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Messages - neuroanatomist

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EOS Bodies - For Stills / Re: Best carry set-up for 7D & 70-200 f/2.8L
« on: January 25, 2013, 06:30:41 AM »
Lowepro Toploader Pro 75 AW as a dedicated bag.  Blackrapid strap (attached to the tripod foot) to carry around.

I cannot imagine a more pointless, unrealistic test. If your goal is to demonstrate a passion for creating the ultimate rig for imaging newspapers taped to brick walls, congratulations, you've succeeded. But if your goal was to demonstrate an understanding of actual photography as practiced by actual photographers....

Again, the test I performed resulted in two images with the same number of pixels in addition to the same perspective and depth of field and background magnification and out-of-focus blur and everything else a photographer cares about. The only variable was format size, and we saw that sharpness is very closely related to format size and not at all related to the number of pixels in the image. All your test demonstrates is that, if you ignore everything that actually defines what an image of anything other than a test chart looks like, you can get two systems with certain similar specifications to make similar images of a test chart and nothing else.

Therein lies your problem. Your test attempted to compare 'the same picture'.  You might have a point...if that were the goal. But we're not asking about 'everything that defines an image', we're asking about only one thing.  Let's revisit the title of this thread: Is FF sharper than APS-C?  Not 'does FF take a better picture'.  Yes, photographers care about 'better pictures' but that's not what's being asked here.  Only sharpness.  So in this case, taking pictures of a newspaper taped to a brick wall would be a far more appropriate test of the question than yours.

"The only variable was format size..."  Really?  Do you understand what a variable is?  Do you know the difference between a dependent variable and an independent variable, and how to tell when a dependent variable becomes a confounding variable?  You used different lenses to take the different pictures. You processed the images differently.  We call those confounding dependent variables.  Your test was not designed to answer the question, and therefore was flawed for the purpose at hand. 

"...the test I performed resulted in two images with the same number of pixels in addition to the same perspective and depth of field and background magnification and out-of-focus blur..." Guess what?  So did the TDP comparison I linked. Same number of pixels (but achieved without scaling), same effective perspective (indeterminate because the image has no depth), same effective depth of field (essentially none, as the entire subject is within it), same background magnification (none, no background), same OOF blur (none, everything in focus).  Unlike your test, the TDP ISO 12233 crop holds everything constant.  It's no accident they're called that - ISO 12233 is the "standard for measuring the resolution of electronic still imaging," and that's what we're talking about here...not 'better picture', sharpness.

An analogy: It's as if I asked, "What is the sodium content of french fries vs. carrot sticks?" Your test is trying to answer a question like 'which one tastes better?''  Yes, that's an important question for a person who wants a snack, but that's not what's being asked.  I'm looking for a chemical analysis of Na+ content, and you are conducting a blind taste test.  Interesting and informative, perhaps, but a complete fail as far as answering my question.

If you want to test the effect of sensor format on sharpness, you must hold everything else constant - especially the lens and the post processing. You varied both.  It's not that your test was invalid per se, but rather that it was not designed to address the question being asked.  Sharpness is just one component of picture quality, but again - that's the one we want to test.

Gee...I don't about getting the actual cameras and putting the same lens on each; changing position to achieve the same FoV; and making sure that all other factors (scene; lighting; aperture; shutter; settings) are equal, thereby isolating the difference you want to measure (sharpness)?  ::)

On second thought...nah...that's just crazy talk  ;D

Yes, that's crazy. Spectacular fail crazy.

Use the same lens on different formats and you get a different field of view. Change position and you get a different perspective in addition to a different field of view. Keep the aperture the same between different formats and you get different depth of field.

I was very specific in what I did and didn't change, and I did it for a reason. My test really was a true apples-to-apples comparison. The shooting position was the same, so the perspective was the same. The shutter speed was the same so the motion blur (not that there was any) was the same. The aperture was different, yes, but it resulted in the same depth of field. The ISO setting was different, yes, but it resulted in the same exposure -- and, unsurprisingly if you know the basics of photography, it resulted in basically the same amount of noise.

I thought at some point in this long, acrimonious thread, AlanF (but maybe someone else) commented that TrumpetPower had failed to isolate the relevant variable.  That's true - way to many differences in this 'test'.

"Spectacular fail crazy."  No, dtaylor is spot on.  I seem to recall that several pages back, TrumpetPower stated that the thing to do would be to use two sensors of the same MP count but different sizes, that's at least barking up the right tree, however, the 'test' didn't do that.

Evaluating sensor sharpness using two different lenses at different apertures? Scaling the resulting images? That's uber-spectacular quintuple-facepalm-type fail. 

TrumpetPower asked what the ideal test would be...first off, not his.  ::)  The solution is the one dtaylor suggested - two cameras, one FF, the other APS-C, with the same MP count.  Use the same lens, and change the distance to match the FoV. As for the objections of problems with changing distance resulting in different perspective and the same apertures resulting in different DoF on different formats, there's an obvious solution: a flat target, parallel to the sensor. That means no perspective to be altered (perspective alters the apparent distance relationship between subjects at different distances, but with a flat target the entire subject is at a fixed distance), and the flat target renders DoF moot.

