Night sky photos and shutter speed.
Jun 28, 2018 11:27:08 #
Silverman wrote:
Wow, never heard of the "500" rule, so, my understanding is, 16mm x1.5 (nikon crop)=24mm, then 500 divided by 24=21 sec. shutter speed, correct?
Would this be good rule for Fireworks too?
Would this be good rule for Fireworks too?
I believe your Nikon D750 is a FF camera so you would use 16mm without the crop factor. 500 divided by 16 = 31.25. , but you are already having problems at 30 seconds. As others have suggested '400 rule' which would be better. 400 divided by 16 = 25 seconds. Try 25 seconds. If you are still getting trails (or tails) it may be coma. I THINK coma appears as little triangular tails protruding from the top right of the star whereas trails from movement of the stars appears on the left side of the star. ( I could be totally wrong about this.)
If the problem is coma and you have an otherwise good lens, you could try a star tracking mount like this instead of switching to a low coma lens. I have no experience with these but I have thought of getting one someday.
https://www.bhphotovideo.com/c/product/1280430-REG/ioptron_3322_skytracker_pro_camera_mount.html?ap=y&gclid=EAIaIQobChMIy9Dh_dP22wIVRiaGCh1wRAorEAQYAyABEgIlv_D_BwE&smp=y
Jun 28, 2018 11:44:21 #
66mikeg
Loc: Exeter UK
A DIY answer to star tracking is a 'barn door' mount made of 2 pieces of wood a hinge and a suitable bolt instructions for building on Google or You Tube. this is not accurate enough to completely eradicate trails but can give exposure times of several minutes. Not only stars but more faint objects can be imaged.
Jun 28, 2018 11:48:37 #
As already mentioned, the trails are there with all star shots, so it's only a question of degree. Since you say you don't like what you're getting, your only option (with the lens and camera that you have) is to use a faster shutter speed. If the trails are short compared to the diameter of the spots (i.e. the stars) they'll be barely noticeable. To my eye that happens at 10sec or less (assuming a wide angle lens is used). The good news is that your D750 has excellent low light capabilities, so deliberately under-exposing is a possibility.
It's a play-off - slower = better exposure but longer trails. The choice is yours. But don't dismiss under-exposing as a viable alternative.
It's a play-off - slower = better exposure but longer trails. The choice is yours. But don't dismiss under-exposing as a viable alternative.
Jun 28, 2018 14:50:31 #
66mikeg wrote:
If you enlarge the image enough you will always get star trails until you reach the resolution limit of your sensor, the only way to avoid these is by using a guided mount with software such as PHD (Push Here Dummy). This will move the mount and the camera in the apparent direction of the star(s) when it detects that the image is drifting to the next pixel.
True. But for most "normal" sized enlargements, the effect will be negligible.
Jun 28, 2018 16:40:38 #
66mikeg
Loc: Exeter UK
I agree but original post states "under high magnification" I assumed not normal sized image, only way to remove trails is by tracking
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