I got a hole in my star photo, is it normal?

[ncelq]

i am using d700 + 14-24mm lens. Took the star photo using 10s, ISO 1600, f/2.8. When i back home and see the photo 100%, i found that there is a hole inside my star, is it normal?

 

[480sparky]

You're not focused correctly.

 

[ruifo]

It's totally out of focus...
Focus it correctly to infinity.

 

[fjrabon]

yeah, you can't use autofocus for star photography, because it totally confuses the autofocus system to try and focus in that case. Use manual focus and focus at infinity. I'd also use the lens' sharpest aperture, probably f/4 or f/5.6 and then a lower ISO and a longer shutter speed. Enable long exposure noise reduction.

 

[fjrabon]

also this is a much brighter exposure than you typically see for star photography. Usually the "background sky" should go to complete blackness.

 

[tirediron]

It's totally out of focus...
Focus it correctly to infinity.

That is key, simply racking out the lens as far as it will go, or moving it to the infinity index mark is NOT necessarily a guarantee you're where you need to be. With today's digital cameras, I would focus manually, by eye through the viewfinder and then confirm using Live View.

 

[ncelq]

also this is a much brighter exposure than you typically see for star photography. Usually the "background sky" should go to complete blackness.

yes, you are right. i took that picture near the sunrise. so, the picture is brighter as usual

 

[480sparky]

That is key, simply racking out the lens as far as it will go, or moving it to the infinity index mark is NOT necessarily a guarantee you're where you need to be. .......

True dat. Given the tolerances in todays mass-produces items, combined with the fact that focusing at infinity is difficult to do with the tiny scales on lenses these days (if there's a scale at all!), I'd do live view as well. And it may take some adjustements even at that.

 

[fjrabon]

also this is a much brighter exposure than you typically see for star photography. Usually the "background sky" should go to complete blackness.

yes, you are right. i took that picture near the sunrise. so, the picture is brighter as usual

that also meant that you could have used a lower ISO, given that there is some pretty major noise going on in the image.

 

[jsecordphoto]

There is some terrible advice going on in this thread. Yes, your sky should be darker, but not black. There is color in the night sky that our eyes don't pick up (mostly because our vision is basically desaturated in low light). In truly dark skies, your sky will have color with an exposure of 25-30 seconds.

Also, stopping down your lens lower than MAYBE f4 in truly dark skies will just result in a totally underexposed sky. I typically shoot at iso3200, 2.8, 25 seconds.