RST300

Users in team Dwarfstars: Hangyeol Kang (2022.01~)

• Specification

1. Mount design: Dual mount – German Equatorial, Alt-Azimuth

2. Gear : Strain wave gear (Harmonic Drive) / Drive: Belt and worm wheel

3. Payload: 30kg (without counterweights), 50kg (with counterweights)

4. Weight: 8.5kg

5. Brake : Built in RA Axis to prevent back-driving.

• Pros

1. RST 300 can lift telescopes about 6 times its own weight and No counterweight needed,

2. As the performance of this mount is NOT sensitive to the weight balance, it can be a very good match with Newtonian telescopes which have asymmetric structures.

• Cons

1. Personally, its design is practical but lagged behind its competitor's, such as Pegasus and Hobym.

2. Once altitude locking knobs are tightened during polar alignment, the altitude increases around 10-15" afterwards. Readjustment is always required, which is a huge hassle. (What I mentioned about RST 300 goes for RST 135 as well)

3. It is a little bit on the expensive side. At this price, you can buy two worm gear mounts of the same class.

4. Short guiding exposures are necessary due to its large PE.

• Verdict

One-line summary: the small chili is spicy

Actually, RST 300's strongest point is not weight. It's volume. Thanks to harmonic mount, I can carry 2 sets of astrophotography equipment including 8inch Newtonian & 10inch RC in my compact car at the same time. this never would happen if I had big worm gear mounts.

When I have extremely bad seeing, I used to use a longer exposure like 2 - 5s with EQ6-R to help average seeing. It is very difficult to use long exposure for guiding with RST 300 due to large PE. with short exposures, guiding is more dependent on seeing than other warm gear mounts. In this light, I believe that this kind of mount is more suitable for short & mid focal length.