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Messages - sarangiman

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196
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 04:38:04 AM »
...
That said, DxO is a complete and total joke. This is a company that ranks consumer DSLRs above medium format digital backs in IQ.
...

There is no rule that says a MF digital back must be better at taking pictures than a DSLR.

If the design and technology used by the DSLR is superior to that of the digital back and delivers better images then it stands to reason that the sensor can be rated above a MF back.

+1

Thank you dilbert for stating what with common sense & logic should be apparent to everyone.

197
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 02:53:49 AM »
2. They get more than 14EV on the normalized comparison, it's normalized to 8MP so with 36MP to play with there is a lot of room to get the extra bits after normalization there.

Exactly. Say you have 14EV DR at the pixel level; i.e. you've perfectly matched your ADC to the DR attainable at the pixel level (e.g. saturation capacity = 16,384 e- & read noise = 1 e-). But say this is for a 100MP sensor.

When you go to make a 4" x 6" print of that 100MP file, you'll be doing a lot of downsizing for a 300dpi printer. That process of downsizing will reduce noise. Therefore you will be able to lift shadows more while still producing an acceptable print. Therefore shadows with a pretty low SNR may suddenly become 'acceptable' the viewer of the 4x6 print.

Yada yada... that's how you get more dynamic range via normalization.

Although I still have a hard time wrapping my head around it.

Because if your SNR is ever <1, you're not going to magically recover the signal by resampling... resampling would only bring you closer to the average of the noise as SNR approaches 0.

But for more reasonable definitions of DR (e.g. Bill Claff's 'PDR' that defines the lowest acceptable SNR as 20), normalization expanding DR makes perfect sense.

198
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 08:28:34 PM »
As I wrote, the problem was the color in portraits was distinctly worse.  The blown highlights were an added problem.  I'm talking about using the cameras for actual photography, not lab tests.  So, yes, consistent with its price, the D7000 was distinctly worse in actual photography.  The D7000 was a bit like a kid who scores great on a standardized test, but is lacking in essential people skills. :)

I understand, but my point is simply that the 'blown highlights', in this case, is not indicative of anything wrong with DXOs sensor scores for the D7000. The (Sony) sensor in the D7000/D5100 really does have significantly more DR than any Canon sensor.

If you found that it blows highlights too often, then perhaps you disagree with Nikon's metering algorithms in those situations.

As for Nikon/Canon color, I'm inclined to agree with you & say my personal taste is for Canon's default colors. But I bet if you really wanted to you could build a DNG profile that makes a Nikon camera match Canon's default colors. Whether or not you wish to do so is another matter altogether.

199
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 08:04:32 PM »
The 5D Mark II's won easily; the D7000's were actually worse in color and more prone to blowing highlights.

A camera being prone to blowing highlights says more about its metering than its dynamic range. The dynamic range of the D7000 is demonstrably worlds above that of any of the 5D cameras. Yes, despite its price. It's all about saturation well capacity & read noise (& megapixel count of course, if we're talking about normalized results).

200
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 07:50:04 PM »
+1

confirmation bias, thats why you didnt also get a response over your comment @ dtaylor and his "the right way" DR test.
Well, let's give @dtaylor some more time to respond. If I remember correctly, he said he uses transmission wedges for his tests, so I'd be very surprised if he got different comparative results between bodies. Absolute results may vary based on what you set as your acceptable SNR on the low end. But even then, the D800 should consistently show ~2.5EV higher DR (pixel-level) than 5DIII. I've tested this numerous times, b/c I was also incredulous at first.

I even remember being incredulous about the D800 beating the D4 in DR, but the data is the data. The D800, despite having a lower saturation capacity per-pixel, simply has lower read noise on a per-pixel basis. Low enough that its DR even trumps the D4. That's also why it's not hard to imagine the D800 beating medium format in DR (though I agree with neuroanatomist that I'm not sure how fair the normalization formula is | e.g. D800 @36MP goes up 1.1EV from screen to print, Hasselblad @50MP goes up 1.35EV, D600 @24MP goes up 0.8EV... I really can't comment one way or the other if it's fair as I haven't delved into their normalization formula yet).

Interesting point about DXO getting the D600 scores out before the 1Dx. Then again, if I had a D600 vs. a 1Dx in my hands, I'd be more excited about testing the D600 b/c the 1Dx has already been shown to not have much more DR than the 5DIII (e.g. here: http://home.comcast.net/~NikonD70/Charts/PDR.htm#EOS%205D%20Mark%20III,EOS%201D%20X)

201
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 06:10:29 PM »
Quote
Really?

actually what techradar results show is that they dont have a clue what they're doing. Just look at the progression of this lines, they dont even make sense!

