|
next PZ lens test report: Canon EF 20mm f/2.8 USM
|
10-22-2012, 08:18 PM
An old lens and it shows:
[url="http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff"]http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff[/url] 
10-22-2012, 08:32 PM
[quote name='Klaus' timestamp='1350937082' post='20682']
An old lens and it shows: [url="http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff"]http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff[/url] [/quote] The field curvature of the Tokina 17/3.5 is the worst that I have encountered so far. I had to sell it because of that and it's a pity because it's a very fun lens to play with.
10-23-2012, 07:15 AM
[quote name='Klaus' timestamp='1350937082' post='20682']
An old lens and it shows: [url="http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff"]http://www.opticallimits.com/canon_eos_ff/775-canon20f28ff[/url] [/quote] The second resolution chart was the oddest one I've ever seen. [quote name='youpii' timestamp='1350937977' post='20683'] The field curvature of the Tokina 17/3.5 is the worst that I have encountered so far. I had to sell it because of that and it's a pity because it's a very fun lens to play with. [/quote] Oddly enough, I wanted to buy this lens once, but didn't. Now I want to find one to try it out despite the lack of any need in it (since I have a 16-35 II).
10-23-2012, 07:43 AM
[quote name='Rover' timestamp='1350976510' post='20685']
The second resolution chart was the oddest one I've ever seen. [/quote] That is the nature of field curvature. Interestingly it (the field curvature) gets worse the more you stop down thus resulting in this roller-coaster ride.
[quote name='Klaus' timestamp='1350978227' post='20686']
That is the nature of field curvature. Interestingly it (the field curvature) gets worse the more you stop down thus resulting in this roller-coaster ride. [/quote] Yeah, I'm pretty sure this isn't a normal behavior... SLRGear review was pretty much in line with your findings and they specifically mentioned field curvature: http://slrgear.com/reviews/showproduct.p.../80/cat/10 Interestingly, their graph shows the lens sharpness to decrease slightly when going from f/5.6 to f/8, though it's nowhere near as wicked as what you've found.
[quote name='Rover' timestamp='1351008055' post='20688']
Yeah, I'm pretty sure this isn't a normal behavior... SLRGear review was pretty much in line with your findings and they specifically mentioned field curvature: [url="http://slrgear.com/reviews/showproduct.php/product/80/cat/10"]http://slrgear.com/r...oduct/80/cat/10[/url] Interestingly, their graph shows the lens sharpness to decrease slightly when going from f/5.6 to f/8, though it's nowhere near as wicked as what you've found. [/quote] This is normal. I would be very surprised if slrgear performed tests on a flat plane rather than on the focus field. This would be naive testing (of defocused zones). Manufacturer MTFs are also provided based on the focus field.
[quote name='Klaus' timestamp='1351019239' post='20689']
This is normal. I would be very surprised if slrgear performed tests on a flat plane rather than on the focus field. This would be naive testing (of defocused zones). Manufacturer MTFs are also provided based on the focus field. [/quote] "Normal" as in "expected and desirable for a lens". I can understand if it's normal for this particular model. By the way, for the sake of completeness here's another review of this lens. The verdict is unsurprising. http://slrlensreview.com/web/reviews/can...ens-review By the way, I was bored today so I compared the results with those of the old Nikon 20/2.8 D, and it looked so much better in comparison (of course I didn't compare exact figures, just the resolution bar heights and general impressions), despite being an old design with mechanically dated implementation. |
| Users browsing this thread: |
| 1 Guest(s) |
