thrice
Established
Cool lookin' little thing. I'll reserve judgment on usability until I get the thing in my hands but the touch screen makes me nervous.
Seen this mentioned a couple of times, but FYI the NEX cameras don't have touchscreens.
semilog
curmudgeonly optimist
It's not just "quality." It's that digital sensors impose different optical requirements than film. There are at least two problems. One is sensor illumination. As one moves from center to corners, the rays fall on the sensor more obliquely. For film, not a big deal. For a CCD or CMOS detector, a huge deal. To get less vignetting, one needs the rays to strike the sensor as close to a right angle as possible. This usually means a bigger lens that produces more parallel rays, especially at wider apertures.
The Leica/Kodak solution was graded microlenses from center to edge, but this introduces a variety of other problems including gradient color s solution hifts that must be corrected, differently for each lens. This is expensive to implement, and it may also reduce the sensor's detection efficiency (though this last is speculation).
The other big problem is that the thickness of the photosites on a CCD or CMOS sensor is effectively zero, while a film emulsion layer is 20-40 micrometers. This means that curvature of field and focus shift are a lot more noticeable on a CCD detector than on film. Each aberration that needs to be corrected adds glass weight, bulk, and expense.
Add to this the weight and bulk of AF and IS, and you're looking at "big."
Note also that correcting aberrations in a physically smaller lens often requires exotic glasses and shapes. Leica excels at this, and it is no coincidence that they charge more than almost anyone else. So you have a choice: the relatively svelte Leica 24 Summilux ASPH, or the far less expensive, big-as-a-beer-keg, and (probably) optically superior Nikon 24/1.4 (the new one).
Last edited:
Bruin
Noktonian
Adapted lens potential
Adapted lens potential
Looks like the NEX series will make an excellent platform for adapted lenses...
1. 18mm register (even shorter than micro 4/3) and lens mount wide enough for an M-mount adapter (unlike Samsung NX10)
2. Image capture possible without lens attached (necessary for adapters without electrical connections).
3. High resolution, auto-gain LCD.
4. MF focus assist 7x or 14x zoom.
5. Compact, decently-fast wide angle lens already available. No shortage of longer focal lengths with adapted lenses; it's the wide angles that are harder to get.
Ok, it's not gonna work for the C-mount crowd. But as a cheap alternative to the RD1 and M8, it's looking real good so far.
Adapted lens potential
Looks like the NEX series will make an excellent platform for adapted lenses...
1. 18mm register (even shorter than micro 4/3) and lens mount wide enough for an M-mount adapter (unlike Samsung NX10)
2. Image capture possible without lens attached (necessary for adapters without electrical connections).
3. High resolution, auto-gain LCD.
4. MF focus assist 7x or 14x zoom.
5. Compact, decently-fast wide angle lens already available. No shortage of longer focal lengths with adapted lenses; it's the wide angles that are harder to get.
Ok, it's not gonna work for the C-mount crowd. But as a cheap alternative to the RD1 and M8, it's looking real good so far.
Last edited:
chrishayton
Well-known
Its not me being 'sniffy'. It was merely a comment about how cameras with bias towards manual controls are now virtually foreign to the majority of the population used to scene modes and automatic exposure.
Just look at all the entry level DSLR stuff. one control dial for both aperture and shutter. not very convenient, and the EPL1 hasn't got a dial at all. just buttons that the secondary features are aperture and shutter control and the new sony which is buried in a touchscreen interface.
Personally I like things manual and simple yet the majority of all camera users prefer a point and shoot system and the market reflects that
Finder
-
Let me get this straight. A digital sensor is absolutely flat and film has a thickness so a digital sensor suffers more from oblique rays of light that cause vignetting? Please cite you source. I would think a completely flat sensor surface would be less in need of telecentric optics as there is nothing to impede the light reaching the photosite.
