Imaging with an AZ-GTI

[Snooze]

On 25/05/2020 at 12:41, robhatherton said:

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. 

Be careful though cause the AZ GTi has a weight limit of 5kg. it's a really nice little mount and I'm having a lot of fun with it.

 

Here are a couple more shots taken with my Skymax102

M104 - Sombrero Galaxy

M57 - Ring Nebula

[robhatherton]

Nice! I’ve seen the Ring Nebula though not in colour of course! Haven’t managed to see the Sombrero Galaxy but I’m hoping the goto will help.

The Ascent weighs about 4kg and my camera is an Olympus Pen so weighs less than a typical full frame slr. The mount will be on a sturdier tripod than the one that is supplied as standard so I’m cautiously optimistic.

[Ags]

I am working on this M57 with my AZ GTi. Gathered 30 minutes of data but only stacked 50% of it so there's still a lot of noise...

:

 

[Snooze]

I got my 72ED pro a couple weeks ago but the weather has not been nice and I have only got 2 sessions out of it so far. The whole setup balances quite well on the AZ-GTi and stars are nice and sharp! There is still CA but much less that any of the lenses I have which is an improvement for me. So far I'm happy with the setup

M51 - Whirlpool Galaxy => 150s subs ISO400 from my light polluted sky for a total of about 40min

M27 - Dumbbell Nebula => 150s subs ISO400 for a total of around 1h. There was a thin layer of cloud when I imaged this target which took away some details

Cheers

 

[fireballxl5]

5 minutes ago, Snooze said:

M51 - Whirlpool Galaxy

 

6 minutes ago, Snooze said:

M27 - Dumbbell Nebula

love the colours in both of these images - nice👍

[fozzybear]

8 minutes ago, Snooze said:

I got my 72ED pro a couple weeks ago but the weather has not been nice and I have only got 2 sessions out of it so far. The whole setup balances quite well on the AZ-GTi and stars are nice and sharp! There is still CA but much less that any of the lenses I have which is an improvement for me. So far I'm happy with the setup

M51 - Whirlpool Galaxy => 150s subs ISO400 from my light polluted sky for a total of about 40min

M27 - Dumbbell Nebula => 150s subs ISO400 for a total of around 1h. There was a thin layer of cloud when I imaged this target which took away some details

Cheers

 

nice images yet in anger to try my new ed72. where about in France are you?

[Snooze]

15 hours ago, fozzybear said:

nice images yet in anger to try my new ed72. where about in France are you?

Thanks! Yes, the weather has been all other the place in France lately.

And I'm in the south of France, in the pink city ^^

[fozzybear]

6 hours ago, Snooze said:

Thanks! Yes, the weather has been all other the place in France lately.

And I'm in the south of France, in the pink city ^^

last time I was there was over 20 years ago at (Airbus) but never left the compound as didn't have my passport flew in and out the same day with work commitments. hope one day to make it down their, beautiful region.

[Icesheet]

I’m waiting on parts for a new mount so I thought I’d dust off the AZ Gti I have and give it a go for imaging in EQ mode. 
 

Shot the North American and Pelican nebula in HA with an Askar FMA180 and ASI1600mm. 30x120sec unguided (darks but no flats here). It seems that’s the absolute limit for me unguided with this. I fiddled for ages with PA and stars still aren’t as round as I would like (camera spacing is also out a little). I even had to throw a good % of subs away. That being said if I add guiding and with the ASIair pro, I think this has great potential for a travel kit. Happy I dusted it off now!

 

Edited September 6, 2020 by Icesheet

[Snooze]

The Great Orion Nebula and the running man nebula - 20 x 120s subs at ISO400

[gaz81]

Well, I certainly like my AZ GTI. 
 

Not that I’ve had any other mounts to compare it to. 
 

 

[wormix]

I have one coming (one day - been a month so far!). Really looking forward to seeing how it performs vs my HEQ5 and EQ5
 

Going to give some basic imaging a try and use it for my new EEVA setup.

