NEQ6 guiding

[Spoon]

Hi all,

I'm currently in Portugal in some of the darkest skies I've been to, nearest light is 10 miles or so away! You can pick out the Milky Way no problem when it isn't even remotely dark yet. It's great, and clear 90% of the time! My question is this: set up the my kit last night, polar aligned to the best of my ability, but when I started guiding the dec was fine but the RA graph was horrible. My calibration step in PHD is 1500 I think, ST80 with QHY5, exp 1 sec. Would decreasing calib. step help guiding, or is it the alignment?

Cam

[kalasinman]

Your sig seems to say the WO isn't on hand? Setting in PHD are FL specific. There is a camera connection wizard that's useful.

Settings such as min. move, exposure time, and aggression will usually have the greatest affect on guiding.

Minimizing RA backlash is essential.

hard to tell what's wrong without seeing the graph.

Post a graph, and clear up what equipment you are using please.

[Tinker1947]

If you use the handset to PA run the routine 2 or 3 times, PA will be as good as you can get it, my NEQ6 with a 250P-DS done 3 minute unguided when tested.......

[kalasinman]

If DEC guiding is ok, PA is probably close.

[Spoon]

Your sig seems to say the WO isn't on hand? Setting in PHD are FL specific. There is a camera connection wizard that's useful.

Settings such as min. move, exposure time, and aggression will usually have the greatest affect on guiding.

Minimizing RA backlash is essential.

hard to tell what's wrong without seeing the graph.

Post a graph, and clear up what equipment you are using please.

I keep meaning to change it, the WO is my main imaging scope, had it for a few weeks now. How do you minimise backlash? East heavy balancing?

[kalasinman]

first, see if you have it. Center up  star (still not sure what software you use) select 2x tracking speed on the HC and slew the scope one way. when it stops, slew it the opposite way in RA. You can see if it hesitates before it starts the second move. That's backlash. You mount instructions should have the way to reduce it. Unbalancing works once you have every other cause eliminated, and overall balance is very good. It doesn't have to be much.

[Spoon]

first, see if you have it. Center up star (still not sure what software you use) select 2x tracking speed on the HC and slew the scope one way. when it stops, slew it the opposite way in RA. You can see if it hesitates before it starts the second move. That's backlash. You mount instructions should have the way to reduce it. Unbalancing works once you have every other cause eliminated, and overall balance is very good. It doesn't have to be much.

I use EQMOD will that still work? I still need to do PEC training but don't know what to do.

[Astroboffin]

Hi all,

I'm currently in Portugal in some of the darkest skies I've been to, nearest light is 10 miles or so away! You can pick out the Milky Way no problem when it isn't even remotely dark yet. It's great, and clear 90% of the time! My question is this: set up the my kit last night, polar aligned to the best of my ability, but when I started guiding the dec was fine but the RA graph was horrible. My calibration step in PHD is 1500 I think, ST80 with QHY5, exp 1 sec. Would decreasing calib. step help guiding, or is it the alignment?

Cam

Not sure I'd this will help, but I used to use an ST80 for guiding and a similar camera, and I only had a calibration step of 750 and worked perfectly

Regards

AB

[Spoon]

Not sure I'd this will help, but I used to use an ST80 for guiding and a similar camera, and I only had a calibration step of 750 and worked perfectly

Regards

AB

I just tried again tonight, the min step I can achieve is 1100 before I get the "RA calib failed, star did not move enough" error message

Cam

[kalasinman]

The most common cause of the "star didn't move" error is attempting to guide on a hot pixel. Be sure to use dark frames or bad pixel map .

[Spoon]

The most common cause of the "star didn't move" error is attempting to guide on a hot pixel. Be sure to use dark frames or bad pixel map .

I was out again last night, RA guiding was fine, but the dec gradually moved away from the middle line to the point where it wasn't even on the graph. Where is the PA tool on the handset?

[kalasinman]

I was out again last night, RA guiding was fine, but the dec gradually moved away from the middle line to the point where it wasn't even on the graph. Where is the PA tool on the handset?

I'm fortunate to have an Ioptron Polar scope, which gets me close enough for guiding. I'll get around to drift align, one day....;-)

My HC hs a PA feature, but never bothered with it. I've read many folks with several brands of scopes say the HC PA is hopeless.

One reason for either RA or Dec to slowly drift off is too low an aggression setting.

[Spoon]

One reason for either RA or Dec to slowly drift off is too low an aggression setting.

What aggression would you recommend? I might do drift alignment tonight. Forgot about that

Cam

[kalasinman]

Get guiding and increase aggression in DEC. I don't know your kit or what it requires. Try 90% or add 10% if you are already near there. Then watch and see if DEC stabilizes. Set HYST to zero. Reduce min. move to a low setting, maybe .05. Decreasing your exposure length to 1 second sometimes helps if seeing permits it.Each of these settings work with each other to increase sensitivity to error.

