Hardware and software advice needed for upgrading to guided imaging

[Davesellars]

Step 9 is an advanced plate solving step called Goto++ which hones in on a target. You need to have plate solved once before to use Goto++

[Pompey Monkey]

Step 9 is an advanced plate solving step called Goto++ which hones in on a target. You need to have plate solved once before to use Goto++

Only with ASPS. With PlateSolve2 it works straight off. I think it's to do with having a starting coordinate set as PlateSolve2 need the approximate coords to begin the search algorithm.

[Davesellars]

You could well be correct, Paul, I've never used PS2 standalone only with APT/point craft which needs it, APT disables Goto++ until you've done a normal plate solve,

[Xiga]

Xiga,

As I mentioned, I do not use Liveview for the very reason you just mentioned.  The only reason I'd use LV would be if the focus really way out of whack and I wanted to move it quickly to the approximate position.

It is far easier to take images of 5 seconds (at 800 ISO is quite enough) for a mag 3 (ish) star.

1. Slew to star and make sure it's pretty central.  I would NOT recommend using a star that is too bright as it will get blown out too quickly. Somewhere around mag 3 or 4 is OK.

2. Pop on the Bahtinov mask

3. Take 5 second image.  If the star is fainter just bump up the ISO to 1600.  The length of time is also generally sufficient to avoid bad focus through changing seeing conditions.

4. Zoom 5x then to 10x

5. Open up the Bahtinov Tool and place the square above the star with the cross at the centre of the star.  hit re-calc.

6. You'll be able to see visually anyway if you are out but look a the number given + it tells you if you are close etc.

7.  Adjust the focus where necessary and re-take image.  Since the star will be in the same position (hopefully if you're polar aligned and tracking well etc!), you don't need to do anything else apart from re-calc on the Bahtinov tool.

8.  Fast scope = naff all margin of error.

9.  Repeat this procedure after every major movement to different area of the sky for a new target.

BTW, I'm pretty much using the same equipment as you.   I have the Bahtinov masks bought from FLO for my 80ED and 120ED.

Yeah, it's a little bit of trial and error but it does not take many iterations to get it absolutely dead on and you will have a sure focus after this procedure - using LV, you will not.

Thanks for this mate, very helpful indeed. I had been trying to use a seperate program called Bahtinov Grabber, but i now see that you are using the in-built Bahtinov Aid tool in APT.

I think i may have confused matters slightly. When i was referring to LiveView what i meant was APT's LiveView mode, not the one on the camera, it's screen is always off. Up until now, I had always presumed everyone else was using APT to somehow focus in real-time using their laptop screen.

However, i just booted up my laptop and APT, to load an image from my last session and try and test the Bahtinov Aid tool. But i couldn't find any way to zoom in on the image like you say. It seems that the zoom function can only work with APT's Liveview or with the Focus Aid tool (similar to the Bahtinov Aid tool but doesn't have dissecting lines and works purely on FWHM).

How do you manage to zoom in using the Bahtinov Aid tool? On my test, it did seem to work fairly well (as in, it was able to tell me if i was near or far, and it even gave me dissecting lines even though the image i used was just a regular image and not a bahtinov one!) but as you can imagine the stars were all extremely small. In reality is this good enough, or do you really need a certain level of zoom to make sure you've got it nailed?

[Davesellars]

Sorry, my mistake! Of course, zoom only available in LV. So not required. I think as long as you have the bahtinov tool centred over the star it's all good. With the 80ed you may need to use a brighter star but not overly so.

[Pompey Monkey]

FWIW, I get better results with the Bahtinov mask when I just use my eyes to judge the spikes. Incidentally, my mask is made from a Shreddies box*.

*Other cereals are available.

[ianpwilliams]

I imagine it could be a bit of a nightmare focusing using a series of images rather than a live image. Surely you would just keep going either side of the focal point, or go further away from it instead of toward it?

[D4N]

I imagine it could be a bit of a nightmare focusing using a series of images rather than a live image. Surely you would just keep going either side of the focal point, or go further away from it instead of toward it?

Not really, I used to do it that way.

You soon learn how far you turn the focuser to move the line by a pixel.