So...two equal MP sensors of the same generation, a flat target framed identically, same lens for both (preferably a sharp one), same aperture.  Where, oh where, could one find such a test? How about here.

What's the conclusion?  Pretty much this:

...all other factors being equal...and I've always found the same thing: FF is sharper out of camera, but the range is small enough to be closed by bumping up sharpening in camera or post. When the sensors are otherwise comparable of course.

Is this a perfect test?  No - there's no such thing with the tools available. The AA filters are different (the 18 MP 7D fares much worse in the above TDP comparison than the T4i, for example, likely due to a stronger AA filter), the firmware is different, etc.  It's a test at one distance per camera, at some distances with some targets the Nyquist sampling issues raised by AlanF are a determining factor. It's a test at ISO 100 - at ISO 3200, the results would be quite different. 

Bottom line - the differences of opinion in this thread far exceed the real differences in sharpness between sensor formats, and the wagging tongues in this thread are sharper than my Wüsthof cutlery.   :P   

Over and out, for me.

Software & Accessories / Re: Rucksack Camera Bags
« on: January 24, 2013, 07:09:03 PM »
I'm debating between the 250 and the 350.  It's always hard to judge online - I recommend taking your gear into a shop if possible.  For example, the Flipside 300 isn't supposed to hold a gripped body, but it does. The Fastpack DSLR Video 250 states 'pro dSLR (without grip) and 24-70' but based on the stated depth a gripped body will fit - I just need to know if an attached 28-300L will fit, despite what the specs say, and if my 17" MBP will fit in the 'holds a 15" notebook' pocket (measurements say yes, reality may be different).

As I said, it's always hard to judge from specs online, but usually Lowepro overestimates the capacity (e.g. if they say body + 4-6 lenses, it means 3-5 lenses or less).  So, I took the camera, white zoom, and Mac into my local Hunt's to try the 250, and to my surprise, the 1D X fits fine (even with the RRS L-bracket), the mounted 28-300L is fine, there's room for two other lenses, and the 17" MBP fits in the laptop compartment, with room for my 13" MacBook Air to fit as well, if needed.  So, I walked out with the Lowepro DSLR Video Fastpack 250 AW.   :)

Nikon 5200 blow 5d of the road, if you have enough good lens on the Nikon

Technically true in terms of sensor performance.  Of course, comparing a camera from last year to a camera from 8 years ago isn't exactly an apples-to-apples comparison. 

Lenses / Re: What nd filter density (combinations) do you use?
« on: January 24, 2013, 01:44:33 PM »
Brilliant, a thread with a particular issue I am having... I need a square filter ND, 6 stops, to stack together with the Big Stopper to get 16 stops... Neuro any idea? Lee make 3 stop NDs, but I guess stacking a 10 stop Big Stopper and two 3 stop NDs would be overkill in terms of vignetting. Hitech, Cokin or BW make a 6 stop 100 mm square filter anyone knows?

Answered in your other thread, two options there...

Software & Accessories / Re: Square 100 x 100 mm ND filters
« on: January 24, 2013, 01:44:00 PM »
Schneider Optics (B+W's parent company) makes a 100x100mm ND1.8 (6 stops), in their MPTV line (motion picture/television) - B&H link.  Note that they're Schott glass filters (they're the only ones that I know of who make glass square/rectangular ND/gradND, vs. resin.  The issue is see is that they're twice as thick as the Lee resin filters.  I know the Lee holder can take them with an appropriate adapter, but I don't know if you can use a 2mm Lee and a 4mm Schneider in the same holder at the same time.

Just found a HiTech 4x4" resin ND1.8 that will fit a Lee holder - B&H Link.

Hope that helps...

Lenses / Re: What nd filter density (combinations) do you use?
« on: January 24, 2013, 12:25:08 PM »
As for the filter system, I can see the hassle with the screw-on version, so I'll have to calculate the cost of  Lee/Cokin with polarizer & nd if getting the adapters and holders from eBay/China - but that's probably beyond the scope of this thread.

I've considered the Lee system, am still considering it, in fact.  But the main reason for that is to use graduated ND filters, where a screw-in filter is not optimal (no flexibility on where the gradation falls).  I like the screw-in solid NDs for portability - easy to throw into a side pocket of a bag.

And I'll want to use it on the 17-40L on ff sooner or later - and even for "normal" sized filters I've read vignetting can occur, that's why b+w sells the slim version. But since I'll have to use a step-up adapter 77->82 for the 17-40L I might get vignetting anyway, even with a slim version?

Not sure about the 17-40 and vignetting.  If you use a step-up to 82mm, vignetting is less likely.  But it's really lens-dependent.  For example, the 16-35 II on FF is very susceptible to increased vignetting with filters, but the 10-22mm on APS-C (equivalent focal length to image circle comparison) can take a couple of stacked filters with no hit on vignetting.

