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Sky Watcher AZ GTI Mount ?


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Hi All,

Is anybody using the skywatcher AZ GTI mount for wide field AP with DSLR and William optics zenith star 61 ?

I know it’s not ideal but wondered what  are the real world experiences with using this combo or similar.

I'm trying to keep as portable and mobile as possible, and by time I’ve priced up something like the ioptron skyguider pro I’m at the point of getting an EQ 5 & kind of defeating the objective.

any thoughts ?

Regards

Andy H

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Just to mention that if you want to guide with a Linux installation such as Astroberry on a Raspberry Pi 4 (KStars/Ekos/Indi), for instance, there is a bug in this latest Firmware V 3.26 which stops t

I'm using it for wide field. With 85mm Samyang lens, and 50mm Canon lens - I can do 60s without much trailing. This is with DSLR and Canon IS STM 55-250. In the mean time I added proper

Ah, ok, here it is in short (although topic by itself is rather large). AzGti is as it name suggests a Alt Azimuth mount. Such mount can track object for longer periods of time but is not suitabl

Posted Images

I use a SW 72 ED / reducer /EFW/OAG/ ZWO 1600 pro on mine, Unguided it's not going to go over about 15 seconds without trailing but guided It works really well.

I get PHD2 graphs usually under 2 rms which is fine for my pixel scale.

Old picture, using an OAG now.

IMAG0748.jpg

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I'm using it for wide field.

With 85mm Samyang lens, and 50mm Canon lens - I can do 60s without much trailing.

setup.jpg

This is with DSLR and Canon IS STM 55-250. In the mean time I added proper wedge to it.

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1 minute ago, Adam J said:

I will be using one at 180mm guided will have to see how it turns out. 

I'll also switch to guided subs - but mostly for dithering rather than actual guiding. If I ever get my new guide scope, that is (order from FLO about month and a half ago - but seems perpetually to be expected in 20-25 days).

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Thanks guys.

Interesting, both pictures seem to be using the Gti with a wedge or ball head? Can you explain to a noob why ? Does it give best of both worlds AZ + EQ ?

with regards to “guiding” in very simple terms can you explain the kit required ? I get the principal but not sure on the why when the mounts profess to track the target object anyway ?

 

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8 minutes ago, Newforestgimp said:

Thanks guys.

Interesting, both pictures seem to be using the Gti with a wedge or ball head? Can you explain to a noob why ? Does it give best of both worlds AZ + EQ ?

with regards to “guiding” in very simple terms can you explain the kit required ? I get the principal but not sure on the why when the mounts profess to track the target object anyway ?

 

Ah, ok, here it is in short (although topic by itself is rather large).

AzGti is as it name suggests a Alt Azimuth mount. Such mount can track object for longer periods of time but is not suitable for astrophotography because this sort of tracing creates field rotation - image slowly rotates on sensor and you get this sort of effect:

image.png.8813ee7ab88780c4d28a6ad73dabf475.png

(These are actually star trails recorded from a fixed mounting - but effect is the same - due to not compensating for earth's rotation).

When you want to compensate for earth's rotation and do proper imaging - you use equatorial mount. Alt azimuth and equatorial mount are rather similar - in fact they are the same in construction with only one difference - where main axis is pointing. With Alt Az mount - it is pointing straight up, but with eq mount it needs to point to celestial pole. In fact - alt azimuth mount is equatorial mount if one is at the north pole and celestial equator is straight up :D

In any case - there is firmware for AzGTI that tells it that it is now in EQ mode (you can switch between two modes each time you connect to the mount) - but in order for it to work properly - you need to get a wedge.

For good tracking in EQ mode, you also need to have CW - luckily it is rather easy to do - it already has connection and you can DIY one or purchase Star Adventurer that can be screwed in with simple adaper (M8 to M12 I think). I think that EQ1/EQ2 counterweight bar fits without modifications, but I'm not sure.

You can use CW in AZ mode as well - it provides more balance and stability.

For guiding to work, you'll need guide scope, some sort of side by side arrangement, guide camera, and computer. There are stand alone guiders as well, but I think that one would need hand controller for AzGti in order to connect guider to ST4 port.

I'll be using Raspberry PI4 with IndigoSky server and my phone for portable setup.

