Canon 5D m2- Real optical viewfinder modification

Hunter Hampton

Hunter Hampton

Carbonite Member
Note: This is a video/cinema specific modification not really intended for still photography, I am just trying to gauge interest as its something I really want to do to my camera and the more people interested the less expensive the modification is.

I recently was in talks with fellow who has the ability to modify Canon cameras- specifically the 5D mark2 to allow use of the optical viewfinder while recording video. (Actually he can do a lot more than that but this is just the start!)

Use of an optical viewfinder while shooting video is something I have dreamed of in a digital camera because other than the Arri-21 (and dalsa origin), all other digital cameras have electronic viewfinders. There are many benefits to optical viewfinders:

The pros:
Zero image lag
Bright and high contrast ratio
"Uncompressed image"
Higher resolution than any HDTV- easy to see focus- more like a 4K LCD...
Requires no power to see through the lens


How it works:
The camera would be modified with a beamsplitter in place of the mirror , a new fiber-optic groundglass could be installed with frame guides for 16:9, 1.85:1, & 2.39:1 and the distance would be perfectly aligned between the sensor and groundglass so that focus is exact. Using a beam splitter in an slr camera is nothing new, there have been slr's from canon in the past that had a beamsplitter instead of a mirror (mainly for high frame rate cameras for sport photography).

The cons:
However, There are some downsides to using a beamsplitter in this method, first would be that it would send part of the light to the groundglass and then part of the light to the sensor, this would use up about a 1/2 stop in light transmission, this doesn't concern me as the 5D mark 2 is already so sensitive and great in lower light. 1/2 a stop is only like going from iso 160 to 100 or from T2 to T1.8- not that big of a deal.

Another possible con is that you would probably lose autofocus, again this isnt something I care about as I only use lenses in manual focus in video mode anyways.

The pros for me out weigh all of the cons by far. Just to confirm, you would click the camera into live view and still be able to see through the lens and record video (while also getting a live image on the back of the camera LCD) You would also still be able to take still photos, and maybe even lift the beamsplitter out of the way if desired.

The modification price is undetermined yet but it would be affordable, Im guessing somewhere between $500 and $1500. Additional add ons could include fully adjustable viewfinders as found on most film cameras (like the Arri 235 for instance).

All of these modifications would be performed in a state of the art facility, NOT BY ME! I just plan on having mine converted and wanted to see how many of you would be interested in this sort of thing as well.

Comments? Thoughts? Interested? Let me know!
 
Hunter,

I thought you sold your 5DII?


Neat idea!

I wonder if there would be prism aberrations from this on the final image. Prism's even in the f900 to th F23 have color fringing issues cause of the Prism. The F35 doesn't, cause the prism is not used.





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I bought another 5Dii after the firmware update!

There wouldn't be any quality loss on the recorded image- 3 chip cameras like the f900 have a totally different kind of beam slitter to separate the rgb channels, the only quality loss would be a 1/2 stop loss of light.
 
hunter richards said:
I bought another 5Dii after the firmware update!

There wouldn't be any quality loss on the recorded image- 3 chip cameras like the f900 have a totally different kind of beam slitter to separate the rgb channels, the only quality loss would be a 1/2 stop loss of light.
Click to expand...

Sounds awesome. Through the lens focusing is unmatched. I Look forward to seeing, and hearing about your results....



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Very cool Hunter. I'm very interested @ around $500. Roughly how long would I be without the precious? I'd have to ship it around the world but it would be worth it. I especially like the 2.39:1 frame guide idea. I'm going to be shooting with a 1.5x anamorphic adapter and doing a vertical squeeze rather than a horizontal stretch in post the thinking being that it might help reduce the aliasing.
 
These are called Pelical Mirrors I think - there was a Canon film SLR that had one years ago

Its a kind of a great idea

One problem is that there is a fundamental difference between viewing when using a camera to shoot stills and movies

When one shoots stills you view with the lens wide open - the camera stops down (closes the iris) as the mirror goes up

If you view optically with the lens stopped down beyond F4 the image in the viewfinder becomes a dark and unpleasant experience that is not as good as liveview

A TLR (twin lens reflex - see Rollei) design that allowed viewing wide open and shooting stopped down would be the ultimate

As the resolution of stills cameras has increased - I have a high res hasselblad - I have become less happy with using optical viewing - I promise it is really hard to focus a Hasselblad H1 to gain critical focus at 39mp

I have been arguing on the stills fora that good live view is the future to shooting great stills - preferably a liveview that shows both a crop of the chosen focus point and the full image

