Imaging with an AZ-GTI

[Snooze]

Hello everyone,

 

I currently have a Star adventurer mini and i've been looking for a mount 'upgrade' for some time. Looking around on various forums, I found the AZ-GTI and saw that people have been getting up to 10min sub with a small refractor and guiding. Why the AZ-GTI you may ask. It's simply because i'm looking at portability and cost. At first I was considering an EQ3-2 but since both have a 5kg payload and can be guided, I thought the GTI would be a better fit and it is also less expensive. However I have a few questions regarding the little mount that I cannot  seem to find anywhere:

• What kind of exposures can I hope to get with a 360/400mm lens/refractor unguided? I'm looking to keep at least a reasonable amount of subs at 1min. I have managed okish 1min subs at 300mm(small 70-300 zoom) with my SAM
• Is the 3 star alignment enough for imaging? I can always drift align to perfect PA. I plan on guiding at some point but i don't want to carry a laptop with me in the beginning.

Now please spare me the get a HEQ5 comments. I'm not new to astrophotography and have been doing so for 3+ years with budget gear and I would like to keep it that way because I like the challenge and it also shows you don't need thousands of dollars to get into the hobby. I would rather spend 250€ on a mount I will use now than wait months/years to get a bigger/better mount plus as I said portability is the most important thing for me. So I would be grateful if AZ-GTI owners could share their experience and if it is worth it considering I have a SAM.

 

Cheers

[Ags]

I'll follow this thread with interest. I am a happy owner of a GTi although it can be a bit temperamental.

Edited February 27, 2020 by Ags

[happy-kat]

There's a huge thread on cloudy nights on imaging with this mount.

I've been following the use of this mount as it has intrigued me.

You'll need to install the eq flavour of the firmware, this flips the side you mount on do read up

There's a great youtube by member wolfie (similar name...) on this mount, imaging and updating the mount

In eq mode it tracks on one axis but if guiding it tracks using both axis

Member @knobbyI think images with it.

 

[knobby]

Did someone mention me 😁

Yes , I love my AZ-GTI. Make sure you buy it from a good dealer (FLO) they are very random in quality, you'll need a wedge ( your star adventurer one is fine ) and a counterweight ( eq1 if you can find one if not the star adventurer one with an M12 to M8 adaptor ) As Kat mentioned the EQ firmware from Skywatcher site.

Mine is good for about 90 seconds unguided at 335 mm focal length and I've managed 300 seconds guided with 1.5 to 1.8 arc seconds fairly consistently.

I noticed in the last sysnscan app that there is a right assension speed adjustment so maybe the unguided accuracy can be tweaked.

Hope you get a good one 🤞

Pics below

Heart neb @ 300 seconds

Horsehead @ 300 seconds

PHD2 screenshot

Mount

[Snooze]

1 hour ago, happy-kat said:

There's a huge thread on cloudy nights on imaging with this mount.

I've been following the use of this mount as it has intrigued me.

You'll need to install the eq flavour of the firmware, this flips the side you mount on do read up

There's a great youtube by member wolfie (similar name...) on this mount, imaging and updating the mount

In eq mode it tracks on one axis but if guiding it tracks using both axis

Member @knobbyI think images with it.

 

I have already looked at the huge thread on cloudy nights but it's more related to visual and the few astro posts were about guiding which I'm not really interested in right away. I'm more interested about unguided performance  

1 hour ago, knobby said:

Did someone mention me 😁

Yes , I love my AZ-GTI. Make sure you buy it from a good dealer (FLO) they are very random in quality, you'll need a wedge ( your star adventurer one is fine ) and a counterweight ( eq1 if you can find one if not the star adventurer one with an M12 to M8 adaptor ) As Kat mentioned the EQ firmware from Skywatcher site.

Mine is good for about 90 seconds unguided at 335 mm focal length and I've managed 300 seconds guided with 1.5 to 1.8 arc seconds fairly consistently.

I noticed in the last sysnscan app that there is a right assension speed adjustment so maybe the unguided accuracy can be tweaked.

Hope you get a good one 🤞

Pics below

Heart neb @ 300 seconds

Horsehead @ 300 seconds

PHD2 screenshot

Mount

Very impressive images @knobby!! 90s unguided sounds great Now i'm even more excited about getting the mount. Concerning FLO, do you guys know how returns are processed from outside the UK? I'm in France and it would suck if I have to pay shipping to send it back in case the mount needs replacing.

