Some time ago I bought another SVBONY branded telescope. This time it is a novelty, the first triplet (on S-FPL51 glass), 80mm in diameter and 480mm focal length, which gives us an focal ratio of f/6.
On paper, the refractor has a pretty nice specification for its price range.
Focal length: 480mm
Resolution 1.45 arcsec
Lens Coatings: SMC
Focuser: 2.5 ”1:10 dual speed
Connectors on the focuser side: 2 ”and M63x1
The telescope was packed securely, the shipment was well protected against damage. Inside,a refractor, a rotator and a flattener (sold separately) were waiting for me. As I only wanted to use the telescope for astrophotography, I immediately decided to unscrew the 2 ”adapter to be able to directly use the M63 thread. Unscrewing this adapter was very clunky and it took a lot of force to get it. Fortunately, there was no loss. I installed the rotator, flattener, the entire adapters and camera.Overall, the setup looks very solid and I was very pleased with the build quality and overall external perception of this telescope.
Now it's time for the first tests.
I immediately equipped the telescope with ZWO EAF, which I switched from my second refractor. So at night it was time for the first tests, and maybe the whole session. The first frames I saw on the smartphone screen (thank you asiair) lit a red lamp for me. The stars were flat, more or less sharp depending on the area of the photo. However, the culprit was not the SV550, but the ZWO EAF (badly set parameters) and the ZWO ASI071 camera, which has a tilt. After dealing with these problems, the frames started to look much better, although I did not deal with the tilt completely.
With the UV / IR CUT filter, this triplet shows no chromatic aberration, which I was very afraid
It is difficult to judge with what success the flattener flattens the field, when the camera has tilt and the distance between the sensor and the flattener requires a slight improvement. However, it seems that the flattener would have done its job quite well after adding a small distance. Currently my backfocus is 55mm.
The SV550 refractor, with a 1x flattener, provides F / 6 focal ratio and, in my opinion, works very well in astrophotography. Sure, there are some shortcomings - but they are due to the flattener's imperfect distance and the camera tilt. For about 3 months I took some photos with this telescope, which I am very happy with.