November 24, 2014, 07:55:46 AM

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Messages - jrista

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16
EOS Bodies - For Stills / Re: Is IQ better with smaller files?
« on: November 18, 2014, 12:25:07 PM »
I read a comment or a post recently which inferred that a 7D II file shot as a jpg at one of the smaller sizes was inherently cleaner than a larger file at similar settings (ISO etc).

Is there any truth to that statement?  If this is crazy talk just say so.

  I bring this up because I own a 7D and if someone can tell me that a Medium Jpg is 10x cleaner than a Large or Raw ... I'm locking those settings in today.  Moreover, is that the case with all cameras?  Is this phenomenon a jpg exclusive or is it the same with Raw?  I mean, I have printed like 40 files of size 8x10 and nothing bigger. So if I can get cleaner images that will print at that size amazing ... Awesome.. 

Why isn't this 'feature' advertised?


I think that saying "smaller files" is the reason the images are better is wrong and misleading. The size of the file really has nothing to do with it. JPEG files are smaller than RAW files, even at full size image dimensions, however RAW files are generally superior, often far superior, in terms of IQ.


It isn't the file size that matters. It is the image dimensions, and more specifically the relative image dimensions, that matters. By relative, I mean in relation to the original image size. A smaller image, in terms of dimensions, generated from the same sensor, means that a greater quantity of information was "oversampled" to produce a lesser quantity of better quality information.


When you take a large image, say a 20mp image, an downsample it, you are taking a lot of original source data, averaging it together and packing it into a smaller spatial area. Averaging many pixels into fewer pixels reduces noise, by the square root of the number of pixels averaged. Downsample an image to 1/4 the original area, and you reduce noise by a factor of two (2x2 pixels averaged into one pixel, SQRT(4) = 2.) Downsampling also has the effect of improving acutance, which improves sharpness, which is a big factor in terms of what we perceive as image quality.


So, no, smaller files does not mean better IQ. Smaller images, in terms of spatial area, often DOES mean better IQ. You can achieve smaller images in a few ways. Obviously you can downsample larger images. You could take a RAW image, process it to optimum quality, then export it as a downsampled JPEG. The results are likely to be superior to a small-sized OOC JPEG every time. You can also use a lower resolution sensor with bigger pixels, however depending on exactly how the sensor is designed, that may or may not actually improve IQ as much as downsampling a higher resolution image (i.e. use and strength of AA filter, or lack of an AA filter entirely, could dictate whether a lower resolution sensor is better than downsampling images from a higher resolution sensor.)

17
Lenses / Re: 6D and BIF
« on: November 18, 2014, 12:12:24 PM »

For BIF, I would say AF system is the most important thing, followed by frame rate. Having the right focal length helps as well...it can be very tough to frame birds in flight with a small frame.


I would recommend the 7D II and 70-200mm f/2.8 as a start. That will get you around a 315mm effective focal length (the 7D II sensor is slightly larger than past Canon APS-C sensors, maybe around 1.55x crop or so), which IMO is very nice for BIF. You could probably slap on a 1.4x TC for maybe around 435-440mm effective focal length, however your losing that stop of light.


Having a FAST lens is also important for BIF, you want as much light a you can get, for two reasons. First, it allows you to take full advantage of the f/2.8 dual cross-type AF point. In lower light, this can be huge for BIF. Second, it improves your SNR for each shot, allowing you to avoid having to REALLY crank up the ISO to get the necessary shutter speed. With a cropped sensor, even the 7D II, you want that extra light. (It might not be quite as important with a 5D III, which would be my second body recommendation.)


The other benefit with a fast prime is you can use a 1.4x TC, and not drop yourself into f/8 territory. While it is possible to do BIF at f/8, it is extremely difficult. Even with AF point expansion (so five or nine points around the center point), your chances of actually locking onto your subject quickly enough to actually get the shot at f/8 are very low. You really don't want to be doing BIF slower than f/5.6, and even then, it's going to be tough. You want f/4 or f/2.8 for BIF.


Finally, frame rate is important. I wouldn't say it is the most important thing for BIF, but after AF, it is probably the next most important. Getting the right wing position and head position relative to the body for a really great BIF shot requires a higher frame rate. The 10fps of the 7D II is going to be a real bonus here. You could get away with it with the 5D III...however having used the 7D for years myself, I really do feel the drop in frame rate with the 5D III (and it's only 2fps, vs. the 4fps difference relative to the 7D II) and BIF. I largely stick to perching and wading songbirds and shorebirds/waders with the 5D III, because it is pretty tough to get just that right pose with the slower frame rate.


If you do get the 5D III, my top recommended lens for BIF would be the 300mm f/2.8 L II, with and without the 1.4x TC III. I think the 420mm f/4 aperture with the 5D III is pretty great for BIF (I've rented that lens twice now, and I really like it...probably the next lens I intend to purchase from Canon, as it's actually great for wildlife, BIF w/ the 5D III, and astrophotography.) Going longer than ~420mm on FF (or effective focal length on APS-C) often presents issues keeping the bird in the frame, and nicely composed within the frame....I've tried BIF with my 600mm f/4 L II, and it is usually very difficult unless the bird is quite far away. About the only BIF I do these days is fairly distant hawks circling overhead, and then, they are usually often too far away even for the 600. Once I get the 300/2.8, I'll probably get back to doing BIF more, as the wider field just makes it so much easier.


