@chupathingie
Forum Replies Created
-
AuthorPosts
-
chupathingie
Participantoh sweet! I hardly thought anyone even knew about these!
Wanna freak someone out? take them outside and say “look over here…” just before a flare happens.
Nice catch, rav.
ParticipantI used two dark frames for a 49 image stack. The dark frames don’t have to be shot on the same lens as the originals, I mean the lens cap is on. I also wonder if the dark frames are as important with this as with astro. There is so much ambient light in these shots.
There is a lot I don’t know about Stacking and I am learning as I go. I’ve no interest in astrophotography, mostly because I live in a place there the sky looks like that^^^^ at night.
Something to keep in mind about darks: You are correct that they don’t care about the lens; they’ll even work just the same with the body cap. One thing they are fussy about though is temperature. They need to be taken at the same temperature as your lights or you will actually introduce more noise into the image. During astro shoots, I typically take my darks in between two shoots of different targets or I break in the middle of a run on a single target to shoot off 20 or so darks.
Thermal noise is pseudo-random. Ideally, it is completely random, but sensors are not perfectly uniform so some areas of the chip (even some individual pixels) are more prone to showing noise than others. So a single dark frame picks up both the random and pseudo-random noise while an averaged stack of darks reinforces the pseudo-random stuff that is similar in each image while averaging the truly random noise into a smaller noise signal.
This works great for large stacks (like astrophotos) because your darks will kill off the hot pixels and areas of the sensor that accumulate noise more rapidly, while the averaging that happens with both your lights and darks will also knock down the random component.
You don’t get quite as much effect when using darks on single images, because you only affect the random component with the darks’ average…there is no averaging going on with a single light frame. However, the pseudo-random component is still affected and the effect is noticeable.
Take look at this image (choose the full-size image to look at…and I used 8 dark frames combined as a straight average for this example) composed of 1/2 unadjusted and 1/2 dark-adjusted: http://www.flickr.com/photos/44012674@N04/7991767839/sizes/l/in/photostream/
This is a ten-second exposure at ISO1600 IIRC (for both the light and darks, of course). In the well-exposed and under-exposed areas, there’s not much difference. But in the intermediately exposed areas (the clouds at the top of the image) there is a pretty sharp difference between the unadjusted and the dark-frame adjusted images. The noise is still there in the under-exposed areas, it’s just not going to become obvious until you try to stretch the low end of the histogram to bring out details…then you see a similar result as what is illustrated in the clouds up top.I never would have thought to use darks for terrestrial images had I not dabbled in the astro side of things. They won’t cure noise, but they certainly knock it down quite a bit. I wind up printing a lot of my better shots, and any decrease in the noise on the final is worth the processing time for me.
ParticipantLooks pretty good so far. How’s the wind? I’m looking for like 5mph gusting to 12 if I’m trying to do 120secs.
Did you use the darks, and if so, how?
Participant*MULTIPLE* darks. a single dark is barely useless.
You’re gonna wind up with a cool series outta this.
Participant^also think that’s very cool… you’re gonna have to school us at some point on that.
Participant/files that away for future use.
If you’re needing uncompressed results ever (or 16 bit/channel), there’s a routine for win/mac/linux called align_image_stack available here that will spit out a series of images from your originals that are registered with each other that you can then load up as layers in your processor-of-choice if you need to do specific things to them. It does a good job of correcting lens distortions and variations in zoom if you’re trying to keep stars stacked/aligned. Not needed for simple trails stacks.
ParticipantWay cool!
BTW, you got punctuation in your video link… extraneous period at the end; leads to a 404.
ParticipantAhh, good. I was leaning that way myself. Also gotta have the obligatory nom noises for that few seconds of grazing in the middle there.
ParticipantMMMmmmmm…. drumsticks!
ParticipantThe only thing I don’t like about the D3100 is that when I plug it into my Linux system via USB cable it doesn’t appear as a mounted filesystem, like the D80 does. Instead there’s some obnoxious special mechanism for accessing the device that only certain applications know how to use. So I have to pull the SD card out and use a USB card reader to transfer photos. I’m not a fan of this particular “progress”.
The D3100 is permanently stuck in PTP mode, not Mass Storage mode. It’ll appear under Linux as a camera device if you have a driver loaded.
That’s a horribly user-hostile way to design a device. That sounds more like something Sony would do.
ParticipantMan… that’s a loss! What a life to have lived!
ParticipantI didn’t drive all the way to Montana to eat at some place I can find in New Mexico. Besides, some times on vacation you just have to say “I’m going to dine like price is no object.” Plus, when I’m camping out in national forests for under $20 a night, the saving allow for splurging on a $50+ dinner.
Hard to argue with that… fortunately I have a handful of friends scattered all over the west to eat with. Solo, I’m usually looking for a pub with decent food and empty enough that I can eat at the bar. Moab Brewery was a nice find for that… great bratwurst plate..
ParticipantI had to drill for that one. 😉
Some codemonkey needs to do up a widget for that.ParticipantI just noticed… does that guy blink at all though the entire clip?
ParticipantLooks like you eat well! OK, except for that sugarbomb…
I hate eating alone, so I wind up doing fast food (like a subway or supermarket deli).
-
AuthorPosts
