tripod - Why are my night photographs always blurry?

I was shooting the lighting of the city that is visible at the top of the trees if you shoot landscape.

No matter what I do, the image is blurry. What have i done:

1. ISO 100


2. Manual focus towards infinity


3. Using a tripod


4. Using really sharp prime & good camera

Basically, everything I could. The only example i have is here, but it is not good, because image is underexposed:

http://www.shrani.si/f/46/b5/1lrphe8A/dsc04702.jpg

The main question: Why can't night photographs be as sharp as daily photographs (with approperiate exposure times of course)?

Answer

Firstly I notice your aperture is set at 1.8. This will make DOF very narrow, making focusing very difficult. Also your camera is very good at higher iso, so try using 1600 / 3200 initially. Try setting the following.

• Use auto focus to focus on something with a defined edge (the tops of the trees?), then switch to manual to keep the focus.


• Use a higher iso, such as 1600+


• Use a narrower aperture to increase dof, try f8 to start


• Try aperture priority to get a close to correct exposure. try this initially. note these settings and switch to manual exposure and adjust the settings from those noted as you see fit.


• Use Dof Calculator to get the hyperfocal distance. You will note that focussing at infinty means everything within approx 100ft is out of focus. At f8, the hyperfocal distance is approx 25 ft, so try focussing on something at approx that distance.

Let me know how you get on.

PS. I also note that from the metadata that you have a brightness value of -4 dialled in, is this intentional?