Serene Life

by garik

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958 reputation
616
bio website
location ND
age 31
visits member for 2 years, 4 months
seen yesterday

Jun
2
comment What's the easiest way to access pure raw data (without demosaicing)?
I was just warning you: it's standard practice on SE to note if you're the developer, especially if it's not a free program. Otherwise someone might flag it as spam. (I won't do that, but since you're new here I thought it's fair to mention it.)
Jun
1
comment What's the easiest way to access pure raw data (without demosaicing)?
It's not free any more though, unfortunately, but it was a nice program when I tried it. It didn't seem to do anything more than dcraw though, other than adding a GUI. Are you one of the devs? If yes, you should make that clear in this post.
May
24
comment Which Nikon DSLRs have an autofocus motor in camera body?
A simple google search brings up the answer.
May
23
comment What is the difference between a linear and a circular polarizer?
The terminology used on photo sites is all messed up. What they call a "circular polarizer" is in fact a linear polarizer stacked with a circular polarizer. The second layer is not a de-polarizer as your post would suggest.
May
21
comment Nikkor 18-55 Lens Hood help
The front of the lens you mention will rotate during focusing. This means that it is very likely to be incompatible with the flower-shaped hood. Even if it is mountable, the flower shaped hood is likely to cause vignetting at 18 mm when it gets rotated into an incorrect position.
May
18
comment Remove violet glowing effect
More specifically, this is lateral chromatic aberration: you can see that the outer (closer to the corner) edges are greenish and the inner ones are purplish. This type of chromatic aberration is easier to correct during postprocessing: RAW converters will typically have an option for it.
May
14
comment What personal safety precautions do I need to take while traveling with a camera in Scandinavia?
You just have to exercise some common sense. In Europe people will actually walk around on the street daily and take public transportation (unlike many "carland" parts of the US which don't even have sidewalks). Don't leave your camera on a bench and wander off in the park because the wrong kind of person might walk by and take it.
Apr
26
comment Why do two zoom lenses set to 200mm on the same camera produce different fields of view?
The keyword here to Google for is focus breathing (I'm surprised that no one mentioned it). It means that the angle of view changes (widens) as you focus closer. It is typical for lenses with very high zoom rations like the 18-200 mm. For a long lens like yours 3 m is close focusing. If you repeat the test and focus at infinity, you'll find that the difference is much smaller.
Apr
8
comment How can I make the most of entry level camera gear?
Stop reading sites where people discuss gear instead of pictures. Then you won't be unhappy about what you don't have ;-) What you have is still much more flexible (and gives better quality) than most new compacts. I used a Nikon D60 with a single 35 mm 1/1.8 lens for > 2 years and I was very happy with it. One of the things that gave me the biggest improvements was starting to shoot RAW and post-processing it. Also, instead of thinking about stuff you can't do (shoot small birds or do macro) focus on stuff you can do with your current setup. I tried some panoramas and time lapses.
Mar
25
comment Nikon 55-200mm or 50mm
Is this going to be your only lens? Or are you getting it together with a kit lens? If it will be your only lens, then the answer will necessarily have to be neither ... if not, it depends on what you like to do.
Mar
23
comment CMYK vs RGB - Can a DSLR take CMYK images?
You might want to read up on these: en.wikipedia.org/wiki/Subtractive_color and en.wikipedia.org/wiki/Additive_color
Mar
19
comment Does median blending / image stacking result in better or worse results than a long exposure?
@KartickVaddadi "But shouldn't the MEDIAN of 10 one-second exposures give less noise?" <-- If you consider the shot noise (Poisson), then taking the median will in fact result in higher noise than taking the mean. However, the median will effectively discard outliers, for example if a cosmic ray hit the sensor during exposure (not part of the short noise), while the mean won't. Some interesting reading on this here.
Mar
19
comment How does a camera implement different white balance modes?
You bring up an interesting point. It is not in fact obvious that the transformation should be an independent and linear scaling of the three channels. I would not expect it to be linear because the RGB values are not linearly related to the light intensity (I would however expect it to be independent). However, WP says that this is actually what is often being done in practice, though not always.
Mar
17
comment Might future advances in sensor technology reduce or eliminate noise?
@KirkBroadhurst Historically, the first model of light was as "rays" (geometrical optics). Then came wave optics. Then quantum mechanics---light is made of discrete units. It is interesting to think that phenomena related to each model (and not explainable by previous ones) do have practical significance in digital photography.
Mar
17
comment Might future advances in sensor technology reduce or eliminate noise?
@KirkBroadhurst That's the whole point: in low-light we aren't. Human vision is approximately logarithmic, and the "stop scale" is also logarithmic. One stop less light means half as many photons. If you start halving, you get to only a few photons very very quickly. If you're mathematically oriented you might want to read up on the Poisson process. Generally, if you have k photons on average per pixel, the magnitude of the pixel noise will be sqrt(k).
Mar
17
comment Photo stretched at corners?
Keeping straight lines straight is not the only kind of property one might desire from a projection. Other useful things are: preserving the angles, preserving areas, etc. Projections with these other properties won't keep straight lines (hence they have barrel distortion), but they produce a more natural look in the corners. This is why I said that if the lens has barrel distortion, then it will usually have a less severe stretching in the corners. So your first statement, that barrel distortion can cause this, is not quite accurate. In fact a lens with barrel distortion will stretch less.
Mar
17
comment Photo stretched at corners?
... projections e.g. in Hugin. What they often call "distortion free", meaning no barrel/pincushion distortion free, is projecting through a point. This is what the idealized thin lens (from middle-school optics) does. It has the property that straight lines in 3D get transformed to straight lines on the photo, but it also "stretches" the corners. This stretching (illustrated in the OP's photo) has nothing to do with "barrel distortion", which refers purely to those lines not being straight any more.
Mar
17
comment Photo stretched at corners?
Actually if the lens has more barrel distortion it will usually have less of this "stretching" (perspective) effect. "Distortion" (while standard terminology) is not the best word for these phenomena, as it implies that the picture doesn't show the subject "true to life", but in a "distorted" way. What actually happens is that the lens needs to project (part of) a sphere (spherical view) onto a plane (the photograph). There are many ways to do this, each with different properties. You can experiment with transforming a photo to various ...
Feb
24
comment Does a larger sensor resolution increase the difficulty of shooting hand-held?
The area ratio is not 2 but 1.5^2 = 2.25 and these two particular sensors have identical pixel pitch. That aside, doing any kind of comparison like this doesn't make sense unless you also talk about what focal length lenses are used on both. If the field of view is the same for both, then the higher resolution sensor will be able to detect smaller motion blur. If the focal lengths are the same for both (and thus the field of you will differ if the sensor sizes are also different) then the smaller pixel pitch sensor will be able to detect motion blur more easily.
Dec
22
comment Demosaic data stored in TIFF
@mattdm Then instead of voting to close, you can vote to migrate it to the right place ... the problem came up in a practical application to photography, so I thought it's more likely I'll find an answer here than on DSP.SE, as more people here would want to do the same thing here. Looking at the other questions on this site I don't see why this is clearly off topic if asking for say noise reduction software is not off topic.