Equatorial Wedge
This picture shows two new things I added up. But this post is about the equatorial wedge and my attempt to compensate the earth rotation for my astrophotography shots. You can see the tripod and on top the wedge and the AltAz mount.
After getting my time focused on sorted the bad shots on which the stars were oblong, I had to admit that the AltAz mount was definitively a big pain for tracking correctly the objects shot. I understood the fact that my pictures would rotate with this mount (the Earth is rotating … yes, yes, it’s a fact), but I believed I could use a software (Siril) to pile the shots and correct the angles of the pictures. Though, when AltAz mount is tracking an object, it used both Altitude and Azimutal gears and if you had some backlash (mechanical issue with worm gear … when it moves, the acceleration is not stopped and the gear continues to roll) for both axis, then I ended up deleting quite half of my shots manually.
Instead of buying an equatorial mount (or also named German Equatorial mount), Celestron was offering a equatorial wedge (sort of table) that you can put between the tripod and the AltAz mount. Well, I thought that if Celestron is proposing it, it should work. And it is quite a bargain, 550euros for this wedge instead of 2000euros for a strong equatorial mount. I got it from a vendor in Italy, and I got it delivered at my place. Fifteen kilograms addition to my setup ! So now, it’s about 44kg in total for a setup I wanted to travel with … not gonna happen … but if it can help at my place or at a car drive distance, it should be ok.
Well, I have to admit that the wedge (if correctly used, and I spent some time on that) is doing its job. The two big results I got were the exposure time increase and less waste on shots. With the AltAz mount, on Deep Sky Objects (DSO), I was very limited to 10-20 seconds of exposure per shot, and 50% waste. With this wedge in between, and the ability to align the mount to the Celestial Pole, and so using only one gear for tracking (you’re switching from Alt/Az axis to RA/DEC axis and with the alignement with the pole you only use RA axis to track the object … I may explain that in another post), I moved to 30-40 seconds of exposure and 20-25% of waste on shots. Big improvement ! I was very okay with this investment despite the substantial addition of weight.
Though, I quickly ended up with my objects disappearing from the camera view after 30 minutes of exposure and I had to recalibrate my object multiple times during the night … annoying. A couple of days later, PegasusAstro (a greek company, in a market dominated by chinese manufacturers …) was announcing their first hybrid mount (on a 1st of April, but it wasn’t a joke) with harmonic drive … I kept a look at them for a couple of months until … well, that will be another post ;)