Here is what that setup might look like (I've found this online to show what I mean, I'm actually going to use larger side by side saddle plate that I already own for my setup)

lJVdQ7M1QAsl_1824x0_kWXURFLk.jpg

 

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7 minutes ago, vlaiv said:

Ah, ok, here it is in short (although topic by itself is rather large).

AzGti is as it name suggests a Alt Azimuth mount. Such mount can track object for longer periods of time but is not suitable for astrophotography because this sort of tracing creates field rotation - image slowly rotates on sensor and you get this sort of effect:

image.png.8813ee7ab88780c4d28a6ad73dabf475.png

(These are actually star trails recorded from a fixed mounting - but effect is the same - due to not compensating for earth's rotation).

When you want to compensate for earth's rotation and do proper imaging - you use equatorial mount. Alt azimuth and equatorial mount are rather similar - in fact they are the same in construction with only one difference - where main axis is pointing. With Alt Az mount - it is pointing straight up, but with eq mount it needs to point to celestial pole. In fact - alt azimuth mount is equatorial mount if one is at the north pole and celestial equator is straight up :D

In any case - there is firmware for AzGTI that tells it that it is now in EQ mode (you can switch between two modes each time you connect to the mount) - but in order for it to work properly - you need to get a wedge.

For good tracking in EQ mode, you also need to have CW - luckily it is rather easy to do - it already has connection and you can DIY one or purchase Star Adventurer that can be screwed in with simple adaper (M8 to M12 I think). I think that EQ1/EQ2 counterweight bar fits without modifications, but I'm not sure.

You can use CW in AZ mode as well - it provides more balance and stability.

For guiding to work, you'll need guide scope, some sort of side by side arrangement, guide camera, and computer. There are stand alone guiders as well, but I think that one would need hand controller for AzGti in order to connect guider to ST4 port.

I'll be using Raspberry PI4 with IndigoSky server and my phone for portable setup.

Here is what that setup might look like (I've found this online to show what I mean, I'm actually going to use larger side by side saddle plate that I already own for my setup)

lJVdQ7M1QAsl_1824x0_kWXURFLk.jpg

 

That's a really helpful summary for someone like me, who is thinking about buying a portable mount at some point in the future. Thank you.

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8 minutes ago, Tiny Clanger said:

That's a really helpful summary for someone like me, who is thinking about buying a portable mount at some point in the future. Thank you.

Agree, very very interesting, as it happens I have an EQ1 mount so could pinch the counterweight.

do you ever have any feelings that the Gti is struggling to cope with the weight ? As it must be getting close to its payload limit ?

Andy

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Yes, goto works perfectly well when in EQ mode - as long as you apply proper firmware first.

You can get it from official SW website here: http://www.skywatcher.com/download/software/motor-control-firmware/

image.png.87205634d86d8c00a999e97e91a8d48b.png

I've so far only mounted lighter things on my AzGTI - both in az mode - Skywatcher Mak102 and in EQ mode - Canon + lens, or Samyang 85mm + cooled astro camera and adapter.

In every case, I think I was below 3Kg and it worked fine.

There are couple of things with this mount that I've found somewhat annoying.

- In visual mode - there is no tactile feedback when using phone to and looking at the eyepiece - you have no idea what you should be pressing to move scope in particular direction. You need to look at phone to make adjustment which is bad for DSO observing as it ruins night vision. Can be solved by adding hand controller (but it costs quite a bit to do so).

- There was some backlash in my sample that I needed to tune out. It can be done but one needs a bit of technical skills to do it - it requires disassembling the unit. There is tutorial on how to do it on youtube.

- There is a bit to much friction in both axis - although mount is using bearings. This makes balancing rather difficult. Again, there is tutorial on how to deal with that, but I did not do it on my unit. I feel this is something that may need be addressed if one is putting more weight on the mount than I do at the moment.

As far as precision of this mount - I would say that people should limit themselves to about 300mm of focal length. I don't like to express things in terms of focal length as it is rather imprecise, so I'll give another measure that is more precise - I think that mount is good for up to 3"/px sampling rate as I think it will be able to guide in 1.2-1.5" RMS range (this is based on stepper motor resolution and general feel of the mount - I still have not guided it yet to be 100% certain).

