Reasons to buy the Ioptron.....its £500 cheaper than the zwo am3, no it doesn't have a harmonic drive on the declination? For the last 30 years I've used only worm drives on both axis because that was what we had coupled with smart drive (periodic error correction). The hem15 has harmonic drive on the right ascension and a supposedly back lash free belt declination drive, with decent alignment via a computer software or asi air type gadget a can't see your going to notice the lack of harmonic on the declination unless your up there with the pros. The ioptron did strike me as a bit fiddly to set up initially and I had to select the hem 27 on my asi Air but it hooked up instantly and aligned and function flawlessly first night. There are a few screws to relocate and the dove tail clamp retaining bolt appears a bit flimsy , you do need to arrange the clamping arrangement so it clears the ra housing (if you pull the lever up it can be repositioned or it will collide with the ra housing. On a very positive note you can buy the hem 15, a stellalyra 6" f4 reflector, a hotch laser and the matching coma corrector for about the same price as the am3....so I did !

This is a huge step up from the AZ-GTI I have been using for the past few years - it looks vastly better made, it sounds vastly better made, it's quick and strong and tracks like an ace. I am using it exclusively with an ASIAIR so can't comment much on its native software.

I bought an HEM15 without iPolar, on the basis that I could use the one on my GEM45 (which I don't use). FLO had pointed me towards an isolated compatability chart which confirmed this was possible. It took under an hour and works perfectly. Thanks FLO!

The HEM15 is well made and has similarities to the GEM45. I've only had one short evening under the stars but it showed it could guide to 1 arc-sec. It handled my 65phq refractor happily.