Yesterday , Friday the 13th , Oct. 2017 was the very first time my D850 was used to photograph the Night sky and I was of course looking for the Milky Way. Well, I was fortunate that the night sky over Bromo-Tengger National Park behaved and I was blessed with a reasonably clear sky.
Before I reveal my findings (no punches pulled as always) , I wanted to share a new Night sky photography rule to obtain Spot Stars (not trails) called the NPF rule which is very much tigher than the common 500 or 600 Rule which were used to figure out the best exposure time to use to obtain Spot Stars.
The NPF rule now takes into account the DSLR's Sensor Resolution.
The screenshot on the left shows the recommended maximum exposure time of 4 seconds for the Nikon D850 (45.7 MP) when used with a 75mm focal length , f4.0 aperture lens.
In comparison , if I had used the Nikon Df which was 16 MegaPixels in resolution , the recommended timing would have been 5 seconds.
This is 1 second longer & would be because, the Df lacked the resolution to resolve that extra bit of star movement that would have been captured by the D850 if 5 seconds was used instead of the recommended 4 seconds for the D850.
For my very first Milky Way capture with the Nikon D850 , I wanted to really make it difficult to really test out the sensor which is why I decided on the following to capture the Milky Way core up close :
- use a "longer" focal length of 75mm
- use a "slower" lens with an aperture of f4.0
- high ISO Noise Reduction set to NORMAL
Just in case you did not quite understand why 75mm focal length would be a tougher scenario to test at ......... compare this , if I used a 14mm focal length @f4.0 , the NPF rule would have allowed 24 seconds to obtain Spot Stars. By testing at 75mm focal length @f4.0 , the NPF rule only allows up to 4 seconds maximum exposure time which means that I would really have to pump up the ISO to get the appropriate overall exposure of the scene. So how did the Nikon D850 do ?
So here goes , this is the resized JPEG of the RAW capture using 75mm focal length @f4.0 , @ISO25,600 @4 seconds (as recommended by NPF rule)
The RAW image as always looks lacking in contrast , but how does it look if I magnify to 200% ?
Screenshot at 200% magnification of raw file ..... of course you can clearly see the grain at ISO25,600 but the image was free of chroma noise and the star details were excellent and they were pretty much SPOT stars. To me , the ISO25,600 performance was really "clean" if compared to my D810 (I would not dare to show here , for reference , the max. ISO I would use for milky way capture with the D810 is ISO6400)
Screenshot at 200% magnification to show the Stars at 8 seconds exposure time which was twice the NPF rule recommendation. You can clearly see the elongated stars.
Now could the ISO25,600 noise / grain of my RAW image could be reduced effectively with my reference Noise Reduction software ? This 200% magnification screenshot will show that it does a very good job. Yes, the edges of the stars are a tad less crisp but that I can easily salvage with the right sharpening process
So how does the FINAL ISO25600 Milky Way image look like after my regular post processing flow using Photoshop CC ? It actually looks GREAT , its detailed and clean , I am really impressed !! I would never have dared to try this with my D810 ...... maybe I would try it with the same workflow with my Nikon Df or Nikon D4 but they only have 16 & 20MP resolution respectively.
This IS a 45.7MP image at ISO25,600 from the Nikon D850 post processed using my regular workflow which took no more than 5 minutes to do the noise reduction , tweak the overall contrast and apply my sharpening step. Note , there was slight 5% crop to the image more for composition reasons.
Ending off with a screenshot of the above final image at 200% magnification.
Conclusion
Yes, the Nikon D850 definitely passes my test as a DSLR capable of capturing SPOT Stars Milky Way.
I would probably use ISO12,800 and lower for my future Milky Way escapades but it is so good to know that I can rely on the D850's ISO25,600 when needed.
Still a few more nights to test the D850 out , so stay tuned !!!
Happy Shooting everyone.