Lightnings taking a ride

by ceinmart

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bio website mattgrum.com
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visits member for 4 years, 11 months
seen 8 hours ago

Aug
28
comment If viewers don't respond to the rule of thirds, why do some photographers still emphasize it?
The rule of thirds is definitely real - I saw somebody use it once.
Aug
24
comment Given the same sensor size lens, will a higher megapixel sensor give more “reach” then a lower one?
@HenkHolterman "perceptual megapixels" is a misleading and gross oversimplification invented by DxO labs. A budget prime from the 1970s can resolve more than enough detail to make use of a 36MP sensor.
Aug
24
comment How to test whether two RAW files have identical contents (but potentially different tags)?
@Mehrdad provided you work in a 16-bit space this ought to work - any changes you make to a 14-bit RAW file will show up in a 16-bit conversion. You can make any binary difference visible by using the levels/curves tool. The only downside to this is that some RAW converters discard edge pixels so the image you get is marginally smaller than the actual number of pixels on the sensor.
Aug
19
comment How can I stop my HDR shots looking so fake?
@Pacerier Photomatix for the first one, Photoshop for the second one. Non-pirated, of course.
Aug
17
comment What is the relationship between focal length and minimum focus distance?
The focal length of a lens doesn't change when adding an extension tube.
Aug
17
comment Shooting video frame by frame / electronic vs mechanical
Actually a lot of early DSLRs with CCDs particularly Nikons did have electronic shutters.
Aug
6
comment Why is a Bayer filter with three colors(RGB) preferred over one with two colors and unfiltered (RBNeutral)?
@BrianKubera He's talking about the Fuji Super CCD SR: dpreview.com/articles/6851251325/fujisuperccdsr
Aug
5
comment Why is a Bayer filter with three colors(RGB) preferred over one with two colors and unfiltered (RBNeutral)?
@DigitalLightcraft you could indeed calculate the green value, the sensor will already have IR and UV blocking filters in front of it. This is in essence how the Foveon sensor works, the top layer is sensitive to red, green and blue.
Aug
4
comment How can I tell what focal length a zoom lens was set to for a photo of the moon?
@PhilipKendall lens reporting of focal length isn't always that accurate as there aren't usually that many sensors on the lens barrel...
Aug
2
comment Why don't we have a single lens e.g. say a 18-200 f/1.2 lens for the SLR camera?
@BrandonDube Do you know how the Zeiss 1700mm f/4 is able to cope with the huge exit pupil and H-mount throat? Also do you have any idea what would happen if you took Sigma's 500mm f/2.8 and mounted a 2x focal reducer? Seems like that would get you to 250mm f/1.4 albeit with a much smaller image circle.
Jul
30
comment Why don't we have a single lens e.g. say a 18-200 f/1.2 lens for the SLR camera?
Are you confusing entry and exit pupils? You can buy a 600mm f/4 today and that has a 150mm opening, so 166mm is not a stretch. Lens mounts have nothing to do with it. There's nothing "physically impossible" about an 18-200 f/1.2 at all, it would simply by very, very heavy and expensive.
Jul
29
comment How was this photo taken
@AndersD by low ISO value I mean 100-400
Jul
27
comment Why don't people care any more about shutter speed accuracy?
@akram The problem was quite obvious, in aperture priority mode shots were coming out massively underexposed, but only at high shutter speeds like 1/1000s or 1/2000s, so I knew it couldn't be the metering. At very fast shutter speeds the rear curtain starts to close before the first curtain is fully open so any synchronisation issue between the curtains will be very obvious whilst not presenting much of a problem at slower shutter speeds where the rear curtain being 1mm ahead of where it should be would not change the exposure significantly.
Jul
22
comment Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”
@shennan it seems you're not getting what happens when you put a lens on a smaller sensor - you get a smaller image, which has the same field of view as a longer focal length on a larger sensor. The lens is not "restricted" to an APS-C sensor, it's just if you put it on full frame you'll get darker corners. They could fix that but the lens would be heavier and more expensive. But even if they did that, it wouldn't change how it behaves on a smaller sensor, it would still give the same field of view as a 52.2mm lens would on full frame.
Jul
22
comment Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”
@shennan No, interchangeable lenses are always sold by their actual focal length. This lens is a 35mm lens. The EFL when used with an APS-C sensor is 52.5mm
Jul
22
comment Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”
@shennan Sony haven't fudged anything, the lens is called a 35mm lens because it's focal length is 35mm. It's 35mm when mounted on a full frame camera, it's 35mm when mounted on an APS-C camera, it's 35mm when it's in the box and not mounted on any camera at all... the focal length helps you work out the FOV, but it doesn't define the FOV by itself. Sony state the focal length that gives the same FOV on a full frame camera, to help people who understand the relationship between focal lengh and FOV on full frame cameras estimate the FOV of the lens on APS-C cameras.
Jul
22
comment Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”
@shennan It's an APS-C lens because the image circle it illuminates is only big enough for an APS-C sensor. When mounted on a full frame camera the corners will be black.
Jul
22
comment Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”
They name it as a 35mm lens because it is a 35mm lens, i.e. it brings parallel lines into focus 35mm behind the second principal plane. This is the definition of focal length, a property of the lens only, one that doesn't change when mounting the lens on different cameras. Focal length does not by itself define the field of view.
Jul
22
comment What are the anomalies in this picture of earth?
@NormLDude a simple paragraph would have sufficed under the pic that was posted on Flickr "May not be exactly as shown here" or "The quality of this image is 44% of the original" - the artifacts you're referring to are completely invisible until you perform a huge shadow boost, so why on Earth would they need to mention it? Should the same disclaimer be placed next to every JPEG image published anywhere in the web? Images NASA posts on Flickr are for PR purposes, not scientific analysis.
Jul
22
comment What are the anomalies in this picture of earth?
@NormLDude "There seems to be a lot of definition (3d)/depth to this 'anamoly'. The other circles surrounded by tiny circles are pretty interesting also." that is all completely explained by my answer - the 3D shapes come from the primitive building blocks which are all based on [co]sine waves.