LRTimelapse Forum

Hi all!

I’ve been using a Nikon D5600 paired with a Sigma 18-35mm f1.8 (DX) with great results for Timelapse and Milky Way photography.

I’ve just switched to a D810 which came with an old Nikkor 28mm f2.8 (FX). I’ve just received it and have no time for thorough testing so, in your opinion, and having to shoot this weekend, what would be the best combination (quality-wise)?

- Using the D810 in DX mode paired with the Sigma 18-35mm?
- Or using the D810 in FX with its Nikkor 28mm?

By the way, what difference in angle of view can I expect when using D810’s DX mode with DX lenses? And regarding resolution (number of pixels in width & height) and file size?

Hope to have explained it correctly, I’m still overwhelmed by sensor sizes and crop factors…

Thanks in advance!

If you use DX lenses on an FX Body, the you will get an Angle of view that corresponds the Angel of View of the Focal Length multiplied with 1.5.
For example, 18mm on a DX Camera (or FX in DX mode) the angle of view will correspond 18 x 1.5 = 27mm.
Bit also Resolution on your D810 will of course suffer, because you will only use part of the sensor.

Ok, makes perfect sense. So if I use my Sigma 18mm f1.8 DX with the Nikon D810 I will get an angle of view of 65 degrees, corresponding to a focal length of 27mm. That is practically the same angle than if I use the D810 paired with the Nikon 28mm f2.8 FX.

I want to do a day-to-night and Milky Way timelapse, and I’m not sure what’s my best choice. I’m assuming that by using the Sigma DX and the D810 in DX mode I will lose total number of pixels (width & height) but will also save file size in megabytes.

By the way the Sigma is a more luminous lens (f1.8) than the Nikon (f2.8), and it has autofocus (that’s a plus). So I believe it is better to sacrifice those pixels and angle of view in favor of luminosity and overall image quality (assuming here the Sigma is a better performer than the Nikon 28mm, a twenty-year-old lens).

1.- Is all this reasoning correct?
2.- What lens would you use if you only had the lenses I’ve mentioned?

Thanks again!

AF is no argument with timelapse and astro.
I thought in DX-Mode using only the center part of the big sensor there's no change in focal length and the crop factor is relevant when attaching a fullframe lens to a crop body?
So I would suggest the fast and wide 18mm lens and the D810 (with better low light ability?) in DX-Mode for milky way and of course test the set up before a serious use.

I use autofocus since it’s daytime when I start shooting. I focus in AF, check the image and then I correct manually if necessary.

I’m not sure if I’m understanding what you say about focal length change. Gunther said just the opposite…

Thanks for your suggestions!