I believe the film base is 20–40 mircons thick. Light does not pass through the base of the film as the emulsion is on top. Can you cite a source for emulsion thickness? From what I know, film companies keep this information secret, but the emulsion is much thinner than the base. Can you also cite a source that depth of focus is actually different for a sensor than a piece of film given the same area. And why is an infinitely thin plan harder to locate within the depth of focus than one that is not flat and has a thickness?
Not that I do not believe you, but your claims sound strange.
antiquark
Derek Ross
I've heard that too. The surface of a CCD is polished silicon, so an oblique ray will basically bounce off.
Film is a translucent gelatin, so it will absorb oblique rays more effectively.
luuca
Well-known
from my point of view they are more interesting than 2xcrop micro43
smaller, with bigger sensor size (1,5x): it's enough to happily wait for a M-mount adapter
probably I found a substitute for my LX3
Last edited:
Finder
-
That does not explain why vignetting is greater. Photosites are design to absorb light. Reflection happens at all angles if it happens at all. So there should be no difference beyond the cosine^4 law. From your example, film should suffer more from the cosine^4 law as light would have to travel through more of the gelatin to reach the photosite.
antiquark
Derek Ross
Also I forgot about the low pass filter in front of the sensor. This will also act to reflect oblique rays.
It's a well known optical principle that an oblique ray is more likely to bounce off a surface than a perpendicular ray, and that the effect increases with a higher refractive index.
Last edited:
HoodedOne
Well-known
Video of the focus speed of the NEX-5
http://www.youtube.com/watch?v=tNxPgNVDGK8
http://www.youtube.com/watch?v=tNxPgNVDGK8
Another camera that caters to the consumer who wants video instead of the photographer who wants control over the camera.
Finder
-
But the angle of incidence is too low to be a factor. If that was the case, a simply UV lens on the lens would cause vignetting. Also, you state the gelatin is transparent, so it would apply to that as well.
Maybe Semilog knows the answer.
Mazurka
Well-known
gavinlg
Mentor
There's some pretty bad info in this thread - I know 2 or 3 people have inferred that it has a touchscreen - it doesn't have a touchscreen.
semilog
curmudgeonly optimist
Incorrect. Essentially all modern detectors have photosites that are smaller than the pixel area. Consequently, nearly all modern detectors are studded with microlenses to focus illumination on the center of the photosites, so as to increase quantum efficiency (note also that the photosites are, on almost all current larger-format CCDs and CMOS sensors, underneath the circuitry, a design as bassackwards as the vertebrate retina; but I digress). The microlenses work better when illuminated at an angle normal to the sensor plane, and less well when the light is shining at oblique angles. This is the problem that Leica and Kodak were trying to solve with their eccentric microlens arrays, so as to support legacy Leica rangefinder lenses. I am not yet convinced that this was better than a kludge.
Erwin Puts describes this in his essay on lens testing, his discussion of the M8 and elsewhere. Lloyd Reynolds also touches on these subjects in his discussions of field curvature, but his articles are mainly pay-per-view.
Some of my favorite claims are the ones that are strange (counterintuitive). It's even more fun when strange claims turn out to be correct.
Last edited:
Pat Donnelly
Member
Semilog
Semilog
Thanks for the articles!
Semilog
Thanks for the articles!
noimmunity
scratch my niche
link to comparison with m4/3
link to comparison with m4/3
A useful comparison table showing some main functions of the NEX line compared against m4/3 offerings from other manufacturers has been put up on a Chinese site. You don't have to read Chinese to guess at the meaning of the values on the table.
http://chinese.engadget.com/2010/05/12/nex-vs-m4-3-comparison-table/
unfortunately it does not include other APS-C cameras (which are really more in its own class, sensor-wise).
link to comparison with m4/3
A useful comparison table showing some main functions of the NEX line compared against m4/3 offerings from other manufacturers has been put up on a Chinese site. You don't have to read Chinese to guess at the meaning of the values on the table.
http://chinese.engadget.com/2010/05/12/nex-vs-m4-3-comparison-table/
unfortunately it does not include other APS-C cameras (which are really more in its own class, sensor-wise).
