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02-09-2015, 01:14 PM   #31
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QuoteOriginally posted by jsherman999 Quote
It will almost exactly match an aps-c camera that's using the same sensor tech as the FF body.

.
Not this again!

The noise level and exposure will be the same as in the FF mode.

It's just a *crop* of such a picture.

The pixel pitch, electronics and heat dissipation design are the same.

02-09-2015, 01:18 PM   #32
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QuoteOriginally posted by clackers Quote
Not this again!

The noise level and exposure will be the same as in the FF mode.

It's just a *crop* of such a picture.

The pixel pitch, electronics and heat dissipation design are the same.
So we can expect an ISO performance same as if we use the camera in full sensor performance? let say something around 2800 ISO without noticible noise??
02-09-2015, 01:26 PM   #33
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QuoteOriginally posted by kooks Quote
So we can expect an ISO performance same as if we use the camera in full sensor performance? let say something around 2800 ISO without noticible noise??
Yes, Kooks, it's just an in-camera crop, for convenience.

If it didn't have such a function, you could do it yourself in Lightroom.

You do not lose exposure, gain noise or depth of field when you crop.

This Equivalence stuff is bollocks once you try to extend it past the obvious.
02-09-2015, 01:38 PM - 1 Like   #34
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QuoteOriginally posted by clackers Quote
Not this again!
You mean the never-ending misunderstand of contexts? jsherman999's comparison is assuming you're still printing (or outputting) at the same size. A pretty reasonable assumption imo, but I guess it's worth stating.

Take a FF picture at 12800 iso. Print it out to 8x12". Now take an aps-c sized crop from the same digital file, print it out to 8x12". Which has more noticeable noise? (and yes, I do realize the images are different, just consider the noise here). While you're at it, think about how the depths of fields compare (assuming the same viewer, from the same distance, no booze in between viewings).

So many of these disagreements are only disagreements because both sides are living within different assumptions (i.e. same final image size or not). I get the feeling this will never change

02-09-2015, 01:42 PM   #35
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QuoteOriginally posted by clackers Quote
Yes, Kooks, it's just an in-camera crop, for convenience.
ok ok.. thanks man .. i had that doubt about this croping feature.
02-09-2015, 01:56 PM   #36
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QuoteOriginally posted by BrianR Quote
(assuming the same viewer, from the same distance, no booze in between viewings).
I like your style, Brian!

As I said, I don't mean the obvious - scaling.

But nervous members who've read pundits blogging about 'equivalence' need to know that when in APS-C mode, the picture cannot become 1.25 stops darker, pixels suddenly convert to luminance noise and your girlfriend's second eye comes into focus!
02-09-2015, 02:11 PM   #37
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QuoteOriginally posted by clackers Quote
I like your style, Brian!
Guinness are of course encouraged after you've done the comparison, or even before, just not during to keep it fair

QuoteOriginally posted by clackers Quote
As I said, I don't mean the obvious - scaling.
As I'm reading it, kooks may have walked away with a false impression Stating the viewing conditions you're considering, 100% pixel peep or same final size output, is pretty critical for understanding!
02-09-2015, 05:48 PM - 1 Like   #38
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It only remains the same if you never enlarge the crop

QuoteOriginally posted by clackers Quote
Yes, Kooks, it's just an in-camera crop, for convenience.

If it didn't have such a function, you could do it yourself in Lightroom.

You do not lose exposure, gain noise or depth of field when you crop.

This Equivalence stuff is bollocks once you try to extend it past the obvious.
Ah, my man clackers.

The only way you "do not gain noise" or lose DR when you crop is when you do not enlarge that crop to the same display size. (Kind of a tough caveat to enforce, no? )

In other words, if you take an image you printed or displayed at 8x10, cropped out a 5x7 from the center (which would happen to be almost exactly 1.5x) and then only displayed it at that 5x7 - not 8x10 - of course it would have the same noise & DR profile, unchanged from the original 8x10.

But people don't do that. They view or display these crops at the same size as the original. The act of enlargement/magnification can't be removed from the event, unless you're describing some special odd (maybe Australian?) event in which all crops must be viewed at smaller sizes!

To kooks or whoever may be misled by clackers point - if you crop the FF image 1.5x and display at the same size as before, you are effectively shooting an aps-c camera that has the same per-pixel performance (same sensor tech) as that FF camera. Because you cropped and enlarged, you didn't use all the total light in the frame that a longer FL on FF would have given you. Cropping (and enlarging) does not maintain the "FF advantage".

BTW, you don't need to have a FF camera to test this. Take say a lower-light (to make it easier to see) ISO 1600+ shot with your aps-c camera, crop it 1.5x and then display or print both the crop and uncropped at the same size. Does the enlarged crop show more noise and less DR? Try it again, cropping 2x and 3x times, displaying the same size. What happens to the noise in the resulting cropped-enlarged image?



.


Last edited by jsherman999; 02-09-2015 at 06:01 PM.
02-09-2015, 07:07 PM   #39
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So basically images will keep the same FF performance ( ISO ), as long as people DONT enlarge the image ( it makes total sense ), but when every people start enlarge the cropped image the noise will start to jump. Correct?
02-09-2015, 07:25 PM   #40
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QuoteOriginally posted by kooks Quote
So basically images will keep the same FF performance ( ISO ), as long as people DONT enlarge the image ( it makes total sense ), but when every people start enlarge the cropped image the noise will start to jump. Correct?
Exactly.