According to the page you linked we can assume that:

Raw (after conversion to TIFF) dynamic range:
  • D4 has the same DR either @ 100 or 1600
  • 1Dx has peak DR @ 3200 and at 6400 it falls to the same level as @ 100 (magic!)
  • 1DIV has a variation of .5stop through the entire range of isos

JPEG dynamic range:
  • 1Dx peak DR @ 12800  :o
  • 1D4 solid DR from 100 through 4000

Its not the 1st time either that there is a discussion about techradar's silly results, just search around here or any other forum.

+1

Ah, yes, I forgot about those results. Pretty strange.

When I mentioned that the general trends between those results & DXO remain the same, I was just pointing to the general DR trends at base ISO (Nikon > Canon), and the general trend that DR for Nikon drops below 1Dx & 5DIII at high ISOs. As well as the trend that pixel-level SNR for D800 falls below that of the Canon sensors -- no surprise there as it has smaller pixels. Normalized SNR, however, is a different story-- with the D800 beating the 5DIII, & the D600 beating both the D800 & 5DIII.

I'm just surprised at how many people call foul at DXO without taking the effort to really analyze what the measurements/results show.

202
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 05:00:05 PM »
Quote
http://gearburn.com/2012/08/canon-eos-1dx-review/

DxOMark doesn't mean anything...

Canon still better, specially in HI ISO...

I see nothing there that disagrees with DXO. One must simply take into account what each measurement/chart means. Those charts you linked to show higher DR at base ISO for the Nikon D800, yet lower pixel-level SNR. DXOMark shows the same thing.

203
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 04:55:09 PM »
Quote
While it does show an advantage for the Nikons on base ISO Dynamic Range, the Canons actually shows a better ability to retain it over the ISO range. 

So does DXOs results on their own site...

204
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 04:54:22 PM »
Quote
"Overall, though, it's difficult to shake the feeling that the EOS 6D simply lacks the 'wow' factor of its main rival. Whereas Nikon seems to have taken the approach of taking away as little as possible from D800 when creating the D600, Canon appears almost to have gone the other way, removing as much as it thinks it can get away with at the price. The result is the kind of conservative, slightly unimaginative design that's become the company's hallmark."

I'm glad dpreview just came out and said it like it is.

205
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 19, 2012, 03:43:01 PM »
Quote
I've personally tested DR for a number of cameras (the right way). My results match results from sites like DPReview. DxO is always off, and always quite obviously wrong.

dtaylor: How do you test DR? When I use a 42 step transmissive wedge, my DR numbers, assuming a lowest acceptable SNR of 1 (which is what I believe DXO does), pretty much match DXO results for RAW capture within 0.2 EV. And to account for lens transmission variability & different ISO mappings between cameras, I take a number of shots at 1/3EV apart & select the shot of the wedge where the brightest patch is just short of clipping... I then use these shots to build an output vs. input curve, & quantitate the range from SNR 1 to brightest patch that isn't clipped.

Furthermore, your results match DPReview? DPReview doesn't test RAW dynamic range... so I'm confused: what are you testing?

Pretty sure Bill Claff's DR numbers also match DXO for the most part; also he uses a possibly more meaningful number: PDR (photographic dynamic range: lowest SNR of 20 adjusting for circle of confusion of sensor). His tests also show ~2.5EV better performance of the D800. Check out his stuff here: http://home.comcast.net/~NikonD70/Charts/PDR.htm

My own 'real-world' tests also show ~3EV better DR on the D800 when I do side-by-side shots of high DR sunsets with my 5DIII vs. D800; the D800 is able to maintain highlights that the 5DIII needs a 3 or 4-stop reverse graduated ND filter to reign in (while keeping shadow noise similar between the two). Put another way: I have to overexpose my 5DIII by 2 to 3 stops at the very least to get its shadows to match the cleanliness of lifted shadows of the D800 file that was underexposed to maintain highlights.

So, respectfully, I fail to see how DXOs DR & SNR, etc., numbers are the 'odd ball out'.

To clarify: I don't at all mean this to be a personal attack; just looking for clarification. Also, I'm tired of people harping on DXO when they're just trying to do good science (though, like others, I do not pay any attention to the 'overall' sensor score... jus the raw SNR, DR, etc. numbers).

