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Messages - sarangiman

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1
Lenses / Re: EF 24mm f/1.4L II USM
« on: July 21, 2013, 05:02:04 PM »
I never used my 24 1.4 II all that much below f/2.8 or even f/4 so I actually ended up selling it for the 24-70 II (which, remarkably, more or less matches it for 24mm quality, other than more distortion and bit worse corners near wide open, but with actually LESS purple fringing/LoCA, many shots stopped down were almost identical between the two other than more distortion and LESS LoCA from the zoom; when I compared the 24 1.4 II to 24-105 OTOH, the prime blew that zoom out of the water, yes even at f/8 or f/10, believe it is a fallacy that all lenses perform the same once well stopped down, not even close.) Here and there I miss the 1.4, but not much and love the 24-70 II.

Hmm. I actually shoot the 24/1.4 at f/1.4 on the 5DIII & center AF precision is quite good after AFMA. I do remember corner/side compositions being quite out of focus though at anything wider than f/2.8 or so during the last wedding shoot, so I had to switch to live view AF. Part of this was also just side/corner softness at wide apertures. Actually, it's quite appalling how bad some of these primes are on the sides once you go to a higher resolution sensor -- plop the 24/1.4 or 35/1.4 on a NEX-7 (no optics in between, just a Metabones Smart Adapter) & you'll see flaws of the lens you'd barely see on a 5D II/III or what-have-you FF body with larger pixels. And that's not even using the full image circle of the lens. Use a SpeedBooster to use the full image circle of the lens & some copies of these primes don't sharpen up on the sides until f/8-f/11 (whereas they're sharp by f/4 on my 5DIII). But of course, in the latter scenario I'm adding extra optics in the way... anyway, I'm getting OT now.

2
Lenses / Re: EF 24mm f/1.4L II USM
« on: July 21, 2013, 04:53:03 PM »

Maybe some copies of the 24 1.4 II have sloppier breaking on the AF and combine that with the older measuring device that didn't measure slop as precisely and then combine that with a less precise AF system (for all the talk about the advanced 7D AF, it's mostly it's speed and having so many points and so many cross points where it is advanced, the one shot AF precision of it is still basically a good deal less than the 1 series or 5D3 and not even quite a match for 5D/5D2 either for one shot precision) and maybe that explains it?


Very good point. Roger Cicala hypothesizes that the extra feedback from the AF motors (or sensors that can measure movement of the focus element) help the more advanced AF systems be more precise. This extra information is present with some of the newer lenses & work in conjunction with newer bodies, apparently. Not sure about the 24/1.4 II since that's a bit older. But who knows? The best you can do is treat the system like a black box & just test it.

3
Lenses / Re: EF 24mm f/1.4L II USM
« on: July 21, 2013, 04:49:01 PM »
Saringiman, I utilized only the central focus point throughout the entirety of the testing process, but thanks for making sure it remained stringently scientific; that is of course of the utmost importance.  I am glad to hear that you've experienced similar fickleness with this lens, as I know many others have as well, but I just really wonder how much of it is the result of the BODY's AF performance in low light, as opposed to simply a lens issue.  This obviously can't be completely the case, because when I pair up the 7D with the EF 100mm f/2.8L IS USM Macro, the issue is completely gone, but I find it interesting that in better lighting conditions, the 24L performs flawlessly.  What design flaw in the lens would cause this?  Is the 85 1.2L a beast in the good sense (performs well) or in the bad sense (is VERY moody), in the context of your comment about it...?  That's certainly another lens I'm interested in, but I need a wide angle solution right now, and this lens is certainly the best horse for the job if it would only behave...

Interesting -- there really are quite a few people here talking about completely random, inconsistent focus. I wonder if the AF motor in the lens is very inaccurate on some copies (one hypothesis for why the nifty fifty is so poor at focus is just that: possible a very inaccurate motor/focus element placement).

I forgot to mention that I'm shooting on a 5D III. I stopped even bothering with primes on my 5D II. You could only use the center AF point, properly microadjusted. And focus & recompose at f/1.4 with wide angle primes where you have to move the camera quite a bit to recompose (compared to, say, >85mm focal lengths) just doesn't work. So my higher levels of consistency may be due to the rather outstanding AF performance of the 5D III.

I should also add that in low light I've typically used the 24/1.4 with a 600EX-RT flash attached to my body; the pattern the flash fires most certainly helped the lens autofocus.

By 'beast' I meant it's very hard to tame the 85/1.2. The optimal AFMA even seemed to change on a day-to-day basis; however, it's hard to decouple variables like subject distance & AF point used, so take that comment with a grain of salt (remember: AFMA can change based on subject distance & AF point; Sigma's new USB dock addresses the former by allowing 4 different AFMA values per focal length). The 85/1.2's particular sensitivity to AFMA is not surprising: at f/1.2, the plane of focus is extremely shallow; furthermore, any uncorrected spherical aberration will have a large effect on focus/sharpness at such large apertures. OTOH, given how sharp the lens *can* be wide open, I would think Canon went a long way to correcting spherical aberration. On a good day, the 85/1.2 can focus tack sharp right at f/1.2. But given that often I don't want to gamble, I find myself shooting at f/1.8-f/2.8. Hence I just picked up the 85/1.8, & may be looking to get rid of the 85/1.2 once I do a controlled AF precision test comparing the two (also against a Sigma 85/1.4).