Last edited:
urban_alchemist
Well-known
In AF speed, the s10 (small sensor zoom) is pretty good... the A12 (the one we're all interested in - APS-C 50mm f2.5)... well...
Sunlight: OK (point-and-shoot speed)
Overcast: Borderline (some hunting)
Low-light: Abysmal. Think 2-3 seconds to get a lock - if it can get one.
In order to get those speeds, too, the image blacks out (both EVF/LCD) until it's locked.
Ricoh's "Snap" function is useless here too, unlike the wide-angle GRs - 50mm is simply too narrow to get meaningful depth-of-field in all situations...
The saving grace is the manual-focus - a gorgeous MF ring with markings on the LCD and in the EVF. However, there's no zoom function, and the throw can be a little long....
And for the record: I'm comparing it to dSLRs and µ4/3 Panasonics - I tried the DP1/2 and X1 (the other APS-C cameras) before I bought my GXR and they're as bad, if not worse....
... and a Leica X1 killer as well... if only it had the red dot.
Yeah, right.
Finder
-
This has always been true, not just with "modern" detectors.
So, like film, sensors have a thickness. But this is not what you said.
This seems a contradiction. So the vignetting on a sensor has to do with sensor optical thickness (or to put it more accurately, alignment)--I have a Phase One digital back with no micro-lenses and vignetting is no different than for film (we use film and digital backs on the same camera.)
The cosine^4 law is true for digital as well as film. Vignetting also causes color shifts with film. I guess I do not share your view that a digital sensor, beyond its optical requirements due to micro-lensing and its thickness, is any different from a chemical medium.
And Puts (which I don't think of as a great or definitive authority) states that a good lens designed for film works well on a sensor--at least that is what the article stated in the link you provided. (Puts also stated that a smaller field of view is the same as stopping down a lens as marginal rays are not use, which is not true as the extent of a field stop (film gate) does not affect the size of an aperture stop. So I think we may be able to question his statements.) He states there is some properties that affect film because of its thickness, but he does not offer any real proof. This sounds like an urban legend type of stuff. If film thickness was a real problem (or solution), then color films would be impossible to make because the focus difference between the yellow and cyan layers (separated by a yellow filter and magenta layer) would have two different images. I question his 20 micron number for emulsion thickness--I don't have a number, but I work in microns enough to wonder where he gets it (and it needs to be the undeveloped emulsion as a developed emulsion is thicker).
Out of focus images, no matter the degree of focus shift, are, generally speaking, out of focus--no big surprise there. The article did not show that this is actually different between film and digital. He does state Leica is making cameras with less tolerance, but that could be Leica catching up to the 21st century--their film cameras could benefit from it too.
But lenses are designed for a format. The smaller the format, the higher the resolution needed. But "digital" lenses are not always great--just look at the examples in the link posted on this thread for the Nex cameras. The optics stink--curvilinear distortion, curvature of field, and vignetting are obvious. My cv 12mm does much better on my E-P1 than the 16mm on the Sony and my cv was not designed for a sensor.
I don't see you claims as "correct." Vignetting is vignetting and the cosine^4 law is no different for film as it is for digital--even down to the color shift. The micro-lensing issue is separate. That is an optical alignment issue.
Film emulsion has a thickness (but does it have significance). Sensors have a Bayer pattern that lowers resolution and so are not really performing at what the pixel pitch would suggest (and can be shown to be different to sensors without one). Neither "fact" really says anything. The post that you replied to could actually be right--we examine pictures more closely and so the imperfections in older lenses are more pronounced. This has nothing to do with "thick" emulsions and "thin" sensors.
However, I do agree that optical design for a sensor with micro-lenses is different. But not always better--as Sony has shown on their camera.
I hope this made some kind of sense--coffee is not doing anything for me this morning. :bang::angel:
:dance:
Last edited: