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Messages - sarangiman

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196
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 07, 2012, 06:15:10 PM »
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OTOH I believe it is said to not be good for astro photography since it messes up proper stacking.

Why would shadow crushing mess up proper stacking? It can change the noise profile, but random noise will still be removed by stacking...

I'm wondering if shadow crushing was the reason astrophotographers generally don't go w/ Nikon (aside from the fact that Canon offers cameras w/ better filters for astrophotography)? But if the read noise is extremely low, that may be irrelevant when compared to the noisy Canon images (especially when you consider FPN).

But I don't really know. Would love for an actual astrophotographer to chime in...

197
I just wish Auto ISO worked w/ EC in M mode... You could say 'just shoot Av' instead, but M allows you to, say, set a minimum shutter speed much more easily than going into Auto ISO settings to change the min shutter speed (which may depend on your setting, focal length, etc.). Auto ISO in M at least allows me to, in dim environments say, set the aperture to the widest setting I'm comfortable with for the DOF I'm looking for, then set the shutter speed to the minimum I feel is appropriate for the lighting/focal length/movement in my scene, then the camera does the rest. That's exactly what I can do right now, just without EC.

Shooting in this manner in Av doesn't allow me to change that 'minimum shutter speed' as quickly as just turning a dial in M, yes?

198
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 07, 2012, 03:42:16 AM »
Canon does preserve the noise information more than Nikon does because of this offset, but I haven't seen any data yet that quantitates how much the noise is 'crushed' by this pseudo-noise removal in Nikon cameras.

I'd like to see what the deviation from the expected logarithmic curve one sees in the actual signals of patches of Stouffer Transmission wedge shots with these cameras. That might give some clue as to what degree shadows are crushed in Nikon RAW files, with the added benefit of a seemingly higher SNR in the dark patches due to the effective lowering of noise (which would give them higher DR estimates if you calculate DR by determining the number of stops between the brightest not-blown patch & the darkest patch that still yields SNR=1). I'm attempting to do this now with transmission wedge shots from the 5DIII & the D7000. As of now, the D7000 yields SNR>1 even at patch 42 (13.2EV), but I'm curious if shadow crushing due to Nikon's special processing of low signals ends up not representing the actual gradation between the darkest patches as well as it might otherwise.

I have no doubt that the Nikon/Sony sensors & signal processing yield better DR than Canon (Fred Miranda's comparison is rather convincing!)... I'm just curious if it's as great a difference in the real world as what the DXO testing methodology indicates.

199
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 07, 2012, 01:59:25 AM »
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Helpful, if you and the rest of the academics really want to improve SNR and DR performance, you'd devise a non-linear ADC and processing system to better utilize those bits by spreading them over a log function instead of a linear one.  Then a 14 bit log ADC could = 14 stops of DR.

But even if you, say, threw a 16-bit ADC into a 5D Mark III, that wouldn't help at all even for low signals, b/c those signals are subject to 6ADU (for a 14-bit ADC) of fluctuation anyway b/c of the ~33 electrons of read noise, correct? All you'd do is represent the noise even more adequately... the read noise would effectively go up to ~31ADU...

So what you're suggesting would only really help for a sensor/read combo that actually has 14 or more stops of DR (I think if read noise were only 1ADU, you might benefit from a little more precision? i.e. read noise of 2 ADU?). Yes?

200
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 06, 2012, 01:46:00 AM »
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Right now the 14-bit data per color channel in the RAW is scaled appropriately to store the dynamic range of the camera's sensor, whatever that might be. If the scaling was changed, then the image from the camera's sensor could actually contain much more data.

Yes, I realize that ADCs are typically matched (loosely) to the DR of the sensor, considering full-well capacity & noise. And what I'm saying is that for the current sensors in question, your statement that the sensor with lower DR will contain more information for a lower DR scene (that is still within the DR of the camera), if of course the end points of the lower DR sensor were still mapped to the endpoints of the ADC, is not correct because of the read noise of the system. If the read noise were lower (say 1 electrons instead of >20 electrons), then your statement would be correct.

