What focal length do you find most versatile for nebulae on full frame?
Hey everyone,
I currently have a Star Adventurer with a Canon EOS 6D Mk II and a 50mm lens. I’ve used this setup quite a lot and now I’m looking to upgrade, mainly to get more focal length. I’m planning to move to a small apochromatic refractor.
I’m aware that the mount is key here. I first considered the Sky-Watcher EQ-AL55i, but I’m leaning toward going straight for the HEQ5 so I won’t need to upgrade the mount again later if I go for a bigger scope.
My main question is about focal length. I’d like something that frames most nebulae well, since galaxies, planetary nebulae, and globular clusters tend to be too small for this kind of setup anyway.
Right now I’m hesitating between:
- Askar SQA55 (264mm)
- Askar 60F (408mm)
- Askar 71F (490mm)
Since I’m shooting full-frame, I’m a bit worried the SQA55 might be too wide. On the other hand, one advantage is that I could still use it on the Star Adventurer (not ideal, I know, but workable), which would let me start using it sooner and save up for the HEQ5 afterward.
I’ve checked a lot of targets on Telescopius, and my impression is:
- some nebulae feel a bit small at 264mm,
- some feel a bit tight at 408mm,
- 490mm looks great for smaller nebulae, but large targets like M31 don’t fit well anymore.
I’d really appreciate feedback from anyone who has used similar setups or these scopes.
Thanks!