900 metres up the Algarve's tallest mountain in the middle of the night. Shockingly dark!
Worth it, though.
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900 metres up the Algarve's tallest mountain in the middle of the night. Shockingly dark!
Worth it, though.
like this
reshared this
Sarah Brown
Unknown parent • •@Neil Brown Ta! Have thermos full of Yorkshire Tea, will travel.
Star trails is 15 minute exposure + 15 minutes for dark frame subtraction. Had someone driven past in the first 15 minutes, it would have wrecked it. So remote up there that nobody did.
Andrew Zonenberg
in reply to Sarah Brown • • •@neil 15 minute single exposure? Wow. What ISO/aperture?
Most of my night work to date has been much shorter (few second) high ISO exposures, which are easier to get but also have much worse SNR.
Sarah Brown
in reply to Andrew Zonenberg • •@Andrew Zonenberg @Neil Brown Fuji XE-4, TTArtisan 7.5mm fisheye. Don’t know the aperture because it was pitch black and it’s a manual lens, so not recorded, but probably about f/4. ISO 160, tripod (obviously).
Basically, drop the iso as low as possible, as long as the camera is able to subtract hot pixels, etc (which the Fuji is).
And pray nobody drives past in that 15 minutes, because it’ll wreck it.
Sarah Brown
Unknown parent • •Sarah Brown
Unknown parent • •@Neil Brown Point camera at sparse source of photons. Leave shutter open for a boringly long time. Go home, see what you’ve managed to get in Adobe Lightroom.
There are two, what I assume to be Starlink, satellites in it if you look carefully.
Sarah Brown
in reply to Sarah Brown • •Sarah Brown
in reply to Sarah Brown • •@Neil Brown Annnyway, at this level the camera is pretty much counting single photons.
And, of course, all the colours are still there. The human eye just doesn’t see colour below a certain intensity.
But cameras do.
Andrew Zonenberg
in reply to Sarah Brown • • •@neil Interesting, your camera does dark frame correction internally? I thought that was pretty much always done in post.
Also, do you have any tips on focusing for these shots? I find with my Sony lenses "run to the end stop" is actually a little past the true "infinity" focus point, and every time I try manual focusing on stars I get it slightly off.
Sarah Brown
in reply to Andrew Zonenberg • •@Andrew Zonenberg @Neil Brown It’s a manual focus lens. I zoomed in to pixel level on the viewfinder and turned the focus ring until the streetlights 50km away were single points of light.
Not easy because the viewfinder image was super noisy.
Autofocus generally has no chance in those kinds of conditions. The other one is a 14mm autofocus lens but that’s only a 1 minute exposure and there was enough contrast left between the sky and the foliage to get an autofocus lock.
Sarah Brown
in reply to Sarah Brown • •Sarah Brown
Unknown parent • •@zip (happy halloween 2024!) @Neil Brown The dark frame subtraction is an option on the Fuji X cameras. After the shot, it closes the shutter and takes another exposure of the same length, but in pitch black.
It then subtracts the second from the first, eliminating stuck pixels, a certain amount of background noise, etc.
Andrew Zonenberg
in reply to Sarah Brown • • •@neil Oh, yeah I didn't even attempt AF because I knew it'd get nowhere.
That's pretty much what I've done, zoom in as far as I can on the EVF and twiddle the focus ring until the stars stop getting smaller. But yeah, noise makes that tricky. I guess I just need to practice more.
Andrew Zonenberg
in reply to Sarah Brown • • •@neil
Here's a few examples of otherwise-nice shots I lost due to this.
I've mostly been able to take camera/tripod motion out of the equation by setting a ~5 second self timer, pressing the shutter button, then stepping away and letting the vibrations damp out before the exposure starts. So this blur should be all defocus.
Sarah Brown
Unknown parent • •Sarah Brown
in reply to Andrew Zonenberg • •Sarah Brown
in reply to Andrew Zonenberg • •Marcos Dione
in reply to Andrew Zonenberg • • •lenses need that extra, post infinity 'reach' to do the autofocusing. Not sure if any of them actually have the infinity properly marked; none of the few ones I have/had had it. My current one has something that doesn't feel very accurate. Looking at manual focus lenses, they implement a similar cursor, but most seem to have the extra info of FoD, which make hyper focusing easier.
I use a similar technique to what @goatsarah explained. I mostly use Jupiter.
Sarah Brown likes this.
Marcos Dione
in reply to Andrew Zonenberg • • •Astrophotography with RawTherapee, Clarkvision.com
clarkvision.com