If one was willing to render the AF system in their camera useless, is it possible to modify the mirror in some way to make it 100% reflective (rather than partially translucent)?
You could try laying some reflective mylar over the mirror. Its thickness would probably affect manual focus accuracy a bit, but it might let you see how bright it can be.
It would be sweet if there was a material with the reflectivity of mylar but the properties of that self-adhesive vinyl stuff that adheres to glass and other smooth objects without any form of adhesive. It could easily be cut to size and then pressed onto the mirror, and easily removed with no mess, restoring AF functionality.
Is this another one of my million dollar ideas that I'll do nothing with?
It shouldn't be difficult for a camera technician to remove the mirror of the 5D, since as Ed mentioned above they tend to fall by themselves, and replace it with a mirror from an old MF camera. I believe older cameras had larger mirrors (and viewfinders) so it will be mostly a job of grinding the mirror to the required size.
Excellent idea by the way! If it works for you, I will be certainly very tempted to do the same on my 1Ds2.
I wonder if it would be possible to remove the 5D mirror, take some careful measurements of the mirror frame and then design a mirror "caddy" that could be glued into place where the old mirror was.
The mirror "caddy" would of course be designed with the facility of easily switching out custom mirrors that have been ground to fit inside the caddy. Maybe the mirrors could simply slide into the caddy from the front and then use some clever mechanism to lock the mirror in place...
asbalyan wrote:
Along with AF, you may loose in-camera metering too... or May be I am wrong...
Since the metering is affected by the type of focusing screen used (well documented) I can only assume that the meter is in the upper part of the chamber, behind the screen, so a 100% reflective mirror would not cause metering to be lost.
You are correct though, that the extra light would likely affect the metering. Hopefully, EC could take care of that.
The meeting is effected by bright screen, but reason is very different. Bright screen has different reflective index (both side), so let go more light side the camera body... and so hitting more to the mirror.
If I am not wrong, the metering sensor is below the mirror. I will check, can be easy to find the designs of the DSLRS.
"The EOS 5D Digital SLR uses the same 35-zone metering
sensor as the EOS 20D, but it has metering functions on
a par with the EOS 1D Series. The sensor and the
metering optics are positioned behind the pentaprism
with the metering lens magnification set to obtain the
optimum correlation between the nine AF points and the
metering sensor zone areas."
cogitech wrote:
"The EOS 5D Digital SLR uses the same 35-zone metering
sensor as the EOS 20D, but it has metering functions on
a par with the EOS 1D Series. The sensor and the
metering optics are positioned behind the pentaprism
with the metering lens magnification set to obtain the
optimum correlation between the nine AF points and the
metering sensor zone areas."
Your problem may not be the mirror, but the penta-prism. One of the better SLR viewfinders is the Leicaflex SL and that camera also used a partially silvered meter.
Skip the caddy idea - doesn't the 5D have an existing mirror frame which is why it has clearance issues? Use that - the mirror must be removable somehow. From there, get an existing mirror from an older SLR and grind to 5D size. You can use a diamond wheel on a dremel to do the job, or any type of grinder. I'd use a front-silvered mirror only, since those have the highest reflectivity, but of course are the most fragile to damage.
whatever the attachment method it's going to have to be robust to handle the high-G accel/decel of the mirror slapping up and down 5 times a second or more.
how much is the transmission on the stock mirror? It can't be more than 20% I'd think, probably less. So, not a huge amount to gain here, I'd think...
Consider the EOS-1nRS - that had a 66% transmissive mirror! (Fixed, pellicle) but the viewfinder was still plenty bright (with the screen that came with it, which was brighter than normal screens I think).
robsteve wrote:
Your problem may not be the mirror, but the penta-prism. One of the better SLR viewfinders is the Leicaflex SL and that camera also used a partially silvered meter.
Robert
But nearly doubling the amount of light that reaches the pentaprism would surely help, no?
Ed Sawyer wrote:
how much is the transmission on the stock mirror? It can't be more than 20% I'd think, probably less. So, not a huge amount to gain here, I'd think...
Make Canon's shortcomings work for you.