But as of ~2008, Martinec convincingly shows quantization error is largely absent because the read noise is more than adequately sampled (~6 ADU for the 5D Mark II/III!). Therefore, any more 'accurate' representation of the signal, as you are suggesting, will only more accurately represent the noise (fluctuations) within that signal, without any tangible benefit in actual image data.

201
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 05, 2012, 09:17:26 PM »
helpful,

Since you yourself pointed to Emil Martinec's website, I'm curious why you're still talking about rounding errors when he shows, rather convincingly, that cameras as of ~2008 didn't really benefit from even a 14-bit ADC b/c, essentially, noise is being oversampled at that point. Canon 5D Mark II's noise level at ISO 100, for example, is almost 6 ADU. That means that noise is being oversampled & it is unlikely that higher bit depth would lead to a more accurate representation of the signal since the signal itself can vary by ~6 ADU.

If the noise level were 1 ADU or less, I would agree that there could be rounding errors due to quantization. But as it stands, Martinec's findings seem pretty convincing to me.

So I'd like to hear your counterargument.

Thanks.

202
EOS Bodies - For Stills / Re: 5D3 Dynamic Range
« on: May 05, 2012, 06:03:22 PM »
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Quote from: helpful on May 04, 2012, 05:39:39 PM
A really high DR better than the 5D3 doesn't really help. As I have explained in previous posts, a lower DR actually stores more data and detail from a scene than a camera with high DR. Ideally the dynamic range would match the scene's DR. Canon's DR probably fits more scenes better than Nikon's. If the dynamic range is higher than the dynamic range intrinsic to the scene, then it actually makes the picture worse (less fine variations in detail of recorded luminosity).
This is false. Increasing the sensor DR will either give you more headroom before clipping, or less noise in the shadows. In both cases, you gain information (for some scenes there might be no data to record there, still you loose nothing).
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In a low dynamic range image (like a frame filled with nothing but green grass), the histogram of a high DR camera like both the 5D3 and the D800 show nothing but a thin peak of data that was recorded. This means lots of detail is being lost because not all 14-bits are being used.
This is false. Most cameras are noise-limited, not quantizer level limited. This means that once the signal reach the ADC, there is (at most) 14 bits of information from the saturation level and down to the noise floor.

Well done clearing up that misinformation, hjulenissen  :)

203
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 03, 2012, 05:24:55 PM »
V8Beast-- you live in Seattle? We should grab a coffee some time :)

Perhaps you'll appreciate this shot from Rizal Bridge I took back in 2010. I went to this stop some 30 times before I finally got an epic sunset. The colors lasted for like 30 minutes... it was insane. Used a 3-stop Daryl Benson Reverse GND filter, & still merged 4 exposures by hand in Photoshop, & still have noise in the trees when I print this. When I denoise the shadows, they just turn muddy. So in the end I chose to just stick with the noise. There's even a little banding in those shadows (this was shot on a 5D). This might be why I'm so interested in higher DR given that, like I said, this was already 4 exposures merged, each taken with that 3-stop Reverse GND...


204
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 02, 2012, 06:56:15 AM »
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Well yes and no. It has been shown in another thread that LR is responsible for many of the "soft shot" complaints aboout the 5D3.

Hmm... skitron-- are you sure you aren't referring to the DPP problem where 'high quality' vs. 'high speed' changed the sharpness of the conversions? I don't remember hearing anything about LR...

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I beg to differ. If a photog with the chops to take advantage of the D800's DR, like smirkypants, encounters these situations in his own shooting, and uses that DR to improve his images, it's a legitimate issue. On top of that, he's using this DR advantage to generate additional revenue. That's as legit as it gets.