This is true whether you crop a FF image to aps-c and enlarge, crop within aps-c to just a smaller image and enlarge that, etc.

Bill Claff's raw SNR/PDR measurements of the D800 'crop mode' and D7000 native show that they almost exactly match, which is what we'd expect from those two cameras as they basically share the same pixel tech.

As to how the K-FF crop mode and the K3 compare, we'll need to wait and see how new that sensor is, how many MP, etc. But if it's basically the same 36MP sensor that's in the D810 for example then we'll see the crop mode being almost an exact match for the K5IIs native output at the same display sizes, which means about the same noise and DR as the K3, just less resolution, less MP in the frame. K3 would still probably be a better birder's camera in several ways then especially with regard to $$, unless you were willing to fork over the cash for the really long telephoto and not crop the FF.

If it's 50MP+, it will be very K3-like in crop mode!
02-09-2015, 09:19 PM   #41
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Crop mode (eg in a Nikon D610) merely 'slices' a 3900 x 2600 pixel rectangle out of the centre of the 6000 x 4000 pixel 24MP FX image recorded by the sensor, shaving off the edges of the FX image in the process.

Hence you get an image that reflects all of the technical capabilities of the camera (noise, DR, colour depth etc), just in 3900 x 2600 pixels instead of 6000 x 4000 pixels, and reflecting a narrower field of view.
02-09-2015, 09:34 PM   #42
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QuoteOriginally posted by BrianR Quote
Guinness are of course encouraged after you've done the comparison, or even before, just not during to keep it fair

Okay, it's Guinness for our first round, I'm buying the next, and it's Kilkenny.


QuoteOriginally posted by BrianR Quote
As I'm reading it, kooks may have walked away with a false impression Stating the viewing conditions you're considering, 100% pixel peep or same final size output, is pretty critical for understanding!

I think we have to give Kooks credit that he understands half the pixels are being lost. His OP is all about ISO, not resolution.


But if viewing conditions concern you, at 300 dpi output you can lose all those pixels and still have the same resolution as the uncropped pic up to close to your example - 8x12 - anyway.


For instance, at 150dpi, half the horizontal lines on all of a Nikon D810 frame is 3680 - that's more than 24 inches.

Last edited by clackers; 02-09-2015 at 10:20 PM.
02-09-2015, 09:44 PM   #43
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QuoteOriginally posted by jsherman999 Quote
Does the enlarged crop show more noise and less DR?
.

What?


See my post to Brian above, Jsherman.


If you think 4% of the noise pixels suddenly turn to 8%, or that stops of dynamic range are lost in the crop, I want some of what you're smoking!


More detail after a certain point of enlargement is of course a truism, but that's not noise, depth of field, darker exposure or dynamic range.

Last edited by clackers; 02-09-2015 at 10:22 PM.
02-10-2015, 06:41 AM   #44
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QuoteOriginally posted by clackers Quote
I think we have to give Kooks credit that he understands half the pixels are being lost. His OP is all about ISO, not resolution.
I'm not convinced everyone's on the same page. I understood the initial question (post #26) to be about how high you can set the ISO before noise becomes objectionable. Viewing size is important here.

QuoteOriginally posted by clackers Quote
But if viewing conditions concern you, at 300 dpi output you can lose all those pixels and still have the same resolution as the uncropped pic up to close to your example - 8x12 - anyway.

For instance, at 150dpi, half the horizontal lines on all of a Nikon D810 frame is 3680 - that's more than 24 inches.
Haha, yea we can toss a pile of pixels away, I did suggest an obscene 12800 iso in hopes of stressing things:P. This is where the D810 trumps the k5 though. Printing at a fixed 8x12 size, the D810 is able to sample over more pixels per unit area of the print compared to a k5 (or a crop of the D810) and the result is cleaner.

Truth is, what we can get out of an aps-c won't stress prints this size at saner iso's, so the k5 may already be 'clean enough' if you're happy with lower isos or are just more tolerant of noise. From a technical quality standpoint (noise, resolution, etc), FF will only be a win if you're already sitting on the boundaries of where you find aps-c acceptable.


Making some prints of a full image and prints of crops at iso's that stress the size you choose is a good exercise for anyone concerned about the quality differences with aps-c vs FF (we'll be assuming same sensor tech for this test). As mentioned, you can use any camera for this exercise, the point is a relative comparison of what cropping and enlarging does. The SNR measurements at DxO comparing the D810, k5iis, and the k3 may also be enlightening, toggle back and forth between screen (100% pixel peep) and print (they assume the same print size).
02-10-2015, 07:09 AM   #45
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QuoteOriginally posted by clackers Quote
But nervous members who've read pundits blogging about 'equivalence' need to know that when in APS-C mode, the picture cannot become 1.25 stops darker, pixels suddenly convert to luminance noise and your girlfriend's second eye comes into focus!
I'm always curious as to the motivation of equivalence denialists. Is it that you are offended by the 24x36mm format being used as the standard?

To the OP and others: The FOV on a FF camera looks much wider than you might think. This makes it nice for the wide shooters, where a decent 20mm lens is easier to find and cheaper than a comparable 14mm one. But I shoot a 300mm on FF (Nikon) and I'll admit to many times wanting a 400mm. I choose to stick a 1.4x teleconverter on it sometimes, but I could just as easily go with an APS-C camera if I had one and be just as happy.
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