…this laptop is ice cold!
“What the…?” you might think? Oh, nothing, I just stood outside in about 40 degree weather for over an hour, to do a 1,967 second exposure on the D300…
Gotta test the camera, ya know? Make sure it can stand up to some, well maybe not extreme, but DIFFERENT conditions? I can’t just buy a weather sealed camera and lens and not put it to good use, right? (There was fog on the polarizer by the end of the exposure. Mmmm.)
I set long exposure NR (noise reduction) on, to remove any “christmas light” noise that can appear even when you’re shooting at ISO 100, and any thermal noise that might come from a hot spot on the sensor. (Major thermal noise on the D70, for example) With long exposure NR on however, the camera has to double the sensing time, so another 1,966 seconds after the shutter closes, the camera keeps sensing so that it can determine what is noise and what is not.
So the camera was sensing for a grand total of 3,934 seconds, or 65 minutes, not counting the half dozen 30 second exposures I made to gauge the perfect long exposure.
Surprisingly, The D300′s high-tech battery meter reads out that it’s still at 57%. WOW! Even a 20 minute exposure on my D70 (40 mins of sensing) would completely exhaust the battery. And that was at 6 megapixels compressed RAW, not 12 megapixels loss-less compressed RAW!
Next I’ll have to test shoot without long exposure NR, since I hear rumors that thermal noise is non-existent with the D300, and then also in a nice warm situation where the battery isn’t taxed so much… Given the right conditions, I might be able to expose for over an hour with a DSLR!!! Wow, how far we’ve come with digital.
Oh, you wanna see the picture? I thought you’d never ask:
Nothing spectacular, in fact I’ve shot this composition many times before. I was HOPING that since it was a new moon, I might be able to get SOME star trails in the photo. But alas, in suburbia there are no stars visible this close to the horizon, I guess. And I’m gonna need to find a lens that has no flare, if I wanna do this in earnest…

(lens used: Nikon 17-55 2.8 DX)
Moving on to the real exciting results of the test, here’s a 100% crop from the original 12 MP image:

And next for the jaw-dropper, here’s one of the shots at ISO 1600 that I used to help calculate the exposure for ISO 100:

SHARP and CLEAN! (Disclaimer: Yes, I used noise reduction. But both images received the same exact NR, which is the important part. And NR is pretty much a given when it’s just one click away in Bridge / Lightroom. I practically leave chroma noise reduction at 25-35 all the time since it’s so non-destructive. I hardly ever touch the luminance NR, though I did a tiny bit in this case. Again, this is not a sterile lab test, this is a REAL WORLD test, and in the real world I use NR… And yes, I also used sharpening in BR. Sharpening is also a given in the real world.)
But wait! The discerning eye will see more sharpness in the ISO 1600 image, even though they have been processed EXACTLY the same. Why? ESPECIALLY when the ISO 1600 image was shot wide open at f/2.8?
Diffraction. The ISO 100 image was shot at f/16, cause it’s so dang BRIGHT in suburbia!!! Stopping down to f/16 causes light diffraction and softens the image a little bit. (don’t ask how, the answer involves confusion, literally!) Stopping down to f/22 would have been slightly worse. The sweet spot of a lens on DX is usually f/8 and f/11, FYI… A full-frame 35mm sensor can do f/16 with much less diffraction, since the pixels are like twice as big, BTW…
(No, the softness is NOT at all affected by the fact that ISO 100 on the D300 is “LO 1″. This was another thing I tested extensively. The only thing you lose by dropping to ISO 100 is a tiny bit of highlight range, which was not an issue in this image…)
Hopefully sometime I’ll be able to get away from suburbia, and put the “f/8 and be there” saying to good use… Although heck if I don’t need the DOF I could shoot a lot closer to wide open, like maybe f/5.6 or f/4 even, if f/2.8 on this lens is already THAT tack sharp!
So, there you have it, a tiny peek into nocturnal, long-exposure photography! Hopefully I’ve sparked your curiosity for more?
I’m just itching to get together with some fellow photographers who are interested in pushing the “limits” of their cameras!
=Matt=
Recent Comments