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Messages - sarangiman

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16
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: November 21, 2012, 11:10:05 PM »
it depends, try to micro adjust a 105 macro or a zoom from the macro mode up to infinity . the best solution is to have all Canon lenses adjusted by a canon service center, a zoom for example  24-105 are adjusted in 8 different positions in the zoom range, in 5dmk2 we  have one, and in 5dmk 3 we have 2 adjustments points.


Thanks for that info on the 8 different positions at Canon FSC. Did not know that.

I've always wondered about this though. Since AFMA can only be accurately set for one subject distance, is it better to get a lens that has a AFMA of 0 with your body than to adjust a lens to, say, -12 for 25x focal length subject distance?

For that matter, is it even possible to get a lens that focuses perfectly (AFMA=0) for both near & far subject distances?

I would guess so, as AFMA appears to me, in my understanding, to simply be an extra correction factor on top of all other correction factors (e.g. correction due to spherical aberration, etc.; more here: http://www.openphotographyforums.com/forums/showthread.php?p=109296); and a simple multiplier (or whatever exactly AFMA is) may not hold across the entire range of subject distances.

17
PowerShot / Re: Canon S100 vs Sony RX100
« on: September 27, 2012, 12:04:32 AM »
It does work in broad daylight but I was referring to fast moving objects where I would need the AF speed of a DSLR.

Gotcha.

Actually I was trying to shoot some clouds out of an airplane window & the RX100 just wouldn't focus. I thought the clouds had enough contrast to focus easily... but it was extremely difficult.

Maybe any compact would've had trouble; I'm not sure. I really do love the RX100. The bounce-flash, the larger sensor, the longer focal length lens for equivalent FOV compared to S100 guarantees that your diffraction-limited aperture is higher (e.g. f/4-f/5.6) --making those smaller apertures actually useful, the contrast of the lens (in the center anyway), etc.

18
PowerShot / Re: Canon S100 vs Sony RX100
« on: September 26, 2012, 02:03:54 PM »
Tested the RX100 in Cyprus for a week - when I don't need AF in broad daylight I won't bother bringing along my 1D4 any more... ;-)

?? Are you trying to say the AF on the RX100 doesn't work in broad daylight? Confused.

19
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 25, 2012, 06:01:10 PM »
Sad. But at least it appears that Velvia 100 is fine (I never liked 100F anyway), & I can still get 120 Velvia 50.

But I'm sure even those will go in the near future.

20
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 25, 2012, 05:50:55 PM »
You would be right in going back to using film for landscapes. Especially Large format velvia... ahhh, Love those colors. Its a shame they don't make velvia anymore.  :-[

What? I can still buy 120 Velvia 50 for my 645 system. It wasn't discontinued in 120, was it?

Velvia on a lightbox really is something to behold. But landscapes shot with the DR of a D800 & then displayed on an 'HDR' monitor capable of a high contrast ratio would also likely be something to behold.

21
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 25, 2012, 05:47:54 PM »
Meh, Use your filters. I've seen plenty of good landscapes taken with crap cameras. I could use a D30 and get a good landscape.

what does an answer like this even means?
let's all go back to film then, i've seen plenty of good landscapes taken with film cameras.

He posted a comparison between the two sensor and the Nikon/Sony one is unarguably better.
Does this means that you cannot take beautiful pictures with a 5D Mk3? NO
Does this means that for a lower price Nikon is offering a camera with a better sensor that let you take beautiful pictures easily? YES

why can't people just admit that? customers should push their brand to do better, not settle down saying "nah i don't care if the competition is offering a better product for less money, I'm happy with what I have, please next time charge me more and remove some features, I will be willing to pay for it anyway".

Heh, agreed. I was just trying to be as non-inflammatory & balanced in my post(s) as possible.

If the rumors about the new big megapixel Canon are true, I'd be pretty excited. It remains to be seen if the sensor has enough DR to even take advantage of a 16-bit ADC. Right now, Canon bodies are just oversampling noise with even their 14-bit ADC...

22
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 25, 2012, 05:24:28 PM »
Meh, Use your filters. I've seen plenty of good landscapes taken with crap cameras. I could use a D30 and get a good landscape.

Yup, updated my post above :)

23
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 25, 2012, 05:15:55 PM »
All these 35mm DSLR's have pretty similar IQ at reasonable ISO's.


Nikon D800 | ISO 100 | 1/100s @f/11:


Canon 5D Mk III | ISO 100 | 1/100s @f/11:


... and that's at 800px web size.

