Some info on the 24 MP Nikon - from a Sony engineer

Started Oct 29, 2008 | Discussions thread
bobn2
bobn2 Forum Pro • Posts: 69,171
Re: expensive strategy

FrankG wrote:

bobn2 wrote:

Tiffles wrote:

That is going to be one expensive sensor for Sony then - wonder how
much they think they will sell in their own bodys. Also, don't Sony
and Nikon have a long business relation in terms of 'sensor pooling'?

How about this pure imaginary bit: Nikon wasn't happy with the sensor
Sony made (no movie function, live view, noisy, in sum worse than
what the new Canon sensor is hoped to be) and now have to design one
themselves.

Well I think Nikon may be considering other options, but not for
those reasons. The A900 sensor is pretty much an upscale of the
sensor in the D300 and D90. With that they manage movie function and
live view. The noise is also not nearly as bad as made out. At equal
output sizes, it seems to be in the same ballpark as the D700, by
comparisons done on this forum, just not quite there (in fact, pretty
much the 1/3 stop worse I suggested). If people insist on looking at
high density cameras at 100% crop, then they're always going to go on
about the noise.
--
Bob

Even at base ISO?

It's tricky to judge at base ISO, since the available sensor DR of decent camera so far exceeds the DR of most available output media, that they all end up looking much the same, even if the measure differently. I haven't done any measurements, but I get the impression (from such things as the DPR DR test, for instance) that the A900 has quite good low ISO read noise, and therefore quite extended low iSO DR.

If you were right then what would be the point of having such a
"higher density" (as you put it) camera if you end up having to
downsize the output to make it acceptable noisewise? If such is the
case then there isn't any point at all.

No-one said anything about downsizing the output. We invariably upsize it, since no-one's keen looking at images 24x36 mm. The issue is, what do you lose by increasing pixel density? The answer is nothing (except file size and processor capacity). If you choose to make an image to your prefences with a low and high pixel density camera with the same size and tech sensor, the noise will be of the same amplitude, so you haven't lest anything. What you've gained is the ability to make larger prints with some detail should you choose. Obviously, when doing so you may choose not to go for extreme ISO's or accept the noise or go B&W, but its an option you don't have with the smaller image size. Moreover, the higher pixel density image will have more detail even at smaller image sizes, even if the advantage is small at small sizes.

Of course I would actually say that there is a point for at least
some applications such as slow landscape and maybe portrait and
studio work at low ISOs where you should easily get clean output from
24Mpix FF cameras.

The great thing about high pixel density is you can choose. low noise? Don't print so big. Big print? Stick to 'low' iso. How often do you really use ISO's greater than 400 anywa? It won't be 'never' but it certainly won't be all the time, either, unless you're doing very specialist stuff.

However as for the A900 being only "one third of a stop" worse noise
than the D700 "at equal output sizes" - would you mind pointing to
your evidence for that?

First look at Emil Martinec's tables ( http://theory.uchicago.edu/~ejm/pix/20d/posts/tests/D300_40D_tests/ ) - the D300 has to stand in for the A900, and adjust for area. This might not be completely accurate, but since sensor efficiency seems to go across sensor families (look at the Canon ones) it's a fair assumption. Now look at Clarkvision ( http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary/index.html ) again letting the D300 stand in for the A900. On the sensor efficiency side (from Emil), we find that the D3(or D700) has about 1/3 stop advantage in area efficiency. Since the sensors are the same size, that translates to overall efficiency. Now look at the read noise figures (from Roger) and we find an advantage (more than a stop) to the A900 at low ISO's, with them being about even at high ISO's. This suggests that if anything the A900 will have a slight advantage at low ISO's. this actually triangulates with real test results, where the A900 seems to have a measurable DR advantage over the D3/D700.

It's a bit more difficult to find noise tests in raw at high iSOs (and JPEG tests tell you nothing about the sensor qualities) but this thread here: http://forums.dpreview.com/forums/readflat.asp?forum=1037&thread=29804929 did an equal size comparison in RAW at 3200 and I'd agree with his conclusion, the A900 holds up quite well, certainly seems to triangulate with my (around 1/3 stop) estimate. Above 3200 we'd expect the D3/D700 to pull further ahead, since its sensor efficiency advantage is still there and relative read noise is dropping. Beware of basing you assessment on JPEGs, the A900 seems to have a very poor JFIF engine. That may affect your purchase decisions, but doesn't tell you much abour relative sensor efficiency.

-- hide signature --

Bob

Post (hide subjects) Posted by
(unknown member)
mjt
Mel
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow