systemlayers wrote:
No that's a video lens which doesn't cover the full sensor of m 4/3 (you'd get a lot of vignette).
Some people use c mount video lenses on m 4/3 but they still vignette a whole lot and have silly swirly bokeh.
The only c mount video lenses worth looking at are the primes from zeiss tevidon from what i've seen they don't vignette at all and aren't that badly price right now.
Actually the 1" format fast 50's do usually cover 4/3rds, it's the 25's which have issues with vignetting.
There's quite a number of C mount lenses which have some value on m43, the biggest problem is that many of the more suitable lenses are not adaptable due to not fitting the recessed adapters. The Senko is one of these and simply making it with an m43 mount solves the issue.
Are you looking at a larger version of this sample? Because I don't see any excessive chromatic aberration, at least not on the subject, which would appear as transverse/lateral color. Axial color does appear but is only really evident in the fringes in the lights on the right side of the frame; otherwise, I might attribute the variation in coloration to other sources (e.g. overexposure + slightly different color temperature of the lights themselves).
The haze could be caused by flare due to imaging relatively bright light sources in the background, as well as overexposure. Again, I need to see more images.
Maybe they chose a bad example to show. It's happened before, you know. Even Canon has done it, and they presumably have access to much more skilled photographers to test their gear. I need to see more. Any lens could be made to take a poor image. I am merely saying that one image is one data point. It is not reasonable to hold it up as the entire scope of what a lens is capable of.
The CA I see is the blue on the cigarette. It's excessive considering I can see it at this size. Though, I'm not sure if that's red on the opposite side of the cigarette. It's too small to make an adequate determination.
wickerprints wrote:
Jman13, it's hard to evaluate the quality of blur in your samples--perhaps a more quantitative test would be to take a shot of a ruler at an angle? This would help assessment of how much DOF is visible.
DOF cannot be evaluated from background blur at all, and a beer bottle is not admirably suitable as a subject for DOF evaluation. You are right, rulers rule.
The thing with DOF is that it is intimately related to the enlargement ratio--the size of the image divided by the size of the sensor. (We can assume that for comparative purposes, all images are resized to the same pixel dimensions and are viewed from the same distance; but due to different sensor sizes, we will see different enlargement ratios.)
The enlargement ratio then gives us a guide to the maximum acceptable circle of confusion, which in turn impacts the DOF. A high enlargement ratio requires a smaller max. acceptable CoC, which in turn decreases the DOF.
But other factors come into play, such as the format size affecting equivalent angle of view for a given subject distance (hence same perspective), and therefore the focal length required for the same subject framing for formats of different sizes. The smaller the sensor, the shorter the focal length required, and consequently, the larger the DOF.
I haven't looked into the actual calculations to see which effect wins out. ...Show more →
I did, and the effects cancel out. DOF is the same in both cases, although strictly speaking this is only true for intermediate to long object distances.
The macro regime is too complicated for me to think about at present.
Here the effects don't cancel out. In fact, it's not even possible to take two photographs with the same perspective *and* field coverage with the 50 and 100-mm lenses. (But it can be done with a different ratio of focal lengths.)
Macro is special - there's so many other things to consider.
But otherwise DoF and amount of light (they're the same thing, inversed!) in pictures at "normal" to far distances are determined by the space angle of view (steradians) and absolute aperture diameter (entrance pupil size). No need to make it any more complicated than this.
I just wish µ4/3 had kept the throat diameter of the "normal" 4/3 format. The 20mm register distance would be just excellent for experiments with wide converters otherwise... :-) This would increase light efficiency and shorthen the adapter thickness - not a bad combination!