Additionally when creating a camera (from scratch) there are significant physical advantages to getting rid of the mirror because one can make a smaller lighter product more rigid product that can use lenses whose rear elements sit closer to the chip

An example of a camera of that nature is 'Alpa' whose lenses outperform the hasselblad H1 range of lenses sigificantly

S
 
Alpas are horrendously expensive, make Hassys seam almost affordable.
Canon made several Pellicle mirror cameras, the original Pellix / Pellix QL (I had one in the early 70's) then the later EOS 3 RT / RS(?). The fact that we've not seen one since may (Or may not) be significant.
I wonder if one reason for poor manual focussing experiance with modern SLRs is due to the crap focussing screens, set up for autofocus, and a fibre-optic, or even a Beatie type screen would give better focus.
Judging by the comments I've read on the AP forums, EVFs are not well liked, hated even.
Dave
 
Hunter how will it fit space wise vs the mirror? There's a couple of lenses I'm interested in but I'm told the mirror needs to be shaved for them to fit.
 
There are many reasons for poor manual focus on modern digital cameras

Screen design

Mirror/chip plane/misallignment

and IMO the biggest factor is the ability to criticise ones own work by zooming to 100% in on a 100mb file

Ive looked at the focus on my early scans and the res is just too low for me to be able to tell the focus point compared to a crisp hassy file

EVFs are a junior technology right now and are mainly rubbish I agree

However if you get a nikon D3 on a tripod the best way to focus critically on a static object is to use live view in a zoomed mode - no debate

Of course with live view you lose the "view at 1.2 shoot at 8 experience" which is a significant reason for 'real viewing' with shooting stills that is unlikely to apply to capturing the moving image too soon because the iris would have to pulse at 25FPS

S
 
I think they would work better with a pellicle since it doesn't have to move. The mirror shave is to stop the lower edge clipping the rear of teh lens when it flips up. No flipping mirror, no shave!
Dave
 
morgan_moore said:
If you view optically with the lens stopped down beyond F4 the image in the viewfinder becomes a dark and unpleasant experience that is not as good as liveview
Click to expand...

There would be minimal image darkening with a fiber optic screen but your right, if your in a very dark environment, live view would be better.
 
Using the 5D2 optical viewfinder in the video mode is a bad idea. There are many draw backs using the optical finder and looking thru the lens.

If you thought focusing at f/1.4 was difficult on the 3" LCD, then forget about it on optical viewfinder. I know you are proposing splitting the light to a ground glass. If you want a ground glass texture that renders the DOF accurately (meaning be able to render clear difference between f/1.2 to f/1.4 to f/2.0 to f/2.8), you're going to loose a lot of light on the ground glass image, in addition to the 1/2 stop lost on the beam splitter. Also if you're shooting at higher apertures, f/2.8, f/5.6, f/8, the optical image will be so dark that it's impossible to perform manual focusing. I've replaced the stock focus screen on the 5D with a focus screen that renders DOF more prominently at sub f/2.8 apertures. It does help a lot but the image is significantly darker!

Also how large would this optical image be? Manual focusing on the 5D2's optical focus screen is much more difficult than on the 3" LCD when working with large apertures.

On the pro photography forums, people are elated at the ability to use live view for focus checks, but on the video forums, people are looking at expensive ways to be able to use the optical finder... hah
 
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Hunter, can your man also exchange the optical low pass filter of the sensor to get rid of the aliasing issue?
 
joe 1008 said:
Hunter, can your man also exchange the optical low pass filter of the sensor to get rid of the aliasing issue?
Click to expand...

the aliasing in the movie mode is not caused by the low pass filter. The aliasing has to do with line-skipping on the CMOS sensor.
 
It's the line skipping, right. The actual low pass filter is designed for 20MP stills, not for 2K video. Therefore it has little to none effect in the video mode. A stronger low pass filter would probably quit or reduce aliasing but the still resolution would also go down significantly.
 
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hunter richards said:
There would be minimal image darkening with a fiber optic screen but your right, if your in a very dark environment, live view would be better.
Click to expand...

You are not reading me right

when any lens is stopped down in a stills camera even on a bright day the view gets dark - irrelevant of the quality of the mirror

just try the 'depth of field preview' button on any DSLR with the camera at 5.6 or 8 or 11
 
@Morgan: I would hope to use a fiber optic screen like on the Aaton cameras, I can stop down to T5.6 or 8 and the image is still quite bright, the only downside with the fiber optic screen being that when you stop down you can start to see the hexagon pattern- and that they are more expensive than glass.

@Joe: Thats the first thing I asked about and it can be done, its just then your actually cutting the resolution to lower than 1080p, even for stills. In front of the lens filtering is a better idea.
 
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