settings as follows: RA Aggressiveness = 125

RA Hysteresis = 30

Max RA Duration = 350ms

Calibration steps = 2000ms

Max Dec duration = 350ms

Star mass tolerance= 0.50

Noise Reduction = None

Dither Scale 1.00 . SSAG exposure set to 0.5 sec. Now I used to use 2.0 secs but having built a dew shield the guide star now becomes saturated after a couple of minutes now. I wonder if the dew shield has cut out some ambient light? Tracked faultlessly last night and I captured four 600 sec subs of M101 before the cloud rolled in and cut me short. I have to say, I am really pleased with the guiding and the only thing letting me down now is the coma (MPCC on the way as we speak). I know that folks cannot believe this level of success, but it does work!! I cannot stress enough the importance of having the mount level and very accurately polar aligned with a fully adjusted and accurate polar scope. The mount is carrying 5.5kg of kit, so is on the limit really, but I do wonder if this is in some way assisting the tracking? With the new settings last night, PHD went from taking 39 calibrations steps N,S,E and West to a grand total of 11 steps in all directions and it went from taking about 8 or 9 minutes to calibrate, to 3 or 4 minutes. 10 minutes consistently good with EQ3! I'm well impressed The trick now is to make these results repeatable, although I cannot see how now this cannot be the case!