Z50 Astro Lens

Started 2 months ago | Discussions thread
EricTheAstroJunkie Contributing Member • Posts: 815
Re: Z50 Astro Lens

dippermethis wrote:

EricTheAstroJunkie wrote:

Honestly all of those are terrible, I've used them all and they all suffer from something significant that results in poor image quality for astro. IMO the single best APS-C specific lens for astro is the Sigma Art 18-35mm f1.8, fantastically sharp with little coma and little LoCA. Other reasonable lenses on a budget are the Rokinon 16mm f2 or 24mm f1.4, if you think you'll ever upgrade to full frame Z you should think about either the 20mmS or 24mmS lenses, both are great.

Eric, I currently have a Rebel T7i with the most basic of lenses. While researching various lens, would you suggest the Sigma 18-35mm over a Tamron 35mm 1.4 for my APS-C? Also, thank you for all the info you provide on this forum.

I think if you are specifically looking for a field of view equivalent of a 50mm on a full frame then the Tamron 35mm f1.4 is the way to go, that lens is amazing even wide open, but in terms of field of view you're obviously locked into that whereas the Sigma offers a good equivalence range (~27mm to ~50mm). The Sigma is a fantastic lens as well, I pretty much universally never recommend zoom lenses for astro work, but the 18-35mm is the one exception for those using APS-C cameras. It's a little soft on each end wide open, the 20mm to ~30mm range is its strong point (even at f1.8) and if you're looking to wring every ounce of quality of it you'll want to stop the lens to f2.2 or f2.5, but there aren't any other constant aperture f1.8 zooms available and it competes very well even with the various APS-C specific primes (if not exceeds most) that exist in that focal range.

The Tamron 35mm f1.4 on an APS-C camera will offer a completely aberration free and super sharp image even at f1.4, my copy had a tiny tiny amount of coma on full frame and really had no LoCA. So it's really up to you, both will cost about the same, it's a matter of whether or not you want a bit of versatility with the zoom at the cost of slightly less sharpness and a little bit more coma/LoCA vs having one of the best 35mm primes available now (but locked into that focal length).

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