Anyway, those are my recommendations. I'd say 7D II + 70-200 f/2.8 L II is my first, and 5D III + 300 f/2.8 L II + 1.4x TC is my second.

18
EOS Bodies / Re: A Real EOS M Replacement Coming Soon? [CR1]
« on: November 17, 2014, 12:36:16 PM »
For me, this camera has no chance of being interesting unless it has dual-pixel focusing, and a standard (slow) zoom that starts at 15mm (24mm equivalent) and retracts entirely inside the camera.


How do you make a lens that retracts into an ILC body? The EOS-M is an ILC, so the lenses have to be able to detach and be swapped out. With the probable flange-to-sensor distance, I find it highly unlikely were going to see a "pancake zoom" that could actually retract inside the EOS-M body[size=78%].[/size]

19
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 15, 2014, 10:03:27 PM »
As far as I can tell, the white swatches in the NEF are just as redshifted as the black swatches. The overall red hue appears to be consistent to me, at least when the image is rendered in linear space. I can do a non-linear screen stretch, and the red hue disappears and the entire image becomes neutrally balanced.

If it was a simple colour shift or WB issue then the three lines in the channel curves adjustment would be straight, but they are not, they are curves. Being curves means the respective colour balance is uneven at different tonalities.


A assume you are working with images that have passed through one RAW converter or another? I am looking at the RAW linear data...and I am not seeing what you are seeing. Is it possible the RAW converter is complicating things?

20
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 15, 2014, 07:52:58 PM »
Here a image taken from the raw data, at the right the canon 5 dmk3 and left the Nikon 750, stretch with ImagesPlus astronomical software, zero noise reduction. crop and arrows with photoshop.
Red arrows:  these are white specks on the card! not noise!
Blue arrow: banding in the Canon image.
Overall: in the Nikon image you see a red hue, but way less noise.
So what you think? especial the red hue, is the card realy red or black?
Garret van der Veen


I am pretty sure the red hue is just due to white balance. I do not believe that is the correct color, but it is easily correctable. The card and wedge should be neutral in color.

It is not as simple as the white balance, if it was all the whites would also be as red, and they are not, don't confuse the magenta fringing as red toned whites. If you look at a channel histogram you can see the red shift in the shadows and a slight lack of red in the highlights.

It is due to changes in the response curve at different tones which could be caused by any number of fundamental things, the only way to sort it out is to apply a channel tone curve, probably several with luminosity masks, to overcome the precise shifts.

The first histogram is the untouched file, the second is the three point three channel corrected file, I have included the tone curve adjustment lines too. Although the resulting lines look linear they are not. And, of course, any adjustments you make to the actual shadows would need a similarly adjusted curves layer.

None of this is that difficult, but the time and skill involved is not as trivial as many would lead you to believe good processing of Exmor files is.


I have not yet opened up the files in a RAW editor. I am still looking at them in PixInsight. As far as I can tell, the white swatches in the NEF are just as redshifted as the black swatches. The overall red hue appears to be consistent to me, at least when the image is rendered in linear space. I can do a non-linear screen stretch, and the red hue disappears and the entire image becomes neutrally balanced.


You can look at the JPEG images I shared in my post a couple of pages back. The Canon image appears to be very slightly blue shifted in the white swatches, while the Nikon image appears to be red shifted in the white swatches. I can share more images...I don't think there is any discrepancy in the red shift between the swatch 1 and swatch 41, or the background for that matter.

21
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 15, 2014, 12:57:16 PM »
Here a image taken from the raw data, at the right the canon 5 dmk3 and left the Nikon 750, stretch with ImagesPlus astronomical software, zero noise reduction. crop and arrows with photoshop.
Red arrows:  these are white specks on the card! not noise!
Blue arrow: banding in the Canon image.
Overall: in the Nikon image you see a red hue, but way less noise.
So what you think? especial the red hue, is the card realy red or black?
Garret van der Veen


I am pretty sure the red hue is just due to white balance. I do not believe that is the correct color, but it is easily correctable. The card and wedge should be neutral in color.

22
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 15, 2014, 12:56:13 PM »
Marsu, that is what happens in the blacks when you lift the shadows like that on Nikon files.

Interesting, I never shot Nikon. Why does the red tint creep in when raising shadows? And why don't they get rid of this effect - is it a basic difference between cr2 and nef files, or the sensors, or... ?


It just looks like a difference in white balance to me. The red shift in the Nikon file appears throughout the level scale...it affects the brighter tones as much as it affects the darker tones.

23
Animal Kingdom / Re: Show your Bird Portraits
« on: November 14, 2014, 06:59:05 PM »
Western Grebe- Clear Lake 28 May 2010 © Keith Breazeal by Keith Breazeal Photography, on Flickr

Nice reflections.
I think I'd call those Clark's Grebes.
If you took the photo in May they'd be in breeding plumage and the black on the head covers the eye on the Western Grebe.

