ahsanford said:
Again, I don't shoot astro, but I keep hearing the mythical dream astro tool is:
Fast + Wide + Coma Free when shot wide open
...but now I'm hearing it needs to be:
Fast + Wide + Coma Free when shot wide open + Low Vignetting when shot wide open
Hayzoose... Each ultrawide that comes out must feel like Lucy with the football for the astro camp. It's Christmas Day that never arrives.
- A
To put vignette into perspective lets compare the 35/1.4L II to the 16-35L III:
A) 35mm 6.0s at f/1.4 ISO 3200 and you have 3 stops of vignette
(after correction, corner IQ is essentially that of ISO 25,600)
B) 16mm 15.0s at f/2.8 ISO 6400 and you have 4 stops of vignette
(after correction, corner IQ is essentially that of ISO 102,400)
The 24L II has been my wider angle lens option. It also has a massive coma and vignette problems wide open, but by f/2.8 it has mostly cleared up and the vignette greatly improves as well. http://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?Lens=1073&Camera=979&FLIComp=0&APIComp=2&LensComp=480&CameraComp=453&FLI=0&API=1
The 35L II also has a significant vignette wide open but improves greatly by f/2.
http://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?Lens=1073&Camera=979&FLIComp=0&APIComp=1&LensComp=994&CameraComp=453&FLI=4&API=0
If I need to close down to f/5.6 to get corners within 2 stops of center then I might as well use my TS-E 24mm L II and shift-stitch to get to a 16mm angle of view. With that approach I can get 2x the resolution with stitching compared to a single shot from the zoom which will help make up for the corner softness on the shifts. http://www.the-digital-picture.com/Reviews/Lens-Vignetting-Test-Results.aspx?Lens=1073&Camera=979&FLIComp=0&APIComp=1&LensComp=486&CameraComp=453&FLI=0&API=2
Stitching Panoramic shots with the faster primes (stopped down slightly) will give less noise and higher resolution than the 16-35L III.