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View Full Version : Why don't dSLRs have video modes?



Coltess
02-14-2005, 07:30 AM
I have been wondering why dSLRs do not have video modes.
I realize that you would not be able to use the viewfinder while recording video, but since all (as far as I know) dSLRs have a monitor on the back that could be used for composition/tracking of the video clip that problem should be surmountable.
Anyone know why?

gary_hendricks
02-14-2005, 07:39 AM
I have been wondering why dSLRs do not have video modes.
I realize that you would not be able to use the viewfinder while recording video, but since all (as far as I know) dSLRs have a monitor on the back that could be used for composition/tracking of the video clip that problem should be surmountable.
Anyone know why?

As far as I know, I've not come across a DSLR that can shoot video clips. :confused:

ktixx
02-14-2005, 07:51 AM
This is my personal opinion, so don't take it as The Word, but I am pretty sure they don't because DSLR's actually mimic film cameras. Basically what I am trying to say is that small point and shoot camera sensors are constantly "seeing" light. There is no physical shutter in front of the CCD, the manuf. consider it an "electronic" shutter. On some DSLR's there is a cleaning mode where the shutter and the aperature will open to their fullest, and the mirror will flip up, but this is primarily for cleaning purposes. If video could be taken during this point, you woudn't be able to see what you were capturing. Overall It is probably a combination of 2 things, the first is what I have listed above, the 2nd is probably the fact that DSLR's are considered more on the Professional side, therefore video isn't as important. The video quality achieved using a point and shoot camera is really sub-par. I am sure with all the technology they have today they could manufacture a DSLR which could take short video clips, but overall I don't think it is that important to most people in the class to purchase a DSLR.
Ken

Rhys
02-14-2005, 08:38 AM
This is my personal opinion, so don't take it as The Word, but I am pretty sure they don't because DSLR's actually mimic film cameras. Basically what I am trying to say is that small point and shoot camera sensors are constantly "seeing" light. There is no physical shutter in front of the CCD, the manuf. consider it an "electronic" shutter. On some DSLR's there is a cleaning mode where the shutter and the aperature will open to their fullest, and the mirror will flip up, but this is primarily for cleaning purposes. If video could be taken during this point, you woudn't be able to see what you were capturing. Overall It is probably a combination of 2 things, the first is what I have listed above, the 2nd is probably the fact that DSLR's are considered more on the Professional side, therefore video isn't as important. The video quality achieved using a point and shoot camera is really sub-par. I am sure with all the technology they have today they could manufacture a DSLR which could take short video clips, but overall I don't think it is that important to most people in the class to purchase a DSLR.
Ken


What I'd like to see in a dSLR is what I get in a Canon S1 IS but with interchangable lenses, faster focussing and less modes. Plus a viewfinder grid that can be used to align the horizon (maybe an internal spirit level too).

aaronl87
04-24-2006, 09:12 PM
ok, just my own opinion.! not quite sure, but i think it's because of the lens. i sell camera at a electronic retail store, and by playing with all the digital cameras (point and shoot) that has video on 'em, i noticed that you cant move neither of the zooms (optical or digital). -well actually you can set them before you record the video. and i think that is why dslr's doesnt have video on them, because you can move the lens manualy, unlike a pointshoot the camera's program prevents you to do that while recording the video. that is why i think dslr are'nt capable of capturing video (*coz the lens can be adjusted manualy and it is quite impossible to capture the lights to create a video). once again im not sure, but i just thought id share my opinion!
but hey! look on the brightside! the technology is driving way too fast, so dont be suprised if dslr's with video shows up in two years! (looking forward to that!)

* note that all digital camrecorder's lenses are not capable of manual movement rather by the camera programs. refer that difference between a manual lens (dslr) and zoom (optical and digital).

DonSchap
04-24-2006, 11:00 PM
One of the funnier aspects of this discussion, that everyone seems to be missing about dSLRs, is the flippin' mirror.:D

The only reason you can see THROUGH THE LENS(1) is because the mirror(2) reflects the image to the pentaprism(7) in the top of the camera, so you can see through the viewfinder (8) what you are shooting BEFORE you shoot it. As the photograph is taken... the mirror flips up (5), temporarily BLINDING the photographer, as the image goes to the shutter(3), which opens in front of the sensor(4) and allows the sensor to capture it.

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If you were constantly in a 'movie mode', you would have no idea what you were seeing, because the mirror would always be in the "upright and locked position". In other words, no reflection to the viewfinder. The LCD does not allow you to view the image until it has been stored in the camera's temporary memory. That's why you can still see an image on your camera, even if you do not have a media card in the camera. Your image is in the small digital buffer (that temporary memory)... until you shoot another photograph or turn off the camera.

