December 20, 2014, 06:26:12 PM

Author Topic: Idea on how to eliminate the mirror and still have a SLR design  (Read 3463 times)

kphoto99

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #15 on: January 29, 2014, 06:23:49 PM »
In this "implementation" all the AF points would be on the sensor (like the sensor in 70D) so no need for 'holes'.

So you couldn't autofocus while looking through the viewfinder?  Yeah, I'd call that a problem.   :o

No, some of the AF points would be angled 45 degrees down, so in the "mirror" mode they would be looking through the lens.

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #15 on: January 29, 2014, 06:23:49 PM »

neuroanatomist

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #16 on: January 29, 2014, 06:59:44 PM »
No, some of the AF points would be angled 45 degrees down, so in the "mirror" mode they would be looking through the lens.

Then in imaging mode they would still be 'holes' in the image.

Regardless, fresh ideas are great, but this one just doesn't seem practically viable.
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kphoto99

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #17 on: January 29, 2014, 07:02:58 PM »
No, some of the AF points would be angled 45 degrees down, so in the "mirror" mode they would be looking through the lens.

Then in imaging mode they would still be 'holes' in the image.

Regardless, fresh ideas are great, but this one just doesn't seem practically viable.

Why would there be holes, the 650D & 700D have extra AF points on the sensor for autofocus in video mode?

neuroanatomist

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #18 on: January 29, 2014, 07:16:41 PM »
Why would there be holes, the 650D & 700D have extra AF points on the sensor for autofocus in video mode?

Indeed, and it's pretty well acknowledged that the on-sensor PDAF of those cameras is slow and not terribly accurate.  The dual-pixel design of the 70D is, so far, the only Canon implementation of on-sensor PDAF that approaches the performance of the dedicated AF sensor, and the latter is still superior in some applications.  DPAF is so effective because ~80% of the sensor's pixels are used for AF.  I suspect and implementation of '45° angled' AF pixels (or clusters) extensive enough to deliver AF performance adequate to replace the dedicated AF sensor would, indeed, leave 'holes'.
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Sanaraken

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #19 on: January 29, 2014, 07:36:45 PM »
Im sure the engineers in Canon thougth of this idea, but it just not possible or else we would have it on our DSLR already. Unless your smarter than the engineers in Canon and you can give them your idea.
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sagittariansrock

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #20 on: January 29, 2014, 07:53:08 PM »
  • rotating in the middle rather than the top frees up space needed in front of the sensor, but what for? That space is already there with EF lenses, and now you need all that space freed up at the front at the back - hence a bigger camera

I think this is the biggest issue- there will be no advantage in going through this whole rigmarole (the numerous problems already so eloquently stated) since you end up with a bigger camera. In other words, it would be much ado about nothing :)

Keep thinking though- successful ideas follow a bunch of failed ones ;)
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Halfrack

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #21 on: January 29, 2014, 09:54:04 PM »
More tidbits to chew on:

-You assume the back of the sensor is a flat plane, where has lots of electrical contacts plus a heat sink
-Microlenses on the sensor would throw a fit - they don't do this off axis stuff, plus would throw a lens color cast
-shutter - leaf shutters can do 1/800 of a second, period.  a focal plane shutter isn't going to like being moved around
-lag time - to take a photo it would have to pivot, close the shutter, take the image, and then pivot back into focus/viewfinder mode - much slower than the current setup
-Mirror box bounce - watch some slow motion video of a few frames, and see how much that mirror box bounces over and over with each frame
-general costs - a mirror box is MUCH cheaper to have replaced compared to a sensor

IMHO, sticking with the current mirrorless setups (rangefinder or EVIL) is a safer bet.
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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #21 on: January 29, 2014, 09:54:04 PM »

AcutancePhotography

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #22 on: January 30, 2014, 11:32:54 AM »
I wonder if there is any advantage in a type of digital Twin Lens Reflex camera?

It would be probably an overly complicated solution to a rather simple problem though.  :)
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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #23 on: January 30, 2014, 11:39:10 AM »
I wonder if there is any advantage in a type of digital Twin Lens Reflex camera?

Consumers would have to buy lenses in pairs.
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Sella174

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #24 on: January 31, 2014, 10:19:12 AM »
I wonder if there is any advantage in a type of digital Twin Lens Reflex camera?

Consumers would have to buy lenses in pairs.

Canon would love it if this concept ever got off the ground ... you'll be needing two EF 24-70mm f/2.8 blah Mark II lenses and two EF 600mm blah blah lenses. Instant doubling of sales. Whoohooo!
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Halfrack

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #25 on: January 31, 2014, 12:56:59 PM »
I wonder if there is any advantage in a type of digital Twin Lens Reflex camera?

Consumers would have to buy lenses in pairs.

Canon would love it if this concept ever got off the ground ... you'll be needing two EF 24-70mm f/2.8 blah Mark II lenses and two EF 600mm blah blah lenses. Instant doubling of sales. Whoohooo!

You wouldn't need to do pairs, a single lens much smaller than your current one would work for the frame & focus, and it could be a semi-superzoom with lots of AF points to cover a wide framing, but as you put on a longer lens, you'd end up with fewer points, but they'd cover the entire frame.  Design it to cover the 18-200mm range, the wider frame wouldn't have as full a coverage, and the tele/supertele would literally have the AF points cover the entire frame, and able to track stuff coming in and out of the frame, so if I'm tracking a subject, and something crosses from outside the frame it ignores it.
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viggen61

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #26 on: January 31, 2014, 01:19:37 PM »
The mirror allows a lot of light to the autofocus points that are behind it, so not all of it is reflected.

The reflex mirror allows a small portion of the light through for AF. It makes no difference to your eye, since your eye has the greatest computer on earth letting you see the image.

The sensor reflects quite a bit of light (I don't know if enough), a nano coating could be optimized to increase the reflectivity at 45 degrees.

The sensor reflects some light, but that is a natural result of having a highly polished surface. (It's like when your smartphone is turned off, you can use as a mirror in a pinch, but you wouldn't want to replace your bathroom mirror with it.) It is not the same as being a mirror. Any coating the increases reflectance will decrease the amount of light passing through it, therefore making the sensor less sensitive to light.

Live view would work just like now, the sensor would go into vertical position.

So how is it AFing again? I thought you said it used dual pixel?

The sensor would not be attached at the edge, but it would be through the middle, it would pivot on this axis. It would move half the distance that the mirror does now.

That might help a little... But one there is another issue. Your mirror box will need to be longer, unless you expect Canon to drop the EF lenses altogether, and make a whole new line based on the new, shorter, registration distance.

Vibration seems to be the biggest problem to me.

That is an understatement, I believe. There is a lot more in the sensor than you can see through the lens mount...
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9VIII

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #27 on: January 31, 2014, 05:20:15 PM »
We already know there's ways to make the mirror fold up that don't involve it slapping forward toward the lens, but really, after reading about the new Sigma 50f1.4 and Zeiss Otus design, I'm not entirely sure if that's actually a problem.

What people want from mirrorless is the advantages of using live view instead of the mirror.
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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #27 on: January 31, 2014, 05:20:15 PM »

100

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #28 on: January 31, 2014, 08:02:08 PM »
This thread made me wonder if anything can be done with the light that gets wasted due to the use of a Bayer sensor.
A Bayer sensor only uses 1/3 of the total amount of light hitting the sensor due to the color filters (RGBG). Could it somehow be possible to use the rest of the light for autofocus and/or some form of an optical view finder? 

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Re: Idea on how to eliminate the mirror and still have a SLR design
« Reply #28 on: January 31, 2014, 08:02:08 PM »