Trouble with wide field nightscapes.

[Galen Gilmore]

I have a Fuji XT-1 camera and a Rokinon 12mm f2.0 manual focus lens, and I have been trying to do nightscapes. I seem to have trouble focusing properly on stars, even when I set the focus to infinity.

anyone have any advice on this kind of stuff?

[MarsG76]

Infinity on lenses is not necessarily infinity.. I use a bahnitov mask from my 80mm frac to focus on a bright near by star than frame the shot... it is always little before or after the infinity marker on the lens.

[Craney]

see this thread, towards the bottom.

Mention of a starsharp2.

[ronin]

If you are using the infinity mark on the lens then more or less ignore that, it will be a good indication only, used to have the same on an old manual camera.

Actually for a 12mm I would have thought that a distant tree or hill would have been sufficent, distant being a mile or so. Your other realistic option is pick a bright star - Sirius, Capella - and get the best focus you can on that then don't move the lens. If the moon is out at all use that for focus then go point at the wide field you really want.

Don't think the milky way will be overly useful (depends if you can see it) although the view should alter from sort of blurred to a better indication of lots of points.

[ollypenrice]

I think you should zoom in to pixel scale on an approriately bright star (chosen by experiment) and then observe the reduction in size as you focus.

Olly

[Owmuchonomy]

Yep, as Olly says, switch on live view and use the zoom feature at 10x (on a Canon) and pick a bright star. Focus to get the smallest image of the star on your camera screen. Leave the focus at that point.

[frugal]

I did see a cute gizmo that you attached to the focus ring and the body of the lens. It was effectively a big sticking out pointer that you could use to get a finer adjustment than turning the focus ring directly. I seem to recall being able to lock the pointer against the backing ring to "lock" the focus.

Found it (or at least something similar): http://focusmaker.com/

[Galen Gilmore]

Thanks for the responses all. I knew that you had the do it before or after the infinity mark, but I didn't know how much I should do it.

I will try what ronin said, if that doesn't work I'll try practicing by zooming onto a bright star.

[rigradio]

Live View Focusing

Scroll down to find the video

[Galen Gilmore]

It seemed to work very nicely! Got a nice shot of a windmill and stars