Good FPL53 doublet vs triplet for astro and daylight shooting?

[Tomx72]

I need a lightweight travelscope and I am wondering how much do I loose if I grab a lighter(!) and cheaper doublet instead of a triplet?

E.g. a Megrez 88 weighs and costs the same (3.4kg, 1k€) as the "usual" 80/480mm triplets while adds 8mm in diameter. What do I loose if I spare the extra lens? My goal is both astrophotography and daylight game/bird shooting with a sony a6000 and a panasonic GX80.

 

[Tristimulus]

I need a lightweight travelscope and I am wondering how much do I loose if I grab a lighter(!) and cheaper doublet instead of a triplet?

E.g. a Megrez 88 weighs and costs the same (3.4kg, 1k€) as the "usual" 80/480mm triplets while adds 8mm in diameter. What do I loose if I spare the extra lens? My goal is both astrophotography and daylight game/bird shooting with a sony a6000 and a panasonic GX80.

You do not loose - without the extra lens you get additional blue halos around bright stars. To fully correct a lens for chromatic abberation three lens elements are required.

 

[Tomx72]

You do not loose - without the extra lens you get additional blue halos around bright stars. To fully correct a lens for chromatic aberration three lens elements are required.

True, that might also show up as purple fringing in daylight shots, I'll stay with a triplet then.

 

[bondiblue]

Quadruplet ED APO is needed if you want a flat field across the full frame.

Alternatively a triplet plus a field flattener -though the cost of these is such that you may as well buy a quadruplet.

 

[Tomx72]

Quadruplet ED APO is needed if you want a flat field across the full frame.

Alternatively a triplet plus a field flattener -though the cost of these is such that you may as well buy a quadruplet.

I'll go with triplet+flattener, because I'd like to use the scope for planetary work too and quadruplets are usually very short focus.