Messages

6511

EOS Bodies / Re: 1D X Limitations Fixable?

« on: January 08, 2012, 04:08:00 PM »

This is a bit like: "I have a Pentium 3! Where can i download the firmware update to make it a i7?"

No seriously... You cant update hardware limitations via Firmware...

No one is suggesting that (at least, I'm not).  Point is, cameras limited to f/5.6 are limited by the firmware, and as the statement from motorhead indicates, when you trick that firmware so an f/8 lens appears to be f/5.6, AF is attempted and can succeed.

I'm not suggesting adding AF points or anything like that. To revise your rather off-base analogy to something better aligned to the current discussion, an i5 processor is limited to a given clock speed by firmware (in effect). While it cannot be turned into an i7, it's quite possible to change the 'firmware' and overclock the processor.  That's pretty much what the pin taping trick does, and if Canon decided to officially support that, it would be a better implementation.

6512

EOS Bodies / Re: 1D X Limitations Fixable?

« on: January 08, 2012, 02:31:58 PM »

I have tried the "tape trick" before on assorted crop sensor bodies and lenses, but never had any AF performance with a f/8 system that I would say was usable. That's why my original comment suggested a difference between having any f/8 AF, and one that works well.

Of course, that's with an AF system programmed not to try to achieve AF narrower than f/5.6, rather than one which has been optimized to do so from a firmware standpoint.

Look carefully at Nikon's D4 AF specs.  With f/8, 11 points including 1 cross; between f/5.6 and f/8, 15 points including 9 crosses. Does that mean the center AF point is an f/8 cross? If so, the shorter baseline means Nikon traded away accuracy.  What about the 8 other crosses that don't work at f/8, but do at, say, f/7.1?  Are those f/7.1-sensitive sensors?  Without seeing a schematic of the sensor or more details from Nikon, we won't know for sure, but I suspect the answers are no and no. I think they'd not choose to sacrifice accuracy, but maybe the sensor is just more complex, and where Canon chose to squeeze more AF points and make more of them crosses, Nikon chose to squeeze in some f/8 and f/7.1 lines.

Still, I think it's possible that Nikon is using the same f/5.6 AF points, and just optimized the firmware to support narrower apertures. If so, it's possible for Canon to do the same (although there may be non-technical reasons that they won't).

I'm not so sure ... there's comments somewhere that Canon changed the sub-mirror responsible for autofocus from being elliptical to flat. If that's actually the case, then it may be that there's less "concentration" of light with the new AF mechanism and thus less ability for AF to work with less light.

I don't think that would matter at all.  The aperture limitation isn't really about the amount of light, but rather about the baseline of the sensors.  An f/5.6 lens won't activate f/2.8 sensors because the sensor lines are widely spaced, and the narrower aperture doesn't allow the light to be spread far enough. Consider - if it were the amount of light, AF would fail with a 3-stop ND filter on an f/5.6 lens, but instead it works fine, as long as the intensity exceeds the EV sensitivity of the sensor (-2 for the 1D X, -1 for previous 1-series, and -0.5 for other bodies).

Also, 'concentrating' the light implies the mirror was concave - I don't think that's what is meant by oblong. Rather, it was more oval rather than rectangular.  Going from oblong to rectangular for the 1D X makes perfect sense - look at the shape of the AF point arrays - oblong on the 1DIV and 1DsIII, rectangular on the 1D X.

6513

EOS Bodies / Re: 1D X Limitations Fixable?

« on: January 08, 2012, 10:19:19 AM »

If they didn't consciously intend for f/8 AF to work when making the AF sensor, no amount of firmware tweaking is going to give it to you in a useful way.

If true, then it would be impossible for an f/5.6-limited AF sensor to focus with an f/8 lens, right?  Why, then, does the pin-taping trick allow AF with an f/5.6 lens and 1.4x TC?  For that matter, how does a 3rd party zoom lens that's f/6.3 at the long end manage to AF using f/5.6 AF points?

The fact that the above do work indicate the possibility of a firmware change to address the f/8 AF.  Now, a pin-taped f/8 AF is only partially effective, and fails sometimes. Canon included an f/8 line in the previous 1-series bodies for a reason, and they lock out the AF narrower than f/5.6 for a reason - likely because AF at f/8 with an f/5.6 sensor doesn't meet their standards. Still, they might be able to adjust the AF algorithms to deliver acceptable performance.

6514

Lenses / Re: Should I purchase the 15-85mm f/3.5-5.0?

« on: January 08, 2012, 09:51:49 AM »

The extra 9mm at the wide end of the 15-85 counts for a lot more than the missing 20 at the long end, IMO. I'd get the 15-85.

+1

24mm on a crop body is equivalent to 38mm on FF, so it's not wide angle.  You can always crop the image a bit, but sometimes you can't back up.  You can't just look at the numbers - even though with the 24-105mm you're giving up 9mm on the wide end for 20mm on the long end, the 9mm is much more significant.

Personally, I find 24mm on APS-C can often be too narrow indoors.  As stated, if you have an ultrawide zoom for crop (10-22mm, etc.), that makes a nice combination with the 24-105mm, as long as you don't mind switching lenses. I also used the 24-105mm as an outdoor walkaround lens on my 7D when it's raining, because the 24-105mm is sealed - not a benefit when using a T1i.

Personally, I'd recommend the 15-85mm - it's definitely a more versatile lens on APS-C.  I actually prefer the faster aperture of the 17-55mm f/2.8 myself.

I'd also suggest that you can answer this question yourself - I presume your kit lens is the 18-55mm (or some other 18- zoom), and you've shot for three years. Look back at the EXIF for your images and see how many were shot wider than 24mm; if it's a lot, get the 15-85mm, and if it's few, get the 24-105mm and keep your current kit lens for times you need wider than 24mm.

6515

PowerShot Cameras / Re: *UPDATE 3* Canon PowerShot G1X Revealed

« on: January 08, 2012, 04:56:00 AM »

Don't forget that Canon called the lens on the PowerShot Pro1 an L lens, red ring and all. IIRC, that camera had a 1/1.5" sensor, too.

6516

EOS Bodies / Re: Replacement? (Equivalent)

« on: January 08, 2012, 04:48:59 AM »

@Fleetie - elflord is correct, as usual.   Log₂ (FF area / APS-C area); rounded down because the 5DII 'misses' some of the light because it lacks gapless microlenses.

I'll also add that the predicted number holds pretty well for sensors of the same approximate technology, and that in this specific case (5DII vs. 7D), my own testing shows about 1.3 stops difference.

6517

EOS Bodies / Re: Replacement? (Equivalent)

« on: January 07, 2012, 09:17:57 PM »

Would the first combination result in more light, thus requiring a lower iso?

Re-read my post, saw that I didn't directly answer this.

Not quite - a FF sensor would need the same ISO for a given scene, assuming the same aperture and shutter speed. But, the same ISO on FF would have a noise level equivalent to 1.3 stops lower ISO on APS-C, so if you needed, you could shoot 1.3 stops faster and keep the same noise.  With a 1-stop slower lens, you'd only gain 1/3 stop.

6518

EOS Bodies / Re: Replacement? (Equivalent)

« on: January 07, 2012, 08:33:45 PM »

The 'FF-equivalent' of the EF-S 17-55mm f/2.8 IS is 27-88mm f/4.5.  So, the 24-105mm on the 5DII is wider, longer, and faster in terms of depth of field for the same framing (i.e. shallower DoF, which you may not want).  There will be no difference in exposure - the 5DII with an f/4 lens would need a 1-stop slower shutter speed than the 7D with an f/2.8 lens  But, the FF sensor in the 5DII does gather more total light, meaning for the same ISO noise you can shoot the FF at 1.3 stops higher ISO, which more than makes up for the loss of a stop.

So, you gain more zoom range, 1/3-stop, and better IQ with the 5DII + 24-105. You lose the superior AF system of the 7D, although if you're using only the center point, the 5DII does better in low light, in my experience.

Now, for concerts and low light shooting with moving subjects, your best bet is really the 5DII with a fast prime, like the 85mm f/1.8, and you're golden.

6519

PowerShot Cameras / Re: Alert: Don't buy early production S100

« on: January 07, 2012, 07:32:30 PM »

Been sort of waiting for an update here; can anyone confirm we're on a 'new batch' yet?

I can't confirm that a 'new batch' is available, but given the time elapsed, I'd think so.

What I can confirm that the decentering issue found by DPR was not a universal problem.  My S100 was an early pre-order from Amazon (minutes after orders were possible), and arrived in late October, so I presume that was an early batch. I tested mine pretty thoroughly and found no decentering - there is some corner softness, especially at f/2 on the wide end, but it's symmetrical.

I did...ummm...'enjoy' reading the comments on the DPR forums about the issue (I don't post there, CR is far more civil).  They seemed to boil down to 'DPR is awesome so the S100 must suck' vs. 'my S100 is fine and takes great pics' vs. 'anyone who says their S100 is fine wouldn't know a sharp picture if they cut their finger on it.'  Nevertheless, I feel pretty comfortable saying 'my S100 is fine and takes great pics' (within reasonable expectations).  FWIW, my testing setup includes, among other things, an Applied Image QA-77-3 resolution chart (an ISO 12233 chart with extra features) that costs half again what the S100 costs.

6520

PowerShot Cameras / Re: *UPDATE 3* Canon PowerShot G1X Revealed

« on: January 07, 2012, 06:27:15 PM »

The best camera is the one you have with you.

That being said, there are plenty of less expensive Powershots out there that will fit the need.

