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Hi All,

I am currently researching which setup to purchase as my first proper scope (once they are back in stock).

I thought I had settled on the Skywatcher Explorer 130ps AZ GTi but then I saw the Skywatcher Star Discovery 150i for just a little more money.

Could anyone please tell me the difference between the 2 OTA's (other than the different aperture size), and also the difference between the 2 mounts?

I realise that the AZ GTi can be modified to run in EQ mode whereas the Star Discovery can't.

Can the Star Discovery view all the way to the zenith or does the OTA catch the mount or tripod before it gets there?



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Hello, and welcome to the forum.

I have the 150i/Star Discovery and can confirm that you can view to the zenith without hitting the tripod (I was hunting objects in Ursa Major last night, more or less straight overhead).  If you're not aware already, the Synscan app has a setting for altitude range, and the default maximum is set below 90 degrees (I presume to stay on the safe side), but you can set it to 90.

As far as I'm aware, the two mounts are the same with respect to software; when I'm looking for advice on the Star Discovery, I also look at threads about the AZ GTi (there seem to be more of them out there). Both mounts have the dual encoders ("Freedom Find") that keep track of the position during a manual slew (I use this a lot). Both mounts have a nominal 5kg capacity, though the AZ GTi has an option to install a bar and counterweight. As you say, the AZ-GTi can also take a wedge and operate in EQ mode.  You will see that the tripods are different - the Star Discovery has a (1.25" leg) steel model, the AZ-GTi's is aluminium. Generally, the balance seems to favour steel over aluminium, though I've seen many positive reports on the AZ-GTi mount. If you prefer, you can replace the tripod with any standard 3/8" photographic tripod (the Star Discovery is different - it attaches to its tripod via three bolts).

As for the OTAs themselves, since both are F/5, the 130 is slightly shorter as well as smaller in aperture. Obviously the weight is also less, hence further from the mount capacity than the 150. Both feature a fixed (non-collimatable) primary for reasons of cost and weight. The secondaries are adjustable in the normal way. Some people worry about this, but mine hasn't budged since I bought it.  I believe the focuser is the same on both - a basic 1.25" rack-and-pinion, again to keep down the weight and cost. The same red dot finder is supplied in both cases. 

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Hi Zermelo,

Thanks for the welcome and the information, it is very helpful.

I am leaning more and more towards the 150i for the obvious advantage of the larger aperture.

The non collimatable primary mirror doesn't bother me, in fact is a bit of an advantage as I have never owned a reflector telescope before so it makes it a bit easier to get used to.

I am drawn to the goto mount (either of them) as it will allow me to learn my way around the sky easily and as I get to know it better I can use the freedom find to star hop manually, best of both worlds.

I was not aware of the altitude range setting in the app so thankyou for informing me of that and I am also glad to hear that the scope can move all the way to the zenith.

Just need to wait for stock to arrive in UK now.


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