Thanks :)  Yes, most are settled on Clark's.  They were courting the whole time I was shooting.


I agree, those are Clark's.

25
Animal Kingdom / Re: Show your Bird Portraits
« on: November 14, 2014, 03:43:49 PM »
Click, forgive me, the Chickadee was for you too! ;)

Thanks everyone for the complements and advice.  Yes, 6d and sometimes the shutter is a little low but not that low, many were 500th and I've personally found ISO's pushing towards 12800 to be quite noisy and not what I like.  Evening or cloudy here is pretty dull and around sunset if I try to shoot at 1000th I'd definitely be at that ISO.  I have moved the AFMA around as I was shooting out there and figured I was OK.  However with one shot center focus (try for the eye) and recompose with a sometimes moving subject I might be missing focus somewhat.

My sensor could be getting a bit dirty as I have noticed the odd spot in the sky and I guess the X1.4 may affect sharpness a little but otherwise I don't know what to think.

Here's a shot of a stationary nuthatch with center spot focus and full frame just as is.  6D 200X1.4  F4.5  ISO 1250  Manual exposure.  The one shot focus point was right on the edge of his eye.  Jon, or anyone doesn't this appear to be in focus?  What else?  Anyway, that's what I'm getting.

Jack


You definitely have critical sharpness there. I think the issue may simply be not enough DOF. Your at f/4.5, which I understand given the lighting. The 6D has excellent high ISO performance, better than my 5D III. I would jack the ISO up to 3200, and stop down to f/7.1, and see how things go. If you can get the bulk of the bird in the DOF, I think you'll find that any issues with getting the birds critically sharp just disappear. Also, the noise on the 6D at higher ISO cleans up very nicely, so don't let ISO 3200 hold you back. For that matter, don't let ISO 12800 hold you back...it is noisier, but again, it's pretty clean noise, and can be cleaned up very well.

26
Animal Kingdom / Re: Show your Bird Portraits
« on: November 14, 2014, 02:01:05 PM »
Nice shots all.

The frost drew me outside before breakfast to freeze my fingers but no complaints.  I think this qualifies as a Red Shafted Flicker (I've only seen/shot Yellow Shafted around here).  Pretty heavy crop.

And the Chickadee was just too cute - for Don.

Jack


The chickadee is fantastic! The perch is excellent, the pose is great, the looser framing is just right!

27
Animal Kingdom / Re: Show your Bird Portraits
« on: November 14, 2014, 02:00:40 PM »
Thnks jrista,

Honest I still remember that recommendation from before but something seems to make me focus on maximizing the bird, for detail I guess.  I'll loosen up.  How's this Downy?

In case anyone wonders, my recent shots have all been 70-200 F2.8 II with X1.4.  The zoom has been handy compared to my 300.

Jack


Definitely better, without question. Your using the 6D, right? With the 6D, you should be getting a TON of detail, even with slightly looser framing than that. If you are not, then I would check your AFMA, make sure IS is kicking in right (or maybe turn it off if you are on a tripod), maybe try a higher ISO so you can get a faster shutter (I have noticed that your shots seem to be fairly dim...I'm not sure why, but if your experiencing softness, you might want to jack up ISO two stops, and shutter a stop, and see if that helps. High shutter, and particularly in winter high ISO, are pretty much essential to getting sharp bird shots.)

28
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 14, 2014, 09:18:15 AM »
It's not a matter of white, it's a matter of bright. Dynamic range has to do with signal power over noise floor. It is possible to have a wedge that transmits less in the darkest swatch and transmits more in the brightest swatch. That would then increase the ratio of brightest over darkest. So yes, it is possible. However, I don't think it is easy, hence the reason the wedges that have more dynamic range are more expensive.

29
EOS Bodies / Re: Canon 7Dii vs Nikon D750 Dynamic Range Test
« on: November 13, 2014, 11:24:20 PM »
I agree, a strip with more dynamic range would be ideal. Don't those cost a lot of money, thought? I looked into the Stouffer step wedges a while back...most of them seemed prohibitively expensive...

30
EOS Bodies / Re: I killed my brand new 7D MK2 today
« on: November 13, 2014, 09:12:13 PM »
You're not the only one:
http://www.the-digital-picture.com/News/News-Post.aspx?News=13892

Couldnt he have posted that earlier.  :-X

It´s still under Warranty i just send it back.
Im pretty sure i will get a replacement without any trouble.


Warranty only applies if it is a manufacturing defect or other liability issue. If you break your own camera by your own stupidity...well, the warranty does not apply. :P


EDIT: And I just now realized that everyone else told you the same thing!  ::)  MAYBE it could be argued that this is a design flaw...I tried it with my 5D III and 7D, the card didn't seem that easy to put in...I had to exert some force, where as it just slides right in when I orient it properly. So, I don't think this could be construed as a design flaw. People just need to pay attention.

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