November 28, 2014, 03:39:00 PM

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### Messages - Jackson_Bill

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16
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 11:03:46 PM »

SNR = sqrt(photon count)

True, but I believe that's photon count per pixel. I'm trying to understand how the the total photon count on the sensor matters.

If you only look at one pixel, the per-pixel photon count would be all that matters.  If you look at a whole image, the whole image photon count is what matters.

I don't think so. You've probably seen this before
http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/

For the shot noise, its only a function of the number of photons captured by a pixel. Its the physics of why the crop (smaller pixels) shot noise can never be as low as the FF.
My impression is that the read noise is also per pixel but I can't back that up.

[Where's jrista when you need him?]
:-)

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##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:27:11 PM »

Yes, if a FF pixel and a crop pixel are the same physical size (and technology) the individual pixels will be identical in terms of signal and noise.

If both images were shot with the exact same lens, the same settings, and the same distance, the central 40 percent of the FF pixels would be exactly the same as the crop pixels.
My point exactly!

In real life, with your equal size pixel scenario, we would try to frame the two pictures the same, so that means either a 1.6X longer lens on the FF camera, or walking closer until the image filled the screen the same. Either way you look at it, that gives you 2.56 times as many pixels of equal quality on the target, so when you "normalize" the FF picture for the same number of pixels as the crop image, you end up with better quality pixels on the FF image. You are choosing between more pixels of the same quality, or the same amount of pixels but of better quality. There is no way for crop to win in that scenario.

In the real world, with the cameras Canon makes now, FF wins the IQ contest in all but one scenario... and that scenario is when you are focal length limited, can't move any closer, have a GREAT lens, and good lighting. Under those conditions (happens a lot with small birds) the quality of your crop pixels is fairly close to your FF pixels, but you have more crop pixels on target so you end up with a better image from the crop camera.  Everywhere else, FF wins.

No argument with any of that either. In fact, I think that's another good version of the summary that Eldar was asking for.

Sorry I got us off track with that amount and intensity of light thing.

18
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:20:36 PM »

SNR = sqrt(photon count)

True, but I believe that's photon count per pixel. I'm trying to understand how the the total photon count on the sensor matters.
Although I'm beginning to regret going off on this tangent.
:-)

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##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 07:32:22 PM »

True, but the 2.56x greater area of the FF sensor will gather more total light.  Comparing noise at the pixel level isn't the same as comparing noise at the image level.

There's shot noise, which is clearly related to the size of the pixel and I thought that the signal processing to convert the analog to digital was done on a pixel-by-pixel basis, which would make the read noise related to the pixel photon count, too.  Is that so? If so, what else would make the image level noise different? In other words, how does the total amount of light collected by the sensor come into the noise calculation?

20
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 10:19:05 AM »
I don't agree with this "amount of light" argument. Consider a full frame sensor and an APS-C size sensor with pixels the same size as a full frame taking photos with the same lens at the same f-stop and the same distance from the subject. The signal to noise ratio for each pixel in the APS-C sensor will be the same as the S:N ratio as the corresponding pixels in an APS-C sized area of the ff.

True, but the 2.56x greater area of the FF sensor will gather more total light.  Comparing noise at the pixel level isn't the same as comparing noise at the image level.

You lost me on the image level noise, Neuro. It seems that an APS-C sized crop of the FF image and the APS-C image in this case would be identical. The number of photons hitting each pixel is the same and assuming the downstream operations are identical, what's the difference?

21
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 23, 2014, 09:47:06 AM »
I must have misread. I was under the impression that some people were arguing that 2.8 lens let in the light of an f8 when on the micro 4/3 mount.
Jarrod
...

A greater intensity of light is what's needed to make a smaller area receive the same amount of light. Simply cutting/cropping out some light, and then magnifying/enlarging what's left afterwards results in less light captured. That's otherwise known as a lower signal, which requires more amplification/enlargement, typically resulting in more noise.

I don't agree with this "amount of light" argument. Consider a full frame sensor and an APS-C size sensor with pixels the same size as a full frame taking photos with the same lens at the same f-stop and the same distance from the subject. The signal to noise ratio for each pixel in the APS-C sensor will be the same as the S:N ratio as the corresponding pixels in an APS-C sized area of the ff.

22
##### EOS Bodies - For Stills / Re: What card(s) will you use for the 7DII?
« on: October 22, 2014, 09:46:58 AM »

As a precaution I shoot in both RAW and JPEG in different card. RAW in Sandisk 32gb 160mb/s UDMA 7 CF Card and JPEG in a Sandisk 16gb 120mb/s SD card. Both formats in high resolution
That is my general intention, shoot raw to the CF and jpeg to the SD.  Not sure of the sizes yet but your method seems good.

