Originally posted by jeverettfine I have been looking at the DA 15's and will probably buy one of them. Interesting that the SMC is rated highest (but many more reviews). What gets me are all the comments about soft corners...
First of all, the wide angle of view of a lens like this will also amplify the near-far relationships in your subject matter. This, coupled with shallow depth of field, is in my opinion the primary cause of the perceived corner softness. If you take a photo of a flat object, you will probably have no real problems. One reviewer talked about how the rocks in the lower right of one image were sharp, but the mountains in the top corners were soft...duh????? Get a view camera and tilt the lens forward a bit and that will fix that. My impression is that most of the low reviews are due to a lack of understanding of what a lens like this will do.
Since I do wildflowers/gardens/ ponds/ etc...either version will probably do me fine. I had a Tamron 10-24 for a while and it was not particularly wonderful. It really was too wide at 10 and since I own one of the FA 20-35 (which I love), a prime 15 will probably be perfect.
Sorry to say that but there is field curvature and this is not that easy to fix. On some photos there no issue, on other it is a real problem.
You can look at an example of mine and take the time to look at the sharpness difference between center and borders by clicking on it and see a higher resolution image in flickr:
DA15, f/8, 1/320s, iso100.
Here it has been said the right corner is so weak that I should get it serviced. But the left corner is not perfect neither. And you'll find that most DA15 have softer on border than center and if you are carrefull that can be visible at full screen size already (1920x1080 in my case).
The question you should to ask yourself if you care or not and if anyway you can find a better lense compromize of weight/size/picture quality. This should not be a game to convince yourself the issue would only arise to other because they are too dumb.
And if you change the angle of the lens to try correct something... well you'll need to correct perspective in post prod to compensate at least for some kind of shoots and that will push softness even more. Speaking of shallow deph of field this really work only for close up. 15mm f/4 giving an hyper focal distance of 2.8 where everything can be in focus from 1.4m to infinite wide open... At 15mm f/.8 you can get everything from 0.7m to infinite in focus.
It is true that DA15 is far better than theses sigma 10-20 or tamron 10-24 but maybe not than DA12-24, sigma 8-16, samyang 14 or 16mm for sharpness. It is far smaller, has very interresting rendering overall, provide more contrast/resistance to flare, provide AF compared to the samyang... But the borders are sure weaker.
Edit: And if you ask, the photo has been sligtly cropped to get a better framing... so you don't even see the worst performance of borders.
Last edited by Nicolas06; 01-13-2015 at 01:35 AM.