I was interested in this lens for night sky - f1.4 and all. The initial reviews look good but - I already have the Sig 10-18 f2.8 and when I compare them on TDP's site they look identical at f2.8 12 mm but the prime looks soft in comparison at f1.4. So if I can do milky way successfully at f2.8 and I'd get a softer image at f1.4, why would I want this? The zoom also has 10 to 18 from f2.8. Why would I want the prime? Legitimate question, feed back welcome.
Here's a picture taken with a Sony camera, wide open, from Digital Camera World. It doesn't look bad. Have to wait and see what the RF version looks like.
Jim
ILCE-7RM512mm F1.4 DC | Contemporary 025 lens12mmf/1.410s6400 ISO0.0 EV
Well, every lens is a compromise. I'm not being critical of anyone's choices. For my purposes:
The Sigma 12mm prime weighs 8.8 oz, $629 and the Sigma 10-18 f2.8 weighs 9.5 oz, $659, and has the same filter size as the RF 100-400.
Here is TDP's lens comparison at f2.8, the zoom's corner sharpness still looks better and the vignetting of the zoom doesn't look much darker to my eyes.
Edit: sorry the link doesn't fill in the Sig 10-18 on R7. This used to work
The coma from both lenses looks equally low looking at Christopher Frosts reviews.
For my use the prime would be a single use lens since I need the 10-18 to cover the <18 mm FOV of my 18-150 and 18-50. For years I carried a 20mm prime to cover wider than 24 on my FF kit but there is too much territory wider than 18 on APS-C to cover by cropping alone.
Fast primes are attractive and I was looking for a compelling reason for this one.
The TDP test looks rather poor. Although the typical Canon Blur-O-Vision AA is at work in the R7, the IQ makes me wonder if the lens is poorly corrected for the close distance of the test.
This is true. The 10-18 has a rather close focus distance at the wide end compared to the prime. Don't know TDP's testing methods enough to know if this is a factor. Christopher Frost's and Gordon Lang's reviews were more favorable of the prime at the edges.
Edit: I compared a couple more Sigma primes with closer focusing, if slower, counterparts and noticed the same behavior. Perhaps TDP is not the best tool for these lenses. I'll add though that I compared the Sony version and it seemed to perform much better. Is the R7 too much for it? I have no doubt that all these Sigma lenses are very good.
I can't speak to the 12mm but I did this shot on Thursday night at Cherry Springs State Park in PA with the 14 mm 1.8
the string of lights arte a starlink train. I'm quite impressed with the Sigma 14
Jeff Nolten wrote: Here is TDP's lens comparison at f2.8, the zoom's corner sharpness still looks better and the vignetting of the zoom doesn't look much darker to my eyes.
Edit: sorry the link doesn't fill in the Sig 10-18 on R7. This used to work
Not mentioned yet is that the TDP sharpness tests are done at less than infinity focusing distance. And with UWA lenses, likely at very close distance in order to fill the frame, even with a very large chart. Therefore it's possible that lens performance demonstrated by TDP is not indicative of infinity performance, especially if an ultra-fast lens is infinity-optimized for wide open performance.