[Snooze]

I've been enjoying my AZ GTi too. Personally i'd say that you cannot get a better guided setup at this price point. The only issue I have with the mount is the lack of a polar scope but other than that I'm pretty happy with it.

 

 

[DroneSaif]

Hi.

 

I am planning to get the following :-

1. Astro Essential 32mm Guide Scope (https://www.firstlightoptics.com/.../astro-essentials...)
2. ZWO 120MC camera (https://www.firstlightoptics.com/.../zwo-asi120mc-s-usb-3...) 

 

Can I use the above combo to guide the AZ-GTI with the following ?

 

Current Setup : 

Sony RX10M3 camera 

( Effective 24-600mm F2.4-4, or 8.8-220mm)

 

Target Setup

 

1. William Optics GT71 (https://www.firstlightoptics.com/.../william-optics-gt-71...)
2. ZWO ASI 178MM (https://www.firstlightoptics.com/.../zwo-asi178mm-usb-3...) Or better

 

Any suggestions would be gratefully received

Edited October 20, 2020 by DroneSaif

[johngm]

15 hours ago, Snooze said:

I've been enjoying my AZ GTi too. Personally i'd say that you cannot get a better guided setup at this price point. The only issue I have with the mount is the lack of a polar scope but other than that I'm pretty happy with it.

 

 

I use my guide scope camera via Sharp cap polar alignment routine. Works a treat 👍

[Snooze]

10 hours ago, DroneSaif said:

Hi.

 

I am planning to get the following :-

1. Astro Essential 32mm Guide Scope (https://www.firstlightoptics.com/.../astro-essentials...)
2. ZWO 120MC camera (https://www.firstlightoptics.com/.../zwo-asi120mc-s-usb-3...) 

 

Can I use the above combo to guide the AZ-GTI with the following ?

Yes, you should be able to guide the mount without any issues with the 120MC-S and guide scope you mentioned

[DroneSaif]

8 hours ago, Snooze said:

Yes, you should be able to guide the mount without any issues with the 120MC-S and guide scope you mentioned

Thank you sir!

 

Now to wait for them to be in stock....

Edited October 21, 2020 by DroneSaif
added a final line

[Bobby1970]

Very interesting thread this is. 

I've been using my AZGti along with ASIAir Pro recently. I guide it using a small guidescope and 120 mini. 

I had some backlash which seemed to affect my images and guiding performance so I disassembled the mount and removed as much of the backlash as I could. Last time out I lost no subs at all guiding at 180s. I use a 72mm semi apo scope and zwo 178mc camera. 

My most recent effort was this :-

[kodurann]

Hi I recently bought AZ-GTi and WO Zenithstar 73 (430/73) and am using my Canon 90D for astrophotography. Can you guys tell me how does this mount perform without auto-guiding, assuming I am doing rough polar and 3 star alignments?

[vlaiv]

7 minutes ago, kodurann said:

Hi I recently bought AZ-GTi and WO Zenithstar 73 (430/73) and am using my Canon 90D for astrophotography. Can you guys tell me how does this mount perform without auto-guiding, assuming I am doing rough polar and 3 star alignments?

In my view - it is rather limited in performance without auto guiding - but not unlike other larger mounts as well.

I used it with resolutions of around 10"/px and it is good for about 1 minute exposures in those conditions.

Your setup is much more "zoomed in" at 1.53"/px and I would not even try to image without guiding if you want to have sensible sub duration.

Also, given that you have 73mm of aperture - use super pixel debayer mode to give you around 3"/px. With guiding and around 1-1.5" guide RMS, that should be about right sampling rate.

[Adam J]

I have one of these on order and I would not dream of trying to use it at 1.53 RMS even with auto guiding. I think this mount is for scopes up to about 60mm aperture / 300mm focal length really or you will most likely lose subs. Ill be using mine at 180mm focal length for portable wide field imaging. 

