Although I am very happy with my iOptron ZEQ25 mount and would recommend it over the more popular (in Europe) skywatcher offerings, there are some areas where it could be improved. The first thing that comes to mind is the dovetail saddle. On paper and on first look it seems like a winner – it seems like a nice spring-loaded saddle that is not cheaply made and will easily secure your dovetail (without marking it). The biggest problem is that it has sort of an extra extrusion which, if you are not careful (e.g. in the dark) can “grab” the dovetail and you might think it is secure when it is not. The second problem is that the screws come dangerously close to the Dec house mounting, even rubbing against it (giving the motor a hard time) at least on my mount for a specific angle of the thumbscrew. Lastly, the two thumbscrews are not much spaced-apart, and that can make it harder to comfortably get a good grip in freezing temperatures.
Enter the replacement saddle from ADM that various ZEQ25 users have been praising. I decided to order one, even though it does not come very cheap at $99 before tax/shipping. Opening the box at least was not a disappointment, quality-wise the money seems well spent – it looks as well made and well finished as you can make a saddle. Replacement was a breeze. In 5 minutes you can remove the Allen screws from your iOptron saddle and use them to secure the ADM one. And then you get to use it…
The difference is amazing. The lack of the extra “extrusions”, the longer length and the much more spaced-apart thumbscrews make the installation of a telescope a breeze. Before, it used to take me over half a minute of fiddling about to try and secure the dovetail correctly. Especially for heavy/large scopes, even after the fiddling I was note certain I had secured it correctly until I checked with a red light. With the ADM saddle it takes 5 seconds and you are certain it is secure immediately. Unfastening is also more comfortable, with the difference probably more pronounced if you are wearing gloves. The screw-rubbing-Dec housing issue is of course gone.
Lastly, but perhaps importantly for some, the longer (6″/15cm vs 3.5″/9cm) saddle seems to give some extra stability to the mount, something very welcome if you are using the ZEQ25 with a relatively heavy OTA. For example, with a C8 and a DSLR camera (around 7kg weight), it takes about 4.5s for dampening to subside after tapping the OTA in the original mount, while after the ADM upgrade this was reduced to under 3s.
Overall I would rate this as a great upgrade to the iOptron mount, and I can only make two small complaints. First, a rubber finish on the thumbscrews would be welcome. In the off-chance that you might want to tighten/un-tighten them in the cold without your gloves, you might not enjoy the experience. Second, the price, similar to many, many astro-accessories, is not very affordable. It is not exorbitant either and I understand that this is not a mass-produced item, so I am more disappointed by iOptron for the inexplicably poor design that made me look for a replacement, than ADM for pricing this at $99. Note that if you might ever need to use a Losmandy “D” dovetail mounted telescope with your iOptron (not a particularly likely scenario I guess), there is also a dual Vixel/Losmandy style saddle for $139, which is also even longer (7″).