It is therefore good mount for scopes like 72ED with reducer flattener and 50/60mm apos - for imaging. Various lens can be used as well.

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7 hours ago, vlaiv said:

I'm using it for wide field.

With 85mm Samyang lens, and 50mm Canon lens - I can do 60s without much trailing.

setup.jpg

This is with DSLR and Canon IS STM 55-250. In the mean time I added proper wedge to it.

How are you using the ball head ? 

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31 minutes ago, Newforestgimp said:

How are you using the ball head ? 

Well, I did say that I added a proper wedge in the mean time since ball head is a bit of a pain to use, really.

I'm going to explain the principle of polar alignment for both ball head and proper wedge because they differ only in mechanics of motion - not the principle of operation. Proper wedge has separate controls for alt and az adjustment, while ball head, at least the model I have - has azimuth separately, but altitude is combined with "spin". Spin is of no consequence for polar alignment, so one only needs to be careful when handling ball head not to make large moves - otherwise it will be the same as proper wedge.

Here is the image of my setup for polar alignment:

polar_align.jpg

It is so simple - even my dog can do it in daylight - as this image documents :D

You don't need dedicated polar scope - simple finder scope will do. One I'm using is Skywatcher 50mm x8 (or is it x9 - does not really matter).

First thing to know is - how precise you want your polar alignment to be. Most people blame polar alignment for trailing in the images, but I've found that even mediocre polar alignment will not cause as much trailing as periodic error. In most cases periodic error will be limiting factor on your exposure and not polar alignment.

For example, if I'm imaging with 85mm lens and using 4.8µm pixel camera, I'm imaging at 11.65"/px

image.png.25cd174becd0e44d6f3e49b0dafa0bfd.png

(use this calculator for above: http://www.wilmslowastro.com/software/formulae.htm#ARCSEC_PIXEL)

I know that this might seem scary - math and all those strange terms, but don't worry about details now. I just want to put some perspective on how important polar alignment is or is not for wide field use (but if you follow the math - you'll be able to apply it for your use case as well).

This means that if I don't want any trailing due to polar alignment error, drift rate due to polar alignment error needs to be about 1px or less. Let's say I want to do 60 second exposure. My drift rate must be less than 1px / 60s = 11.65" / 60s = ~ 0.194"/s (or 11.65" per minute).

Using this tool: http://celestialwonders.com/tools/driftRateCalc.html

We can calculate drift rate based on how far away we are from NCP (North celestial pole).

For example if I'm 44 arc minutes away from NCP (you'll see later why is this important), I get this result in worst case scenario:

image.png.752b8f7653d1a46b230b8852043d5cba.png

My drift rate is 11.5" per minute - very nice, I'll have just shy 1px of drift per exposure in worst case scenario.

Why did I choose 44 arc minutes, you may wonder? Well, it is because of this:

image.png.f44bbe3a1a3a0bd44247841e0e7b8d6c.png

Polaris is roughly 44 arc minutes away from NCP. If you polar align to Polaris or closer - you'll get above drift rate or better. Btw, 44 arc minutes is 50% larger angular size than the full Moon!

Both the Moon and the Sun roughly have half of degree of angular diameter - that is 30 arc minutes. So you can be as much as full Moon width away from true north and still have no trailing in wide field shots.

This just shows level of importance of precise polar alignment - with wide field - it is not as important as often believed.

Ok, now on to polar alignment procedure (same for ball head and for wedge).

1. Align finder scope to RA axis.

In this part - you only need to touch alignment bolts on finder scope - and not ball head / wedge (you will move them but not for alignment purposes).

- Turn finder scope to one side of pier - let's say east (make finder scope lie on its "side" - much like in image above).

- Using ball head / wedge  - train cross hairs of finder scope onto Polaris

- Now turn finder scope on other side of pier - west (if first one was east) by rotating mount 180 around RA axis.

- Look thru finder scope - if Polaris is still under cross hairs in the center - you are done. If Polaris is off center - use finder scope adjustment screws to move finder cross hairs half way between where it is and Polaris.

Here is diagram for better understanding:

image.png.693fd0796efad828e65fc047be78434d.png

After that, return to step one of this part and repeat (move finder scope east of pier, center on Polaris, .....)

