Suggestions for wide angle lens (for landscape/astro/street)

biza43 wrote:

Tim van der Leeuw wrote:

biza43 wrote:

For astro, the important thing is the light gathering ability of the lens, not so much the focal length. The X100V is a fantastic camera that is suitable for a lot of applications.

The wider the focal length, the longer you can expose without seeing the movement of the stars. Depending on the actual light gathering abilities of the lens (lower f-stop is not always a guarantee for more light) and the focal lengths you're comparing, the lens with a wider focal length but somewhat higher f-stop might win in actual light gathering ability.

At some point I downloaded a spreadsheet comparing various camera/lens combos for astro using the NPF rule that calculated actual EV numbers, and started modifying that to add my own lenses and lenses that I was considering. That gave me a table of what settings (camera, ISO, focal length, f-stop) would give me the lowest EV (lower == better in this case).

Light gathering ability from the subject:

https://clarkvision.com/articles/characteristics-of-best-cameras-and-lenses-for-nightscape-astro-photography/

Example provided: a 35mm f/1.4 lens has a light gathering ability from the subject 21x higher, compared to a 15mm f/2.8 lens.

But from what I can see, is that this article doesn't take exposure-time into account. If you can have a 4x longer exposure (8 seconds instead of 2 seconds) that makes up for 2 stops of exposure difference.

I'll need to do a bit more digging myself as well now, and next night out I should perhaps remember to do some more-or-less controlled experiments.

Edit:

Reading a bit more into the article, he assumes you can use a star-tracker so that evens out differences in exposure time a lot. If you're not using a star-tracker then a longer exposure is often better.

Also, he compares a 30 second shot from the 35mm lens to a 20 second shot from the 200mm lens but does not explain why he didn't shoot a 30 second exposure at 200mm...

He also goes into mosaicing, by which I assume he means panorama-stitching or something similar. That is getting into advanced astro photography subjects and at that point the wider focal lengths are less interesting indeed, but the shots will also require more and more dedication!

In my opinion, a wider angle and wide aperture are best for getting started in astro photography. 16mm f/1.4, or 12mm f/2.0 are great for that. Or even 7.5mm f/2.8 fisheye.

(Or the Meike 6.5mm f/2.0 circular fisheye but I've never shot with that myself! )