/Dan

Sent from my iPad using Tapatalk

[Pompey Monkey]

I imagine it could be a bit of a nightmare focusing using a series of images rather than a live image. Surely you would just keep going either side of the focal point, or go further away from it instead of toward it?

This is how it's done with a CCD.

That's one of the things I like about this hobby: It's not easy - it's all about a series of small victories lining up in a row. Of course you can make some of these battles easier by throwing money at the problem and living in a pristine dark-sky site, but that's not the reality for the vast majority of us imagers!    

[ianpwilliams]

Step 9 is an advanced plate solving step called Goto++ which hones in on a target. You need to have plate solved once before to use Goto++

So just to confirm, in step 3 it's:

Click Point Craft

Click "Objects" in the "Current Image" section and select the object (in this case a star near the target)

Click "Auto" in the "Current Image" section

and in step 9 it's:

Click Point Craft

Click "Objects" in the "Center FOV at Position" section and select the object (in this case the target)

Click "GoTo++" in the "Center FOV at Position" section

Is that right? And should there theoretically be no need for any other input from me in each case?

Regarding Mirror Lockup, do I have do deactivate that on the camera? The APT manual suggests so.

I'm also unsure when it comes to Anti Vibration Pause, and also Pause (within plans). It seems like Anti Vibration Pause is best left to zero, and it seems like Pause is the pause either before or after each exposure so allow for vibrations, so maybe 10 seconds?

[Xiga]

Maybe someone else with more experience can chime in here, but i'm not convinced of the need for step 3.

Personally, i would just do two slews, both of which are more or less click-and-go. One, to get to to a nearby high mag star using GoTo++, then focus and then do your Phd calibration, before slewing to your target, again using GoTo++. 

[ianpwilliams]

I'd be interested to know if that's the case.

The problem I'm having is that I've only used APT to take subs so far. I've not used it for mount connection and GoTo, or for plate solving, or for focusing using the Bahtinov Aid, and I can only test the mount connection and GoTo indoors (which I'm going to do today), but not the other stuff. So that's why I'd like to try to be as prepared as possible in order to avoid going outside and reaching a point where I have no idea what to do, particularly given how rare clear nights seem to be these days.

[Pompey Monkey]

 So that's why I'd like to try to be as prepared as possible in order to avoid going outside and reaching a point where I have no idea what to do, particularly given how rare clear nights seem to be these days.

It is absolutely correct to be ready, but it doesn't matter how prepared you think you are, something will more than likely come along to bite you on the backside. The more new techniques you try at the same time, the greater the chances are of it going wrong and leaving you disappointed.

It's best not to try to do it all at once, but to build up your experience in smaller chunks. This way you stand a good chance of getting some results that will spur you on to greater things The best images you see here are usually the result of years of hard-won experience.

The lack of clear nights is very frustrating, even more so for you because you are starting out, but all of us in the UK all feeling it at the moment.

[ianpwilliams]

As far as I can tell plate solving is for centering the target, which can be done manually if required. And focusing can be done without using the Bahtinov Aid (but with the mask). I suppose the most important thing is getting guiding with PHD2.

[Xiga]

Another tip is to install the original Phd as well, just as a fail safe. I've only guided 3 times myself, the 1st time I used Phd and it worked fine. The 2nd time I used Phd2, which also worked fine. But the 3rd time Phd2 wouldn't show any stars, I tried for ages but couldn't work out what was wrong. Thankfully I had the original Phd also installed and setup, so I was able to salvage what would have otherwise been a wasted session.

Basically the more Plan B's you can have in this game the better!

[ianpwilliams]

Good idea, I'll do that. PHD2 was to be the next stage in my last session when the laptop battery ran out.

Tracer battery and adaptor are ordered now anyway, and the dehumidifier bags have arrived, I just need to order a tall round table for putting the laptop on and I'll be ready to go.

[Davesellars]

Maybe someone else with more experience can chime in here, but i'm not convinced of the need for step 3.

Personally, i would just do two slews, both of which are more or less click-and-go. One, to get to to a nearby high mag star using GoTo++, then focus and then do your Phd calibration, before slewing to your target, again using GoTo++. 

