Really starting to wonder why I bothered

[FrankieValley]

Hi Malcolm,

What do the stars look like in an image of 2 to 5mins? Pls post an image.

The RMS value is pretty good in your screenshot, so I'm wondering how they look.

Also, can you give a few of the figures you see similar to my screenshot below and a screenshot of the guide star profile (tools menus to get that).

What is the exposure time? Too fast and it will chase the twinkle - 2s is good.

[Earl]

Malcolm,

Don't use your finder for doing alignment, or even a dslr image - use a high power reticule eyepiece in your main scope. Define three points in a triangle around your your target and don't ever sync on nebula, galaxies, planets etc - they are too big!. You'll only get accurate gotos if you define accurate alignment points.

Chris.

Interesting you say dont use a DSLR is live view not accurate enough?

[FrankieValley]

Alignment is irrelevant for guiding. You can have no alignment points and PHD will guide, but I suggest tracking is set to 'sidereal' in EQMod as not sure PHD will guide a stationary mount.

[Veracocha]

Without alignment surely the guiding will have to work harder?

[MG1]

Alignment is irrelevant for guiding. You can have no alignment points and PHD will guide, but I suggest tracking is set to 'sidereal' in EQMod as not sure PHD will guide a stationary mount.

Wow...!

But surely guiding happens after the error has taken place, so it can only ever approximate the response required to get back on the target...and PE will compound the problem.

Accurate PA coupled with PEC results in smaller guide movements/ corrections and therefore a better graph and associated better image.

Or is the magnus wrong?

[FrankieValley]

Without alignment surely the guiding will have to work harder?

Nope. Alignment helps you find stuff. PHD does not care where the scope is, the mount moves in RA at a sidereal rate and PHD can adjust for drift - to a point. Good polar alignment helps. It doesn't have to be perfect, but bad polar alignment will make PHD work harder and generally the star will drift off slowly in one direction. Malcolm's polar alignment looks ok from his graph.

[Veracocha]

Nope. Alignment helps you find stuff. PHD does not care where the scope is, the mount moves in RA at a sidereal rate and PHD can adjust for drift - to a point. Good polar alignment helps. It doesn't have to be perfect, but bad polar alignment will make PHD work harder and generally the star will drift off slowly in one direction. Malcolm's polar alignment looks ok from his graph.

I know you are trying to help but this answer is rather contradictary.

[FrankieValley]

Wow...!

But surely guiding happens after the error has taken place, so it can only ever approximate the response required to get back on the target...and PE will compound the problem.

Accurate PA coupled with PEC results in smaller guide movements/ corrections and therefore a better graph and associated better image.

Or is the magnus wrong?

Confusion... I was referring to star alignment as being irrelevant as one post was talking about that. Yes, polar alignment is required, but can be a bit off. PHD will guide out a bit of PA and probably all PEC errors. Of course, the better they both are, then the better the graph will be, but not so sure the stars will be any rounder :-)

I have never corrected PEC errors after hearing or reading that Craig Stark said his PHD will guide around PEC.

[FrankieValley]

I know you are trying to help but this answer is rather contradictary.

Hopefully I have cleared up the confusion.

[Veracocha]

Yes, polar alignment Vs star alignment ?

[malc-c]

You now use an ST4 cable rather than choosing ASCOM in PHD - can you elaborate a bit more on how to do this ? I have an st4 cable and might try that

[Veracocha]

I still use Ascom driver Malc but in PHD there is a label for "mount" and in the drop down list I select "on camera" which let's the camera give the mount a pulse I believe to move it it unison.

[FrankieValley]

You now use an ST4 cable rather than choosing ASCOM in PHD - can you elaborate a bit more on how to do this ? I have an st4 cable and might try that

Choose On-Camera from the Mount menu in PHD and connect the cable between the ST4 port on the camera and the ST-4 port on the mount. Make sure it is an ST4 cable - EQ6 SkyScan ST4 Autoguide Port Wiring

...and not a phone cable.

[malc-c]

Gotcha - just trying that now. I've re-done the alignment in EQMod and now have had 4 successive goto's on the trot that have been spot on, so alignment must be quite good.