The only camera I ever saw that allowed for pictures WITHOUT a moving mirror was the Canon F-1 High Speed Pellicle Mirror Camera.

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The mirror was a fixed, semi-transparent surface which allowed for both the viewfinder and the film in the camera to see the image, simultaneously. Pellicle disadvantages are slightly degraded image quality since the pellicle is always in the optical path, loss of about 1/2 f/stop of light to the film since light is directed to the finder, a slightly dimmer finder since all the light is not directed to the finder for focusing, and difficulty keeping the pellicle clean since it attracts dust like a magnet (sounds like a sensor we all know and love, eh? ). Older pellicles, such as those in the Canon Pellix, have shown a tendency to yellow and separate.

That was one expensive camera, believe me. I don't think the buying public would really spring for it, these days. They will buy their crappy little pocket digital movie cams... and like it.

Why are point and shoots so popular? Because you don't even have to be interested in photography and will still get a relatively decent photograph of your toady and the gang. :p

Coltess
04-24-2006, 11:06 PM
ok, just my own opinion.! not quite sure, but i think it's because of the lens. i sell camera at a electronic retail store, and by playing with all the digital cameras (point and shoot) that has video on 'em, i noticed that you cant move neither of the zooms (optical or digital). -well actually you can set them before you record the video. and i think that is why dslr's doesnt have video on them

That is just plain wrong. Get your hands on a Konica Minolta A200. It has manual zoom controls and it works just fine during "filming". The reason that dSLRs don't shoot video is that you would not be able to see what you were filming since the mirror would be up to allow light to get to the sensor.

Take a look at a movie I shot last summer with my A200: About 2/3 through I zoom in with no problem. http://www.nilssons.dk/us/video/vand.htm

DonSchap
04-24-2006, 11:23 PM
Yes, very well said, Coltess. I kind of wish I had been that... to the point. :D

Coltess
04-24-2006, 11:27 PM
Yes, very well said, Coltess. I kind of wish I had been that... to the point. :D
Thanks!

The LCD does not allow you to view the image until it has been stored in the camera's temporary memory. That's why you can still see an image on your camera, even if you do not have a media card in the camera. Your image is in the small digital buffer (that temporary memory)... until you shoot another photograph or turn off the camera.
That should be a fairly simple fix, unless the current sensors can't handle being on for extended periods of time for some reason, but I hadn't thought of the "dust sucking effect" of the sensor.
It doesn't matter anyway. I get seasick just thinking about shooting video with a 300mm lens even with the AS on my 7D :D

timmciglobal
04-24-2006, 11:35 PM
Yes that is the exact reason. The sensors get very hot and produce increasing noise as exposure time goes with high levels of light.

It's why the 20Da had live preview but required a cooldown period.

Tim

coldrain
04-25-2006, 02:11 AM
There are two reasons. The 1st reason is exactly the reason you do NOT have life preview on DLSRs (except 1): the sensors are so big and use so much power that they gett way too warm to be used for a longer period of time.

The 2nd reason is, that the ONE camera that does have life preview, the E-330 (has a smaller sensor though, and a new type at that) can not focus during life preview and will need manual focussing then. You really do not want a video mode where you have to keep manual focussing! The AF system does not get light when the mirror is up... so that is the reason for that camera.

Shosta
04-25-2006, 02:33 AM
The 2nd reason is, that the ONE camera that does have life preview, the E-330 (has a smaller sensor though, and a new type at that) can not focus during life preview and will need manual focussing then. You really do not want a video mode where you have to keep manual focussing! The AF system does not get light when the mirror is up... so that is the reason for that camera.

It depends of the mode A or B. In A mode the autofocus works.

http://www.dpreview.com/reviews/olympuse330/

coldrain
04-25-2006, 02:45 AM
It depends of the mode A or B. In A mode the autofocus works.

http://www.dpreview.com/reviews/olympuse330/
In the A mode the image is so crap it is unuable for anything, so no video that way.
So, that is why i don't mention that mode. It is irrelevant in this discussion.

Shosta
04-25-2006, 03:01 AM
The ccd that takes the image in Mode A has 5 Megapixels. I find this enough to take a VGA video.

Norm in Fujino
04-25-2006, 03:06 AM
In the A mode the image is so crap it is unuable for anything, so no video that way.
So, that is why i don't mention that mode. It is irrelevant in this discussion.

Sorry, Coldrain, but that's just, well, "crap" :D ; i've used (read: briefly tested for a couple hours) the E-330 in both A and B modes, and the image was perfectly good in mode A as well as B; they appear pretty much identical, in fact, aside from the 92% field of view in A mode versus 100% in B mode. How did you have the camera setup, and what did you see that made you feel the A mode image was "crap"?

