# Why can't I use the optical viewfinder with Video?



## JonB8305 (Nov 1, 2013)

Is this a technical limitation of DSLR's?


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## neuroanatomist (Nov 1, 2013)

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 (Nov 1, 2013)

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 (Nov 1, 2013)

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 (Nov 1, 2013)

Zv said:


> 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 (Nov 1, 2013)

neuroanatomist said:


> 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.


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## duydaniel (Nov 1, 2013)

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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## Orangutan (Nov 1, 2013)

duydaniel said:


> 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.


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## Nishi Drew (Nov 1, 2013)

duydaniel said:


> 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


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## Zv (Nov 1, 2013)

neuroanatomist said:


> Zv said:
> 
> 
> > 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.
> ...



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.


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## Marsu42 (Nov 1, 2013)

Orangutan said:


> duydaniel said:
> 
> 
> > I wished they have never included the video features but focus on improving image quality instead.
> ...



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.


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## Orangutan (Nov 1, 2013)

Marsu42 said:


> Orangutan said:
> 
> 
> > duydaniel said:
> ...



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.


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## Marsu42 (Nov 1, 2013)

Orangutan said:


> 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.



Orangutan said:


> 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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## mackguyver (Nov 1, 2013)

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 (Nov 1, 2013)

Marsu42 said:


> Orangutan said:
> 
> 
> > 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.
> ...



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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## Marsu42 (Nov 1, 2013)

Zv said:


> 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?



Indeed, that's why aa filter is spelled "anti-aliasing" 



Zv said:


> Without it you would have to deal with that in post.



Probably yes, but the point is: only if required and only in that particular area! And moiré effects on full res stills should be very far in between, maybe 1% of shots in 10% of the image?, that means that for the others you're getting sub-optimal stills because the moiré effect in video is much more ubiquitous.

With your argument Canon could also force the camera to apply all other image "enhancements" to raw like lens profiles, de-vignetting, CA correction, nice poppy colors, ... but also all at the cost that if you don't want these in post you cannot get rid of them. If you shoot raw it should be as raw as possible, postprocessing software is always better at doing the job, even if more time and work consuming.


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## neuroanatomist (Nov 1, 2013)

Marsu42 said:


> ...Canon could also force the camera to apply all other image "enhancements" to raw like lens profiles, de-vignetting, CA correction, nice poppy colors, ... but also all at the cost that if you don't want these in post you cannot get rid of them. If you shoot raw it should be as raw as possible, postprocessing software is always better at doing the job, even if more time and work consuming.


Post-processing is quite effective in correcting vignetting, CA, and boosting saturtion. How easy is it to remove moiré in post? Care to have a go at fixing this?


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## Marsu42 (Nov 1, 2013)

neuroanatomist said:


> Post-processing is quite effective in correcting vignetting, CA, and boosting saturtion. How easy is it to remove moiré in post? Care to have a go at fixing this?



I'm not disputing there might be cases where a stronger filter can be useful and also that postprocessing is weak at removal - but if this would be such a severe problem in actual, real life stills shooting, Nikon wouldn't sell any d800-e ... and a quick search for this tells me that even after the removal of the low-pass filter non-recoverable moiré effects seem to be far in between except if deliberately provoked.

Btw here's some information on this from our favorite reviewer  http://kenrockwell.com/nikon/d800/vs-d800e.htm

My point is, following the discussion of the last couple of posts: If video would be excluded from a dslr or it would be tuned for stills shooting, the aa filter would be modified on Canon cameras like Nikon did.


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## duydaniel (Nov 1, 2013)

Marsu42 said:


> Btw here's some information on this from our favorite reviewer  http://kenrockwell.com/nikon/d800/vs-d800e.htm



Of course, what he basically said was the 800E is for pixel counting nut and the 800 for working pro


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## Mt Spokane Photography (Nov 1, 2013)

Nishi Drew said:


> Nikon started adding video later than Canon


What ever gave you that idea??
The First DSLR with Video was the Nikon D90. The 5D MK III is notable because it was FF, and had much better video quality, but it wasn't the first.

http://gizmodo.com/5042209/nikon-d90-official-first-dslr-ever-with-hd-video-recording


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## Marsu42 (Nov 1, 2013)

duydaniel said:


> Marsu42 said:
> 
> 
> > Btw here's some information on this from our favorite reviewer  http://kenrockwell.com/nikon/d800/vs-d800e.htm
> ...



As KR usually labels everything beyond midrange amateur level as utterly useless, this is high praise indeed, and he goes on writing...

"The D800E is for tweaks _who care more about pixels than pictures, but that's most of my readers_! Yes, I'm sure the D800E will be much sharper at 100% on-screen when shot by an expert under controlled conditions"

... which means if it's most of his readers, it's 99% of the readers around here


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## Zv (Nov 2, 2013)

Marsu42 said:


> Zv said:
> 
> 
> > 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?
> ...



It was a rhetorical question. I know what the AA filter does. As someone who shoots buildings I'd much rather not have to deal with removing moire, which Neuro has kindly demonstrated as being rather difficult. 

Also I don't know about you but removing moire from several hundred wedding photos of a brides dress might drive me insane.


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## Orangutan (Nov 2, 2013)

Marsu42 said:


> "The D800E is for tweaks _who care more about pixels than pictures, but that's most of my readers_! Yes, I'm sure the D800E will be much sharper at 100% on-screen when shot by an expert under controlled conditions"
> 
> ... which means if it's most of his readers, it's 99% of the readers around here



I think this may be the key sub-quote here:



> _when shot by an expert under controlled conditions_




This means studio or landscape using tripod, where you can anticipate and avoid moiré at capture, rather than (fail to) correct it in post. The numbers in this market segment will be very small. A camera without AA filter will also incur a substantial support cost since all the newbs who don't understand what they're buying will return their new purchases as defective (my buddy's iPhone doesn't do this!) On the plus side, that means more available from the refurb store!

My guess is that camera vendors could only get away with such a specialty product if it's so expensive that the clueless newb buyer would be embarrassed to admit he (probably a he) made a mistake in buying it.


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## Marsu42 (Nov 2, 2013)

Zv said:


> It was a rhetorical question. I know what the AA filter does.



Sorry, I missed that (it's harder in writing, esp. in a foreign language).



Zv said:


> As someone who shoots buildings I'd much rather not have to deal with removing moire, which Neuro has kindly demonstrated as being rather difficult. Also I don't know about you but removing moire from several hundred wedding photos of a brides dress might drive me insane.



Fair enough - I freely admit I don't (and cannot) know how severe the effect of a weaker or missing aa filter is, and I can only read about it in the reviews of the d800e. Btw here's also an interesting part from the dpreview review of the d7100 regarding the removal: 

_"In short, even if you were willing to put the best glass available on the D7100 and shoot at a wide aperture, you're not likely, even with a lot of effort, to leverage visible benefits of the OLPF removal. While this may be a bit of a disappointment for some, the very good news is that to date we've seen no practical downside to the filter's removal for still photography. It is essentially neutral with regard to image quality."_

There are also some interesting sample shots in this link: http://www.dpreview.com/reviews/nikon-d7100/18


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