Hi there, I'm still just getting into astrophotography using an equatorial mount and am looking into getting a solid refractor telescope to go with my SkyGuider Pro. I'm thinking about the Zenithstar 73 II but was wondering if the 430mm focal length would be too much for the tracking capabilities of the SkyGuider Pro, especially since I don't have the I Polar to go with the mount. Any advice on this would be great. Thanks!
Zenithstar 73 II With a SkyGuider Pro
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I have both of those but haven't used them together. I don't think that's too high of a focal length as I can get a couple minutes with a Sigma 150-600 at 400mm on a full frame sensor, I got more concerned about the weight. 5.5lbs for the scope then a field flattener and 2lb camera and spotting scope gets you up there. For that reason and the fact that it would be much easier to have goto capability to find the objects that I ordered an iOptron cem40 to go with the scope. My Skyguider Pro has iPolar and I love it, also upgraded to the William Optics base for the Skyguider, it's awesome compared to the iOptron one, much solider and smoother.
Not sure what camera you're using but if it's a crop sensor (like a 1.6 Canon) then a little Redcat 250mm is actually 400mm and the zenithstar73 is 688mm. Assuming you have Stellarium plug the numbers into it to see how the framing is for the objects you want.
Not sure what camera you're using but if it's a crop sensor (like a 1.6 Canon) then a little Redcat 250mm is actually 400mm and the zenithstar73 is 688mm. Assuming you have Stellarium plug the numbers into it to see how the framing is for the objects you want.
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Hi,
I have the ZS73II and combined with the flattener and a D7500 DSLR it brings my EQ35M close to its limits. It does work but needs careful PA and balancing and I can see the guider working overtime. It is not just the weight (2.8kg for the ZS + 0.4kg for the flattener + 0.7kg for the Nikon = 4kg total), it is also the torque and susceptibility to winds because it is a lengthy instrument. The same mount, when I use a Vixen VMC110L and a ASI178MM (a combo that is about 1.5 kg lighter and 20cm shorter) just works great, period.
I think you would be operating very close to the nominal 5kg capacity of the Skyguider Pro. You absolutely need good balancing, which might mean a second counterweight. And a sturdy tripod, capable of holding the whole thing without vibrations. And very good, which means computer assisted polar alignment. Also keep in mind it is not terribly easy to find targets at a 430mm focal length.
I think this class of small trackers (Star Adventurer, Sky Guider, Astrotrac, Vixen Polarie) is ideal when you have just a camera and a photographic lens or a small Petzval and do very wide field.
So in my opinion you have to go with a smaller scope designed for that use such as the RedCat (or a lens like the Samyang 135mm). Alternatively, if you want to commit to the refractor, you need an equatorial mount with GoTo, guiding on both directions and a 2inch tripod, the EQ35M or the CEM25P being the bare minimum. Small refractors and portable trackers are two different worlds.
Cheers,
Dimitris
I have the ZS73II and combined with the flattener and a D7500 DSLR it brings my EQ35M close to its limits. It does work but needs careful PA and balancing and I can see the guider working overtime. It is not just the weight (2.8kg for the ZS + 0.4kg for the flattener + 0.7kg for the Nikon = 4kg total), it is also the torque and susceptibility to winds because it is a lengthy instrument. The same mount, when I use a Vixen VMC110L and a ASI178MM (a combo that is about 1.5 kg lighter and 20cm shorter) just works great, period.
I think you would be operating very close to the nominal 5kg capacity of the Skyguider Pro. You absolutely need good balancing, which might mean a second counterweight. And a sturdy tripod, capable of holding the whole thing without vibrations. And very good, which means computer assisted polar alignment. Also keep in mind it is not terribly easy to find targets at a 430mm focal length.
I think this class of small trackers (Star Adventurer, Sky Guider, Astrotrac, Vixen Polarie) is ideal when you have just a camera and a photographic lens or a small Petzval and do very wide field.
So in my opinion you have to go with a smaller scope designed for that use such as the RedCat (or a lens like the Samyang 135mm). Alternatively, if you want to commit to the refractor, you need an equatorial mount with GoTo, guiding on both directions and a 2inch tripod, the EQ35M or the CEM25P being the bare minimum. Small refractors and portable trackers are two different worlds.
Cheers,
Dimitris
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Thanks for the replies! I ended up going with the zenithstar 61. Based on your feed back and some extra research, I think this will probably be a better fit for my sky guider pro. Im thinking the shorter focal length and it being lighter weight should give great results and be easier on the mount.
Thanks very much for the help,
- Aidan
Thanks very much for the help,
- Aidan
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Thanks for the replies! I ended up going with the zenithstar 61. Based on your feed back and some extra research, I think this will probably be a better fit for my sky guider pro. Im thinking the shorter focal length and it being lighter weight should give great results and be easier on the mount.
Thanks very much for the help,
- Aidan
Hi Aidan:
I currently use the Skyguider with my ST80. DSLR + OTA = 5lb. I can get several minutes unguided with a good alignment. I'm thinking of upgrading to the Z61, and I'm so curious about how this combo is working for you. Are you enjoying the experience?
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