20D - improved Katz Eye focsuing screen - Part 1/1

Started Aug 13, 2005 | Discussions thread
PN Regular Member • Posts: 234
Really usable at F11? Try this.

I have a doubt about the claim of usability at F11. Try this:

Use an MF lens which you can focus stopped down. With my Contax FU-4 matte screen in the 20D, I manage to use the split prism up to F8 roughly.

But here is the surprise: While the split prism reacts consistently until up to F5,6, it will shift beyond that, i.e. using it at F8 would result in front focus! Of course, looking at the photograph, you might not notice this due to high DOF.

So try this stop down your MF lens to F8 (or F11 for that matter) and focus a fairly close object with the split prism, then open the lens: Is the object still in focus according to the split prism?

What happens, I ignore, Doug may explain this better.

Also, strangely, I thought I hat front focus with my screen, but this concerns one lens only, but that one, quite a bit for close objects :-O, globally, I can recommend the Contax FU-4 for DIY matte screens.

Post (hide subjects) Posted by
SPy
.
swp
SPy
PN
PN
PN
PN
PN
PN
PN
PN
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow