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Messages - neuroanatomist

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7441
EOS Bodies / Re: making a case for that crop body camera
« on: February 03, 2013, 11:58:01 AM »
Other than the first two reasons listed, the main reason I couldn't part with it was my EF-S 17-55. I love that lens so much that I had to keep a body to use it with.

I hear this a lot.  In case you didn't know, the FF equivalent of the EF-S 17-55mm f/2.8 is a hypothetical 27-88mm f/4.5 lens (adjusted for AoV and DoF for same framing), so the 24-105mm f/4L kit lens is longer, wider, faster, still has IS, and will deliver sharper images on FF than the 17-55 on APS-C.  The better ISO performance of FF (>1.5 stops from 7D to 5DIII) more than makes for the loss of a stop of shutter speed.  The only thing you're theoretically giving up is the high-precision center AF point...and since the center point of the 5DIII is reportedly more accurate than the center point of the 7D, and the 5DIII has overall superior AF, it's not much of a sacrifice.

My advice: sell the 17-55 (I did), and probably the 7D, too.

7442
Animal Kingdom / Re: Open up and Say Ahhh...
« on: February 03, 2013, 10:27:36 AM »
Great shots of some ugly (but very tasty) fish!

7443
Lenses / Re: Resistance to Larger Filter Size, Kills Great Lenses?
« on: February 03, 2013, 10:05:42 AM »
ditto, it would be a badass looking lens with the 95mm filter size

I just got the business idea of dslr tuning - make it appear more impressive by adding false elements to the front, dummy buttons to the back for a more difficult pro-look, a *double* red ring as a chick magnet ... just like car tuning with spoilers, lower chassis and broader tires (that actually slow you down) :->

Sort of like that pimped-out nifty-fifty!


7444
Lenses / Re: Resistance to Larger Filter Size, Kills Great Lenses?
« on: February 03, 2013, 09:49:29 AM »
It's well known, based on patents, photographs of prototypes

Out of curiuosity, can you provide links to patents or pics of a prototype 24-70/2.8 IS lens?

7445
Lighting / Re: Help for Speedlight MT-24 EX / 600EX-RT
« on: February 03, 2013, 09:36:48 AM »
Yes, you can add a second 600EX, with one on-camera and the other as a slave, or get both off-camera by connecting one with an OC-E3 cord (or 3rd party copy).

You mention the high cost of the MT-24EX, but RRS gear isn't cheap, either.  To get the pair of flashes out to the subject, you'd need another mount and a pair of extenders, plus a lens collar plate - close to $500 in RRS gear, plus the cost of the 600EX-RT.

I would probably not be inclined to buy an MT-24EX for use with just a 100L, but it's the right choice for an MP-E 65mm, and since I got the twin-flash for that, I also use it with the 100L.  I considered getting the RRS setup above, a second mount plus a second extender (I had one already to get the Better Beamer further off-axis with the 600L) for the twin light, but I think that setup is limiting in terms of flexibility.  Instead, I opted for a pair of Wimberley F-2 brackets.

So...my current 'ultimate' macro lighting rig is the MT-24EX in the hotshoe with the twin heads each on a Wimberley F-2 bracket to light the subject, and the 600EX-RT on the RRS bracket w/ extender as an optical slave to light the background.

7446
If you stop down past f/4 the cross-type points turn into normal old af points that only reference details in a single direction.

Sorry, but that's not true.  You can stop down to f/22 if you want, the aperture you select is irrelevant - phase-detect AF is always performed with the lens wide open.

What does matter is the max aperture of the lens - that's what determines available AF points.  An f/5.6 lens (e.g., 100-400 or 28-135) on a 5DIII is limited to the central 3 columns of cross-type points (plus 40 single orientation points), whereas that same lens on a 7D gives all 19 cross-type points. An f/2.8 or faster lens gives 41 cross-type including 5 high-precision points on a 5DIII and 19 cross-type including one high-precision on a 7D.

The other issue is AF accuracy.  Having shot with both the 7D and the 1D X (same AF sensor as 5DIII), I find the frequency of AF misses to be noticeably lower with the 1D X (even with the lateral points).  Some aggregated data from Reikan FoCal are consistent with that observation.

7447
EOS Bodies / Re: making a case for that crop body camera
« on: February 03, 2013, 07:22:30 AM »
That crop body will put more pixels on target, birds in flight or that child playing BB in the gym, than will that FF camera, pixels on target determines IQ.

