Hello, I'm Rene from the Netherlands and I'm a sport photographer. I want to get involved in time lapse photography and need to buy some gear to get started.

First I want to buy a new 20mm lens. I'm thinking of the Nikon f1.8 or the new Sigma f1.4 Art. I read that the Sigma is a bit sharper than the Nikon and it's a 1.4 instead of a 1.8. But the Sigma front lens is so round, it will not accept a filter. On the Nikon I can use my 77mm filters I also use on the 24-70 and on my 70-200. So what will be more important in the field, the extra stop light or the ability to use filters?

The second thing is a intervalometer. How important is it to have the ability to change the interval over time. I'm thinking to order the Michron (Alpine Labs Michron). Does anyone have any experience with this device and is it enough to do some static shots? After time I will buy me a Stage One system but to start I will only use my tripot.

I'd go for the Sigma 20 f/1.4 - especially for Astro- and Night Time lapse it's a godsend.
The guys from http://logodeckel.de are developing a filter case for that lens that supports 15x15cm filters.

No experience with the michron. But you can do interval fairing with qDslrDashboard too.