Z6ii or Z8 for Milky Way Photos

[Bob k.]

When I compare Milky Way shots with foreground elements shot on my Z6ii and on my Z8 shot under similar circumstances I notice that the Z6 files have less noise. I have always heard that the cells are larger on the lower mega pixel camera and so can gather more light per cell than in the higher mega pixel camera. I don't know why I was surprised when I saw the impact of this fact in my own pictures. The photos from the Z8 come out with more noise than those from the Z6ii. Even after running them through the de-noise program in LR the Z6ii images are cleaner. I am getting ready for another Milky Way shoot and I would like to hear the groups thought on which camera might produce the best results. Thanks in advance for your thoughts.

 

[DRwyoming]

The Z6Ii has slightly (very slightly) better noise performance than the Z8 when viewed at the same output file size. IOW if the Z8 files are down sampled to the Z6Ii file size or the files are otherwise upsized or downsized to equal pixel dimensions.

But if you evaluate both images by zooming in to 100% in a tool like Lightroom or Photoshop (1:1 pixel view) then yes the higher resolution Z8 files will look a lot noisier. But zooming in to a 1:1 pixel view isn’t a great way to compare a medium or low resolution camera to a high resolution camera as that zooms in to a much smaller portion of the image for the high resolution camera.

For an apples to apples comparison of what both images would look like displayed as the same size on a screen or printed to the same size the files should be normalized to the same pixel dimensions by resizing (not cropping) one or both images.

 

[GregT943]

Are you stacking images for the foreground and sky? Are you doing one long exposure for foreground, and is it a blue hour shot or night shot? Also what lens are you using? If you are using a star tracker make sure your Z8 ISO is at 500 as well.

 

[Bob k.]

Thanks DRwyoming. "For an apples to apples comparison of what both images would look like displayed as the same size on a screen or printed to the same size the files should be normalized to the same pixel dimensions by resizing (not cropping) one or both images." I am comparing the images side by side on LR with the goal of printing some at something like 16x24. It seemed to me that the images from the Z8 were a little harder to clean up and didn't have more detail than those from the Z6. Admittedly my sample size was small and they were taking in similar circumstance but on different days.

 

[Bob k.]

Greg, I was looking a single images. I used my Z 20mm 1.8 in both cases. I would love to use a tracker but I don't get out that often so I try and keep things simple when I do. I typically use the lens wide open with an exposure of about 13 seconds and ISO of around 5000.​

 

[EricBowles]

Thanks DRwyoming. "For an apples to apples comparison of what both images would look like displayed as the same size on a screen or printed to the same size the files should be normalized to the same pixel dimensions by resizing (not cropping) one or both images." I am comparing the images side by side on LR with the goal of printing some at something like 16x24. It seemed to me that the images from the Z8 were a little harder to clean up and didn't have more detail than those from the Z6. Admittedly my sample size was small and they were taking in similar circumstance but on different days.

If you are looking at both cameras at 100% or 200%, the Z8 image is a more magnified version. For the purpose of evaluating noise, export both images with the same dimensions. This may mean slightly different edit settings for sharpening and NR, but LR Classic should do a pretty good job without intervention.

 

[MrFotoFool]

I have not done a comparison (and only own a Z8). But I think your intuition is correct, a smaller megapixel sensor has larger individual pixels which should show less noise in low light and/or long exposure images.

Before I got my Z8 (my only body now) I had a D850 (also 47MP) and a Sony A7IV (33MP). I shot both in dim light at same settings with high ISO and the lower megapixel Sony did have slightly less noise.