It usually takes only one to two rounds to align finder scope with RA axis if you are careful and Polaris stays under cross hairs on both sides of pier. Btw - you move east / west of pier by releasing RA clutch and rotating whole mount - not by wedge / ball head nor by adjusting polar scope.

2. Part two - polar alignment.

- If you are happy with 44 arc minutes of polar alignment error - you are done, just leave cross hairs on Polaris

- If you want more precise polar alignment, then you need to either use same finder as I'm having or get Stellarium and Oculars plugin. It allows you to simulate what you'll see thru your finder scope.

image.png.e5cde7330002acc98d975265f9d448c8.png

This is roughly the view you'll see thru 8x50 finder. There are three important stars. First is obviously Polaris - it will be by far the strongest one. There are two additional stars - around magnitude 6. They will be visible and brighter than other stars so you should not be having trouble identifying them - but they will not be as bright as Polaris. You find them by finding nearest bright star to Polaris and then finding next star by distance from Polaris - having same brightness as that first one.

Procedure is fairly simple - imagine line connecting those two other stars. Find middle of that line and mentally make line perpendicular to it. Take two lengths of distance between first line and Polaris. That is the place you should put your finder cross hairs at. Do it by moving wedge / ball head in az and alt.

Here is what it should look like without "helper" lines and markings:

image.png.0e7ffb9a33452ddda857ba26e2c37b4c.png

Note that rotation of stars will be different each time you do this, but relative distances will be the same if you use same finder scope.

With this method you'll get within 5-10 arc minutes of NCP which is good 2.6" / minute of drift. Good for one minute exposure under highest resolutions I would recommend being imaged on this mount (3"/px), or longer exposure if you use lower resolution.

In fact, like I said - periodic error is more likely to cause issues than polar alignment. I think that worm period for AzGTI is around 10 minutes. With common periodic error for small mount of around 60" - this gives us something like 10" / minute of drift or worse (depends on actual PE curve). This is at best on level of Polar alignment error drift - and probably worse.

Here is animation from my recent session with AzGti. This is one hour of exposure - 60 x 60s exposures - not aligned and animated to show star drift:

azgti.gif.6d90238efd47ea97b1b279f1afe4d71c.gif

Left to right motion is due to periodic error of the mount and slight downward drift is due to polar alignment error. You can see drastic difference between the magnitude of the two errors, and it also nicely shows how "periodic" - periodic error is (hence the name obviously).

In order to combat periodic error - one really needs to guide (or use periodic error correction  - but that is whole another story).

 

 

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28 minutes ago, vlaiv said:

Well, I did say that I added a proper wedge in the mean time since ball head is a bit of a pain to use, really.

I'm going to explain the principle of polar alignment for both ball head and proper wedge because they differ only in mechanics of motion - not the principle of operation. Proper wedge has separate controls for alt and az adjustment, while ball head, at least the model I have - has azimuth separately, but altitude is combined with "spin". Spin is of no consequence for polar alignment, so one only needs to be careful when handling ball head not to make large moves - otherwise it will be the same as proper wedge.

Here is the image of my setup for polar alignment:

polar_align.jpg

It is so simple - even my dog can do it in daylight - as this image documents :D

You don't need dedicated polar scope - simple finder scope will do. One I'm using is Skywatcher 50mm x8 (or is it x9 - does not really matter).

First thing to know is - how precise you want your polar alignment to be. Most people blame polar alignment for trailing in the images, but I've found that even mediocre polar alignment will not cause as much trailing as periodic error. In most cases periodic error will be limiting factor on your exposure and not polar alignment.

For example, if I'm imaging with 85mm lens and using 4.8µm pixel camera, I'm imaging at 11.65"/px

image.png.25cd174becd0e44d6f3e49b0dafa0bfd.png

(use this calculator for above: http://www.wilmslowastro.com/software/formulae.htm#ARCSEC_PIXEL)

I know that this might seem scary - math and all those strange terms, but don't worry about details now. I just want to put some perspective on how important polar alignment is or is not for wide field use (but if you follow the math - you'll be able to apply it for your use case as well).

This means that if I don't want any trailing due to polar alignment error, drift rate due to polar alignment error needs to be about 1px or less. Let's say I want to do 60 second exposure. My drift rate must be less than 1px / 60s = 11.65" / 60s = ~ 0.194"/s (or 11.65" per minute).