Do you still calibrate when "mount" has been selected ?

[Veracocha]

Yes, calibration occurs just once so I have found out and subsequent "guides" work immediately.

[malc-c]

...and not a phone cable.

It came with the mount when I purchased it S/H - it's a bit wider and flater than a phone cable

[Veracocha]

Malc, the one I had (faulty) was flat and black, very different from a standard phone cable however the pinouts were completely different to the new cable I received this week. Neither look like a standard phone cable.

[malc-c]

That's a nice graph by the way. I would be please to get the lines to follow each other rather than diverge !!

[malc-c]

just for fun I tried AA5, using autocalibrate this was what I got. Don't know if this is better than PHD or not... and shortly after the screen grab RA went to ring 5 or more !!!

I'm knackerd and giving up for tonight

[ollypenrice]

To be honest, the first thing I'd do is a drift alignment. This way you are working directly from the sky, not through intermediary hardware and software. If you can get to the celetial equator in the south and either the east or the west then the photo method is cute. You start an exposure of say 20 seconds then during the exposure you slew in RA out and then back at a slow rate. If you are aligned you will get the trails out and back exactly superimposed, ie a straight line. Otherwise they will create an elongated vee shape. I can only get to the CE in the south so I use this method to perfect my azimuth alignment and use the old method for altitude, using a star in the east.

Guiding in AA5; first, be aware that AA5 will calibrate the scope response speed but cannot tell east from west, north from south or RA from Dec. Do a few tests to find out, first, whether or not the Y axis really is dec. (Just give it a push via handset or PC in Dec and see whether it jumps in x axis or in y. I like y to be Dec so, if it isn't, rotate the camera through 90 degrees.) Then see that it is guiding the right way in both x and y. Once a guide command comes in, see whether it pushes the mount the right way or not. If it is pushed the wrong way, tick or un-tick the Invert x or Invert y boxes. Also remember that this will be altered when you do a meridian flip.

And finally, don't rely on AA5's speed calibration. I often fine tune mine.

Hope the cold is better and that things will resolve themselves. I know that Chris is a true software expert and generous in sharing his work but I'm one of those people who prefers to have anything that can controlled manually, controlled manually! There is no doubt at all that 19 problems out of every 20 are PC related down here. It only takes an update or a change of USB cable or a USB in a different port to knock out some vital bit of software and your evening is down the pan. For me, with guests counting on me, that is just a plain no-no. Call me old fashioned. I am!

Olly

[malc-c]

To be honest, the first thing I'd do is a drift alignment. This way you are working directly from the sky, not through intermediary hardware and software. If you can get to the celetial equator in the south and either the east or the west then the photo method is cute.

Olly

Hi Olly,

I've used that method with a dSLR before, but whilst I have a decent view to the south, I can't get low elevations East or West due to restrictions (houses, hedges etc). The best I can get is around 30 -40 degree (will have to measure it correctly one day), and often or not any bright star that low is lost in the LP.

I hear what you were saying about PC's etc but if the intention is to run everything from a warm room etc then we have little choice. I'm hoping to get out of Christmas shopping (hate crowds) so I can do some dummy runs in using the hand controller and CdC or one of the other planetarium software packages, and see if that works any better - mind you I was getting good go-to's after the second round of polar alignment trials, comparable with the days of using the handset on the old EQ5

[blackparticle]

Uhmmmm... just need to run an extension cable from the mount to the warm room so I can use the handset in comfort

Now why didn't I think of that !! You've just saved me loads of time phaffing about going in and out of the caravan.

[malc-c]

OK not perfect confitionds with a full moon, hazy cloud etc, but after checking the alignment again, I slewed to scheat and set PHD calibrating whilst I went and had a meal. This is the result.... not perfect, but at least both traces are following the center line !

[Veracocha]

Outstanding Malc, massive improvement on your previous attempts. progress indeed. Was it via the ST4 port?

[Earl]

I have got my phd guiding inbetween the first bars so im happy.

However the focuser on the Meade is like a wizards sleeve :|