I am looking for a 35 mm lens for astrophotography. I've been looking at RF 35/1.8, but the sticking point is coma/astigmatism which is severe wide-open.
But ... does this problem go away when the lens is stopped down? For example, here is an aperture sweep of my RF 24/1.8 which has bad astigmatism wide open but produces nice results from f/3.5 and up.
I shoot with a star tracker so f/4 is not a big deal.
I know that there are other lenses out there that have well-controlled astigmatism wide open: EF 35/1.4 L mk2, Tamron 35/1.4 di USD, Sigma 28/1.4 Art. But these are big and heavy lenses, and I'd love to have a small, nimble little lens, particularly for other uses. RF 35/1.8 has a lot going for it: nice bokeh, close focusing, sharp, lightweight, punchy colors, small, great price. There is just the astigmatism problem. Does RF 35/1.8's astigmatism problem go away when stopped down? Is there an aperture sweep out there that anyone can point me to? Usually I look at Lenstip for that, but they don't have a complete review of this lens.
One more thing. Does RF 35/1.8 have field curvature? Field curvature and astro don't go together very well. I've been burned by that before with other lenses.
Thanks.
But ... does this problem go away when the lens is stopped down? For example, here is an aperture sweep of my RF 24/1.8 which has bad astigmatism wide open but produces nice results from f/3.5 and up.
I shoot with a star tracker so f/4 is not a big deal.
I know that there are other lenses out there that have well-controlled astigmatism wide open: EF 35/1.4 L mk2, Tamron 35/1.4 di USD, Sigma 28/1.4 Art. But these are big and heavy lenses, and I'd love to have a small, nimble little lens, particularly for other uses. RF 35/1.8 has a lot going for it: nice bokeh, close focusing, sharp, lightweight, punchy colors, small, great price. There is just the astigmatism problem. Does RF 35/1.8's astigmatism problem go away when stopped down? Is there an aperture sweep out there that anyone can point me to? Usually I look at Lenstip for that, but they don't have a complete review of this lens.
One more thing. Does RF 35/1.8 have field curvature? Field curvature and astro don't go together very well. I've been burned by that before with other lenses.
Thanks.