Exposure times are a trade off determined by seeing. Short exposures increase mount control at the expensive of SN of star. You need to be around SN 7-9 minimum to guide, hopefully higher. If seeing is poor you may need to increase exposure to 2 or even 3 seconds. I find past that, seeing is too poor to image anyway.

Once you get drift align really close, and you have nearly eliminated backlash, then you can experiment with reducing aggression, maybe going to .05 min move if you ended up going to zero to get good guiding.

My mount is very fast, so don't necessarily copy the settings I mention. You can, but getting the idea of which settings give what result is the idea. In general, if your graph line is above or below the center line and/or drifting off (undercorrecting), you need quicker response. If you graph sawtooths back and forth across the center line, you need less sensitivity (overcorrecting).

[Tinker1947]

My NEQ6 does slide the DEC off the graph when the PA is out, the handset option for PA, requires a 2 star align then it show in the same section, i find it easy to use with the guide scope set to show stars central that are also centred on the sensor, so do a couple of alignments on different stars using the PHD graph with the bullseye on this saves any sort of back strain as you look at your screen while adjusting,  my mount managed a 3 minute sub unguided, when guiding the RA and DEC graphs were pretty flat.....

[Astroboffin]

How have you got your scopes set up, piggybacked, or side by side, if side by side are they completely parallel with each other, and if piggybacked the same applies really.

Assuming you are using a separate guide scope that is.....?

AB

[Spoon]

Get guiding and increase aggression in DEC. I don't know your kit or what it requires. Try 90% or add 10% if you are already near there. Then watch and see if DEC stabilizes. Set HYST to zero. Reduce min. move to a low setting, maybe .05. Decreasing your exposure length to 1 second sometimes helps if seeing permits it.Each of these settings work with each other to increase sensitivity to error.

Exposure times are a trade off determined by seeing. Short exposures increase mount control at the expensive of SN of star. You need to be around SN 7-9 minimum to guide, hopefully higher. If seeing is poor you may need to increase exposure to 2 or even 3 seconds. I find past that, seeing is too poor to image anyway.

Once you get drift align really close, and you have nearly eliminated backlash, then you can experiment with reducing aggression, maybe going to .05 min move if you ended up going to zero to get good guiding.

My mount is very fast, so don't necessarily copy the settings I mention. You can, but getting the idea of which settings give what result is the idea. In general, if your graph line is above or below the center line and/or drifting off (undercorrecting), you need quicker response. If you graph sawtooths back and forth across the center line, you need less sensitivity (overcorrecting).

So from what I read I need a faster response in dec and slower in RA as it is sawtoothing quite a lot. I'll try drift alignment then go from there.

How have you got your scopes set up, piggybacked, or side by side, if side by side are they completely parallel with each other, and if piggybacked the same applies really.

Assuming you are using a separate guide scope that is.....?

AB

I piggyback the ST80 on the GT81 and on both sensors they are both pretty bang on the target

Cam

[Tinker1947]

My particular set-up is a ST-80 with adjustable tube rings, this allow for the PHD screen bulleys to have stars centred as preciesly as the CCD/DSLR sensor....

[kalasinman]

One reason that settings are specific to the rig is the relative pixel scale between the imaging camera and the guide camera. In one example say using a 1000mm main scope with a DSLR might yield a scale of let's say 1.2" . If one guides with a 50mm guide scope with a camera with large pixels, the scale might be say 5" or more. I am just inventing convenient figures here, for illustration BTW.

OK so guiding ( I don't know how to get off bold) with an error of 2 " would be a deviation of 10 pixels in the main camera. This is undersampling and the result would not be so good.

My rig uses an OAG with a guide camera with small pixels. My imaging scale 1.3" and my guiding scale 1.03". With the arc seconds of error the imaging error would be 2.6 pixels. This is oversampling, and in this case gives nice stars.

PHD2 has wizards to assist in converting your actual kit into recommended settings.

[Spoon]

Right ok so I've just gone into PHD2, Adv. Parameters, Mount, then Calib Step, Calculate, put in my FL etc. but how do you determine the 3rd 4th and 5th boxes down?

[kalasinman]

start with max duration for both. Next 2 blank. Last one is useful for DEC guiding If you allow your PA to be a little off, RA will still take care of itself, but DEC will be off always the same way. First try North, then South, and see which gives a better graph. Auto often results in sawtooth from DEC backlash. This solves that.

[wuthton]

Eqmod is your friend here. Personally I hardly touch the settings in PHD, if it's guiding you're good to go. I prefer to adjust the width gain in Eqmod to flatten the graph or increase aggressiveness.

[kalasinman]

Not everyone has a Synscan mount.

[wuthton]

Not everyone has a Synscan mount.

I use EQMOD will that still work? 

[Spoon]

Eqmod is your friend here. Personally I hardly touch the settings in PHD, if it's guiding you're good to go. I prefer to adjust the width gain in Eqmod to flatten the graph or increase aggressiveness.

http://youtu.be/WX2uXMu0crw

Thanks. I'll have a look at at in a minute

Cam