Are you actually writing the RAW and jpg both on every shot? It seems that would seriously impact the high speed frames per sec.

23
##### Lenses / Re: 400 f/2.8L II IS on sunny days and white jerseys
« on: October 20, 2014, 02:03:10 PM »
Quick example.  Here's another game that started at 1pm.  I had the AF point locked on her face; this is frame 3.  Notice the ref's face on the far right, so this front-focused.
Something to consider - I'm not so sure I'd conclude that this shot was front focused. If you look at the grass you can see a clear line of sharp focus. I think the kicker's body and the ref's foot are in that line of sharp focus. Is it possible that we're seeing motion blur in the kicker? What was your shutter speed on that one?
As someone else mentioned - that's a thin line of focus, too. On a sunny day you should be able to get away with a higher  f-stop.

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##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 17, 2014, 08:31:53 PM »
...

After about page 3 I thought I´d try to sum up the opinions so far, but I don´t think I´m the right guy for that. But it would be interesting if someone could try to make the comprehensive and objective list of pros and cons FF and crop.

'''
But again, If someone could take on the challenge of making the ultimate objective guide to crop vs. FF ... Thank you in advance

Eldar - I've seen the stuff you've posted and the techniques you've described and if you aren't the guy then I know I'm not!
As the discussions in this thread continue, I'm not sure anyone could ever come up with the final word on crop vs FF.
Interesting topic though.
Bill

25
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 17, 2014, 11:29:28 AM »
Well, in addition to comparing two heavily cropped images, the 5DIII shot at 1/800 f/7.1, ISO 800 (+1) and the 7D at 1/640, f/5.6, ISO 400 (+0.7)...
Heavily cropped only to show the detail easily in this forum. Comparing on any other crop level would show the same.
Yes, it wasn't exactly the same exposure because I wasn't thinking of performing a rigorous comparison at the time. I had both bodies, changed the 500 from one to the other, and after the fact thought about comparing them.

The images you are comparing should be the situation where the 7D beats the 5DIII because you used the same lens, are "reach limited,"...
That's my situation the majority of the time.

And yet, you are "not seeing that much difference."
The discussions in many of the FF vs APS-C threads could lead one to believe that the FF is always superior so I'm thinking "not much difference" is pretty good.

The different DoF could have also be a factor.
Not really, and any advantage would go to the FF in this case. The DOF of the 5Diii is about 80 ft while the DOF of the 7D is about 40 ft by my calculations.

The obvious example is high ISO conditions.  Compare shots from ISO 800 on up and tell me which you prefer?
No argument there - that's why I bought the 5Diii.

Speaking of post, have you seen how much better the 5DIII files respond to PP compared to the 7D files?  It isn't even so much that you can push the files further (although you can), it is that I like the response of the file better.
Other than the undisputed fact that the FF has lower noise, how does one RAW file perform better than the other?

While both can use Canon's lens lineup, the majority of L lenses are better suited to a FF sensor (possible exception of the super telephotos)
How do you figure that? If anything, I'd say the EF lenses would do better on the APS-C because the APS-C is not using the edges where peformance falls off.

AF is better, especially in low light
We're comparing APS-C vs FF, which shouldn't make any difference to the AF. OTTH, having about the same number of shots on my 7D, I fully understand the AF issue.

But, as you have both cameras, if you could only have one, which would you take?  For me, it is FF and the 5DIII.  Lee Jay picked two 7DIIs.

At this point (and I have less than 100 shots on the 5D), I'm less impressed by the FF than I thought I'd be. And given the price of the new superteles, stepping up to a 600mm or longer is just not going to happen. I'm thinking that the 7D will still be my main wildlife lens and if I had to choose which to take into the field, I'd take the 7D. If Canon would ever improve the high ISO performance of the small pixels to that of the Exmor, I could easily live with just the APS-C.

26
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 16, 2014, 09:57:07 PM »
I have the simple answer to this one.  Hand me a FF camera (6D, 5DIII, 1DX) and tell me that I can never shoot crop again and I will be ok with that.  Give me a crop camera, even one as capable as the 7D/7DII, and take away my 5DIII and tell me I can never shoot FF again and I will beat your %\$#^@   *&%\$#.  That is the difference.  How many here feel differently?

Granted, they're both cropped heavily but tell me what I'm doing wrong with my new 5Diii, please, 'cause I'm not seeing that much difference.

