vdo1 wrote:
That doesn’t look good at all. From 15m one should be able to discern the bricks surface texture. I suggest to consider returning for a replacement.
I didn't buy that copy, I only quickly tested it at the store.
The next day I did buy one. Another copy from their stock. This one looks sharper.
I can also confirm the AF-C issues. Hopefully Sigma will release a firmware update.
What I noticed is that this lens does have some curvy field curvature. When shooting a planar subject the midfield (not very far from the edges) is softer than the center and edges.
Just something to keep in mind. Depending on the scene more stopping down might be required to mask it.
Love the feel of this lens. Tiny, solid and a great aperture ring that has a 'grip'.
The rendering is quite nice too. Not as sharp, but much smoother than the FE 35/2.8.
Some more infinity comparisons against the CV40. I'm no specialist, but I am under the impression the Sigma has the edge in good/strong light, while the Voigtlander trumps it in lower light, at equivalent apertures, in the center of the frame.
Jochenb wrote:
It's not really strong, but noticeable depending on where you focus and how deep your DOF is.
Is your copy centered?
I've tested the Sigma 45/2.8 Contemporary for field curvature and it is flat field at infinity distance. It's sharper around the center area and shows a gradual resolution fall-off towards the corners. https://www.fredmiranda.com/forum/topic/1608234/0#chapter3
I've tested the Sigma 45/2.8 Contemporary for field curvature and it is flat field at infinity distance. It's sharper around the center area and shows a gradual resolution fall-off towards the corners. https://www.fredmiranda.com/forum/topic/1608234/0#chapter3
Here's an example, shot at F5.6 (on 24MP):
100% crops
Center:
Mid:
Edge:
This shows that it's not completely flat field at infinity. The mid field looks softer than both center and edges.
It's symmetrical on both sides, so no decentering at play.
Your test doesn't cover the mid field, only center and corners.
This shows that it's not completely flat field at infinity. The mid field looks softer than both center and edges.
It's symmetrical on both sides, so no decentering at play.
Your test doesn't cover the mid field, only center and corners.
It may not be due to field curvature though.
You can do an experiment.
At f/2.8:
Focus at center and take a picture and than focus at mid-field and take another picture. Compare both images at center and look for differences.
Fred Miranda wrote:
It may not be due to field curvature though.
You can do an experiment.
At f/2.8:
Focus at center and take a picture and than focus at mid-field and take another picture. Compare both images at center and look for differences.
Yes it is Fred.
I did that test. I had to do it from my window, but you get the idea.
As this lens is an internal focus design: some of these lenses are very prone to a change
in flange focal distance which often results in an added field curvature
(had that with my Sigma 35mm 1.4 which had noticeably less field curvature on my A7III than on my A7rII).
So if mount and lens tolerances play in favor of @Fred Miranda@ and not in favor of @Jochenb@ it could be possible you are both right.
@Jochenb,
Thanks for posting your test. You were right!
I agree that the Sigma 45/2.8's mid-field shows slightly higher curvature compared to other areas, making FC a bit wavy. I've tested this again today comparing the amount of curvature for mid and corners.
Yeah, I'm definitely going to rent one for a trip in a couple weeks. Need some hands-on time with it to determine if it's just GAS or if I really need an AF lens. I'm loving everything I'm seeing so far - except for the concerning possibility of copy variance.
Stop it Fred! I’m enjoying my new 35 1.2 first, and I’m loving it. I played with the 45 and all my shots were back focused and slightly soft when at portrait distance. But I see you’ve all done the research on that so I’ll revisit it when I’m off the road.
I’m enjoying my new 35 1.2 first, and I’m loving it. I played with the 45 and all my shots were back focused and slightly soft when at portrait distance. But I see you’ve all done the research on that so I’ll revisit it when I’m off the road.