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983 reputation
716
bio website
location ND
age 31
visits member for 2 years, 6 months
seen 14 hours ago

Nov
14
asked What is the precise definition of SNR, as used by DxOmark?
Oct
2
awarded  Popular Question
Oct
1
comment Do official extension tubes degrade image quality?
... not have the same performance for closer objects. This much is clear from physics and geometry. Whether this does have a tangible effect in practice, when one uses an extension tube to allow focusing on objects closer than the lens was designed for, I do not know. The effect may be negligible. I do have a subjective feeling that one telephoto lens I use does not perform as well close to the minimum focusing distance as for distant objects, but that's just a subjective observation that I have never tried to test rigorously.
Oct
1
comment Do official extension tubes degrade image quality?
Image quality is a function of the object distance too though. It is impossible to create a lens that will map any one point (the object) into a single point (image). It's possible to design a lens which maps one particular object point into a perfect image point, but it's impossible to create one which maps all object points into perfect image points instead of smudges. (Think about mirrors: for objects at infinity you need a parabolic one, for closer objects you need an elliptic one.) So theoretically if a lens is optimized for objects beyond a certain distance, it may ...
Sep
19
comment What are some Chinese/Asian photo sharing websites similar to Flickr?
@Alendri And even when/where it is not blocked (it changes from region to region within China), it is simply unusably slow, like many other non-Chinese sites.
Sep
13
comment Demosaic data stored in TIFF
@PatrickHurley I have a single channel which looks like no. 2 here. I'm looking for a tool that'll reconstruct no. 4. I'm not looking to implement it myself.
Sep
13
comment Demosaic data stored in TIFF
Use case: same as here.
Sep
13
accepted How can I change the pixel data in a DNG while keeping all the metadata?
Sep
13
asked Demosaic data stored in TIFF
Sep
12
answered What Windows software can assemble a sequence of photos into a timelapse?
Sep
12
comment What Windows software can assemble a sequence of photos into a timelapse?
ffmpeg can do this. It's a command line program that works on all major platforms, including Windows. I have used it on Windows to assemble a time lapse. It's free and relatively easy to use (compared to other command line alternatives).
Sep
7
comment Canon 70-200 f2.8 non IS or f4 IS
Take a look here and here
Sep
5
comment Does shooting RAW vs JPEG have a significant effect on battery life?
You don't lose quality by shooting JPEG. You only lose some flexibility of adjustment. Since the result is downscaled anyway, even a small size JPEG is good enough.
Sep
5
comment How does software raise exposure in post-processing?
@Octopus There are no separate channels in RAW sensor data. What you get from the sensor looks like the 2nd picture here. In a RAW converter exposure compensation would be applied before demosaicing, using a formula similar to yours. As I said, your formula is simply incorrect if you apply it to RGB values. It's only correct for (linear) raw data coming form the sensor.
Sep
4
comment How much does a camera move in 1/250 of a second?
The shutter speed needed to avoid motion blur will depend on the focal length of the lens. With a telephoto lens even a slight movement translated to very visible shake in the viewfinder. The guideline I've seen most frequently is to use a shutter speed 1/2f with a lens of focal length f. Thus with a 30mm lens 1/60 s should be rather safe to use.
Sep
4
revised Does shooting RAW vs JPEG have a significant effect on battery life?
added 70 characters in body
Sep
4
revised Does shooting RAW vs JPEG have a significant effect on battery life?
deleted 3 characters in body
Sep
4
answered Does shooting RAW vs JPEG have a significant effect on battery life?
Sep
4
asked Does shooting RAW vs JPEG have a significant effect on battery life?
Sep
4
comment Portable tripod recommendations for those on a budget
@dpollitt I managed to borrow a Benro A0690T today (~$150), I'll try it during the week to get an idea about what compromises I'd be making with this model exactly.