CCD DSLR with video recording

Matthew P

Matthew P

Well-known member
How come there's not been one yet? Is there something about the technology that makes it more difficult, or is it just the industry has moved towards the cheaper-to-manufacture CMOS sensors?

Pretty much all DSLRs used to have CCD sensors, and it would be great if one came along that did video recording because there would be no rolling shutter.

Rolling shutter does have a subtle effect on most footage, and subconsciously makes footage look far less solid than CCD-acquired images. Even now I love using CCD cameras/camcorders because of the solid look they give footage.
 
Not sure, I think CMOS have better dynamic range, and CCD highlights streaking is hard to control. Viewers instinctively associate streaking with video which makes it a quite unattractive artifact AFAIC.
 
I believe there's none because when it comes to CCDs you need prisms. Would probably be difficult to implement....cheaply. Plus...CMOS is just sharper IMO.


I dunno what the heck I'm talking about though :happy:
 
Ian-T said:
I believe there's none because when it comes to CCDs you need prisms.
Click to expand...

With a single chip camera?

The dichroic prism is used to split the image into RGB for a 3-chip camera, but there's no need to make that split for a single image sensor.
 
Hehe, so much misinformation out there with CCD technology. The process of making a CCD is not more expensive than CMOS really, because both require VERY tight tolerances for imager use. Both are analog in nature. Neither one is limited to one chip, neither is global shutter only. There are CMOS chips that have global shutters. There are CCD systems that have rolling shutters. The difference between both technologies is actually just the construction of the devices. How they are read/scanned is up to the developer.

Single CCD cameras are pretty noisy to me. 3CCD cameras look great, but suffer from needing a prism (which also, splits the incoming light). What it all comes down to is the design.

I talked with Red about why they didn't do a global shutter on their sensors and they didn't want to take the negative aspects of using one, and there is, you lose active area so the sensor is not as sensitive.

The BIGGEST advantage of CMOS is that you can put both the digital AND analog circuits on the same die. That is not only a cost savings, but also, a performance enhancement as well. You don't lose the time of being translated from one technology method to another (and that can be slow with level shifting and such).

What I want to see happen is eventually global shutters introduced into CMOS designs as the process gets better and the noise kept lower.

By the way, I am an IC designer and work with CMOS everyday! :)
 
No, both technologies are looking at a line at a time, the difference is, in a global shutter, you are not allowing the active device to continue to store photon information. I am being simplistic, but there are a multitude of methods that you can do that by. For instance, on some CCD technologies, you transfer all the stored photon information into an identical set of storage devices in the die, and then read them out since they will not be modified from that point forward.

The problem is, to implement the global shutter on CMOS, you loose active area. You become less sensitive AND your will suffer as well (as the DR is a function of how big the storage areas are). It seems that the amount to give up is not worth it from most manufacturers.

There are however global shutter CMOS sensors, but they seem to be more geared towards industrial use (where DR and sensitivity can be controlled much easier many times)

CMOS with global shutter: http://www.dalsa.com/mv/news/news.aspx?itemID=185

Cannot find a CCD with a rolling shutter, but I assure you, there is NOTHING preventing it from being made. That said, who would want too? :)
 
Can they make a CCD that do not streak highlights? To me, this artifact is worse than jello.
 
chon said:
Can they make a CCD that do not streak highlights? To me, this artifact is worse than jello.
Click to expand...

They could, but I am sure they'd have to give something else up to make that happen. I've seen some white papers on companies that have designed technologies to prevent this from happening, and I've read why they streak, but I think it is partly due to how they implement a global shutter and how they shift out the information on each row. (It's been awhile since I've read them). What would be interesting to me is to look at the Alexa design because their shutter looks almost global from what I hear!
 
Seems like I read something about some heat dissipation issues with CCD's....that being the reason we never saw 1/2" HD CCD sensors. Was there anything to that? Knowing me, I could have totally mis-read.....
 
Large CCDs are used in astronomical imaging (Without Bayer filter). I recall that in order to eliminate streaking they have to implement an "electron leak" which affects astrometric accuracy. So two types are made, with the leak for "pretty pictures" and without for accuracy.

Sorry if this sounds vague, I'm dredging my memory. A question posed over in stargazers lounge imaging section might elicit a more accurate reply.

Dave
 
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