On a related note, I hope Sigma comes out with a 85/1.4 'Art' lens where we can adjust AFMA for 4 different subject distances. OTOH, if Canon's 70D Dual-Pixel AF system makes AFMA irrelevant... that'd be revolutionary. It's an exciting time in photography (always is :) )!

4
Lenses / Re: EF 24mm f/1.4L II USM
« on: July 21, 2013, 04:44:39 AM »
Apebrains,

Sounds like you're doing a good job of some controlled testing. Apologies if I missed it, but, are you choosing the focus point? In order to eliminate yet another variable in your testing, you need to choose a focus point & stick with it. For simplicity, say, the center focus point (different AF points can show different performance &, actually, can require different AFMA values).

Low light definitely stresses AF systems, & can result in lower precision. This lower precision can, in turn, make it hard to choose an appropriate AFMA value. Since AFMA can also depend on subject distance (and, as I already mentioned, AF point), things can get complicated very fast.

In short, though, I'm not surprised with what you're seeing. My f/1.4 & f/1.2 lenses are extremely moody (the 85/1.2 is a beast in this sense), but in general I can find a somewhat optimal AFMA value per lens.

I do wish someone would test AF precision of various lens/body combos, including at different EVs, though I realize it's rather difficult & potentially resource-intensive/prohibitive. I recently was surprised by the poor low-light AF precision of my Sony NEX-6 + Sony 10-18mm f/4 OSS lens (which otherwise performs great in daylight), and that's CDAF, not even PDAF! The Zeiss Touit 12mm, OTOH, focuses with near 100% precision (repeatability) at f/2.8. This is the sort of information that, I feel, could be very valuable to consumers investing in a lens/system (as long as the tests are performed carefully/appropriately).

5
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: December 21, 2012, 03:35:32 AM »
I don't recall anyone nitpicking a lens so much for it's bokeh when everything else is fab, generally the consideration for the quality of bokeh of a lens, especially at these price points and class of lenses is always there, but this must mean though that Sigma just has no other faults to look at, so everyone wants to point at something it's not the absolute best at. And talk about onion highlights? The 35L can produce those onions too!
http://www.flickr.com/photos/pong0814/5596735626/#

And, unlike the Sigma, the 35L doesn't keep rounded circular highlights when stopped down if that matters for anyone.


+1

Very, very well said.

I've always complained about Canon's 8-blade apertures... you start seeing octagons in OOF highlights when you stop down even 2/3 of a stop on many of Canon's primes (e.g. the 'venerable' 85/1.2). What I hate even more is that 8-blade aperture lenses produce 8-point sunstars.

Just adding one blade gives you 18-point sunstars. AND circular OOF highlights.

Nikon's had 9-blade apertures for a while now.

What took Canon so long?

6
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: November 30, 2012, 04:46:36 PM »
Compared to 35L:
http://lcap.tistory.com/entry/Sigma-35mm-f14-vs-Canon-35mm-f14-L


Yes thanks, that's a great review/comparison.

Look at those gorgeous 18-point sunstars & the circular bokeh even at f/2. Canon's 8-blade apertures has been one of my biggest gripes. Nikon has been putting out 9-blade aperture lenses for some time now; Canon's only playing catch-up now. And who knows when they'll replace their 24L, 35L, & 85L lenses...

Also, if you look at the OOF bokeh with pictures of the leaves, it appears to me that either the Canon lens has more contrast or has a lower exposure. Does anyone else see this?

7
Third Party Manufacturers / Re: At least we have Canon quality control
« on: November 29, 2012, 01:06:01 PM »
Zv,

You'll likely be disappointed if you start rigorously testing expensive equipment. You'll start finding flaws that you thought shouldn't exist for such high quality/price products. But I find it's great to know about these limitations so I know how to work around them.

For example, 3 copies of the highly venerated 70-200 f/4L IS I tested all showed erratic softness on one side of the frame relative to the other, even at f/8 sometimes. By f/11 most of the time every shot was acceptable, though not always on at least one copy. Contrast that to the 70-200 f/2.8L II I finally bought b/c I was tired of the poor performance of the f/4L for landscapes. Typically, at 200mm | f/2.8 it's at least as sharp across the entire field as the f4L ever was. At 70mm though, the extreme left side doesn't sharpen up until f/5.6. Which isn't a big deal, and now I store that tidbit of info in the back of my head so when it becomes relevant I'll know how to set my aperture.

