PHD2 dither with SW Adventurer

[Allan the plumber]

Hi can any one assist

My lovely wife purchased me the full SW Adventurer package as I requested I wanted a grab and go to use with my modded Dslr when travelling

All great!! have set up and have got a few widefield shots over last few days. As with DSLR colour mottle is a big problem and having used dithering with my GT81 and 460EX and with a lot of the DSLR processing tutorial advising extreme dither I thought I'd have a go.

The mount has a ST4 interface and the manual suggests that any auto guider should work.

So in brief I have usb powered hub which is powering the SW Adventurer, I have both the camera and QHYII guide scope (Altair Astro 60 guide scope) dual mounted. The Canon D1100 and QHYII are connected to USB hub and in turn this feeds back by active USB to laptop.

I have the ST4 cable connected to the QHYII and mount.

PHD2 can find the QHYII but its asking for a mount ( normal It would be my AZNEQ6)

BYO is used for software capture for the Canon ( this has a PHD dither setting ) which when a test signal is sent connects but PHD2 (latest version) PHD starts calibrations but seems stuck in clearing backlash

I know the SW Adventurer only has RA and no DEC but if it can auto guide I'm hoping it can dither as well.

If anyone can advise settings in PHD2 or if this can be done I would be gratefully as I would like to use this great little mount as much as possible as it was a Xmas gift and I wont hear the last of it if I pack it away

Thanks

Allan

[Cornelius Varley]

Just to correct you. The mount has RA but no DEC.

[Allan the plumber]

Just to correct you. The mount has RA but no DEC.

Thanks my bad doh

[Thalestris24]

Hiya

You have to select 'on camera' to do ST4 guiding. Also, the camera has to be set to 8-bit (not sure if the qhy5 has a 12-bit option) to use the ST4 interface. Yeah, it can only guide in RA. One problem is that you can't calibrate properly with PHD2 since there's no DEC though you can (have to!) switch DEC guiding off in PHD2 and calibrate in RA only. Accurate PA is important to prevent rapid DEC drift.

Not sure about dithering - not tried it but the RA has a large periodic error. My SA is broke at the moment anyway...

Louise

[Allan the plumber]

Hiya

You have to select 'on camera' to do ST4 guiding. Also, the camera has to be set to 8-bit (not sure if the qhy5 has a 12-bit option) to use the ST4 interface. Yeah, it can only guide in RA. One problem is that you can't calibrate properly with PHD2 since there's no DEC though you can (have to!) switch DEC guiding off in PHD2 and calibrate in RA only. Accurate PA is important to prevent rapid DEC drift.

Not sure about dithering - not tried it but the RA has a large periodic error. My SA is broke at the moment anyway...

Louise

Thank you Louise, have been reading some of your threads concerning the SW Adventurer and have read about the large Periodic errors but you seem to have sorted it. Am sure the QHYII can be set to 8 bit as I'm sure software that came with the camera had a capture suite that enable the change will dig it out and take a look

Sorry to hear your mounts broken nothing that cant be fixed I hope 

Thanks again

Allan 

[Thalestris24]

Thank you Louise, have been reading some of your threads concerning the SW Adventurer and have read about the large Periodic errors but you seem to have sorted it. Am sure the QHYII can be set to 8 bit as I'm sure software that came with the camera had a capture suite that enable the change will dig it out and take a look

Sorry to hear your mounts broken nothing that cant be fixed I hope 

Thanks again

Allan 

Hi

Yeah, I had a lot of play in RA but the periodic error is intrinsic to the SA design and can't be improved afaik. I've seen people put a motor on the DEC axis to enable guiding in DEC (think it was on a German web site). Not sure if it's worthwhile. The qhy-ii will certainly be configurable for 8 bit.

I was powering my SA via the usb but managed to trip over the cable. You'd think the cable would have just pulled out from either the PC end or the SA end. But instead it ripped the usb-mini socket out of the pcb! I'm waiting for a replacement socket (from China...) and will try and repair it. It might not be easy to remove the bits that are left soldered but I'll have a go. If I can't fix it I'll probably pack it away and it likely won't see the light of day again...

Louise

[Astroboffin]

Just to correct you. The mount has RA but no DEC.

I am confused, as that is what he said....!!

Or do these mounts only have Dec and no RA....wouldn't have thought so...

[Cornelius Varley]

I am confused, as that is what he said....!!

Or do these mounts only have Dec and no RA....wouldn't have thought so...

The mount only has a right ascension axis. It is basically an imaging mount which is driven in the right ascension only.  http://www.firstlightoptics.com/skywatcher-star-adventurer/skywatcher-star-adventurer-astronomy-bundle.html . Think Vixen Polarie or Ioptron Star Tracker rather than a conventional telescope mount. And the post has been edited by Allan at 11.35am (10mins after my post) to correct the mistake.

[Thalestris24]

I am confused, as that is what he said....!!

Or do these mounts only have Dec and no RA....wouldn't have thought so...

I think the OP edited the original post

[Cornelius Varley]

The original line was

"I know the SW Adventurer only has DEC and no RA but if it can auto guide I'm hoping it can dither as well"

which was corrected to

"I know the SW Adventurer only has RA and no DEC but if it can auto guide I'm hoping it can dither as well"

[Astroboffin]

Oh, ok I only saw the edited version, thought I must have gotten it wrong as it would not have made sense....appologies..

AB

[Davey-T]

I think the whole point of the SWSA is that it is a quick grab and go mount, it can do really good unguided exposures up to 10 mins wide field so trying to guide it seems to defeat the object,

Once PAd you can keep the illuminator on and refine it to keep it tracking round the circle.

Dave

Couple of examples, 90secs Canon 300mm f/4 and 1020secs Canon 24-105 at 24mm.

[Allan the plumber]

Thanks for feed back guys and sorry about the confusion over DEC and RA as mentioned I did edit it as was trying to not look the fool 

Concerning guiding and wide field imaging. All I'm trying to do is incorporate dither into the subs. Most exposures taken in LP skies with a DSLR suffer from "Colour Mottle" this is due to the Bayer Matrix of the chip making noise as each image is stacked with the same corresponding colour of that chips matrix. Ie you end up with a red pixel over a red  pixel sub after sub etc If you can randomise this by introducing dither when your stacking software should look at each sub  and removes this colour mottle problem and in theory producing a much cleaner image.

I found a tutorial by Tony Hallas on YouTube   https://youtu.be/PZoCJBLAYEs, Itseems to work I'm still waiting for clear skies to get the dither subs. (Will use my main mount for this) its looking like the SW Adventurer won't offer me dither. yes I know its a grab and go but since it has the ST4 port and will except most guide scopes (according to SW), I thought I'd as asked to see if anyone had tried to guide/ dither

Thanks again

Allan 

Thanks again 

Allan 

[Davey-T]

You could just dither manually, don't think it matters about all the dithering being a constant number of pixels, you can use the arrow buttons and the dec screw adjuster, don't know what PHD does, ie: Dec and RA together or only one .

Will give it a try if it stops raining 

Edit: Can't get the link to work

Dave

[Allan the plumber]

Hi thanks for the reply Davey-T try this link

[1DegreeN]

I've been experimenting using dithering with my Astrotrac mount, using BYEOS and PHD2. Like the StarAdventurer, the Astrotrac can only be guided in RA. Unless you have very good polar alignment I think you will find that during dithering BYEOS shows the measure as 2.55 and this never decreases to the settle value, so BYEOS times out the dithering after 90 seconds. I suspect this could be because the DEC error in PHD is too large, and can't be reduced so PHD can't get close enough to the target position. However the images are still dithered (in RA), its just the 90 second timeout that is initially worrying but ultimately just inconvenient since it reduces your imaging time. To get better polar alignment you can use the drift alignment procedure in PHD2 but this is very fiddly and time consuming. If your PA is reasonable and stars are round then dither away and just accept the 90 second timeout between shots. My first attempt at dithering was just last week and I was surprised at how much more detail is visible: https://flic.kr/p/CjKcjF

[wxsatuser]

You could just dither manually, don't think it matters about all the dithering being a constant number of pixels, you can use the arrow buttons and the dec screw adjuster, don't know what PHD does, ie: Dec and RA together or only one .

Will give it a try if it stops raining 

Edit: Can't get the link to work

Dave

I'm doing 12 pixels, HEQ5, in a spiral pattern with the Lacerta, seems to work well.

Think as long as the movement is quite large like 10 to 12 pixels it should be ok.

It's definately the way to go.

I always knew there was extra in my images that I could'nt quite bring out.

Have had only a couple of good sessions dithering and this quick image of the Californian

did it for me. Never managed to get all the extra dust around this nebula until I tried dithering.

Not the finished polished article, still working on that but I was pretty pleased at what came out.

[Allan the plumber]

Thanks for that going to try tonight skies allowing! Going to use my main mount tonight using a combination of BYO, Neb3 and PHD2 and see what I get

I'm going to try the SW Adventurer tomorrow and the dither option after I've had chance to read up on setting up PHD in RA only and see what happens there

If I don't get the dither results tonight with main mount then I may go back to my ccd and just hope we get more nights with clear skies

Allan