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Author Topic: Why can't I use the optical viewfinder with Video?  (Read 3732 times)

JonB8305

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Why can't I use the optical viewfinder with Video?
« on: October 31, 2013, 09:28:54 PM »
Is this a technical limitation of DSLR's?

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Why can't I use the optical viewfinder with Video?
« on: October 31, 2013, 09:28:54 PM »

neuroanatomist

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Re: Why can't I use the optical viewfinder with Video?
« Reply #1 on: October 31, 2013, 10:06:40 PM »
dSLR = digital single lens reflex.  Reflex refers to the reflex mirror that reflects light up to the viewfinder (via a pentaprism or pentamirror), which lets you see through the lens.  The mirror flips up out of the way ('reflexively') to expose the film/sensor.  So either the viewfinder or the sensor sees the light, not both at once.

I wouldn't call it a technical limitation, more of a design limitation.
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BozillaNZ

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Re: Why can't I use the optical viewfinder with Video?
« Reply #2 on: October 31, 2013, 10:57:00 PM »
It's like why can't you see things with your eye lids closed.

When the sensor is active, the mirror inside the camera is flipped up, hence the light path to the optical viewfinder is cut off.
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Zv

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Re: Why can't I use the optical viewfinder with Video?
« Reply #3 on: October 31, 2013, 11:24:34 PM »
Ummm haven't you ever used Live View?? Same thing happening there!

You'd need some kind of special mirror that let some light pass through to the sensor and yet reflect part of it up towards the OVF. Even if that were the case only part of the light coming in through the lens would be hitting the sensor and it would affect either exposure or the viewfinder brightness or both.

Physics 101: Light can't be at two places at the same time.
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neuroanatomist

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Re: Why can't I use the optical viewfinder with Video?
« Reply #4 on: November 01, 2013, 12:04:28 AM »
You'd need some kind of special mirror that let some light pass through to the sensor and yet reflect part of it up towards the OVF.

It's called a pellicle mirror. Canon used them in a few film SLRs a long time ago, Sony uses them today (the SLT series), and if you check the main CR page, you'll see that Canon recently had a pellicle mirror patent publish.
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JonB8305

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Re: Why can't I use the optical viewfinder with Video?
« Reply #5 on: November 01, 2013, 12:07:02 AM »
dSLR = digital single lens reflex.  Reflex refers to the reflex mirror that reflects light up to the viewfinder (via a pentaprism or pentamirror), which lets you see through the lens.  The mirror flips up out of the way ('reflexively') to expose the film/sensor.  So either the viewfinder or the sensor sees the light, not both at once.

I wouldn't call it a technical limitation, more of a design limitation.

I figured that was the issue.

duydaniel

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Re: Why can't I use the optical viewfinder with Video?
« Reply #6 on: November 01, 2013, 12:39:44 AM »
I wished they have never included the video features but focus on improving image quality instead.
You know stuff like iphone trying to do multiple things at once aren't good at everything

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Re: Why can't I use the optical viewfinder with Video?
« Reply #6 on: November 01, 2013, 12:39:44 AM »

Orangutan

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Re: Why can't I use the optical viewfinder with Video?
« Reply #7 on: November 01, 2013, 01:01:07 AM »
I wished they have never included the video features but focus on improving image quality instead.

This is likely a false premise, and it has been well-hashed here.  There is very little to suggest that including video has negative impact on stills (with one exception a few months back suggesting that there was a trade-off regarding speed at which the sensor is cleared, if I remember correctly).  Also, any camera that can't do video these days is a niche product: it will not sell well, and so will be much more expensive, regardless of IQ or features.

Finally, consider that the D800 sensor everyone drools over also does video.

This idea probably doesn't hold any water: video is largely a software thing, and is essentially a free bonus.

Nishi Drew

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Re: Why can't I use the optical viewfinder with Video?
« Reply #8 on: November 01, 2013, 01:11:51 AM »
I wished they have never included the video features but focus on improving image quality instead.
You know stuff like iphone trying to do multiple things at once aren't good at everything

There a particular problem with image quality? DSLRs have gotten better and better in the recent years, Nikon started adding video later than Canon and look at their D800, decent video but amazing IQ. Why NOT include video when you can and every other camera's got it? Knowing Canon, they haven't put much effort into improving video on the DSLRs since 2009 anyways, so the inclusion of video capabilities can not be blamed for the lack of desired progress in sensor technology. BUT, I can understand the sentiment for Canon bothering with video when they should be working on a lot of other stuff as well, just that I've been kind of making a living off of the 5DII and it's video

Zv

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Re: Why can't I use the optical viewfinder with Video?
« Reply #9 on: November 01, 2013, 05:11:33 AM »
You'd need some kind of special mirror that let some light pass through to the sensor and yet reflect part of it up towards the OVF.

It's called a pellicle mirror. Canon used them in a few film SLRs a long time ago, Sony uses them today (the SLT series), and if you check the main CR page, you'll see that Canon recently had a pellicle mirror patent publish.

