grabbed some boat pics before the fog blew in tonight. I've started fiddling around with astronomy image processing techniques for these long-range (~14 km) pics—the results are pretty amazing! here's CMA CGM CHILE and MSC ALANYA, the latter both with and without image stacking.

@midendian I have a shot in my head that is about 15km but all I've got is my 6D and a 70-200 on a 2x extender. Any tips? Am I buying a tripod?

@numist these were with a ~450mm f/6.4 (but on a very small sensor) so you’re in the ballpark with the 400mm (f/5.5 if you have the 2.8 version). plenty of light so you shouldn’t need a tripod but it may be easier to refine the composition with one. if the air is very rough you want as short of exposure as you can get anyway! also if you can tolerate greyscale use only the red channel to get the sharpest image.

@midendian I think ideally I'd capture at dusk or dawn but I should probably just get it in broad daylight once first so I'm not compromising between Tv and ISO. What's your stacking process?

@numist def do a practice run! If you’re stacking, ISO doesn’t matter and indeed for very short exposures you want to set ISO as high as it needs to be to nearly make the brightest point saturate (to limit quantization noise). I used Autostakkert for these, but I haven’t tried it with color images from an SLR, but it should support it fine. Also try Registaxx for sharpening, it’s way better at bringing out detail in this kind of image than anything in photoshop.

@numist you got me curious how well this works with colour DSLR pics. here's one of the same targets with a 6D Mk2 and 100-400L Mk2 (heavily cropped). fastest exposure possible (1/4000th) and ISO 400 at about 6pm. Single image then stacking best ~100 out of 600 acquired with Autostakkert and sharpened in Registaxx. Not quite as sharp but still pretty good improvement!

@midendian holy nuts, 600 exposures?