It's a bird

by Vian Esterhuizen

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bio website mattgrum.com
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visits member for 4 years, 9 months
seen 14 hours ago

14h
comment Are there lenses that exhibit absolutely no focus breathing?
@feetwet it's more that case that cine lenses are specifically optimised for focus breathing whereas other lenses aren't, that doesn't mean there aren't SLR lenses with little focus breathing, though. I imagine it could be reduced to zero, but with everything in lens design it's a compromise so it's never going to be zero in a real lens.
17h
comment What is the impact of the EU discussion on restricting freedom of panorama?
It's important to note that this is an EU directive not an EU regulation, that means states are free to interpret the content and implement it (or not) however they see fit.
22h
comment Why do some cameras have a higher resolution sensor even though the max resolution is smaller?
@Muhatashim The edge pixels are permentantly masked, so there will be no difference when turning noise reduction on or off. The masked area is also probably larger than 16 pixels, I suspect the D3300 simply has a marginally larger masked area. 16 pixels on a 6,000 pixel wide image are fairly inconsequential anyway...
22h
comment Why do some cameras have a higher resolution sensor even though the max resolution is smaller?
@DrMoishePippik No, DSLRs have dedicated metering sensors, metering via liveview uses regular pixels. Some mirrorless cameras (and a couple of Canon DSLRs) have phase detection AF pixels on the main imaging sensor but those are still used to produce the image. That article is about a very specific sensor design used only by Fuji.
2d
comment Why are superzoom lenses small but giant telephoto lenses huge?
The picture doesn't really explain anything on it own, I'm afraid.
Jun
18
comment What algorithm can I use to simulate bokeh?
Provided the operations are all additive you wont get the problem of dark areas spreading out. It's true you need a sharp mask to get sharp circles, but the major problem is that his bokeh operation is being applied to non-linear data.
Jun
18
comment Why did manufactures stop including DOF scales on lenses?
@akram The problem is DOF scales on lenses just aren't very accurate, they are based on the assumption of a very small output size (this is where the dependance on megapixels comes in, with a higher resolution sensor you are more likely no notice if something is out of focus), they also require you to estimate the distance to objects in the scene for them to make any sense. They were better than nothing in the days of film, but now it's easy to check if something is actually in focus using the LCD.
Jun
9
comment Is it possible to digitally capture a full 3D point of view?
@null You can make guesses, certainly, which is what that paper is doing, but that's not the same as having actual 3-d data. The correspondence between two images taken from different positions does contain 3D information.
Jun
9
comment What causes barrel distortion?
I don't have a time to do the full mathematical proof right now, but you do need a FOV of at least 180 degrees to see both vanishing points of two straight parallel lines.
Jun
8
comment Is it possible to digitally capture a full 3D point of view?
@null you can guess at depth, but that's it, there's no information there, from a technical standpoint. The best example of this is that it's impossible to tell the difference between a photograph of an object (that has depth), and a photograph of a photograph of an object (which has little-to-no depth). The reason you can't tell the difference is because there is insufficient information in the image.
Jun
8
comment What causes barrel distortion?
I'm afraid this is wrong. Barrel distortion is not a consequence of trigonometry or perspective. It is a defect (or rather a compromise) in the design of a lens, there are lenses with zero (or as close as makes any difference) barrel distortion. Your example shows a FOV greater than 180 degrees, this is impossible without introducing some form of curvature, however every FOV less than 180 degrees can be achieved with zero barrel distortion or curvature of straight lines.
Jun
4
comment Why don't people care any more about shutter speed accuracy?
@DanWolfgang people obviously care when their camera stops working, the question is why don't they care when choosing a camera in the first place, there's nothing about shutter accuracy on the spec sheets etc.
Jun
3
comment Why don't people care any more about shutter speed accuracy?
This doesn't seem to answer the question of why people were more concerned with shutter accuracy in the days of film.
Jun
3
comment What properties of an image could be used to programmatically discard it as “bad”?
You could detect camera shake, over/under exposure easily enough, and if you were really smart you could attempt to identify the subject of the photo to test whether it was in focus, but that's about it.
Jun
3
comment How close are we to the sensor pixel size limit?
@DigitalLightcraft the two concepts are intrinsically linked, as diffraction is independent of sensor size when comparing images with the same depth of field.
May
27
comment Can a Sigma dp3 quattro be used for Macro Photography?
@knb Focus stacking is used to extend DOF, it wont help with resolution at the focal plane. Essentially the DP3 Quattro will photograph a 70mm x 45mm area, any smaller than that will require cropping, how much cropping is required depends on how much smaller, and how much loss of resolution is acceptable is up to you. That's about all I can say to answer your question, other than the poor high ISO performance of the camera can avoided by using a tripod and longer exposure at ISO 100.
May
26
comment Can a Sigma dp3 quattro be used for Macro Photography?
@knb Cropping to a 1cm x 1cm square at maximum magnification will drop you from 20 megapixels down to 0.6 megapixels, not exactly what I'd call "more than enough pixels"...
May
22
comment Imbalance in green pixels
Sounds like an instance of PRNU (photo response non-uniformity).
May
22
comment Do wide angle lens adapters maintain DOF but still keep the higher FOV?
Yes APS-C lenses will technically fit, and you can also mount the adapter on a full frame mirrorless body, but the image circle will not be large enough in both cases so it's not particularly useful...
May
22
comment Do wide angle lens adapters maintain DOF but still keep the higher FOV?
It's worth pointing out that the Metabones speed booster is a rear mounted wide converter and so only works with full frame SLR lenses on APS-C mirrorless cameras. It will not work on DSLRs, as there is no space for the adapter (due to the mirror box).