You know, I read that rumor and I was like 60% sure what a pellicle mirror was! Thanks for clearing that up. The Sony SLT is a fixed mirror that splits the light towards a phase detect AF sensor and the rest to the image sensor. Since Canon already have dual pixel AF, what would be the advantage to Canon in pursuing a pellicle mirror?

Update : I figured it out! The Canon patent is for a variable translucent mirror. Interesting.
« Last Edit: November 01, 2013, 05:23:31 AM by Zv »
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Re: Why can't I use the optical viewfinder with Video?
« Reply #10 on: November 01, 2013, 06:14:29 AM »
I wished they have never included the video features but focus on improving image quality instead.
This is likely a false premise, and it has been well-hashed here.  There is very little to suggest that including video has negative impact on stills

But there is: For video, esp. with sensors that don't scale down to video res as well as the 5d3, you need a (stronger) anti-aliasing filter which at the same time reduces stills sharpness - that's why Nikon has two versions of their d800.

Orangutan

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Re: Why can't I use the optical viewfinder with Video?
« Reply #11 on: November 01, 2013, 08:39:53 AM »
I wished they have never included the video features but focus on improving image quality instead.
This is likely a false premise, and it has been well-hashed here.  There is very little to suggest that including video has negative impact on stills

But there is: For video, esp. with sensors that don't scale down to video res as well as the 5d3, you need a (stronger) anti-aliasing filter which at the same time reduces stills sharpness - that's why Nikon has two versions of their d800.

There is a potentially legitimate argument there; however I think there are few people who print so large that the AA filter makes much difference in sharpness.  Also, I think the D800E is targeted at those who want to go MF but can't afford it.  If the AA filter is the main concern, Canon doesn't need to forgo video entirely, they can just offer versions of the 5-series and 1-series without AA filter.  Problem solved?

And it's still true that any model of DSLR without video will be a niche product, and will cost more.  Again, think of the D800E: it costs $200 more to get a camera without the AA filter.  Shouldn't it cost less?

I'm not a big video person: I've shot maybe 20 minutes of video on my 3-year 60D, but video is here to stay.  If you have specific needs, well, that's understandable, but it won't do any good to curse video.

Marsu42

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Re: Why can't I use the optical viewfinder with Video?
« Reply #12 on: November 01, 2013, 10:47:18 AM »
There is a potentially legitimate argument there; however I think there are few people who print so large that the AA filter makes much difference in sharpness.

Probably not, but with that approach you can scrap a good part of the L lenses - but as the gear lineup is concerning iq and price, it's a bit strange to purchase a multi-thousand €/$ lens and then let the sharpness be reduced by a small piece of glass in front of the sensor with an aa feature that is good for nothing if you don't shoot video.

And it's still true that any model of DSLR without video will be a niche product, and will cost more.  Again, think of the D800E: it costs $200 more to get a camera without the AA filter.  Shouldn't it cost less?

Sure, but that's supply (production amount) and demand (unique feature) - I'd like the aa filter choice for every dslr, for example the 6d is really crappy with video, so there would be ample demand for a sharper 6d-e version.

Nikon has seen this problem, and as far as I understand it also severely reduced the aa filter strength for their latest cameras like the d7100.

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Re: Why can't I use the optical viewfinder with Video?
« Reply #12 on: November 01, 2013, 10:47:18 AM »

mackguyver

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Re: Why can't I use the optical viewfinder with Video?
« Reply #13 on: November 01, 2013, 10:53:46 AM »
No sarcastic replies???  I guess I'll have to add my own:

You can't use it because Ken Rockwell says you don't need an optical viewfinder for video ;)
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Zv

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Re: Why can't I use the optical viewfinder with Video?
« Reply #14 on: November 01, 2013, 12:26:21 PM »
There is a potentially legitimate argument there; however I think there are few people who print so large that the AA filter makes much difference in sharpness.

Probably not, but with that approach you can scrap a good part of the L lenses - but as the gear lineup is concerning iq and price, it's a bit strange to purchase a multi-thousand €/$ lens and then let the sharpness be reduced by a small piece of glass in front of the sensor with an aa feature that is good for nothing if you don't shoot video.

And it's still true that any model of DSLR without video will be a niche product, and will cost more.  Again, think of the D800E: it costs $200 more to get a camera without the AA filter.  Shouldn't it cost less?

Sure, but that's supply (production amount) and demand (unique feature) - I'd like the aa filter choice for every dslr, for example the 6d is really crappy with video, so there would be ample demand for a sharper 6d-e version.

Nikon has seen this problem, and as far as I understand it also severely reduced the aa filter strength for their latest cameras like the d7100.

Hang on a minute - doesn't the AA filter actually serve a purpose other than just smudge our images? Doesn't it reduce moire and aliasing? Without it you would have to deal with that in post. I'd much rather just add some sharpening (which I'm gonna do anyway) in post to bring the final image back to what it should be like without the AA. And anyone with a 24-70L II would testify to this - their images are plenty sharp already! I don't see the big deal. The fact that Nikon haven't completely removed it in the D7100 should tell us something.
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Re: Why can't I use the optical viewfinder with Video?
« Reply #14 on: November 01, 2013, 12:26:21 PM »