However, if you're some tech head (this isn't directed at you) that posts links to other people's blogs as examples of why you personally need 14 stops of DR, and anything less is unacceptable, you have no credibility. You're basically implying that if you shot in X situation, then you'd need 14 stops of DR, but since you don't here's a link to someone else's blog. This implies that these people are more in love with the idea of having more DR than actually needing more DR in real life shooting scenarios. That's kinda lame, don't you think?

  • No, that's not lame, b/c some people are just into optimization
  • You seem to speak of the knowledge of any given photographer as static. What if he/she's technique exceeds that of a lesser camera within a short period of time? Or what if the extended abilities of a better sensor help he/she realize a unique style to his/her photography that would've been otherwise unrealized? Or any of a # of other scenarios.
  • Why require a so-called 'tech head' to produce photos to prove his/her discussion is legit? Why are you assuming he/she is bad until proven otherwise? It baffles me. I never walk into forums assuming someone is a bad photographer to begin with. Because when you assume, you run the risk of making an...
  • For example I didn't assume you were a bad photographer just b/c you didn't care at all about the sensor tech talk way back a few weeks ago. And good thing I didn't: because I love your work! You've found a way to make very well balanced images despite what looks like potentially difficult lighting in a # of your shots. It works for you. Great. The Canon system generally works for me as well. But I've run into a # of situations where I didn't feel comfortable printing large or raising shadows b/c I saw the banding all the way to the print. I could do without those scenarios, especially if it doesn't require me sacrificing too much else. That's what these discussions are about... optimizing what we work with. In fact, it's precisely b/c of these conversations that I was intrigued enough to do my own tests to see just how much better EXMOR sensors are over my entire 5D line (not all of us have the luxury of shooting Canon & Nikon interchangeably whenever we want, so this has been a learning experience for me). Actually, before doing many of these tests myself, I was disinclined to even believe DXO... my opinion was completely reversed when my own tests confirmed their observations... and these well-controlled tests happen to explain what people are seeing in real-world shooting scenarios. So, in my mind, these discussions are incredibly productive, b/c they solidify the reality of difference between these sensors (a reality that a lot of people were unwilling to accept when DXO initially published their findings). In fact, your statement to the effect of 'yes, now we all know that Nikon's sensors are better than Canon, accept it, move on'... I would argue that, yes, we do seem to know that now... but many more of us know & believe that precisely b/c of these blog postings & these discussions. Remember when LTRLI initially posted his assessment of the DR of the 5DIII? People just blasted him left & right, & boy am I glad I didn't. I questioned his methodology, b/c I also wanted to understand it. Now it seems generally accepted that his estimates were pretty much spot on. So, these discussions can be incredibly productive in helping us all arrive at some objective conclusions. And if you don't care, just leave us be, you know? These tech head vs. photographer discussions are so off-topic and are just adding noise to otherwise intelligent discourse.
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All the tech stuff can be learned, as can technique, but some people are just born with a natural gift for light and composition that can't be learned.

Ok if that's what you think... but keep in mind that's just your opinion :) Like LTRLI said: your statement is another topic entirely. Nature vs. nurture is still hotly debated.




205
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 01, 2012, 06:56:36 PM »
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Plus with LR your 5D3 files get the bonus feature of that soft look.

...glad i don't own that POS (LR that is).

I hope that was a joke :)

Well I just tried DPP 3.11.26. Initially I thought the image looked cleaner but that's because it's applying luminance noise reduction which actually makes the image appear softer than in LR. You can get a similar effect in LR by applying luminance NR. The banding is still there in my images, even in DPP. I doubt it's doing any additional intelligent subtraction to get rid of banding (or if it is, LR is doing just as much, since I see pretty equivalent amounts of banding). DPP's sharpening is useless & introduces weird artifacts (puts a weird texture all over the image when raised).

Anyone else want to give this DPP vs. LR comparison a try to see how shadows are handled?

Matt, it's possible your particular 5D3 sensor just has less banding...?

206
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 01, 2012, 05:31:01 PM »
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Uh, no. There is no correlation whatsoever between techiness (or not) and artistry.