Inevitably, someone's going to wonder why I severely underexposed the photo & then lifted the exposure; rather than getting into the logic of why I did that, I'll just post the following comparison, where each camera was exposed so as to not clip the red channel in the sky near the sun. Shadows were then lifted to reasonable levels for viewing:

First, the full-frame images:

Nikon D800:


Canon 5D Mark III:


Now, let's view them side-by-side at 100%, w/ the D800 downsized to 5DIII size for easy/fair comparison:


Please view it at 100% here; else you won't fully appreciate the difference: http://cl.ly/JipE/NikonD800_vs_Canon5DIII-SunsetDR.jpg

For certain types of photography, this matters. For others, it doesn't. Beautiful photographs from the previous posters, btw. Despite the results of these comparisons I've done above, I stuck with the 5DIII for various reasons since I find it suits my people photography better right now (AF accuracy/precision, wireless RF flash, love the joystick for AF point selection, cross-type AF points, higher FPS, etc.). But I wish it had a D800 sensor for when I shoot landscapes (using over $1k worth of Singh-Ray filters for now) or for those moments when my flash mis-fired or the meter completely underexposed an image b/c of a strong backlight, or what have you, & by the time I re-adjusted I'd missed the moment (and I can't salvage the underexposed photo because of noise).

In the end, we choose which limitations of a system to accept & work around, & which ones are unacceptable. I was still able to work around the limited DR of Canon & get these, for example:




But back to the topic at hand: it's great to know about advances in technology, & how they may help us achieve our vision. DXO's quantitation, to an extent, helps some of us do that.

Cheers.

24
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 24, 2012, 01:03:44 AM »
I honestly don't see why people keep beating this dead horse.  It's dead, and its been beaten, now your beating on it more ---  But I gess it needs to be said again---for this round of bodies canon seems to have chosen to leap ahead in high ISO performance


These dead horses are beaten over & over again in order to dispel myths like the one you yourself just attempted to propagate; namely, that Canon has jumped ahead in high ISO performance.

In fact, it has not. Look at SNR 18% between the 5D Mark III, the D800, & the D4 here:

http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/(appareil1)/795%7C0/(brand)/Canon/(appareil2)/792%7C0/(brand2)/Nikon/(appareil3)/767%7C0/(brand3)/Nikon

You must look at normalized results, not pixel-level results. The only place D800 falls behind is at ISO 25,600, & even then it's by 0.5dB.

The Nikon D800 has higher DR & higher resolution than the 5DIII, and yet still has the same ISO performance as the 5DIII for images scaled down to 5DIII resolution all the way up to ISO 12,800. That's quite a feat.

25
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 24, 2012, 12:54:38 AM »

When I've compared their results to other sites, or to my own experience, they have not matched. One example: according to DxO the 7D (Canon's 18 MP sensor) has little DR gain over the 10D / 20D. I could tell you before formally testing them that it was large, 2 stops easily.



DXO's results show a ~1 stop improvement (normalized) for the 7D over the 10D, so I'm not sure why you consider that 'little DR gain':

http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/(appareil1)/619%7C0/(brand)/Canon/(appareil2)/281%7C0/(brand2)/Canon/(appareil3)/437%7C0/(brand3)/Canon

26
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 24, 2012, 12:51:28 AM »
Measuring sensor performance and writing RAW decode software are pretty different things.
+1
And BTW, when people do go and try to replicate their sensor findings themselves, surprise, surprise, the results come out close to what DxO reports.
Yes, when people know what they're doing & emulate the methodology that DXO outlines (lower base of SNR=1), results end up being extremely similar to DXO. DXO numbers are *not* just BS if you understand what they are comparing.

And controlled tests are typically the best (if not only) way of consistently comparing systems. Having side-by-side 'real world' examples does, however, really buttress your case. DXO not having the latter may hurt them in the sense that people who don't understand the numbers or their methodology may just call BS if results fly in the face of prior, and therefore expected, experience.

27
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 10:31:29 PM »
I think you'll be happy with the Mark III, Mike. Actually Canon's AF as implemented in the Mark III in combo with its 24L, 35L, & 85L primes is the only reason I'm sticking with Canon right now. The DR & Auto ISO implementation on the D800 would otherwise be enough to make me want to switch. Well, and native use of the 14-24 :)

Note that for primes you'll want to microadjust based on your shooting habits. Since I tend to use the primes to shoot rather close subjects (that's more my style), I microadjust using a LensAlign at a distance of 25x focal length. I think manufacturers tend to suggest 50x focal length, as the best compromise. Certainly, using 25x focal length, infinity no longer focuses properly at wide apertures... it's a shame camera companies haven't implemented some sort of interpolation for microadjustment values based on subject distance (like they've done for focal length of zoom lenses). Maybe it's coming?

This does affect me in real-world shooting. For example, the other day I happened to be using my 85L in a non-standard way, shooting subjects more distance simply b/c of the way the event was set up. I noticed I got better results by resetting my microadjustment to 0 (which works best for distant subjects).

And then there are days where the microadjustment just seems to be off... haven't quite figured that one out yet... but luckily, it's not too often.