Plate solving using the Auto function is quick there is no point in missing this step.   The point of this step is in preparation for PHD calibration - This I don't actually need to do all the time with a permanent setup but if you're setting up every time it will be absolutely necessary to re-calibrate unless you have a setup wher the guide-scope/camera has not changed position to your imaging scope.

If your mount is not pointing at the correct position it thinks it is in RA/Dec, correspondingly, it makes sense that when you connect to PHD and calibrate when it makes N/S/E/W movements those movements will not be correct.   Also, the reason for the first slew is to a position in the sky for PHD and not for the target.  PHD needs to be calibrated in a particular area of the sky (no more than 30 degrees up and to the East or West position).  Once it has finished calibrating then slew to a star near target of which could be anywhere else and finalise the focus and centre your actual target using Goto++

One thing I've learn since starting imaging is that the devil is in the details...  Sure, while getting going and setting up stuff for the first time your priority should be just getting it running, however there are much more important things than the guiding. I didn't buy a guiding setup for a couple of months and this made me really focus on the polar alignment, balance and concentrating on the imaging aspect rather than the guiding...  Focus is actually far more important than anything else and learning what the affect is of bad polar alignment/balance so when it comes to integrating guiding in to your setup there's a few things you worry about less.

Once you've integrated guiding in to your setup there are more steps and more complication.  I've realised that guiding works great only if other factors are near perfect, even with an NEQ6.  With guiding you can forget about PEC for example and you'll be able to get consistent 5 min subs for example.  I was limited to 4 mins without guiding, imaging with an 80D and throwing a reasonable amount of subs away due to random motion.

[ianpwilliams]

When you say

"PHD needs to be calibrated in a particular area of the sky (no more than 30 degrees up and to the East or West position)."

Is that no more than 30 degrees up and to the East or West of the Home position (pointing at Polaris) or of the target position?

[Davesellars]

Probably clearer to say around 30 degrees (altitude) from the horizon to the West or East.  It has nothing to do with the target.  Your target could well be an area where it is impossible for PHD to calibrate from.   This is what is given in the PHD instructions and certainly when I've attempted to calibrate to far to the North or too high up for example, it will take an eternity and then probably tell you afterwards that it cannot calibrate.

[ianpwilliams]

OK so East or West, no higher then 30 degrees from the horizon, I'll make a note of that. I can't remember seeing that in the PHD2 instructions so I'll have another look

[D4N]

Ok except it really isn't necessary for PHD to know which way the mount is pointing in order to calibrate.

ST4 guiding would not work at all if this were the case.

It simply tells the mount to go west and sees which way the guide star moves.

It does need to be told about flips though, if you calibrate on one side of the meridian and then do a flip it won't be able to guide unless it knows this.

The position input is helpful for drift alignment but also not necessary.

As long as you point the scope in the right part of the sky it will work anyway.

I was getting annoyed at the guiding last night and ticked the Dec orthogonal to RA box and recalibrated in RA only, the guiding in Dec got a lot better! It is a lot quicker to calibrate just one axis

/Dan

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[ianpwilliams]

Last time I looked at the PHD2 instructions it made out that it was very straightforward ie connect to guide camera, click the loop button, get the exposure level right, click on a star, and click Guide and it will calibrate and then guide. But what's been mentioned here makes it sound more complex.

[Davesellars]

Actually this is the info from PHD...  30 degrees (alt works for me) but hey...   Actually it says between -30 and +30 in Dec...  anything above that and star movement will not be sufficient, you can resolve that by adjustment.  I guess that works for me with my permanent North to East facing position.

http://openphdguiding.org/man/Basic_use.htm#Automatic_Calibration

Guiding is a bit of an art-form in itself, lots of parameters as Dan has just mentioned and messing about...  I had no problem with my 80ED and then when I moved to my 120ED things got a whole load messier...  Some nights it seems to work perfectly and others it's a pig.   The PHD guiding manual is long.....

[D4N]

Wait what? There's a manual?!? [emoji54]

I'm imagining something like the monster book from Harry Potter, that would be quite appropriate.

/Dan

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[ianpwilliams]

OK so looking at that my guess is that I will be failing at the calibration step on my next attempt...but at least it'll present an opportunity to get everything into the shed.