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PHD2 guiding - Silly question


souls33k3r

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Hi All,

Am taking baby steps here with PHD2 guiding. Spent nearly all day today learning about different settings and what it means.

I've heard from people that one should calibrate PHD at dec 0.

So here's the questions. If say my target for the night is somewhere in the sky, am i right in saying that i first move the guidescope to calibrate at dec 0 - 30 (what PHD recommends) and then once calibration is done i move it to my target and expose again and then only hit guide button?

Sorry about such noobish question.   

Thanks in advance.

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Hello  souls33k3r:hello2:

Actually, there are no silly questions, only St...d answers !! is what I think.. :happy5:, so do not worry about asking, is the only way you can gain knowledge !!

Even if you change targets after the calibration is done  with at DEC 0, PHD2 will automatically handle autoguiding and no need to re-do calibration if PULSE guiding is used. PHD2 automatically will ead the new Declination coordinates of the new target and will make necessary adjustments for autoguiding to process with success...

BUT !! If you guide via or using the ST4 port, then the situation changes, when I guide with or via ST4, I always recalibrate ( actually I prefer PULSE GUIDING )..

Cheers

 

Martin

 

PS! I guess others may also contribute with some answers, and excited to see if my answer or process is supported by others also..

 

 

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While it might be best to calibrate near the Celestial Equator and Meridian, I find in practice that so long as you are not too near the Zenith or North Celestial Pole, you can calibrate wherever your target is. Otherwise, as you say, slew to a point near the Celestial Equator and Meridian, calibrate PHD2 and once it has finished it will start guiding, stop the guiding, then centre up on your target, select a guide star and click start guiding. Simples!

Good luck,

Gavin.

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Nice one, many thanks @artem & @PhotoGav.

Like i said, only started to look in to guiding so wanted to be sure of the required steps.

On a separate note, (well another silly question) i've seen a few threads where people have had issues with guiding when their guide cams were connected via USB 3 hub (even star tech shock, horror!). 

My setup is as follow, i have an ASI1600MM-C which has 2 built in ports. One port is used for FW and the other i'm using it for guide cam (I have QHY5L-IIm). The USB 3 from my ASI1600 goes in to a USB 3 powered hub. Also on the hub i have my EQDIR cable.

Now given this setup, do you think i would suffer from any guiding issue in terms of signals/data? I ask this because i've heard that some guide cams are very fussy about being used with hubs but in my case the guide cam goes in to the ASI hub and then to another powered hub.

I must say that i have used the above setup (Minus the USB powered hub) and have not found any issue but for the last two times that i have used the powered hub i have one time where my scope was out of balance (hopefully that should  now be resolved) and the second night i had issues even calibrating the guidescope (even using MaximDL which i am comfortable using).

Thought i'd get some advice on this too while on the subject matter.

 

Many thanks in advance

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11 hours ago, souls33k3r said:

My setup is as follow, i have an ASI1600MM-C which has 2 built in ports. One port is used for FW and the other i'm using it for guide cam (I have QHY5L-IIm). The USB 3 from my ASI1600 goes in to a USB 3 powered hub. Also on the hub i have my EQDIR cable

The asi on-board hub is usb2. Anything connected to it is automatically treated as usb2, afaIk. The eqdir cable is also usb2. If you have communications problems with that, you should be able to adjust the speed (baud rate) in the eqmod/ascom driver. At least that's how it works with my indi driver.

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It should work, but I have found that USB is the Achilles Heel of my system. Things are capable of dropping out randomly. If you have problems with your setup it might be worth plugging the guidecam straight into the powered hub rather than through the ASI camera. The good thing is that recent versions of PHD2 will automatically reconnect the guidecam if it drops out - that’s saved me on many an occasion!

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15 hours ago, souls33k3r said:

Hi All,

Am taking baby steps here with PHD2 guiding. Spent nearly all day today learning about different settings and what it means.

I've heard from people that one should calibrate PHD at dec 0.

So here's the questions. If say my target for the night is somewhere in the sky, am i right in saying that i first move the guidescope to calibrate at dec 0 - 30 (what PHD recommends) and then once calibration is done i move it to my target and expose again and then only hit guide button?

Sorry about such noobish question.   

Thanks in advance.

Calibration tells PHD2 how big a pulse it needs to send to the mount to move a star a given distance on the sensor and in what direction. For declination that stays pretty constant but in RA the pulses need to be bigger as you get closer to the pole. So if PHD2 does not know your declination (e.g. with ST4 or On Camera guiding) you need to calibrate on each target or at least for a change in declination.On the other hand if it does know your declination it can automatically adjust the RA pulses to suit. Since a guide star moves furthest at dec 0 for a given pulse it is more accurate to calibrate there and let PHD2 do its adjustments for your target declination. To use calibration in this way: on the Guide tab of the brain you need to tick "Auto restore calibration". You can force a new calibration any time by holding down the Shift key when you click the guide button.

14 hours ago, souls33k3r said:

On a separate note, (well another silly question) i've seen a few threads where people have had issues with guiding when their guide cams were connected via USB 3 hub (even star tech shock, horror!). 

My setup is as follow, i have an ASI1600MM-C which has 2 built in ports. One port is used for FW and the other i'm using it for guide cam (I have QHY5L-IIm). The USB 3 from my ASI1600 goes in to a USB 3 powered hub. Also on the hub i have my EQDIR cable.

Now given this setup, do you think i would suffer from any guiding issue in terms of signals/data? I ask this because i've heard that some guide cams are very fussy about being used with hubs but in my case the guide cam goes in to the ASI hub and then to another powered hub.

The issue has typically arisen with cameras designed for USB2 connected to a USB3 port or hub. The older ASI20 was particularly known for this but the newer ASI120MM-S is designed for USB3 and has no issues in this regard. It also works fine with USB2.

Personally I do no connect my guide cam through the ASI1600 USB port. The ASI1600 uses a lot of bandwidth so I orefer to connect the guide cam through a completely separate port albeit on the same hub.

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Cheers @kens & @PhotoGav, i will see if i can loop my guidecam cable and plug it directly in to the USB hub. I think connection from hub to another hub and then to the laptop might cause a few issues with the USB 2 data rate so will most certainly give this a go.

@ChrisEll, i'm using the EQDIR cable so can use the same calibration as far as i thought or do i calibrate on each target if i choose to go for a new one on the same night? (Not that i will ever be imaging multiple targets in one nights).

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> i'm using the EQDIR cable so can use the same calibration as far as i thought or do i calibrate on each target if i choose to go for a new one on the same night? (Not that i will ever be imaging multiple targets in one nights).

Yes you can re-use the same calibration... it's just that if you do re-calibrate for whatever reason PHD2 won't pick up the new Dec automatically if you've changed target since, need to visit Calibration Calculator and update the step size.

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Cheers @solarboy, apart from a few settings my PHD looks exactly the same. I ended up using guiding assistant that helped with the algorithm numbers. 

Funny thing is, my guiding was way better (in numbers) when using MaximDL but when I used PHD, the numbers went a bit high ... Might be due to the wind ... Will need to find the right balance for my guidescope and phd. Still lots to learn it seems.

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I have been finding that the last couple of recent nights I’ve been able to image, my guiding has not been great. I think this is due to sky conditions, which looked OK, but looking closely at the all-sky-cam time lapse I realise that there has been a lot of thin high cloud scuppering things. So, don’t be too disheartened by recent results!

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