I am testing my new mount : the Sky-Watcher AZ-GTI GoTo mount. I am sharing here my setup and my first tests.
============================================================================ What I was looking for... ============================================================================
- replacing both the Vixen Polarie mount and the Star Adventurer mount in one unique mount - 2 motorized axes for easy motion, panoramas, 2 axes guiding... - GoTo for targetting more easily small objects - portable - easy powered
At first sight the AZ-GTI is an alt-az mount so not suitable for photography. Sky-Watcher has released a firmware to turn the mount into an equatorial mount. The firmware was experimental at the beginning but now it seems to be a stable release. I thought it was the right moment to jump into new experiences.
- the AZ-GTI mount + tripod + extension tube (all this is in the full package)
- an equatorial wedge for easy polar alignement. You can use the Star Adventurer one. Mine : link [UPDATE] the chinese wedge was not very strong. Some play in it. I decided to upgrade to the William Optics wedge. Expensive but strong and very pleasant to use (link).
- a polar scope, attached in the blue support : link There is no illumination so I can not see the reticle. Not needed for now in my process. [UPDATE] I do not use the polar scope anymore in DSO setup. Sharpcap is enough.
- counterweight * shaft + counterweights : link * additionnal counterweight : link
- dovetail plate : link The SA plates also works. For simple setup (shooting milky way) I will use the SA ballhead adapter : link
- Samyang 135mm + ASI183MM Pro + ASI to Sony E mount adapter adapter : link [UPDATE] Now I use ASI183MM + ZWO Electronic Filter Wheel (small one) + Canon Samyang 135mm + adaptors.
- Datyson T7c camera (ASI120 clone) + 32mm guidescope * guide scope : link * pan/tilt head : link NB : the guide scope may be better attached, using less weight (the pan/tilt head is heavy) but for now it does the job :)
- focusing * I will use my DIY motorized focuser (link) * for the tests I have used a follow focus ring : link
- powering : from the manual it runs at 12V and it draws 750mA. I have measured the power consumption with a multimeter : when tracking the mount draws about 50 mA. When the motors move at the highest speed the peak is about 300 mA. * in the backyard a classic 12V wall converter will do the job * on the go : -- you can put 8 AA batteries inside the mount ; not very practical to charge 8 batteries but it may be useful one day -- I have successfully tested this 5V->12V/1A converter, plugged to a USB power bank : link -- of course a classic 12V power tank will fit. I have this one : link
- one PC running Windows 10, connected to the mount WIFI
- total weight on the mount is about 3.2 kg. The mount is rated for 5 kg.
- polar alignement : * rough alignement with polar scope : just putting Polaris in the scope. * fine alignement : with Polar Align tool in Sharcap. Works great. [UPDATE] Now i do not use the polar scope anymore when using Sharpcap. Going roughly manually while Sharpcap is solving is enough to be in the pole area. - focusing : with Focus Assistant tool in Sharpcap [UPDATE] I also focus by visually inspecting a star in the field, zooming at 400-600 %. With Samyang 135 at f/2.8 and 1.5 seconds exposure one can see if the star is focus or not. - star alignement : with Sky-Watcher SynScan Pro app (PC or smartphone version). [OLD] 2 stars alignment seems to be enough for this setup (FOV is 3.15° x 2.12°). - targetting : with SynScan Pro app [NEW] What i do now is : * slew to target in SynScan, without doing star alignment * take a picture with Sharpcap (~ 10 s) * launch All Sky Plate Solver software, connect the mount, solve * in SynScan, delete alignment model if any, click align with scan and go back in All Sky to sync * disconnect mount in All Sky, slew to target again in SynScan * If needed, repeat the steps before. For me one iteration is enough - shooting : with Sharcap - guiding : with PHD2
============================================================================ Use cases and results ============================================================================
Please note that these are my own first tests. This is not a complete review of what the mount can do. For instance the tracking results could vary depending on the declination target.
- milky way landscape / timelapse setup : Sony A7s (unmod) + Samyang 24mm, tracked during 30" * minimal setup (no guide scope, small plate, no counter shaft / weight). * shot at f/2.8. * resolution : 72.1" per pixel. * looks no problem. * only rough polar alignment (Polaris in scope).
- milky way close up / landscape / DSO scape / timelapse : Sony A7s + Samyang 135mm, tracked during 30" * same minimal setup except that shaft and counterweight are needed ! * shot at f/2.8. * resolution : 12.82" per pixel. * only rough polar alignment (Polaris in scope) To be confirmed. Maybe I was lucky and a better Polaris position in scope would be needed (this would require illumination to see the reticule) * looks no problem, see pic D, close up in pic E.
- DSO setup, unguided light version * no guide scope, no guiding camera. * shot with 12 nm Ha filter, gain 180, sensor temperature 28°. * focus not at the best in this test. * resolution : 3.66" per pixel. * polar alignement was "Excellent" in Sharcap. * autostretched images. Looks nice until 60" (see pic F and close up in pic G). At 90" there was some trails.
- DSO setup, guided * shot with 12 nm Ha filter, ASI178MM with gain 180, sensor temperature 27°. * resolution : 3.66" per pixel. * polar alignement was between "Fair" and "Good" in Sharcap => possible improvement here. * PHD2 displayed a warning message after calibration => possible improvement here ? * autostretched images. * North America, 4 minutes : looks fine. See pic J and close up pic K. * M31, 5 minutes : fine at 1:1 scale, pix L. However close up (pic M) shows not perfectly round stars.
It's just the beginning but for now I am happy with this mount. A few points : - It looks like a Star Adventurer with additionnal features. - Need more tests to see the possible exposure limits. - GoTo feature is very nice (and fun !). Endless plate solving for targetting is over ^^
Tadej Skofic's YouTube channel (setup tutorials and results) : link David Parks's review on using the AZ-GTI with different devices (Windows PC, ASIAIR, and Stellarmate) : link David Parks's full setup with 73mm APO : link Giant thread on Cloudy Nights : link