11-02-2015, 01:40 PM
Quite nice ... but with a field curvature issue at the wide end.
http://www.opticallimits.com/m43/961_olympus714f28pro
http://www.opticallimits.com/m43/961_olympus714f28pro
|
11-02-2015, 01:40 PM
Quite nice ... but with a field curvature issue at the wide end.
http://www.opticallimits.com/m43/961_olympus714f28pro
11-02-2015, 05:04 PM
OMG! I guess the bad quality of double surface spherical lens made this huge field curve. like the 17 1.8
I wonder if the landscape picture corner or the architecture picture corner suffer more from field curve?
11-02-2015, 08:48 PM
Is the filed curvature worse at the very close testing distance than it is in practice (~infinity)?
11-03-2015, 01:20 PM
You mentioned the panasonic 7-x f4 as the lens you prefer. One question (I own neither) a frequent complaint of the panasonic lens is that it produces purple frining as well as heavy flare both of which the olympus lens lacks. Have you noticed an issue with purple fringing and would your view of the two lenses be different if your focus was city scape (non-infinity) images.
11-03-2015, 04:09 PM
Quote:Is the filed curvature worse at the very close testing distance than it is in practice (~infinity)?I am curious what would be Klaus's answer to that. Basically many lenses show a curved image field at close focusing distance, even "bold" ones like the 12-60 at 60 mm and MFD. It would be also interesting to know how long is the object distance at 7 mm in the test. Regarding field curvature: my ex-Tamron 17-50 non-VC had it, the workaround was either hyperfocal distance or focus at2-3 m or so, when doing landscape. By the way I also suspect that the FT version has a slight bit of it too, however I never digged into that. Other than that it is a bit disappointing the the best µFT-glass is sort of underdesigned here; I suppose that is the price to pay for the moderate dimensions.
11-03-2015, 05:35 PM
Quote:I am curious what would be Klaus's answer to that. Basically many lenses show a curved image field at close focusing distance, even "bold" ones like the 12-60 at 60 mm and MFD.My guess is the curvature "will" be there at infinity, judging by the way Klaus describes it's influence in the real world, it is generally less noticeable at closer distances unless you're artistically photographing brick walls. In fact it's such a shame that the lens has this problem,especially at it's price point, when you consider the small dimensions of the µ4/3 sensor, it's so small it hardly has any edges! Regarding the Tamron 17-50mm non VC which I have, the curved field is noticeable at 17mm in the corners with landscapes, also the Sigma 10-20mm F4/5.6 suffers a similar fate, DPreview tested it using compromised/hyperfocal focus. Maybe also the Nikor AF20mm F2.8, either that or soft extreme corners, (how could I say anything against the AF-D range?) but hey, I'm talking about a cheap S/H lens here, God bless it!
11-04-2015, 12:16 AM
Quote:Is the filed curvature worse at the very close testing distance than it is in practice (~infinity)? Does it matter in this case ? I mean why would you care about the corners in a close focus scenario ? The effect at infinity can be observed in the sample images.
11-04-2015, 01:42 AM
It matters because the measurement was at close focus, so the effect might seem worse there than in "reality"?
11-04-2015, 05:57 AM
Quote: My guess is the curvature "will" be there at infinity, judging by the way Klaus describes it's influence in the real world, it is generally less noticeable at closer distances unless you're artistically photographing brick walls.Well, therefore it is interesting to know how far was the testchart. And what does the sensor size have to do with the field cuvature? µFT just allows the manufacturer to use smaller lens elements that with 35 mm, for instance.
11-04-2015, 12:01 PM
Quote:Well, therefore it is interesting to know how far was the testchart. And what does the sensor size have to do with the field cuvature? µFT just allows the manufacturer to use smaller lens elements that with 35 mm, for instance.The test chart is at around 51x the focal length distance. For 7mm that means around 7 x 51 = 35,7mm distance. There are no test images at f2.8 or f4 or even f5.6, so no way to tell if the corners will be that badly affected at more normal UWA distances, or how ones photography would be impacted? |