If you start testing the AF precision (repeatability) of AF points on any of these high-end dSLRs with primes, you may find yourself pretty surprised. Or not, if you've ever tried shooting a 5D Mark II + 85/1.2 combo anywhere below f/2.8... :)

8
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: November 24, 2012, 06:40:04 PM »
jukka,

Not sure if you saw my previous post, but do you know the answer to this question:

Since AFMA for a particular body/lens combo changes as a function of subject distance, it's not possible to have an AFMA value for all subject distances. Is this any different for a lens that appears to require 0 AFMA? I.e. will it also have 0 AFMA for all subject distances?
hmm My Finnish English do not understand what you're asking, can you simplify the question and I try to answer

Ok, let me try to rephrase.

Let's say you get a 85/1.2 prime lens that needs no microadjustment for perfect focus. Will it focus perfectly for both close & far (infinity) subjects (at f/1.2)?

My 85/1.2 needs a microadjustment of +12 for a subject distance of 25x focal length (~85 inches distance). But now infinity is no longer perfectly in focus.

So what I'm asking is: since the AFMA value you enter into the camera is only really valid for the subject distance you used to determine that AFMA value, is it better to get a lens that appears to need no microadjustment whatsoever with your body?

Or will even those lenses show different back/front-focusing for subjects at various differences?

Of course, I'm only speaking of wide-aperture primes here... Above f/2.8 or f/4 you won't even notice these sorts of variations (unless your lens is really, really far off).

9
Third Party Manufacturers / Re: At least we have Canon quality control
« on: November 23, 2012, 11:35:11 PM »
And speaking of the D800 left AF problem... it evolved into a center AF front-focusing problem (relative to left & right AF points, which at least then agreed w/ one another) for some units sent back for repair.

I wonder if they finally fixed everything. That whole saga was a mess.

My leftmost AF point on my 5D Mark III slightly backfocuses compared to other points, but not drastically so... it's something I can live with.

These are very complex products, with tighter & tighter requirements for tolerance as people put higher demands on these systems. I think proper QC will always be important, but quick & easy testing methodologies for the consumer may be equally or even more beneficial.

10
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: November 23, 2012, 11:27:00 PM »
jukka,

Not sure if you saw my previous post, but do you know the answer to this question:

Since AFMA for a particular body/lens combo changes as a function of subject distance, it's not possible to have an AFMA value for all subject distances. Is this any different for a lens that appears to require 0 AFMA? I.e. will it also have 0 AFMA for all subject distances?

11
Third Party Manufacturers / Re: Sigma 35 f/1.4 DG HSM First Impressions
« on: November 21, 2012, 11:42:34 PM »
Oh, also: 9 blade aperture primes for Canon FTW!! I can finally get my 18-point sunstars :)

12
EOS Bodies / Re: !!!FIRST!!! - Full Frame Mirrorless Camera
« on: November 21, 2012, 11:31:34 PM »
I work at Sony Electronics. :)

Yea we've got FF Mirrorless already.

We're often times the first to market or very early to market. I remember announcing the world's lightest laptop 6 months before the first macbook air. Even after the launch of the AIR our's was still the thinnest and lightest but did anyone know haha? I remember carrying the world's first OLED TV to a convention in Las Vegas. We never advertised it though, the images were stunning and the design was sleek. 2 years later Samsung made a huge TV ad campaign and without saying it made it sound like they were the first to make the OLED TVs. And their TV was IDENTICAL to our aesthetically, they basically took our tv and rebadged it as a samsung. I think that's my biggest frustration with this company. We don't advertise anything and unless you're really looking for a product you would never know we made it. I'm so tired of watching great products get launch with zero visibility.

Just wanted to release some steam about the biggest issue that irks me about Sony. Other than that the company is awesome, they treat us real well, we get good discounts and the work culture here is great (I knew a few people who worked at Samsung that we're very happy).

Hi Minh,

I must say I agree with you re: your advertisement comments. For example:

  • The Sony RX100 has a bounce flash built into it. Really sets it apart from other P&S cameras (save for an Olympus one; I can't remember the model). Why wasn't this advertised? It's not even listed as a feature at all on the official features/specs page!
  • Sony makes the world's best CMOS sensors. Why not flaunt this for the Sony cameras that have this high dynamic range/low noise? Some of Sony's sensors are practically ready for the ISO-less revolution (if it ever comes)!
  • Whatever happened to that really cool 84" projection screen that was matched to reflect the RGB primaries of a paired projector while rejecting all other wavelengths? Such a cool idea... a prototype was demonstrated years ago... never heard anything else about it.

I love the fact that you guys make & push cool new technology horizons. It can often be high risk (RX1, e.g., albeit that's probably a stepping stone to another product coming soon...), but can be highly rewarding. For those of us that care about quality, I must say I, for one, really appreciate the work Sony's doing. Be it Blu-Ray, 4k, SXRD, high DR/low read noise CMOS sensors, 1" sensor pocketable P&S (RX100 was one of Time's top 25 inventions of 2012!!), the list goes on.

Never considered myself a fanboy of any company... but Sony comes close.

Just don't get me started on the subpar lenses Sony's been putting on its HW30/HW50 line of projectors... good grief. Why take a great tech like SXRD & mar it like that!

13
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.

14
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.

15
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.

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