cozmo2312 wrote in post #16804889
Since I also own the 16-35, I'm thinking of using the Rok solely for Astro use. Here's my question, anyone ever locked focus on a lens? For example, focus it perfectly for star shots once and then find a way to lock it there so there is no guess work when I get out somewhere at night. It'll always be focused where I set it, so I just compose and start shooting. Any ideas? Little superglue on the focus ring, or is this just a bad idea in general?
I have done just this with my rok 14. I focussed on stars one night and then adjusted the lens so that the hard stop was on that position. So now when im shooting stars I simply set my camera on the tripod, turn the focus ring towards infinity until it hits the hard stop and then shoot and the stars are in focus.
There was a video posted in this thread previously that showed how to adjust the lens. It was in spanish I think with English subtitles. Basically though you do the following (from memory so might be worth a search for the video!)-
1 - Fold back the rubber on the focus ring on itself to expose the lens (basically fold it in half back on itself, it goes easily)
2 - Use a knife and cut the cellotape below (the cellotape is what is stopping the focus scale from rotating)
3 - There are 3 small screws around the lens. Loosen each one (DO NOT FULLY REMOVE)
4 - Now focus on the stars (I done this out my back garden at night on a clear night. I done steps 1-3 and then mounted the camera to the tripod)
5 - Once focussed on the stars, make sure you dont turn the focus again and use your small screw driver to rotate the internal section of the lens (This is less scary than it sounds, there is a recess and you can see a silver barrel below and all you do is turn it until you get to the end stop and it doesnt turn anymore)
6 - You now have your lens set at the focus stop and foccused on the stars
7 - Re-tighten the 3 screws
8 - Slide the folded over rubber down to fully expose the outer focus scale section.
9 - Rotate this to your desired position (I set mine so that the infinity mark was at the focus stop point)
10 - Put cellotape on to prevent further rotation
11 - Unfold the rubber part of the focus ring
This was literally a 5 minute job. You are effectively calibrating the infinity point on the lens and combining it with the focus hard stop.
Any questions give me a shout. Alternatively you could just buy my lens