Sunset in Kruger

by MrFrench

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

98,609 reputation
4207358
bio website mattgrum.com
location
age
visits member for 4 years, 7 months
seen 9 hours ago

May
20
revised Is the bokeh in this picture naturally occurring, or added in post-processing?
added 455 characters in body; added 68 characters in body
May
20
answered Is the bokeh in this picture naturally occurring, or added in post-processing?
May
19
revised Why can't my SLR autofocus on certain parts of a scene?
added 788 characters in body
May
19
answered Why can't my SLR autofocus on certain parts of a scene?
May
18
awarded  Nice Answer
May
17
comment When do the differences between APS-C and full frame sensors matter, and why?
@ysap It's the same lens in the sense that I didn't take anything off the camera, I don't think most people consider zooming to be "changing lenses". When I have time I'll shoot some better examples, including one where a different fstop is used to get the same DOF.
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
Why use a different approach when comparing a 2/3" sensor to a 36mm sensor than you'd use to compare a 23mm sensor to a 36mm sensor? And again I fail to see why moving the camera closer means fewer variables change than if you zoom in. Exactly one variable changes in either case!
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
@jrista Of course you have to have to scale to the same output size when comparing sensors, otherwise if you compare a P&S with a DSLR you wind up comparing a 6"x4" to a postage stamp. It just doesn't make sense! There is exactly the same number of factors in play when comparing sensors and changing focal length and when comparing sensors by changing focal length: one. But changing focal length yields images that look roughly the same and have the same perspective, so that's clearly the right choice to me.
May
16
comment Does noise in images depend upon “Megapixels” or “ISO”?
@Colin sorry I didn't read the bit about SNR, yes you get a higher absolute noise level when you increase ISO but you get a better signal to noise ratio. When I talk about noise I mean signal to noise ratio, as this is what determines the amount of noise you see in an image. To answer your question the ISO100 shot was underexposed. By boosting exposure digitally I amplified both the image noise and read noise giving a worse SNR compared to the analogue amplified high ISO image.
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
@jrista cont. Imagine you are comparing the depth of field between a compact and FF DSLR, the crop factor is about 7, using the same focal length so you'd have to be seven times closer with the DSLR, which would yield a totally different looking image, and may even have problems focussing on the subject without a macro lens! I don't get what you mean by "dynamic focal length" masking the real reason FF DOF is shallower... the reason is simple, with FF you have a larger aperture for the same f stop & field of view. Finally sensor size does factor in DOF equations as it has to do with CoC size.
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
@jrista I can't remember the exact subject distance but I kept it as constant as possible between shots. Likewise I don't know the focal length (I'll see if I can look it up from the EXIF) but the length used with the 5D was about 1.6 times as long. I've seen plenty of sensor size DOF comparisons that vary focal length rather than subject distance, in fact I regard this as the correct way!
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
I always assume the same final output size (in which you do get shallower DOF with the larger sensor) as it's not like people print images from P&S cameras a tenth of the size as those from DSLRs, no people tend to print/view images the same size regardless of how large the sensor is!
May
16
revised Why does a bigger sensor lead to a shallower depth of field?
added 48 characters in body
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
@jrista you can zoom without changing the lens! I never said the focal length was maintained, only the optic that was used. As far as I'm concerned moving the camera results in a different image (as the relative positions of objects and their appearance can change), making the comparison invalid.
May
16
comment Why does a bigger sensor lead to a shallower depth of field?
Yeah I changed focal length, as far as I'm concerned zooming counts as using the same lens (others seem to disagree)
May
16
comment Does noise in images depend upon “Megapixels” or “ISO”?
Because it's counter-intuitive, and because noisy images tend to have been shot with high ISO, by association they attribute this to high ISO. So when you come along and say "increasing ISO actually improves the signal to noise ratio (all else being equal)" people refuse to accept it, even when you provide the results of a simple experiment that proves this.
May
16
comment Does noise in images depend upon “Megapixels” or “ISO”?
It doesn't though. Look at the example I posted. Raising the ISO considerably reduced noise.
May
16
revised What is special about lenses with f-number < 1?
added 24 characters in body
May
16
comment What is special about lenses with f-number < 1?
Yeah I meant diffraction problems. I'll clarify.
May
16
comment Does noise in images depend upon “Megapixels” or “ISO”?
Ok so every noisy high ISO image would be even noisier if shot with a lower ISO. Likewise every noisy high ISO would be less noisy if shot with a longer exposure. So I don't understand why people call it "high ISO noise" and not "insufficient light noise". ISO doesn't create noise, which is exactly what statements like "all digital cameras exhibit image noise which rises as ISO increases" implies. If you instead say "all digital cameras exhibit noise which increases as incoming light decreases" you would be correct without the need to state any assumptions!