Pixels on target is clearly not the sole determinant of IQ.  If it was, the 7D should produce noticeably sharper images than a 1D X or 5DIII cropped to the same FoV - yet, at low ISO the IQ is quite similar, and at high ISO the cropped FF image is superior. 

In 'focal length limited' situations, the only advantage of more pixels on target is just that - more pixels.  If the fewer MP of the cropped FF image are sufficient for the desired output (e.g., a reasonable sized print), the APS-C body doesn't offer any advantage except that it cost less to get that same IQ.

As Don points out, the lower weight of some crop bodies, and the lower weight and smaller size of lenses with a smaller image circle, can also be an advantage.

7448
Lenses / Re: Odd AF microadjustment behavior with a new lens
« on: February 03, 2013, 06:49:09 AM »
Definitely odd. No, Canon lenses don't store AFMA values. If it recurs, I'd say a call to Canon is in order...

7449
Third Party Manufacturers / Re: Canon may be expensive but...
« on: February 03, 2013, 06:34:12 AM »
Yes hitting the HTP button doesn't change the total light now hitting the sensor

Thank you, you can stop there.  I fully understand how HTP works 'under the hood', and how to emulate or 'improve' on it when shooting RAW, as do you - I don't think we need to explain it to each other.  My point was that someone who states the opposite of the quoted statement above (repeatedly) is wrong, and does not understand the general mechanism of HTP.  Incorrect statements like that can confuse people who are trying to understand the concept, and which is unfortunate and should be corrected.

7450
EOS Bodies / Re: making a case for that crop body camera
« on: February 02, 2013, 11:26:33 PM »
I disagree with some of the points above with the APS-C big advantage being mostly about price.

When I bought my 7D, I was choosing between it and the 5DII. I chose the 7D over the 5DII because I felt, for me,  it was a better "camera" overall.

Exactly - the 7D is a better 'overall camera' than the 5DII - and it's cheaper (at least based on Canon's pricing), because it's an APS-C body. 

Put it another way - to get a camera that exceeds the 'overall' performance (considering not just IQ, but AF, build, etc.) of the 7D, a year ago you needed to buy a 1-series body.  Today, you could get something as 'cheap' as a 5DIII to beat the 7D...and that's twice the cost.  It's not that the performance aspects that make the 7D a great camera aren't available in cameras with larger sensors - they are, it just costs a lot more to get them. That's what I mean by the APS-C advantage being lower cost.

Like you, I had a 7D and 5DII, and used the former for birds, wildlife, and for my 4 year old's gymnastics.  The 5DII's AF wasn't up to the task.  But now that I have the 1D X, the 7D is relegated solely to gathering dust and hoping the 1D X breaks so it can fulfill its one remaining function - backup camera.

7451
EOS Bodies / Re: making a case for that crop body camera
« on: February 02, 2013, 09:16:39 PM »
+1

The real 'case for that crop body camera' compared to FF is that it's cheaper than FF.  That's not a slam on crop bodies - affordability is very important in the real world!

7452
Third Party Manufacturers / Re: Canon may be expensive but...
« on: February 02, 2013, 09:06:40 PM »
@ LetTheRightLensIn - Changing the ISO has no direct effect on the amount of light that hits the sensor.  At ISO 400, enabling HTP does not result in a change in the amount of light hitting the sensor, no difference in the number of photons. Period. What the camera does is apply one stop less gain to the signal generated from those collected photons, then applies a tone curve to the jpg data to boost everything but the highlights back up that one stop. 

Suggesting that at ISO 400, HTP reduces the light hitting the sensor is not just misleading, it's plain wrong.  Neither aperture nor shutter speed are changed - and that's a damn good thing because aperture should be selected to give the desired DoF and shutter speed selected to control motion in the image as desired, and the camera shouldn't be changing those parameters if I don't want it to.  I disagree with your statement, "...if I want to do HTP myself what do I need to do? To get the exact same result I shoot at my selected ISO, keep my selected aperture and then I raise the shutter speed 1 stop faster."  What if you wanted motion blur of a fountain, but to preserve the highlights in the scene - would you sacrifice the motion blur you wanted, or stop down and change your DoF or lose sharpness to diffraction?  I would do what the camera does with HTP - underexpose by lowering ISO as many stops as needed, and if that took me to ISO 100, it would be time for an ND filter.

HTP has limitations, foremost being it's limited to one stop of 'highlight recovery'.  But if you understand the technical principles behind it, you can overcome those limitations to some extent, while still capturing the desired image in terms of DoF and motion control.

Like Mikael, you are confusing the actual collection of light by the photon wells of the sensor with what happens to the electronic information into which the energy of those photons is subsequently converted, and with the processing applied to the digitized form of that information even later in the image acquisition process. Those are discrete steps with their own characteristics, and if one is going to discuss the technical details of the image data generation, one should correctly describe and apply those details.  You can think of it as a semantic issue if you like, but there was no semantic confusion about providing an incorrect answer to simple yes/no questions - questions which you answered correctly but Mikael did not.

At the outset, everyone deserves respect, appreciation of cultural and linguistic differences, patience, and the benefit of the doubt. If, over time, someone consistently displays rude and insulting behavior (to the self-admitted point of being placed under strict regulations by the mods), makes no significant effort to contribute in anything but a negative manner, is repetitious and combative, and offers neither apology nor any redeeming characteristics, that person deserves to lose the respect of the community...as Mikael has certainly lost mine.

7453
Reviews / Re: Kirk Security Strap review
« on: February 02, 2013, 06:59:36 PM »
Makes perfect sense - thanks yet again!

7454
Third Party Manufacturers / Re: Canon may be expensive but...
« on: February 02, 2013, 06:41:41 PM »
no Im saying by exposure after 400 iso you have create a head room by 2 stops compare to 100iso
what is so difficult to understand Neuro! = exposure after 400 iso = halving the hitting lights twice compare to 100iso


Hypothetical example: I shoot jpg. I am taking a picture of a forest scene. I am in Av mode, and I set f/8 to obtain the desired DoF, and I chose ISO 400 to get a 1/100 s shutter speed at metered exposure to avoid camera shake, because I foolishly left my tripod at home. Please note, I couldn't care less about what exposure settings would be at ISO 100, 50, or 3200, that's tangential and irrelevant - I choose f/8 and ISO 400 for the reasons I stated.  I take a shot, look at the review image, and see blinking highlight alerts where I want detail of the sun-dappled forest floor. I've read that HTP can preserve my highlights.

If that scenario is confusing, I'll summarize - with HTP off, I set the camera in Av mode, f/8, ISO 400, and the metered exposure gave a 1/100 s shutter speed.

Answer these questions about what happens when I set HTP to Enable:

1) Does my selected aperture of f/8 change?
2) Does the camera-selected shutter speed of 1/100 s change?
3) Does the amount of light hitting the sensor change?

Please, no hand-waving, no 'please read my earlier posts', no repeating what you've posted before, no referring to what may happen at some other ISO setting that I didn't select and don't care about - just answer those three, simple questions with a yes or a no.

 Answer : yes

Sorry, Mikael - it was a pass/fail test, and you have failed.  The answer to all three of those questions is "no".  In Av mode, f/8, ISO 400, enabling HTP does not change aperture or shutter speed, and therefore the amount of light hitting the sensor does not change. If anyone believes there a chance Mikael is right, feel free to set Av, f/8, ISO 400 then enable HTP and see if shutter speed or aperture change as a result.

Back in the other thread, I had come to the conclusion that this was semantics and your inappropriate extrapolation of what happens in the special case of ISO 100 in an autoexposure mode to a general explanation of how HTP works.

But...the fact that you answered "yes" to the above questions clearly demonstrates that you do not understand how HTP really works.  Despite repeated attempts by several people, including TheSuede, to provide an explanation which you could understand, you fail to grasp some details of the concept.  At this point, the only logical conclusion is that you are simply incapable of understanding the mechanism of HTP.  Not due to language, semantics, etc. - just a fundamental inability to comprehend this concept.  You are wrong, you don't get it, and apparently you never will, much less admit that you're wrong and/or incapable of understanding the concepts.

To paraphrase an earlier statement of yours, it's impossible to discuss this with someone who does not understand the basics - and that someone is you, Mikael.  For my part, this discussion is done.  Any further statements or questions from you on this matter will be ignored.

7455
Lenses / Re: 300 f4 + 1.4 TC v's 500 f4.5
« on: February 02, 2013, 04:40:30 PM »
The 500mm f/4.5L is an electronic manual focus lens, and AFAIK Canon no longer services that model. So, if the AF motor gives out (which happens on those lenses), you will be unable to focus the lens at all, leaving you with a $3000 rather heavy cricket bat.  I'd pass.

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