Using this tool: http://celestialwonders.com/tools/driftRateCalc.html

We can calculate drift rate based on how far away we are from NCP (North celestial pole).

For example if I'm 44 arc minutes away from NCP (you'll see later why is this important), I get this result in worst case scenario:

image.png.752b8f7653d1a46b230b8852043d5cba.png

My drift rate is 11.5" per minute - very nice, I'll have just shy 1px of drift per exposure in worst case scenario.

Why did I choose 44 arc minutes, you may wonder? Well, it is because of this:

image.png.f44bbe3a1a3a0bd44247841e0e7b8d6c.png

Polaris is roughly 44 arc minutes away from NCP. If you polar align to Polaris or closer - you'll get above drift rate or better. Btw, 44 arc minutes is 50% larger angular size than the full Moon!

Both the Moon and the Sun roughly have half of degree of angular diameter - that is 30 arc minutes. So you can be as much as full Moon width away from true north and still have no trailing in wide field shots.

This just shows level of importance of precise polar alignment - with wide field - it is not as important as often believed.

Ok, now on to polar alignment procedure (same for ball head and for wedge).

1. Align finder scope to RA axis.

In this part - you only need to touch alignment bolts on finder scope - and not ball head / wedge (you will move them but not for alignment purposes).

- Turn finder scope to one side of pier - let's say east (make finder scope lie on its "side" - much like in image above).

- Using ball head / wedge  - train cross hairs of finder scope onto Polaris

- Now turn finder scope on other side of pier - west (if first one was east) by rotating mount 180 around RA axis.

- Look thru finder scope - if Polaris is still under cross hairs in the center - you are done. If Polaris is off center - use finder scope adjustment screws to move finder cross hairs half way between where it is and Polaris.

Here is diagram for better understanding:

image.png.693fd0796efad828e65fc047be78434d.png

After that, return to step one of this part and repeat (move finder scope east of pier, center on Polaris, .....)

It usually takes only one to two rounds to align finder scope with RA axis if you are careful and Polaris stays under cross hairs on both sides of pier. Btw - you move east / west of pier by releasing RA clutch and rotating whole mount - not by wedge / ball head nor by adjusting polar scope.

2. Part two - polar alignment.

- If you are happy with 44 arc minutes of polar alignment error - you are done, just leave cross hairs on Polaris

- If you want more precise polar alignment, then you need to either use same finder as I'm having or get Stellarium and Oculars plugin. It allows you to simulate what you'll see thru your finder scope.

image.png.e5cde7330002acc98d975265f9d448c8.png

This is roughly the view you'll see thru 8x50 finder. There are three important stars. First is obviously Polaris - it will be by far the strongest one. There are two additional stars - around magnitude 6. They will be visible and brighter than other stars so you should not be having trouble identifying them - but they will not be as bright as Polaris. You find them by finding nearest bright star to Polaris and then finding next star by distance from Polaris - having same brightness as that first one.

Procedure is fairly simple - imagine line connecting those two other stars. Find middle of that line and mentally make line perpendicular to it. Take two lengths of distance between first line and Polaris. That is the place you should put your finder cross hairs at. Do it by moving wedge / ball head in az and alt.

Here is what it should look like without "helper" lines and markings:

image.png.0e7ffb9a33452ddda857ba26e2c37b4c.png

Note that rotation of stars will be different each time you do this, but relative distances will be the same if you use same finder scope.

With this method you'll get within 5-10 arc minutes of NCP which is good 2.6" / minute of drift. Good for one minute exposure under highest resolutions I would recommend being imaged on this mount (3"/px), or longer exposure if you use lower resolution.

In fact, like I said - periodic error is more likely to cause issues than polar alignment. I think that worm period for AzGTI is around 10 minutes. With common periodic error for small mount of around 60" - this gives us something like 10" / minute of drift or worse (depends on actual PE curve). This is at best on level of Polar alignment error drift - and probably worse.

Here is animation from my recent session with AzGti. This is one hour of exposure - 60 x 60s exposures - not aligned and animated to show star drift:

azgti.gif.6d90238efd47ea97b1b279f1afe4d71c.gif

Left to right motion is due to periodic error of the mount and slight downward drift is due to polar alignment error. You can see drastic difference between the magnitude of the two errors, and it also nicely shows how "periodic" - periodic error is (hence the name obviously).

In order to combat periodic error - one really needs to guide (or use periodic error correction  - but that is whole another story).

 

 

Wow !! There’s a lot to digest there but I think I get it, I’ll need to read through a few more times but thank you ever so much for taking the time to explain. It’s looking like there is definitely more than one way to skin a cat.

where would I find the ccd pixel size value ? I guess googling the cameras specs ?

👍

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6 minutes ago, Newforestgimp said:

where would I find the ccd pixel size value ? I guess googling the cameras specs ?

Yes - that is the easiest way to do it - check the specs.

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I'm a happy AZ-GTi user. It's a worthy upgrade over traditional "trackers" if you want the Go-To functionality, while keeping a lightweight package similar to a StarAdventurer or SkyGuider.

It also works very well in Alt-Az mode (i.e. non equatorial), which is very convenient if you want to do planetary imaging or observing with small scopes as well. I'm using it with a small 4" Maksutov, and everything fits in a backpack. That's great for sharing our passion with some friends or family, without bringing a truck full of gear!

The only thing to bear in mind is that the AZ-GTi is designed to be an Alt-Az mount, and nothing else. Everything on top (the equatorial mod, auto guiding, etc.) is a bonus, courtesy of Sky-Watcher, and is more in the realm of experimentation. This mount has its quirks, and a lot of users end up frustrated because of them. But again, this mount was only designed for Alt-Az mode, and given its price point, we can't ask too much of it!

This being said, mine has been working flawlessly, but it took some time to figure everything out and find the right accessories to solve the little problems I encountered. I think this mount unlocks its full potential when paired with a device like the ASIAIR, that brings easy polar alignment, plate solving, autoguiding, automated imaging sequences, etc. It's really the perfect companion for the AZ-GTi in my opinion, if you want ultimate portability but with advanced functionalities.

Useful upgrades I would recommend if you have the budget:

  • A counter weight is very recommended, for any setup > 1kg. I think the one from the EQ1 is compatible.
  • The saddle from ADM, it's much better than the default one and doesn't drill holes in your dovetail bars...
  • The EQDIR USB cable, it really makes everything easier. You can control the mount via Wi-Fi, but a direct connection is always easier!
  • The polar wedges from Sky-Watcher and iOptron work well, but the one from William Optics is just so much better. Pricey, but worth it!

There's a group of AZ-GTi users on Facebook, if you're looking for tips: https://www.facebook.com/groups/402745617192175

Here are a few pics I took with the setup below (William Optics RedCat 51, ZWO ASI1600MM or Fujifilm X-T3) :)  Exposures were between 180s for M31 and 600s for nebulae, guided in RA only with the ASIAIR.

7F301345-4C13-427B-9AE4-3BF53B9CF04A-555-000000597C3BBEC9.thumb.JPG.c63c36a3a7d9ded387a9e54bdf0819bf.JPG

NGC7000_202008_XT3_v1.thumb.jpg.382389ddb0bce3dfb58a4c325e8ee939.jpg

B455D165-75C1-4BC9-A74E-2B1FECBBCCFB-8853F85F-0B46-490D-99FE-481007813976.JPG.cdf68a37ba0bb4c3896114d6eebafd0c.JPG

A313F45A-5D59-46AC-8C62-1085CD9AA341-105FD9B6-82BA-4BE3-AC31-AF3B84FCB2F7.thumb.JPG.c8b6f1520e3fc8bdd812013b1a915951.JPG

Edited by Space Oddities
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On 21/11/2020 at 00:59, Space Oddities said:

I'm a happy AZ-GTi user. It's a worthy upgrade over traditional "trackers" if you want the Go-To functionality, while keeping a lightweight package similar to a StarAdventurer or SkyGuider.

It also works very well in Alt-Az mode (i.e. non equatorial), which is very convenient if you want to do planetary imaging or observing with small scopes as well. I'm using it with a small 4" Maksutov, and everything fits in a backpack. That's great for sharing our passion with some friends or family, without bringing a truck full of gear!

The only thing to bear in mind is that the AZ-GTi is designed to be an Alt-Az mount, and nothing else. Everything on top (the equatorial mod, auto guiding, etc.) is a bonus, courtesy of Sky-Watcher, and is more in the realm of experimentation. This mount has its quirks, and a lot of users end up frustrated because of them. But again, this mount was only designed for Alt-Az mode, and given its price point, we can't ask too much of it!

This being said, mine has been working flawlessly, but it took some time to figure everything out and find the right accessories to solve the little problems I encountered. I think this mount unlocks its full potential when paired with a device like the ASIAIR, that brings easy polar alignment, plate solving, autoguiding, automated imaging sequences, etc. It's really the perfect companion for the AZ-GTi in my opinion, if you want ultimate portability but with advanced functionalities.

Useful upgrades I would recommend if you have the budget:

  • A counter weight is very recommended, for any setup > 1kg. I think the one from the EQ1 is compatible.
  • The saddle from ADM, it's much better than the default one and doesn't drill holes in your dovetail bars...
  • The EQDIR USB cable, it really makes everything easier. You can control the mount via Wi-Fi, but a direct connection is always easier!
  • The polar wedges from Sky-Watcher and iOptron work well, but the one from William Optics is just so much better. Pricey, but worth it!

There's a group of AZ-GTi users on Facebook, if you're looking for tips: https://www.facebook.com/groups/402745617192175

Here are a few pics I took with the setup below (William Optics RedCat 51, ZWO ASI1600MM or Fujifilm X-T3) :)  Exposures were between 180s for M31 and 600s for nebulae, guided in RA only with the ASIAIR.

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NGC7000_202008_XT3_v1.thumb.jpg.382389ddb0bce3dfb58a4c325e8ee939.jpg

B455D165-75C1-4BC9-A74E-2B1FECBBCCFB-8853F85F-0B46-490D-99FE-481007813976.JPG.cdf68a37ba0bb4c3896114d6eebafd0c.JPG

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Intrigued by the photo of your setup, what is the device that seems to be off the side of the focuser area ? I can’t quite make it out.

andy

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1 hour ago, Newforestgimp said:

Intrigued by the photo of your setup, what is the device that seems to be off the side of the focuser area ? I can’t quite make it out.

andy

That's probably the off-axis guider :) There's no 10:1 focuser like on normal scopes, it has an helical focusing mechanism (like a lens)

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On 18/11/2020 at 13:37, vlaiv said:

Yes, goto works perfectly well when in EQ mode - as long as you apply proper firmware first.

You can get it from official SW website here: http://www.skywatcher.com/download/software/motor-control-firmware/

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As far as precision of this mount - I would say that people should limit themselves to about 300mm of focal length. I don't like to express things in terms of focal length as it is rather imprecise, so I'll give another measure that is more precise - I think that mount is good for up to 3"/px sampling rate as I think it will be able to guide in 1.2-1.5" RMS range (this is based on stepper motor resolution and general feel of the mount - I still have not guided it yet to be 100% certain).

It is therefore good mount for scopes like 72ED with reducer flattener and 50/60mm apos - for imaging. Various lens can be used as well.

Just to mention that if you want to guide with a Linux installation such as Astroberry on a Raspberry Pi 4 (KStars/Ekos/Indi), for instance, there is a bug in this latest Firmware V 3.26 which stops the DEC axis guiding properly. A workaround for the moment is to revert to Firmware V 3.20 which is still available on the Sky-watcher website. In my first successful use with the 3.20 firmware last night, with a ZWO Miniscope 120mm fl and ASI120MC for guiding, the DEC axis was still a bit uncontrolled at times, probably due to the DEC backlash, and the guiding graph reached 5 arcsecs occasionally, and yet for long periods was around 1 arcsec rms. My main 'scope' was my Canon DSLR with a 50mm lens so this was not an issue in practice. I'll try to refine the performance with some guiding rate adjustments before trying it with my 61mm/275mm refractor.

By the way, the AZGTi uses DC motors and large ratio reduction gearboxes, so not quite the precision of stepper motors, but still fantastic for the job in hand!

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  • 1 month later...
3 hours ago, Space Oddities said:

Hmm strange, there are new posts every day... If you want, PM me your username, maybe I can add you from inside?

Thanks .. I have sent you PM.

I also sent a messenger  message to one of the two admins but still no joy, and yes I see that the group has had 49 posts in the last month.

Paul

 

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