You need one Mini TT1 on the body you're using.  If you use two bodies during a shoot, it may make sense to have a second Mini TT1.  A single Mini TT1 transmitter can control a whole bunch of receivers/tranceivers.  I use an on-camera Mini TT1 to control a pair of Flex TT5s and a PowerMC2 for an Einstein monolight (and it's the ability to trigger that monolight that's holding me back from Canon's RT system). 

The Flex TT5 can be either a receiver or a transmitter, so you could have a Mini on one camera and a Flex on the other camera with one flash, or a Mini on one camera and a Flex on each of two flashes.

The Mini/Flex system allows E-TTL automatic flash metering, the Plus III system does not.

Lenses / Re: What nd filter density (combinations) do you use?
« on: January 24, 2013, 08:57:36 AM »
Good points above.  The 'Maltese cross' artifact with variable ND's gets worse the darker you go and the wider the AoV (it's caused by uneven polarization, like you see with a CPL on a UWA lens).  Since one of my main uses for a 10-stop ND is to blur people out of city scenes, often shot with the TS-E 24 or 16-35, I've avoided a variable ND.

Although sometimes it's bright enough to use Live View with exposure simulation, normally you'd set composition and focus, meter, then screw on the ND, adjust exposure, and shoot.  A stable ballhead is a must (a little camera shake won't hurt a 30 s exposure, but you don't want to shift your composition. Probably not applicable, but a rotating front element won't work.

Lenses / Re: Advice for shooting pictures of eagles
« on: January 24, 2013, 08:14:25 AM »
Eagles are big, and if you're close in the blind you may find that the DoF at 400mm f/2.8 or 560mm f/4 is actually too shallow.  There's no issue with diffraction on the 1D X up to f/11, I'd try the f/5.6 - f/8 range.

Lenses / Re: 200mm F2 IS OR 135mm F2
« on: January 24, 2013, 07:55:37 AM »
If you can afford it and have room to use it (outdoors or a large indoor space), get the 200/2!

EOS Bodies / Re: EOS-1D X Firmware Specifcations
« on: January 24, 2013, 07:51:51 AM »
Ahhh, now I see the issue.  Yes, that's true - I suppose it's a result of the transmissive LCD.  The older cameras you mention have the AF points etched onto the focus screen - they're always 'on' and because of the etching, when illuminated, the light hits them in such a way that pretty much only the selected AF point lights up.  With the transmissive LCD, when it's illuminated the selected AF point(s) are 'lit' but to a lesser extent the whole VF glows red. That is a bit distracting, sort of like wearing rose-colored glasses or suffering from a bad hangover.  ;)  That glow also mucks with the metering, which is why it turns off after AF lock, and why the AI Servo 'fix' is the illumination blinking on/off rather than steady.

Personally, while the transmissive LCD has some drawbacks, I think those are outweighed by the benefits of AF point display flexibility, on-demand grid display, etc.

Lenses / Re: What nd filter density (combinations) do you use?
« on: January 24, 2013, 06:49:26 AM »
1.  I have 3-stop and 10-stop filters.  If I had to choose just one for nature/architecture it would be the 10-stop.  The 3-stop is great for shooting fast primes wide open for outdoor portraits, and it does 'ok' for moving water if you stop down a bit.  But for architecture shots where you want to blur out people, 10-stops is what you want - 6-stops likely would not be enough to get you to the 30-60 s exposure time. In fact, I didn't bother with an 82mm 3-stop (I have 72mm and 77mm), I just have a 10-stop in 82mm (also in 77mm).

2.  The only real-world drawback might be increased optical or even mechanical vignetting, depending on the lens.  For example, with the 16-35L II, stacking an F-Pro ND and a Slim CPL will add 2-stops of optical vignetting at 16mm f/5.6, and cause mechanical vignetting at 16mm f/2.8.  OTOH, I often stack my 82mm Slim Käsemann CPL on my 82mm 10-stop ND on a TS-E 24L II, no problems there.

3.  My 10-stop NDs are uncoated.  If there has been MRC versions available when I bought them, I'd likely have done so (in fact, when I bought my 82mm 10-stop, the only one even available as a screw-in was from Schneider Optics, B+W's parent company). But, it hasn't been an issue.  The coating makes cleaning easier, but you're not going to have to clean an ND too often.  The main benefit of a multicoated filter is to increase transmission by reducing reflection (an uncoated UV/clear filter will cost you 8-10% of the light, a multicoated one loses <1%).  But the whole point of an ND filter is to lose light...  Yes, in theory there may be some extra flare (due to reflections between the front element and the back of the filter), but the coatings on the front element minimize that, and I haven't found it to be a real-world problem.

Hope that helps...

PW and Canon RT can't trigger each other.  Different freqs, different protocols.

You'd need the 600EX-RT on a Flex TT5 to trigger it. Or, go all Canon with an ST-E3-RT or a second 600 on the camera to trigger the 600 (but the 580 can't be radio triggered without a 3rd party trigger, or at all by the ST-E3).

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