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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

"mirrorless" with optical viewfinder

Beam splitters...

Beam splitters...

hunterrichards said:
Keep the form factor of a dslr but instead of a flipping mirror use a beam splitter... That way you can always look through the lens (with out looking at pixels!:sick: )
Click to expand...

In this thread I said something about that issue,

http://www.reduser.net/forum/showthread.php?p=282349&posted=1#post282349

A cube beam splitter would only work with special lenses, and a Pellicle Beamsplitter is hard to clean (but can work with everyday lenses), so there are issues.

Another option is to look at the sensor face with off-axis optics, that way you do not harm the main image, but the eye-cup must fit tight so that you do not get any light going back from your eye to the sensor.

You could use a rotating shutter single blade or butterfly, a single blade would work with most SLR and reflex movie lenses and does not harm the image much. It would also let you use global reset and not get rolling shutter artifact, maybe put it below the frame like in a Konvas on a stepper motor or small servo motor in sync with the sensor. The mirror could be plastic since it is just for the viewfinder.
 
I know this sounds outrageous but is this possible? Have a spinning/vibrating/oscillating sensor/sensors, sort of like 35mm adapters, for unique image? :)
 
NO BEAMSPLITTER, NO PELLICLE MIRROR! Please, If you look at history it has never worked out well at all.

Hunter there have been several SLR's and film cameras over the years that have worked like that, and they all had huge drawbacks compared to normal slrs.
 
I'm wondering if there is a way to use liquid crystals to turn mirrored effect within an angled glass plate, on and off electronically like in a LCD?

In one state the panel would be transparent and light hits the imaging chip. Flip the state and the panel reflects light up into the view finder???
 
Haze...

Haze...

DaveT said:
I'm wondering if there is a way to use liquid crystals to turn mirrored effect within an angled glass plate, on and off electronically like in a LCD?

In one state the panel would be transparent and light hits the imaging chip. Flip the state and the panel reflects light up into the view finder???
Click to expand...

I have not seen anything that is transparent enough to not have haze that would affect the image. If you find something let me know. PLZT can be used as a shutter, there are some other things but I have not seen a good mirror high speed electronic mirror.

Also anything thicker than about 0.0002" will give a ghost image, since it is at 45 degrees to the sensor face. If you put a dust cover window over the Pellicle Beamsplitters it could be used, but some lenses stick back too far for that to be used with them.

Also an inclined plate will cause aberration in the image since one part is closer than the other, the OLPF does that but since it is Parallel to the sensor the aberation is more even over the image, not more on one side.

Spining morror is used on movie cameras because it gets out of the way for the exposure. You could use a Guillotine but on a large sensor that would make for too much mass to move at 24fps or faster, it goes back and forth like a piston. Guillotine are good for Super8 size sensors, not SLR size...
 
Flip...

Flip...

Mike Prevette said:
NO BEAMSPLITTER, NO PELLICLE MIRROR! Please, If you look at history it has never worked out well at all.

Hunter there have been several SLR's and film cameras over the years that have worked like that, and they all had huge drawbacks compared to normal slrs.
Click to expand...

The problem with the flip up mirror for a movie camera is that you cannot see what is going on while you shoot except for the electronic screen on the back of the camera.

Also the flip mirror will break, we have that problem in our scanner, the camera will break after a few thousand feet of negative scanned, the curtain shutter is even more of a problem, since if the DSLR mirror would lock up and STAY up you could shoot a million or more expsoures, but it will not STAY up (do you know of one that will?).
 
OK, this is a bit 'out there' but what if the imaging chip was mounted on some sort of horizontal spindle.
On the back of the chip a mirror is mounted.
Spin the assembly so that the imaging chip, then the mirror is presented to the lens.
????
 
DaveT: What advantage does that have over a mirror in front of the sensor? Both solutions make optical viewfinder / sensor operation mutually exclusive. Unless maybe you flip the mirror / sensor continuously, dividing the exposure per frame between them. (Good as long as exposures are less than 16ms, and you'd probably notice a flicker in the viewfinder. Nothing comes without compromises!)
 
Is it possible to make a transparent image sensor and put the mirror behind the sensor, instead of in front?
 
I don't mind having a video viewfinder as long as it includes some good focusing guides. I've used the Leaf live view software, and it is adequate, but not ideal. Of course I'd like to have something that can be used as a waist level finder, and not just as a eye level finder.
 
Shaocaholica said:
It seems like the simplest solution is to use an EVF but instead of all the horrible EVFs of the past, really go all out like an extension of the new Panasonic G1s EVF which uses a high res(1600x900) LED-illuminated Direct-view LCOS system. I'm sure that could be pushed to 1080p with a higher pricepoint.
Click to expand...

It's an 800x600 apparently.
 
I mentioned optical viewfinder originally and I had the vision that there would be a 45 degree transparent mirror sending direct reflection to the sensor and passing through to the view finder:

light --------\-----optical viewfinder
.................|
..............sensor

I don't know if you could get the mirror to have the right amount of light pass through the mirror and provide correct color and at the same time deliver maximum light to the sensor. Maybe you'd loose some stops, I don't know.

KO
 
Hmm, maybe a mirror that can make itself transparent when current is passed through it -- like a HUD display, but reflective instead of just blocking?
 
Look at the Olympus E10

Look at the Olympus E10

knock out said:
I mentioned optical viewfinder originally and I had the vision that there would be a 45 degree transparent mirror sending direct reflection to the sensor and passing through to the view finder:

light --------\-----optical viewfinder
.................|
..............sensor

I don't know if you could get the mirror to have the right amount of light pass through the mirror and provide correct color and at the same time deliver maximum light to the sensor. Maybe you'd loose some stops, I don't know.

KO
Click to expand...

http://www.dpreview.com/reviews/olympuse10/
http://a.img-dpreview.com/reviews/olympuse10/images/e10cutaway.gif

Unfortunately you lose out both on the brightness in both the viewfinder and the sensor.
 
Why do you want a mirror? I forgot. Oh, I remember now... so you can't see in low light.

I remember going to CML early in the RED ONE development. The only advice I was given was that if we did not have an optical viewfinder, we wouldn't sell any cameras and wouldn't really have a professional camera. We haven't had one request for an optical finder in the last year and a half.

Jim
 
All ideas which involve something being between the sensor and the lens are impossible.

A flat piece of glass changes the optical path - Bolex came up against this on their reflex cameras. You need a specially designed lens (they call them RX lenses) to compensate.

The only advantage I see of an optical finder is that you can always see your frame, even if the system is off. I still double-take on EVF's when the AC has helpfully shut down the camera during some downtime.

It sounds stupid, but it is very nice to always be able to see.
 
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