ZWO AM3 Mount

[GoldTop57]

For those of you who are interested there is more information here: https://www.zwoastro.com/products/asimount - scroll to the bottom and click Sizes and Product Specifications.

[SamAndrew]

Save people going to the site:

Edited April 12, 2023 by SamAndrew

[Dark Raven]

As a backpacking mobile imager with AM5 and WO RedCat 51, I was hoping for something closer to 3kg... That would knock it out of the ball park for me instantly. This way, I´ll wait till I upgrade the OTA first.

Edited April 12, 2023 by Dark Raven

[SamAndrew]

3 minutes ago, Dark Raven said:

As a backpacking mobile imager with AM5 and WO RedCat 51, I was hoping for something closer to 3kg... That would knock it out of the ball park for me instantly. This way, I´ll wait till I upgrade the OTA first.

They'd have been better off making the AM5 a bit heavier to start with, then there'd be a bigger gap. I'm predicting price will be £1500-1700.

[Dark Raven]

Looking at the designs it appears they have omitted the hot shoe. I am aware it not recommended to put ASIAIR there and can cause cable snags, but hot shoe was nice...

Edited April 12, 2023 by Dark Raven

[Dark Raven]

The rumor has it that the suggested retail price appears to be $1499 (ex-factory) with availability in June. 

[Elp]

Certainly undercuts the competition by a large factor. The payload is for a particular niche however, and I still think it looks a bit larger than it should be.

[Dark Raven]

6 hours ago, Elp said:

Certainly undercuts the competition by a large factor

That MSRP is (ex-factory) so do not forget to include FX and VAT.

6 hours ago, Elp said:

I still think it looks a bit larger than it should be

I agree
 

Edited April 13, 2023 by Dark Raven

[Dark Raven]

It´s available for order on ZWO site:

ZWO AM3 Harmonic Equatorial Mount – ZWO ASI (astronomy-imaging-camera.com)

[Martthebass]

A bit surprised by this, I thought they'd go for a higher capacity job first.  

As the weight isn't that much lower than the AM5 (but the mount capacity is) I think the final RRP in the UK will need to be a good bit less than the AM5 otherwise the AM5 would make more sense from a flexibility point of view.  I'm more than likely going to be proved wrong though...

[Elp]

You'll find it is much less in price if you look, for the payload it should probably be slightly cheaper.

Edited April 13, 2023 by Elp

[vlaiv]

Do people find value in these mounts and if so, what is it? Portability? Lack of backlash?

Spec wise, I don't see them being high performing mounts. P2P periodic error of >25". Period of periodic error of 288 seconds - faster than other mounts which puts strain on guiding (faster change in periodic error).

0.17" / micro step tracking resolution being in the same ball park as for example Heq5 or EQ6 (in fact these have ~0.14" / micro step).

Reduction of 300:1 requires steppers to operate on 128 micro steps. Period is actually one full revolution of stepper motor

200 steps * 128 micro steps = 25600 micro steps per revolution of stepper motor

Sidereal rate is 15.041"/s and if stepper resolution is 0.17"/ micro step that makes ~88.5 micro steps per second (sidereal / resolution). 25600 micro steps per one motor turn / 88.5 micro steps per second = ~289 seconds per motor turn.

I wonder if PE comes directly from step motor?

In any case, I see these mounts as being overly expensive for what they offer - unless I'm missing something that people value.

 

[Elp]

Value = it's more than I'd like to pay, but I setup and breakdown every single session, so removing that 15-20Kg gem package (w CWs) out of the equation (and also an additional 5kg tripod) and having the mount packed together with my scope, means less trips and more likelihood I'd use it. Its convenience more than anything. Less stress on your body too if moving the whole setup in one. They have their appeal.

Its the main reason I tend to use my azgti more than the gem, sacrilege I know.

Edited April 13, 2023 by Elp

[Dark Raven]

I can only echo the post above and add backpacking portability to it as can be seen below. Reducing weight from 5.5 kg to 3.9 kg would allow for a larger capacity battery going from 18 Ah to 30 Ah and perhaps a cooled camera.

Spec wise it has fantastic guiding regularly achieving under 1 arc-sec and quite often sub 0.5 arc-sec. All of that with no dead weight in the form of counterweights. Super fast to set up with no need to balance. 

AM5 is total overkill for my RedCat 51, but it allows for future growth. AM3 would be more appropriate, but not sure I can justify another mount with so few clear nights this year.

 

 

Edited April 13, 2023 by Dark Raven

[tonypysm]

I have received the HEM15, it's only  2.6kg and a load capacity of 7kg. It is very portable！😁

[Dark Raven]

1 hour ago, tonypysm said:

I have received the HEM15, it's only  2.6kg and a load capacity of 7kg. It is very portable！😁

How do you find the saddle compared to AM5? Many have complained about the saddle on HEM27. Do you have to balance the DEC due to worm/belt system?

