I have short sight. I use glasses for correction. Can I do perfect mannual focus in an SLR camera?

Question

Even though I uses glasses for correction, it is not 100% solution for the vision problem. Though glasses correct my vision, there still is a residual difference between my actual sight and correction using glasses. I feel that will add an offset to the focal length if I try to focus manually in an SLR camera (using view finder). That means, even if it looks as a perfect focus to me, in reality it may not be the perfect focus to the camera sensor.

Does anyone give expert comments on this problem. How is there any solution for this?

Answer 1

Yes, you can. You just need to adjust the diopter for your use.

Here's what you need to do:

- Point your camera at a blank wall.

- Completely unfocus your lens.

- Change your diopter until the AF squares and other markings in your viewfinder are in focus.

There should be a little dial next to your viewfinder that will adjust the diopter focus. On my Canon 20D it's on the top-right of the viewfinder and has a I-+ symbol next to it.

The thing to remember with this is that if other people try to use your camera they'll now be a little off with focusing.

Answer 2

As long as the focus in the graticule is good then your picture will also be in focus.

So if you focus with your glasses on, then no problem.

Glasses off, you should use a correction eyepiece on your viewfinder so you can see the focusing graticule.