Mode B is obviously a "macro mode", specifically called so by olympus and explicitly meant for tripod use, due to the manual focus necessitated. But there are some not-obvious advantages to that as well. Here are some excerpted comments from part of a Japanese review (http://dc.watch.impress.co.jp/cda/longterm/2006/04/25/3702.html) that just came out this week (this is just one part of a six-part series review of the E-330)

"One area in which mode B shows its value is the use of heritage lenses. An attraction of the 4/3 system is its ability to use a wide variety of mount adapters permitting the use of many different heritage lenses. Of course, you're limited to manual focus, so the decision comes down to whether to use them through the OVF or in mode B, but since I like to use heritage lenses wide open, I consider the B mode with its 10x magnification a godsend.

"Another blessing for fans of heritage lenses is the ability to set the live view boost mode to ON; in this way, even when using heritage lenses with stopped-down metering, you can focus with the iris stopped down and still have a bright image on the LCD. This may not make much sense to present-day users who are hooked on wide-open metering, but users of heritage lenses will understand the benefit of this function. And it is also beneficial when not stopped down, by providing a bright image in dark environments.

"Another convenience when using mode B is to set the drive/copy/print button to Preview B. Then, when shooting in mode A, if you feel the screen’s 92% coverage is insufficient, all you have to do is to press the button to temporarily switch to mode B, compose using its 100% field of view, then release the button [to return to mode A], and use the AF to focus and snap the shot. This is a well thought-out function.

"Looking over many different digital cameras, I often think, 'If I had been the designer, I would’ve done it this way. . .' and in the case of the E-330, too, I might not have even included mode B. But without mode B, this camera wouldn’t be half of what it is, and I’m sure I would’ve later regretted omitting it."

(my translation).

coldrain
04-25-2006, 03:34 AM
"The quality of the view depends on what live view mode you're in. In the everyday "A mode", the quality is decent, but not as good as you'd find on most compact digicams (including the Stylus 800 from which the secondary CCD comes). Things just seem darker and grainier than I would've expected, especially in lower light conditions. The view in "B mode" is much brighter and sharper, but as I stated at the beginning of the review, it's only for manual focusing. For brightening things up you can turn on the Live View Boost feature, which does make things easier to see. However, the view flickers and is quite grainy, at least on my pre-production camera."

From Jeff Keller's review of the E-330. So, why is the A mode darker and grainier? Because it only gets part of the light, the rest goes to the AF and viewfinder. Not very usable for video.

jsiren
04-25-2006, 04:27 AM
Folks,

This whole discussion is a bit like "why is a hammer not good at turning small Torx screws, and how could we better adapt the hammer for turning small Torx screws"... :D

You're all partially right, although most of the problems could be solved. Cooling systems could be devised, AF could be implemented together with video (it's routine in video cameras!), and the viewfinder system could be adapted for video use. Apart from artistic and battery life issues, zoom is no problem with video, except for the acoustic noise the motor zooms make in small cameras (that's why they're disabled).

The ultimate obstacle for video in dSLRs, however, is the sensor type. Unlike CCD, CMOS sensors must be read and cleared in the dark. That's why they're best suited in a SLR, behind a shutter. A CCD sensor can be used for video, a CMOS sensor cannot. CMOS sensors are used in cameras primarily for their image quality. Would you be willing to compromise that in a dSLR for a video capability?

If you want to do a video camera with CMOS sensors, you'll end up with something resembling a rotary-shutter film camera, the sensor replacing the film.

j.siren

coldrain
04-25-2006, 04:51 AM
That is not true at all, there are video cameras with CMOS. Also, the E-330 chip is more like CMOS than like CCD and it has live preview. CCD gets a lot warmer (uses more energy too) in the sizes DSLRs use.
The Canon EOS 20Da has live preview for 20 secs. It has a normal CMOS. Nonsense that it "has to be cleared in the dark".

Video cameras are NOT Single Lens Reflex so that point of yours is useless. They are more like normal compact digital cameras.

So all in all I do not get your ideas at all.

David Metsky
04-25-2006, 06:13 AM
While there are several technical reasons why (nearly all) dSLRs don't take video (or do live preview), the main one seems to be that dSLRs are designed to take the best still photos possible. Anything that reduces image quality or usefulness has been removed.

Video and live preview would both have a significant impact on the prime focus (pardon the pun) of a dSLR, in order to deliver features that aren't absolutely required by the folks who buy SLRs and the expensive lenses. Someday, when they can be added without compromising image quality I'm sure they will be.

-dave-