 

Cheers

[knobby]

Edit ... Scrub the 90 seconds @ 335 mm, that was @ 105 mm 

[david_taurus83]

Like knobby I also image with a GTi after scaling down a lot of astro gear until we can move house. I bought a Star Adventurer first but quickly got bored with manually aiming a 330mm scope and manual meridian flips!

I bought mine second hand but it was virtually new. I opened mine up and inspected the innards. Gave everything a bit more grease where it needed etc. The RA side of things is fine. Hardly any play and it tracks and guides well, I get similar figures in PHD to knobby. Dec though, is very poor on mine. It has loads of backlash. It's not a gap between the teeth of the gears either. The actual output shaft of the dec motor on mine has a lot of lateral play. No way to adjust it. That said, I can still calibrate in PHD and it guides fine. I wouldn't even contemplate unguided imaging with this at a focal length over 300mm.

My kit is just under 5kg and I still need 2 x 1kg weights to balance it. I got a metre length of M12 threaded bar from B&Q for a couple of quid and cut it to size with a hacksaw.

It makes for a super portable setup! I can lift the lot with ease with everything attached in and out of the house making for quick setup and packing away.

[Snooze]

I pulled the trigger and ordered the AZ-GTI and an omegon 50mm guide scope.  Hope I get a good unit that tracks well.

[Snooze]

My AZ GTI arrived. I'm so excited and also found out I need a couple of adapters to makes things work.

 

Looks like I need another retaining bold for the eq wedge cause the plastic head is slightly too big. I also need an adapter to make the counterweight bar from the star adventurer work 😕 Hope I can sort these out before saturday so I can start testing things :D.

[fireballxl5]

No chance for a full imaging session using my 60mm refractor/ASI071MC Pro/AZ-GTi/ASIair Pro combo yet owing to cloud, but first time guiding on Sunday evening gave this...

Managed to polar align, plate solve and guide using the ASIair Pro on first proper session. Still need to adjust flattener/sensor spacing but looking good so far. This guiding performance should be ok for imaging at 3.9 arcsec/pixpix when travelling. Cooling was off to save battery😛

PS, guided using 50mm finder/ASI224 setup.

Edited March 10, 2020 by fireballxl5
added PS

[david_taurus83]

On 10/03/2020 at 22:04, Snooze said:

My AZ GTI arrived. I'm so excited and also found out I need a couple of adapters to makes things work.

 

Looks like I need another retaining bold for the eq wedge cause the plastic head is slightly too big. I also need an adapter to make the counterweight bar from the star adventurer work 😕 Hope I can sort these out before saturday so I can start testing things :D.

I used a normal bolt and just tightened up with a spanner.

 

As for the counterweight bar, I just bought a length of M12 threaded bar from B&Q and cut it to size. I tried the Star Adventurer bar first but it's too short for my setup to balance. I got one of these off ebay. Just need to clean off the locking compound with an old toothbrush under a tap and it fits nicely.

[Snooze]

So I got an M8 bolt for the wedge and a threaded rod for the counterweight. Everything works like a charm

 

Went out tonight to test everything and Go To was not too bad. Everything was in the field of view with my 200mm lens but tracking was all over the place.

 

I pointed the mount with DSLR roughly facing north and centered Polaris in the view finer. Then I did a 2 star alignment on Venus and Sirius. Then told the mount to slew to M42 and it was more or less centered on my DSLR screen. I proceeded to take a 1min exposure and there was no star trails, then a 2min exposure and I got a little bit of star trail. I did a second 2min exposure and suddenly i had lots of star trails. I did a reset and started over again and same result. The first exposure after alignment was good but the next one had star trails. Anyone had a similar issue?

 

First 120s exposure

Second exposure

After that I stopped trying to fix the tracking but instead played around with the Go To which I found was pretty nice.

 

Now for the questions:

1. Does the 2 star or 3 star alignment compensate for bad polar alignment? Or is it used only to for the Go To functions? (first time using a Go To mount)

2. there is a polar alignment feature in the app. I tried it but found that I could not centre the star with altitude/azimuth adjustments(mount probably not level) so I just gave up. Is this feature reliable?

 

What I'm tempted to do next time is mount my little star adventurer with polar scope on the AZ-GTI for polar alignment and then remove it to mount my dslr. 

[michael8554]

Possibly you hit the worst part of your mount's Periodic Error on the 2nd and 3rd shots.

Try taking more exposures and see if there's a pattern to the good and bad exposures.

Michael

[david_taurus83]

That's pretty impressive what you've got with just a rough polar alignment. The 60s shot looks good. At 2 minutes though you really are into the realms of guiding, especially with this little mount that's not really designed with imaging in mind.

[Snooze]

I will try to get a better polar alignment next time and see if i can achieve consistent 2min exposures. In the meantime, here is a processed single shot image at 120s from the last session with rough polar alignment.

 

Cheers

[Snooze]

Is the RA axis of the mount supposed to rotate 360° when the clutch is disengaged? Cause mine has some resistance when trying to rotate it fully around the RA axis. Also this RA axis is a bit stiff on one side. Is it the same for you guys?

[fireballxl5]

that sounds right. The RA axis on mine has some resistance and seems well balanced so does not move unless pushed by hand - I have a counterweight bar. I'd say that the resistance to moving is equal in both directions around RA on mine.

Here's a test shot from last night, 15x180s guided using ASIair Pro.... 1-1.5 arcsec guide error using a 50mm finder/ASI224 guider setup.

HTH, Andy

PS, clearly M3 using my travel setup, a Tak FS60CB @ f4.2 with ASI071MC Pro

PPS, clearly travel at the current time means moving the scope from the garden room to the patio🤣

Edited March 21, 2020 by fireballxl5
added PS

[fireballxl5]

and another shot using the same rig but in slightly better conditions on Sunday evening...this time M51, not really the best focal length with this camera...

 

[Snooze]

That's a great image!

 

I'm stuck inside because of the confinement period 😕 can't wait till this is over so I get to play more with the mount

[Ags]

Here's Messier 3 - AZ-GTi and C6, 333ms frames, kept the 75% best of 42 minutes of data. 6 minutes of lights and darks.

[Snooze]

Hi guys, I played with my AZ-GTi yesterday night and had a lot of fun imaging from my window. Gave guiding a shot and did 2 minutes exposures with a 300mm lens. I roughly pointed the setup North using the compass on my phone and did a 1 star alignment and was surprised when the phd graph showed an RMS of about 3" which was fine by me since my polar alignment was not accurate at all. Go To was really nice too (considering a 1 star alignment) and both of my targets were close to the centre at 300mm  

However I ran into an issue (known issue with the ASI 120MC?) where PHD2 would randomly shift the image or mirror the image which would result in the loss of the guiding star. I had to deal with this all night. Sometimes it would go back to normal after a few seconds but most of the time I had to stop the guiding and start it again but the issue would come back after a couple of minutes. I was very frustrating but I worked through it and capture M5 and M10. 

M5 : 14 * 2min exposures

M10: 21 * 2min exposures

 

Image quality is not the best here because I have a street lamp pointing at my window at about 10m away, but overall I'm happy to have managed to capture these 2 targets.

 

Cheers

[Snooze]

Played some more with my mount these last couple nights. 

First one is Bode's and Cigar at 260mm f7.1. About 20 x 2min exposures guided. Didn't bother going longer because of light pollution.

 

And my latest one, M13 with my Skymax102. 24 x 30s exposures unguided at ISO3200

 

Pretty happy with the mounts performance so far

[robhatherton]

Do you think it would do short subs in AZ? I’ve heard it’s possible in theory and the stacking software might cope with the field rotation. 

Edited May 20, 2020 by robhatherton

[Snooze]

On 20/05/2020 at 14:18, robhatherton said:

Do you think it would do short subs in AZ? I’ve heard it’s possible in theory and the stacking software might cope with the field rotation. 

In theory you should be able to do 20-30s exposures before field rotation becomes noticeable but i have never tried imaging in AZ mode

[robhatherton]

Hi thanks. I’m hoping to get an AZ Gti Mount in the next couple of weeks together with a Starwave Ascent. I believe with a photo adapter I can put the mount on top of my CG4 Celestron tripod which is quite sturdy. Mainly for visual but I’d like to try some imaging as well and it might be an introduction. 
 

I have an xlt 120 refractor but I thought I’d upgrade. I’m already using the mount in AZ configuration as it avoids the awkwardness of a long refractor and eq mount.