Adam 

[vlaiv]

2 minutes ago, Adam J said:

I have one of these on order and I would not dream of trying to use it at 1.53 RMS even with auto guiding. I think this mount is for scopes up to about 60mm aperture / 300mm focal length really or you will most likely lose subs. Ill be using mine at 180mm focal length for portable wide field imaging. 

Adam 

I'm awaiting for delivery of that AstroEssentials 30mm guide scope from FLO, so I'll be able to see how well AzGti guides. I'm hoping for 1-1.5 total RMS guide figures - something tells me mount should be able to achieve that, but we will see.

If it indeed guides up to 1.5 RMS total - I would not mind imaging in 3-4"/px resolution with it. In fact - I plan to do just that for fun - use 1300mm FL scope (mak102) and image at about 3"/px with it

What I wanted to say is - it's not the focal length, it is sampling resolution that counts.

[Adam J]

17 minutes ago, vlaiv said:

I'm awaiting for delivery of that AstroEssentials 30mm guide scope from FLO, so I'll be able to see how well AzGti guides. I'm hoping for 1-1.5 total RMS guide figures - something tells me mount should be able to achieve that, but we will see.

If it indeed guides up to 1.5 RMS total - I would not mind imaging in 3-4"/px resolution with it. In fact - I plan to do just that for fun - use 1300mm FL scope (mak102) and image at about 3"/px with it

What I wanted to say is - it's not the focal length, it is sampling resolution that counts.

My setup comes out at 4.2 arc-seconds per pixel so ill be fine as long as the RMS is lower than 2. Above I meant to say 1.53 arc-seconds per pixel but wrote RMS by mistake. 

The problem with this mount is its periodic error is not guided is >6 arc-seconds and over a reasonably short period. Or so I am told, hence not suitable for use unguided for imaging. Unless you have a very big pixel scale. 

Adam

[shropshire lad]

I got my AZ-GTI 3 days ago and havent had a clear night yet, will be using either my Canon 80D and 70-200mm f2.8 lens or my SX50 bridge camera.

As I'm new to astro I will start with AZ and later try EQ mode, need to get a M12 long threaded bolt and some weights first though.

Any tips or help would be greatly received.

 

 

[vlaiv]

17 minutes ago, Adam J said:

The problem with this mount is its periodic error is not guided is >6 arc-seconds and over a reasonably short period. Or so I am told, hence not suitable for use unguided for imaging. Unless you have a very big pixel scale. 

I did not actually measured PE error precisely from this mount, but we can do some very basic assessment of how it behaves.

Here is animated gif that displays effects of tracking errors over a course of one hour (60 subs of 1 minute):

Ra is roughly aligned with X axis and Y is DEC (there is very small drift in DEC due to rough polar alignment - I just used finder scope and pointed it to Polaris - not actual polar scope and did not account for offset).

I counted 6 "returns" of the star over the course of one hour - that corresponds with my calculation that worm period should be 10 minutes / 600 seconds.

According to this page:

http://eq-mod.sourceforge.net/prerequisites.html

It has 144 RA teeth - and hence each tooth in worm is 24 * 60 / 144 = 1440 / 144 = 10 minutes.

Stepper resolution is given as 0.0625" - which I believe is error and should be 0.625" according to other numbers. About x3-x4 should be guide RMS if I compare that to my HEQ5 that guides at 0.5" RMS and has ~0.143" step.

Although, I've heard a claim that AzGTI does not use stepper motors but plain DC motors instead, coupled with encoders? Not sure (I did open my mount to fix backlash, but did not pay attention. There are 4 wires to each motor if that means anything).

As for magnitude of the error - it goes like this, I measured 13px p2p on x4 zoomed in image, that makes 3.25px p2p on original image. Original image is roughly 4.8µm pixel at 85mm FL, so 11.65"/px.

This means that p2p is roughly around 40" - not unexpected given that entry level Synta mounts like Eq3 and Eq5 (even odd Heq5) have similar p2p values (30-40" p2p).

From what I'm seeing - it should be ok to guide this mount at about, well, maybe not 1-1.5" RMS (because of stepper resolution) but 1.5-2.0" RMS certainly.