quock wrote:I bought a reasonably cheap second-hand film SLR some time ago to play with.
What is this film thing, of which you speak?
--SS
Personal computing discussed
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quock wrote:I bought a reasonably cheap second-hand film SLR some time ago to play with.
SecretSquirrel wrote:quock wrote:I bought a reasonably cheap second-hand film SLR some time ago to play with.
What is this film thing, of which you speak?
--SS
Aphasia wrote:Even though watching a digital slideshow on the projector in 1920x1080 is nice, there is a certain tactile thing with actually having a slide projector doing the projection, having the kachick when it changes image, etc... not for the quality, but for feeling and nostalgia. That said, there are some really good slide films out there, although they are starting to fade away. I shoot alot of slides before going over to digital and liked it.
jobodaho wrote:I had to play with it a bunch in Lightroom to get it how I wanted, but it definitely still has a lot of noise due to the extremely long exposure. Does anyone know how I can reduce the noise for such a long exposure?
ludi wrote:jobodaho wrote:I had to play with it a bunch in Lightroom to get it how I wanted, but it definitely still has a lot of noise due to the extremely long exposure. Does anyone know how I can reduce the noise for such a long exposure?
That's a pretty good cleanup already. If you want more precision, maybe you could try duplicating in Lightroom what Canon's "Long Exposure Noise Reduction" feature does -- takes a second, black frame at the same exposure time as the original, and then uses that information about the sensor performance as a reference to clean up some of the noise in the captured frame.
You might not need a full hour and a half for the reference frame, but (say) 15 minutes with the body cap installed, at the same ambient temperature as the time exposure, might do it. Then overlay the reference noise frame against your image and try a few blending filters to see what, uh, develops.
Voldenuit wrote:ludi wrote:jobodaho wrote:I had to play with it a bunch in Lightroom to get it how I wanted, but it definitely still has a lot of noise due to the extremely long exposure. Does anyone know how I can reduce the noise for such a long exposure?
That's a pretty good cleanup already. If you want more precision, maybe you could try duplicating in Lightroom what Canon's "Long Exposure Noise Reduction" feature does -- takes a second, black frame at the same exposure time as the original, and then uses that information about the sensor performance as a reference to clean up some of the noise in the captured frame.
You might not need a full hour and a half for the reference frame, but (say) 15 minutes with the body cap installed, at the same ambient temperature as the time exposure, might do it. Then overlay the reference noise frame against your image and try a few blending filters to see what, uh, develops.
Pretty much what ludi said. The image you posted was a little small to be able to tell just how bad the noise was, but the general principles apply.
To elaborate:
1) Use the pixel map function on the camera so the body processes out hot pixels automatically. Some people suggest using live view for a while to heat up the sensor first, so that marginal pixels that would otherwise only show up in long exposures get stressed enough to be seen by the camera. Note that Canon bodies reset the hot pixel map data after firmware updates, so your old hot pixel map may have been deleted.
2a) Use the long exposure noise reduction function. This is great if you only have to take 1 exposure, but it is very time consuming, since it takes a long exposure after every shot. Not a good idea if you want to chain multiple exposures together.
2b) Alternatively, take a single long exposure with the lens cap on immediately after your last long exposure. I do it after instead of before since the sensor will probably be at its hottest at the end of a series of long exposures. Subtract the dark frame from the exposed pictures in photoshop (there are filters and scripts that can automate the process for you, or you can do it manually with a variety of techniques).
As for base noise (vs hot pixels), that's just an unfortunate characteristic of CMOS sensors and the read noise characteristics of your given body (which get exacerbated by long exposures). You can use the NR filters/algorithms in PS/LR to reduce the noise, or work in layers (with the star trails on a separate layer/mask) to preserve detail areas etc.
jobodaho wrote:Thanks for the tips guys, I just did the re-mapping trick for both of my cameras, and my 60D always had a dead/hot pixel right in the middle of the frame which drove me nuts and it is now gone! I followed the technique here:
http://www.youtube.com/watch?v=WJBuGhMnvFo
But just so I'm clear I'm going to ask a few more questions...
So with Long Exposure Noise Reduction on, does it automatically take the next reference image OR upon the next time you press the shutter does it activate? Does the next long exposure need to be as long as the first? I'm planning on this next image being in the 2-3 hour range, and I most certainly don't want to be out there for over 6 hours! Would using a script in Photoshop require the exact same length in exposure time for the next shot?
Voldenuit wrote:Tethering to a laptop is easy enough with a USB cord. I've got an intervalometer that can handle those sorts of things. You should be able to shoot a similar scene as a series of exposures (say as 18 four-minute exposures at f/2.8 with one minute between shots), then composite them digitally.Pity you can't write up a macro to fire off a batch of long exposures with the lens cap on... or can you? I'm afraid I haven't done much experimenting with the tethering software available for Canons.
Voldenuit wrote:Long Exposure Noise Reduction automatically takes a second exposure after the first one. Normally, the exposure is as long as the first one, though if you're using bulb mode (as I presume you are for a 3 hr exposure), then I'm not sure (I've grandfathered my 40D to my dad and no longer have it with me for testing). Long Exposure Noise Reduction both subtracts hot pixels (to a greater degree) and reduces noise (to a lesser degree) - mostly read noise and baseline sensor noise.
jobodaho wrote:Great shot aces!
ludi wrote:Two engines parked back-to-back on a siding with an interesting structure in the background. My kingdom for a blue sky with light cloud activity In retrospect, given the lighting conditions, I should have grabbed the Red #29 and then made a proper black-and-white job out of it, instead. Still, with a bit of deliberate over-saturation, I can get this:
aces170 wrote:Nice pics, I do notice some good background formation but its getting overexposed. I think this would have been shot in the harsh afternoon light.
ludi wrote:aces170 wrote:Nice pics, I do notice some good background formation but its getting overexposed. I think this would have been shot in the harsh afternoon light.
Thanks! And yes, it was around 2pm/1400 (the EXIF says differently because I apparently don't have the camera's clock set correctly).
Incidentally I do like that HDR shot -- lots of interesting layers to the image. All it needs is a two-page glossy layout in National Geographic.