Choosing your next telescope
Achromat or APO
The AR102, AR127 and AR152 are f/6.5 achromatic doublets: the most aperture for the money and fine for visual observing, with some purple fringing on bright targets. The ED80, ED102 and ED127 triplets, in Hoya FCD1 glass, and the FCD100 models correct color almost completely and suit astrophotography.
Aperture and mount
Most of these are optical tubes, so budget for a mount that carries them: a 127 mm APO triplet at 18 lb needs a mount rated for 25 to 30 lb or more once a camera is attached. The FirstLight 127 Mak, at 7.6 lb, is the light option for the Moon and planets.
Upgrade paths
- More aperture for visual observing: the AR127 or AR152 doublet.
- Clean color for imaging: the ED80 or ED102 triplet, with a field flattener.
- Planets in a short tube: the FirstLight 127 Maksutov-Cassegrain.
Frequently Asked Questions
Bigger achromat or smaller APO?
A 127 mm achromat gathers about 2.5 times the light of an 80 mm APO and shows more of faint deep-sky objects. The APO gives cleaner views of bright targets and is the one for imaging.
Do I need a field flattener?
For imaging with an APO, usually. Most APOs benefit from a dedicated flattener, which keeps stars round out to the edges of the frame.
What eyepieces do these take?
The refractors have 2-inch focusers, which take 2-inch eyepieces directly and 1.25-inch eyepieces with an adapter; the FirstLight 127 Mak takes 1.25-inch eyepieces.
For three levels of 102 mm refractor compared, read AR102 vs ED102 vs ED102-FCD100, and for the trade-offs, APO vs Achromatic Refractors.