Being a tech head and being artistic are in no way connected. You can be one or the other, or both, or neither.

+1.

These posts attacking so-called 'tech heads' on a forum topic initially started to discuss the low ISO sensor performance of the 5DIII vs. the D800 baffle me. It's just noise injected into an otherwise intelligent conversation where we're just trying to understand & discuss the magnitude of the differences between these sensors.

Let's keep the conversation productive.

207
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 01, 2012, 05:24:41 PM »
Matt, that's very interesting! Do you think DPP is just doing more noise reduction, or perhaps using the top rows of the RAW data to offset vertical banding? Those shadows look much cleaner than what LR is producing, as you yourself have noted.

I haven't even tried DPP yet... perhaps it is time to.

208
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 01, 2012, 03:19:55 PM »
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God pixel peepers are a joke. Ansel Adams surely never questioned this type of crap.

That's pretty comical, especially if you've read any of Ansel Adams' (very scientific) writing.

skitron: I'm not at all surprised by your observations. I own the 5Dc, 5DII, & 5DIII, & have taken numerous photos with friends' 5D/5DII. Banding often varies from body to body, I find. For example, it's not too offensive on my own 5DII. But it's easily seen on my 5DIII, albeit only in the vertical direction (landscape orientation).

As for comments on having two systems: Nikon for landscapes & Canon for everything else... true extended DR is extremely useful for landscapes, but often I find myself wanting to lift shadows in other types of photography where something wasn't ideal (wrong exposure b/c of backlight, flash created unwanted shadow because of suboptimal placement, or I don't have time/ability for an off-camera flash setup yet want the background landscape as well as the people in the shot). For these types of shots, the Nikon would undoubtedly be more forgiving. In fact, low read noise downstream of ISO gain application allows for more aggressive exposure compensation in post (i.e. I believe the D800 is a step in the direction of the theoretical ISO-less camera).

209
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: May 01, 2012, 02:05:12 AM »
Nice shots smirkypants!

I see banding even when pushing exposures 1.5-2 stops w/ my 5D Mark III. I'm actually switching to Nikon for the time being, b/c the lack of sensor improvement was the colloquial 'last straw' for me. 9-blade apertures standard on Nikon lenses & the 14-24 f/2.8 & the faster AF on the 85mm prime being the other major factors.

Since these cameras/lenses hold their value, the nice thing is that a switch doesn't cost too much monetarily. More so in terms of learning a new system/ergonomics, and I admit I like Canon ergonomics much better.

As well as their entire radio-triggered wireless flash setup with the 600EX-RT...

As well as their cross-type AF sensors all over their field.

As well as their Live View implementation.

As well as their... oh dangit!

WHAT DO I DO??

:)

210
EOS Bodies - For Stills / Re: 5D MK3 vs. D800 - fredmiranda
« on: April 29, 2012, 03:29:53 PM »
I shot a Stouffer Transmission Wedge (13.2 stops DR total) with a 5DII, 5DIII, & a D7000.

The 5DIII required 1/3EV less exposure than 5DII to keep any channel (meaning: green, since that blows first) from blowing out in the brightest patch of the wedge. The D7000 needed 2/3EV less exposure than 5DII (i.e. 1/3EV less exposure than 5DIII) to keep any channel from blowing out.

But regardless of the highlight handling, the D7000 retained a SNR>1 down to the darkest patch, giving it ~13EV DR if your lower limit is SNR of 1. The 5DIII was stuck somewhere around 11.3EV DR (again, assuming lowest acceptable SNR is 1), b/c its SNR went to 1 at patch #35 (whereas D7000 maintained SNR>1 down to patch 42). These patches are 0.1 density increments, so you can calculate the DR by doing the following calculation:

DR = log2[(10^#of patches for which SNR>1)/10)

So that pretty much debunks the whole theory that the Canon sensors might still have really good DR b/c of how they handle highlights.

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