27
##### EOS Bodies - For Stills / Re: How to differentiate crop vs. FF
« on: October 16, 2014, 07:30:12 PM »

I have been involved in a number of crop vs. FF discussions lately. I thought I had the arguments for and against well set. But, based on these discussions, I´m not so sure anymore.

What I´d like your views on are what you see as the key arguments for and against the two sensor formats are from your perspective.

PS! I know DR is one, but please avoid turning this into a for/against more DR thread.

All I have to say is looking at the 1DX and 600 f/4 II vs the 7D and 500 f/4 IS USM - in most, if not all cases, the 1DX combination wins, with the exception, as Neuro has mentioned, of affordability - the 7D and 500 costs much less.

28
##### Photography Technique / Re: Yellowstone in Winter - what to take?
« on: October 13, 2014, 02:01:32 PM »
If the snowcats that you are using have a heated cabin, beware of humidity! People go outside, snap a picture, track snow back inside, and it becomes humidity.... as well you have breath and perspiration... it could be very humid inside.... might be time to invest in a pelican case....
Don's right - this is a major factor. Heated or not, there will be plenty of bodies in the vehicle to fog up the windows. Garbage bags for the camera and lenses, for sure. And put it in the bag BEFORE you get in (or back in) the snowcat.

Assuming your trip is the standard from West Yellowstone to Old Faithful:
1. The cabins of the snow cats are crowded - most of that gear list would have to go on the outside (roof) or back platform with the skis.
2. Unless you're on a special trip, not everyone is a photographer so the time for photography will be limited on the trip in / out. Probably not a lot of time to set up tripods, etc.
3. After you get into Old Faithful, you can certainly spend quite a bit of time around Old Faithful and Biscuit Basin by ski or snowshoe. The various geysers are always interesting. There's also a must-do trail from Old Faithful that takes you up a ridge overlooking OF and the lodges.
4. The snow cats will also be available for group day trips. They'll take the group out to various destinations and you ski back. That way, you can spend more time on the photography.

For gear, I'd say your list is much too long.
1. The 24-70 f2.8 II is mandatory.
2. Pick either the 300 or the 70-200. I think I'd lean towards the 70-200 for the convenience of the zoom. Maybe bring the teleconverters but changing lenses and converters in the wind, snow, and cold is tough.
3. Its nice to have a backup camera but you might consider just the 5Diii

The thing is, winter is a different environment and you'll be carrying a lot of other stuff - so plan on lighter rather than heavier. A good pack is important.
Canon specifies the low working temperature of the 5 D (and I assume the 1Dx) as 0 C. It can certainly get much colder than that in Yellowstone during Feb. I've used my 7D in near 0 F temperatures but YMMV.

29
##### EOS Bodies - For Stills / Re: POLL: Would have your earlier shots improved by better gear?
« on: October 10, 2014, 05:18:12 PM »
Yes, my earlier shots would have been improved with better gear, but short of getting a Delorean, a flux capacitor, and 1.21 GigaWatts of power, you can't go back and change things.... so it really does not matter.

LOL - Great humor, as usual.

I, like others here have mentinoed, moved from several years of film to the digital world, with an old 7Mp Sony. If I had today's cameras instead of the Sony, there's no doubt I would have gotten at least a few better shots - faster response time, better AF, better sensor.
For the more general question of should a newbie buy a high end camera or not, I'd say that depends.
If you don't know for sure that you'll turn into an avid amateur or pro then buying something less expensive would be smart. Also, there's plenty to learn that can be learned on a Rebel as opposed to a 1Dx.
OTTH, if you can afford it, why not buy the high end camera?

30
##### Lenses / Re: Which prime lens for nature fotography?
« on: October 10, 2014, 10:09:05 AM »
Your primary body is probably going to be the 7D because of the AF.
Having used a 7D since they came out, I would not pick the 7D based on AF performance. And, the high ISO performance is poor. However, the reach, high frame rate, and construction are all very good.

The optical performance of all those lenses are great. My experience with the 1.4x II teleconverter and the old 500 f/4 is that I can clearly tell the difference (reduction) in the resolution when I put the converter on, and I I've stopped using it. However, others on this forum routinely use the 600 and a 1.4x. I believe the 2x is even worse.
If by "carrying it around all day" you mean stalking in the woods, then one of the shorter lengths would be the answer. If you are in a situation where you are set up some distance away from large animals or you are photographing birds, you need one of the longer lenses.

My opinion is "when in doubt, go long".

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