206
Lenses / Re: Canon 14-24 2.8 - With our powers combined....
« on: September 18, 2012, 05:39:04 PM »
Oh, sure, if you're a landscape shooter I see no reason to stick with Canon save for its TS-E lenses.

D800's >2 extra stops of pixel-level DR (and more normalized DR) is game changing for landscape photographers. Combine that with good graduated ND filters & you'll probably almost never have to HDR stuff.

Reason I'm not switching yet is b/c the 5D Mark III's focus accuracy/precision for <f/2 shallow DOF shots is pretty awesome. Precision on the D800 is great as well, but I'm trying to quantitate exact accuracy/precision before I decide which system works better for wedding/people photography. I've found a strange phenomenon with Nikon body/lenses in terms of focus accuracy at fast apertures, which I do not see on the Canon. Trying to confirm then publish my findings.

Do you use filters with your 14-24? 6x9 filters get incredibly expensive...

207
Lenses / Re: Canon 14-24 2.8 - With our powers combined....
« on: September 18, 2012, 01:11:54 AM »
Quote
It seems, maybe that the times I'm getting good corner results the corners are only a few meters away, with the central subject at a similar distance.  At longer distances it's very soft.

Right, that's the whole problem with wide-angle lenses. Small shifts in elements changes the actual focal plane in focus tremendously. Ideally, you want only the plane you're trying to focus on in focus across the field of view. The short focal lengths & high effective refractive indices of wide angle lenses necessitate small tolerances on lens focal plane/sensor parallel alignment. If anything is slightly off, a whole different plane will come into focus on the relevant portion of the sensor.

Remember also lens manufacturers attempt to correct for field curvature to a certain extent; how well they do this probably also affects how well the lens can keep only the plane in focus.

I usually test wide angle lenses by shooting a horizon (near infinity). Although in lots of wide-angle photography, you do actually want both something near & far in focus, with whatever that is near typically more on the edges of the frame, you don't want the scenario where your nearby object happens to be on the edge of your frame where your lens actually focuses better *beyond* the focal plane you've focused on!

So are you shooting w/ the Nikon 14-24 on your Canon? If so, what adapter are you using?

208
Lenses / Re: Canon 14-24 2.8 - With our powers combined....
« on: September 17, 2012, 10:06:47 PM »
Quote
at the wide end it cleans up quickly above f/8 but you only have until about /16 before diffraction softening starts to show up too.

Well, you're lucky. The 17-40s I tested just never cleaned up satisfactorily until diffraction set in. One lens I had actually was repaired by Canon... when I got it back, it did clean up by ~f/8. I let it sit around without touching it or moving it for a few months. Next time I put it on, it was decentered terribly again. In my opinion there's just something wrong with the design of those ultra-wide zooms. Maybe they just do need the large bulbous front element a la the Nikon 14-24 to get sharp edge-to-edge sharpness... and of course that comes with its own set of issues (that I, personally, would put up with).

I tested the Tokina on my 5D Mark III & was not impressed. I briefly tested a Nikon 16-35 on my 5DIII & it seemed to perform respectably, but not as well as the Nikon 14-24. That being said, it may be worthwhile to revisit the 16-35 & really assess its edge-to-edge performance b/c the 77mm filter thread makes it extremely convenient for landscapes... ND filters, polarizers, grads, etc... all of which you *especially* need when shooting with the limited DR of Canon sensors.

One thing that bothers me about the 16-35 is the VR which, of course, wouldn't be engaged on a Canon body. I just feel like image stabilization adds more elements which translates to more chances of decentering/misalignment, etc. Perhaps I'm being paranoid?

209
PowerShot / Re: Canon S100 vs Sony RX100
« on: September 17, 2012, 09:59:02 PM »
Quote
Sony really does seem to be the more innovative camera company these days...

Actually, I should add Fujifilm to that list.
http://www.fujifilm.com/products/digital_cameras/f/finepix_f550exr/features/

210
PowerShot / Re: Canon S100 vs Sony RX100
« on: September 17, 2012, 08:38:08 PM »
Quote
True, but that 1" sensor is the clear advantage.

To an extent, yes. But remember that that 1" sensor has better dynamic range than my much larger Canon 5D Mark III full-frame sensor.

So there are a number of factors, not the least of which is the pixel-level read noise, which is extremely low for Sony sensors. As well as for the Canon S100 sensor, in fact). Pixel-level DR on the RX100 is only slightly better than on the S100, but given the extra pixels (~20 vs. ~12), normalized DR is significantly better.

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