[Martthebass]

14 hours ago, vlaiv said:

Do people find value in these mounts and if so, what is it? Portability? Lack of backlash?

Spec wise, I don't see them being high performing mounts. P2P periodic error of >25". Period of periodic error of 288 seconds - faster than other mounts which puts strain on guiding (faster change in periodic error).

0.17" / micro step tracking resolution being in the same ball park as for example Heq5 or EQ6 (in fact these have ~0.14" / micro step).

Reduction of 300:1 requires steppers to operate on 128 micro steps. Period is actually one full revolution of stepper motor

200 steps * 128 micro steps = 25600 micro steps per revolution of stepper motor

Sidereal rate is 15.041"/s and if stepper resolution is 0.17"/ micro step that makes ~88.5 micro steps per second (sidereal / resolution). 25600 micro steps per one motor turn / 88.5 micro steps per second = ~289 seconds per motor turn.

I wonder if PE comes directly from step motor?

In any case, I see these mounts as being overly expensive for what they offer - unless I'm missing something that people value.

 

I think individuals value different things. Having experienced ill health of late I was looking at something lighter and quicker to set up than my previous AZEQ5 Mount with 90mm APO set up.

The AM5 set up is now an easy one lift solution. I also don’t need to be concerned about balance. The PA adjustment is easier and quicker also; generally I can be up and running in less than 10 minutes which means I use the set up more as I can take advantage of short or unexpected periods of clear sky. I’ve always considered the best set up is the one you use the most.

Regarding guiding, it’s better than my AZEQ5 was with me typically getting 0.6”rms and on good seeing nights (like last night) around 0.3”. I’d maybe get better on an EQ6 type but lugging it around would mean it would gather dust.

I don’t disagree that it’s not a cheap option but for some, like me, it’s been a game changer.

[tonypysm]

25 minutes ago, Dark Raven said:

How do you find the saddle compared to AM5? Many have complained about the saddle on HEM27. Do you have to balance the DEC due to worm/belt system?

Yes you should balance the DEC roughly, and the saddle is  the same as HEM27. Due to weather conditions, I haven't tested it yet, but I think the guiding accuracy should be similar to HEM27.

[Dark Raven]

1 hour ago, tonypysm said:

the saddle is  the same as HEM27

yaiks.... 😬

 

[tonypysm]

Compared with other mounts.😆

[michael.h.f.wilkinson]

5 hours ago, tonypysm said:

I have received the HEM15, it's only  2.6kg and a load capacity of 7kg. It is very portable！😁

That is interesting, especially for airline travel, with all the weight restrictions that brings. Where did you get the HEM15? What does it cost?

[tonypysm]

51 minutes ago, michael.h.f.wilkinson said:

That is interesting, especially for airline travel, with all the weight restrictions that brings. Where did you get the HEM15? What does it cost?

HEM15 is currently only sold in China, so I can buy it. However, soon it will be available in other regions . I don't know it's overseas pricing, but in China it's priced lower than AM3.

[Elp]

Its also available via ioptron but their shipping price (plus later local taxes) "encourages" you to buy locally.

Edited April 14, 2023 by Elp

[SamAndrew]

On 13/04/2023 at 19:07, vlaiv said:

Do people find value in these mounts and if so, what is it? Portability? Lack of backlash?

Spec wise, I don't see them being high performing mounts. P2P periodic error of >25". Period of periodic error of 288 seconds - faster than other mounts which puts strain on guiding (faster change in periodic error).

0.17" / micro step tracking resolution being in the same ball park as for example Heq5 or EQ6 (in fact these have ~0.14" / micro step).

Reduction of 300:1 requires steppers to operate on 128 micro steps. Period is actually one full revolution of stepper motor

200 steps * 128 micro steps = 25600 micro steps per revolution of stepper motor

Sidereal rate is 15.041"/s and if stepper resolution is 0.17"/ micro step that makes ~88.5 micro steps per second (sidereal / resolution). 25600 micro steps per one motor turn / 88.5 micro steps per second = ~289 seconds per motor turn.

I wonder if PE comes directly from step motor?

In any case, I see these mounts as being overly expensive for what they offer - unless I'm missing something that people value.

 

The figures are conservative, and measured across the full 360 degrees, max cycle error is about 15" on the below example:

On my AM5 it's less than 10" Peak to Peak across the full 360", it consistently guides better than either of the two EQ6-Rs I've owned and the CEM120. I've gone from a permanent setup to a pier that I dismantle between good spells of weather (currently very rare in the UK), and not having counter weights or having to balance the scope saves a lot of setup time, plus it's a fraction of the weight of the CME120 and EQ6-R, and doesn't have the fussy softwear of the Mesu. It's my favourite mount by far, I'm hoping they do one with a bigger capacity one day.

[SamAndrew]

Just to add, I literally wouldn't recommend a traditional GEM mount to someone who has to tear down each session if they can afford one of these. Everyone who get's an EQ6 or bigger soon desires an observatory.