+1

If Canon comes up with some clever way to flout the laws of physics and mate a large sensor with the rumored lens, and manages to sidestep the compromises and deliver excellent IQ from the G1x, it will be very interesting.  I think it's a pipe dream, but hey...dreams are good!

But for decent IQ in a truly portable package, I like my S100 (had an S95, which my wife now carries in her purse).  The S100 fits in my pocket, which is ideal if I can't bring a larger camera.  A G series or m4/3?  Might as well bring the 5DII and 24-105mm, at least.  Fortunately, my wife has grown very tolerant of me carrying lots of gear around on family outings, and also to me shooting frequently at home. The key, for those with wives and kids, is taking great shots of the kids.  The proof in the pudding was in early December - my wife was heading out to do some shopping, and said she wanted to take some family portraits for cards later that day.  She returned and walked into the living room, to find a 9' backdrop set up, and three light stands with a pair of 24" softboxes (430EX II's in them), and a monolight with a 48" octabox.  All I got was a raised eyebrow. 

6521

PowerShot Cameras / Re: *UPDATE 3* Canon PowerShot G1X Revealed

« on: January 07, 2012, 06:23:58 PM »

But given the f/16 spec...

So...here's a question.  Even a very low (<6) MP APS-C sensor is diffraction-limited at f/16.

No, they aren't.

Why can EF-S lenses be stopped down to at least f/22 and in many cases to f/38?

Because sometimes DOF or correct exposure are more important than preservation of detail.

You're saying images taken using a dSLR with a typical APS-C sensor are not affected by diffraction at f/16?  Can you provide some evidence to back up that claim? 

BTW, the question about why diffraction-limited apertures are available was rhetorical.  Your examples illustrate my point - diffraction resulting in loss of sharpness is not a reason for Canon not to make f/16 available on a 1/1.5" sensor, which was the argument being made to support the idea of an APS-C-sized sensor in the G1x.

6522

Landscape / Re: Look up

« on: January 07, 2012, 01:00:29 PM »

Great shots!

Continuing with the theme...


EOS 7D,  EF-S 17-55mm f/2.8 IS USM @ 17mm, 1/30 s, f/8, ISO 500

6523

EOS Bodies / Re: Clarify some Canon 5d M2 in-camera processing questions

« on: January 07, 2012, 11:03:19 AM »

A few settings aren't metadata but rather alter the RAW data (HTP and long-exposure NR) so those are baked into the RAW image data no matter what you use for PP.

Thought I should clarify the above.  While long exposure NR is truly baked into the RAW image data (a dark frame is shot after the exposure, subtracted from the exposure, and the result is written as the RAW image), HTP is a little different.  It's not so much that HTP affects the RAW data per se, but it does affect the RAW metadata in a way that's not handled properly by anything but DPP.

What HTP does is deliberately underexpose by one stop, and 'misrecord' the ISO in the metadata - that's why ISO 100 isn't available when you turn on HTP, i.e. you set ISO 200, it shoots at ISO 100 but records 200, or you set ISO 800, it shoots at 400 and records 800. If shooting JPG, it processes the underexposed image to brighten everything except the highlights (meaning it applies a tone curve).  If shooting RAW, it sets a metadata flag so DPP can apply that tone curve. 

If you open that RAW file in a 3rd party converter, results vary. Some ignore the flag and you just get an underexposed image.  Others compensate by just boosting the total exposure by one stop - I think ACR (LR/CS) does that.  Of course, that just re-blows your highlights and adds shadow noise. AFAIK, no 3rd party converter tries to replicate the tone curve to preserve highlights. 

So, if you shoot RAW and use a converter other than DPP,  I'd leave HTP off so your reported ISO reflects the actual ISO used to take the shot, and just expose properly to preserve highlights.  You can apply your own tone curve, not limited to the one full stop forced by HTP.

6524

EOS Bodies / Re: D4 AF vs 1d X AF

« on: January 07, 2012, 10:22:18 AM »

Over to Neuroanatomist...?

 

Noticed and hypothesized on yesterday:

http://www.canonrumors.com/forum/index.php/topic,2707.msg57623.html#msg57623

In short, my take agrees with yours - it's a firmware implementation, and there is a possibility that Canon could match it with the 1D X (if it works well enough with their sensor, and if the choose to (they may not, either for marketing reasons - driving customers to buy longer lenses - or to avoid being seen as reacting directly to the competition).

6525

PowerShot Cameras / Re: *UPDATE 3* Canon PowerShot G1X Revealed

« on: January 07, 2012, 06:13:43 AM »

But given the f/16 spec...

So...here's a question.  Even a very low (<6) MP APS-C sensor is diffraction-limited at f/16.  Why can EF-S lenses be stopped down to at least f/22 and in many cases to f/38?

Of course, the press release could simply be fake, or wrong...

Isn't it fun to speculate when we'll find out who is right in a few days?

Absolutely right on both counts!