The good thing about the Mark III is that its precision is good enough that usually you can tell if the lens if front focusing or back focusing. Not so much with my Mark II, which had so low precision that I just couldn't tell b/c focus was all over the place.

Now, I realize I'm placing high demands on the system b/c I'm shooting below f/2.0... but why else buy a prime if not for that almost 3D look of having a subject pop out from a blurred background? That's generally what I'm interested in when I'm using primes... not always, but most of the time.

The Mark III brings me closer to achieving that, without having to take 100 shots just to get 15 or 20 in focus at f/1.4.

The Nikon D800 also has very good (similar to Mark III) precision. But there are other issues with lenses that I won't get into here, but will hopefully write an article about soon. Furthermore, their focus points being totally miscalibrated with respect to each other is just something I don't wish to deal with. Luckily, my 5DIII focus points are pretty consistent (the leftmost one slightly backfocuses compared to the others, but its acceptable and nowhere near as drastic as what I've seen testing 4 different D800 bodies).

28
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 09:26:35 PM »
If you folks are concerned with DR then just go back to film because film is still the king.


Not necessarily. For higher acceptable SNR on the low end, digital sensors trump negative film.
http://www.dxo.com/var/dxo/storage/fckeditor/File/embedded/2012%20Film_vs_Digital_final_copyright.pdf

Of course, this also depends on size of film, since larger film formats will allow for more detail to be pulled out of shadows while maintaining acceptable SNR for reasonable sized prints.

P.S. Just for that paper alone, DXO rocks :)

29
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 08:13:15 PM »
For a living I don't take pics, but I do publish papers in theoretical physics. Now, compared to the complete lack of rigor in photography testing (at least from my very limited experience of forum, blogs, and other online sources reader), the DxO tests seem outstanding, especially when compared to those of the various Ken Rockwell and company (including DPreview, which now roots for Canon like a cheerleader in the interpretation of their results). Are the DxO tests rigorous enough to be published in a serious scientific journal? Very likely, no. But for what they are meant to do (publicize a software), they are outstanding.


I agree.

I'm also in the sciences & therefore appreciate that DXO is significantly closer to rigorous testing (at least for their sensors) than most other tests out there. Roger Cicala is also doing a good job on his blog over at lensrentals. Bill Claff does excellent work as well. Emil Martinec has written outstanding treatises. I like that photography does, in many instances, attract science/engineering-minded folk! Incidentally I've been working on a methodology to rigorously quantify AF accuracy & precision (much like what Cicala has started to do, although he's using a different method) as I find a serious dearth of such information on any site (but lots of qualitative statements everywhere, like, 'I feel like this lens focuses 100% accurately!!'). I think problems like the D800 left AF issue should be easily identifiable by consumers; many other such problems go unnoticed, but actually do affect real-world shooting, surfacing as reduced hit-rates of focus. For example, D800s sent in for the left AF issue, as well as some newer D800 bodies probably going through the same calibration center, now exhibit large front focus of the center AF point in relation to the leftmost & rightmost AF points (which agree with each other). This is not something that microadjustment can fix, and is something that'd go unnoticed by most shooters who microadjust using only the center point. When buying new lenses/bodies, it'd be great to know what sort of AF accuracy & precision we can expect from the combo, and it's not unreasonable to expect wildly varying results given what a complicated process AF is (e.g. correcting for a lens' spherical aberration and how it affects the offset the AF system must apply to the phase data off the AF sensors which only evaluate light from the outer edges of the lens, etc.).

The thing is this stuff is quantifiable. And I'm glad someone (DXO) is doing it properly for sensors. I'd like to see it done for AF, & Cicala has made a great start with his tests.

As for dpreview, actually look at what they had to say about Canon & the 6D:

"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. It's still bound to be a very good camera, of course; just perhaps not quite as good as it could be."

http://www.dpreview.com/previews/canon-eos-6d/6

I think dpreview does a good job of trying to remain unbiased.

30
EOS Bodies / Re: DxOMark Sensor Performance: Nikon vs. Canon
« on: September 20, 2012, 06:59:29 PM »
No academic journal would publish a DxO report without both Data (in an Appendix) and Methods (with a clearly defined algorithm stating the parameters for weighting each category). In the world of peer review, Black-Box methodology would simply have REJECTED stamped on it and returned.

Yes, it'd be wonderful if they published their full methodology & made their RAW files available. As you mention, that's what'd have to happen in a peer-reviewed journal. I think they might gain more credibility if they did these things.

As for the lens tests -- how many copies of the 70-200 f/2.8L II did they test? The II is most certainly sharper than I wide open on the few copies I've handled. Copy variability can definitely skew results, as has been mentioned before. Not so much the case with sensors, which is why I trust their sensor data.

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