Improvements to SLR camera design digital makes possible - Page 3
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Old 09-29-2011   #21
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Default Re: Improvements to SLR camera design digital makes possible

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Originally Posted by 12step View Post
With the advancements in digital sensors alone in cameras, soon we will be able to do things that we thought wasn't possible.
How short are our memories! We already do things that we didn't used to think possible. Who would have thought in the days before digital photography that it would be considered routine to customize the ISO and color balance for each frame of a small-format camera, or even to let the camera decide these settings in auto mode? (Not that I recommend using auto ISO or color balance!) And the color balance could be customized without having the lens wear a stack of color correcting and compensating filters? When was the last time you saw the need to put a color compensating filter on your digital camera? When could you fire off a burst at 3 frames per second with even an entry-level camera? In the 1970s, who would have thought that you could get a zoom lens that opened up to f/2.8 throughout its entire zoom range and still gave decent image quality? Or who would have thought that wltra wideangle zooms of decent quality were even possible? Or that autofocus would not only be possible possible but routine?

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Originally Posted by Sailor Blue View Post
The reason CCD's cameras can use an electronic shutter, i.e. read out the sensors fast enough for that to act as a shutter, while CMOS sensors can't is because of the way the chips work.

CCD or CMOS pixels are always sensitive to light and are continuously accumulating charge from stray light inside the camera or from dark current. Before the image is taken each pixel is read out in order to zero out the charges that have collected on them. The shutter opening and closing is what limits the exposure to light. The amount of charge that collects in each sensor pixel during the exposure is directly proportional to the amount of light absorbed by that pixel.

A CCD sensor is like a bunch of bucket brigades. Once the exposure is finished all the individual sensor pixel charges are moved almost instantly down the row of sensor pixels into a row of storage wells. The sensor pixels will now start accumulating a new charge, but that doesn't matter because only the original charges from the exposure will be read out and the non-exposure charges will be zeroed out before the start of the next exposure.

A CCD sensor is like a row of buckets filling with information all at the same time (exposure) then almost instantly the information in those buckets is passed them down a bucket brigade to another place to store the buckets until someone can come along and measure the amount of charge in each one individually (A/D conversion).

With CMOS you have to connect to each pixel sensor individually and do an A/D conversion. There is no way to set up a bucket brigade to store the information - you have to get it from each pixel one at a time unless you have multiple A/D converters. Addressing each pixel individually takes too much time to allow for electronic shutters.
You have only said that CMOS sensors cannot be set up in a "bucket brigade" configuration without explaining why or pointing us to more information that might explain this phenomenon more thoroughly. I was hoping for something better than that.

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Originally Posted by Sailor Blue View Post
Electronic shutters also have auxilliary mechanical shutters that actually open and close up to, say, 1/125th of a second. This helps to protect the CCD from dust and damage. Beyond that speed, the computer just grabs a progressively smaller slice of time from the CCD and "fakes" higher shutter speeds electronically.

The Nikon D70s have an electronic shutter. It is small, light, not particularly heavy-duty and sports a 6.1MP chip. That sounds small by today's standards (the camera is about a year old) but it gives more than 3,000 pixel on the long dimension. Which is plenty for my needs.
You can turn a sensor on and off electronically without any moving parts. In fact, I did exactly that back in 1983-1984, when I had to turn a photodiode's sensitivity on and off electronically. I did this with a network of CMOS analog switches that operated entirely from electronic signals. When the photodiode was "off," its integrating capacitor was shorted out with one of these switches so it couldn't charge. A second switch was opened to prevent any stray charge from entering the amplifier. The photodiode was switched "on" by electically opening the switch shorting the capacitor and closing the switch in series with the current input from the photodiode. Zero moving parts.
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Old 09-29-2011   #22
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Default Re: Improvements to SLR camera design digital makes possible

There have been some whacky camera designs over the years, but what gets forgotten is how the human body is designed, and how a photographer (not snapshooter) works.

Why are car controls still designed the same? Why don't we have steering wheels like the car from "Knight Rider" or have a joystick instead?

Because it's a tried and tested design that WORKS!!!!

I've used those mirrorless SLRs, and I HATE THEM!!! The video is still poor in low (and high) light, and can't keep up (for auto racing photography).
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Old 09-29-2011   #23
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Default Re: Improvements to SLR camera design digital makes possible

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Originally Posted by scoundrel1728 View Post
You have only said that CMOS sensors cannot be set up in a "bucket brigade" configuration without explaining why or pointing us to more information that might explain this phenomenon more thoroughly. I was hoping for something better than that.
I think I understand what he's saying. With CMOS you'll get rolling shutter issues. With a CCD, they clear and "latch" the light at a precise time across the whole sensor, while CMOS does not. So the CMOS is more like the camera's curtains rolling across it, except that while the 2nd curtain is closes on a pixel, the first opens up again on that pixel.

However, this shouldn't matter with a flash which is mostly what we're talking about.
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Old 12-27-2012   #24
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Default Re: Improvements to SLR camera design digital makes possible

i hate live view. its slow and inconvenient. id rather have something that you can electronically see through the viewfinder with information of everything. i only use live view when i have a tripod, and taking landscapes(but thats barely my style)
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Old 12-27-2012   #25
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Well, there's no law that says you have to use live view. I find cases in which having your face immediately behind the camera is inconvenient. For these cases, I use live view, such as in overhead shots, very low extreme closeups in the field, shooting directly down on an object in the middle of a large table, such as a sheet cake at an event. I upgraded to the Canon 40D partly for this feature. Now, if only the screen were articulared...


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