I need some advice, please. I ordered a copy of the 40mm, and in testing I found the vignetting to be extra dark in the upper left corner -- the other corners were not symmetrically dark. Things improve as I stop down, but the top left is still darker, even at f4. So, I ordered in a second copy. The corners on the second copy didn't get sharp, even by f5.6. So, I ordered a third, and it's not as sharp as the first copy, either. So, I'm wondering whether the asymmetrical vignetting I'm seeing is simply typical or whether I need to keep trying to get a good copy. Test images follow. The house is about 200m away, shown at 100%. Thanks for the help.
I'd say that corner is very sharp for such a lens at f/5.6. What kind of expectations do people have?
Vignetting is kind of hard to measure. How did you ensure that your target was perfectly equally illuminated all over?
I see no real problem with the corner. Maybe my right upper corner is "sharper" at f/4 than yours - but how do we know that without making the same thing (target and distance). Maybe it is less sharp.
Vignetting.
It's easy to check if holding the camera vertical: first aim at something at shoot away. Then turn the camera180 degrees, aim at the same place and take another series. (Same as when checking for decentering, just a little easier to do than first holding the camera in normal position and then upside down).
Assuming your target is perfect my copy clearly has less difference between the four corners, pretty much equal actually. But - shooting at the sky will most often give you uneven light. Try it again as described and you'll perhaps feel better about the vignetting.
EDIT: Sorry for repeating rsrsrs advice, I was interrupted while typing.
I did flip the camera 180 during the sky vignette test (and lined the shot up similarly using a roof line that I left just out of the top of the frame and a tree just outside the lower right corner), and the asymmetry did seem to follow the rotation of the camera. Specifically, compared to the center, at f1.2 I see corners of -0.8EV, -0.5EV, and two corners -1.7EV, so it's really not all just about the one corner, it's overall symmetry and whether -- on balance -- there's a significant shortcoming in my copy.
When I created the previous grid of houses above I didn't use the top left corner since it wasn't representative. But, I think you all are right in that the more useful question is perhaps comparing the 4 corners relative to each other, so I've recreated the grid below showing only the corners. Note that these are the extreme corners, and I really don't expect much from these areas at the widest apertures.
Add me to the list of CV40 owners .. as well as the CV65. lenses should arrive early next week.
Saw a mention of cameraquest ... maybe on this thread .... and checked the company out. had a great buying experience with steven. prefer to support small businesses with a good reputation.
I am learning how to get what I want out of this lens - not to 100% pixel peep wide open (rather focusing on the final image at final size), getting the focus accurate, getting the framing better for candids, paying attention to the background/foreground, etc. Some people think this lens is over-priced, but I'm coming around to thinking the price is about right. If it was 100% pixel level sharp across the frame wide open, it would be 3x the price.
Not my best of efforts, but it's getting me images I like.
Parariss wrote:
Thanks so much for the suggestions, all.
I did flip the camera 180 during the sky vignette test (and lined the shot up similarly using a roof line that I left just out of the top of the frame and a tree just outside the lower right corner), and the asymmetry did seem to follow the rotation of the camera. Specifically, compared to the center, at f1.2 I see corners of -0.8EV, -0.5EV, and two corners -1.7EV, so it's really not all just about the one corner, it's overall symmetry and whether -- on balance -- there's a significant shortcoming in my copy.
When I created the previous grid of houses above I didn't use the top left corner since it wasn't representative. But, I think you all are right in that the more useful question is perhaps comparing the 4 corners relative to each other, so I've recreated the grid below showing only the corners. Note that these are the extreme corners, and I really don't expect much from these areas at the widest apertures.
I'm having a slight case of the jitters here. I have the funds and am going to be purchasing this lens this week, but am a bit concerned that B and H is one of the only sellers, and a number of folks here seem to have returned lenses to them.
I'm in Philadelphia, and have purchased from B and H quite a few times over the years without ever having an issue, but this will be one of the pricier items I've bought from them.
Should I be concerned about being sent a "re-stocked" item? Are there other options out there for customers in the US?
I’d order from an Authorized distributor through amazon eg CameraQuest or Photo Village. The return thing you will just have to deal with. We all do.
imagesfromobjects wrote:
I'm having a slight case of the jitters here. I have the funds and am going to be purchasing this lens this week, but am a bit concerned that B and H is one of the only sellers, and a number of folks here seem to have returned lenses to them.
I'm in Philadelphia, and have purchased from B and H quite a few times over the years without ever having an issue, but this will be one of the pricier items I've bought from them.
Should I be concerned about being sent a "re-stocked" item? Are there other options out there for customers in the US?
