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 6 hours ago

Apr
29
comment Why are some big telephoto lenses so expensive compared to telescopes?
@BogdanWilli "fluorite will not "magically" reduce chromatic aberration" actually it will, but it's not magic - it's physics, fluorite is a low dispersion material which means different frequencies of light spread out less when passing through, so it will reduce chromatic aberrations compared to a similar element of standard optical glass.
Apr
29
comment Why are some big telephoto lenses so expensive compared to telescopes?
You don't need fluorite to make a lens shorter than it's focal length (telephoto), there are many telephotos at much lower price points. Fluorite reduces chromatic aberrations.
Apr
28
comment Why are some big telephoto lenses so expensive compared to telescopes?
Yeah it's mostly #4, many more elements and a much more sophisticated optical design to reduce aberrations in the corners of the image. You can spend $180,000 on a telescope, however.
Apr
22
comment What is the difference between 16-bit and 32-bit high dynamic range images?
Photoshop also uses a linear gamma curve in 32-bit mode so you get more accurate blending.
Apr
17
awarded  Good Answer
Apr
17
comment Why is the field of view of my lens narrower than my calculations show it should be?
@BenJO I would try and rule out lens correction first as it's the most likely cause. Are you shooting RAW or JPEG?
Apr
16
revised Why is the field of view of my lens narrower than my calculations show it should be?
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Apr
16
revised Why is the field of view of my lens narrower than my calculations show it should be?
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Apr
16
revised Why is the field of view of my lens narrower than my calculations show it should be?
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Apr
16
answered Why is the field of view of my lens narrower than my calculations show it should be?
Apr
13
comment Are 2 megapixels enough for HD resolution pictures?
@jrista I don't know what the situation is in the US, but here in Europe Lanczos and other kernel based filters are part of the preschool curriculum ;)
Apr
13
comment How to take upright grave stones without squatting down?
Taking a laptop is a bit extreme, some cameras allow you to focus and compose with a smart phone which more practical!
Apr
10
answered What is the importance of the back focal length of a lens?
Apr
9
comment How can a super tiny iPhone 6 Plus lens produce significant DOF?
So much misinformation... it's the result of focusing close. Nothing more.
Apr
9
answered How can a super tiny iPhone 6 Plus lens produce significant DOF?
Apr
9
comment How can a super tiny iPhone 6 Plus lens produce significant DOF?
This is mostly incorrect. Whilst the aperture ratio (f-stop) influences depth of field it is by no means the determining factor, in fact the absolute diameter is more important than the ratio. A 50mm f/1.0 lens on M43rds camera will give you the same depth of field as a 100mm f/2.0 on a full frame camera, as the absolute diamter of the entrance pupil is 50mm in both cases. An f/2.2 lens gives completely different results on a cell phone camera as a DSLR, as the focal lengths involved are very different.
Apr
9
revised Does getVerticalViewAngle() give actual Camera Angle Field Of View(CAFOV) value?
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Apr
9
answered Does getVerticalViewAngle() give actual Camera Angle Field Of View(CAFOV) value?
Apr
9
comment Does getVerticalViewAngle() give actual Camera Angle Field Of View(CAFOV) value?
The image will have been cropped slightly by the demosaicing process, though probably not enough to account for 1.8 degrees, so either the value returned by the function is not accurate, or your measurements are not accurate, or a combination of both
Apr
9
answered What is the relationship between ARW delta compression and dynamic range?