New to Digital cameras

Techniques and equipment.

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Postby BrianC » Feb 8, 2007 8:35 pm

I don't know what bulb setting is , My A630 only can be set for 15 sec. shutter.
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Postby MoonshineR DavE » Feb 8, 2007 10:18 pm

The bulb setting is rarely used on digital cams these days. I allows the shutter to stay open while you walk around and "paint" with your flash. If it 15 sec. is as long as the shutter will stay open then it doesn't have the bulb setting. Sounds like I'll have to buy some more flashes. Oh well, I don't have a problem with it but "she" probably will. :nono:
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Postby Teresa » Feb 9, 2007 12:24 am

If you want to do 'Bulb' painting with a digicam you are likely out of luck. My husband has access to a $1500 DSLR which said it had a bulb setting. Yep. It did. A B on the camera settings ring. He tried it. He kept getting only the first flash of the strobe. Nothing in the camera book said anything different, but when he did a web search under the fine print specifications, it turns out the B setting is only for 2 minutes max. This apparently has something to do with the max length time of receptivity of the CCD in the camera, and no one at the camera co. could envison a reason you would want to have a camera exposure longer than two minutes. (Never heard of painting with light, or tripod time exposures of night sky shots.)

Sometimes, you just gotta use a cheap film K-1000....
(evil grin).
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Postby NZcaver » Feb 9, 2007 12:57 am

According to the specs, 15 seconds is the slowest shutter speed on the Powershot A630. So no bulb setting. However, many modern flashguns have a fairly quick (if not instant) recycle time with good batteries - so you can probably do a little fast painting with light in 15 seconds. My Sunpak 383s (with a Guide Number of 120) take about 10 seconds to recycle on full power. So I could get 2 flashes in a 15 second window if I needed to. And if I dial down the power, the recycle time gets a lot quicker. Just a thought.

Interesting info on the DSLR "bulb" setting - thanks Teresa. :grin: Sheesh! :hairpull: What make/model is that camera?

Incidentally, can someone try this for me? Take the Powershot A630 and a regular slave flash (not the digital pre-flash ignoring type). Set the camera to manual shutter and aperture, turn the flash on, and see if it fires a single flash that sucessfully triggers the slave. I'm curious to see if this might work with the 630, like it does with my 540.
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Postby paul » Feb 9, 2007 8:14 am

NZcaver wrote:Conclusion - the little A540 does have some form of aperture that affects depth of field. I'd post the photographic evidence, but the test shots aren't very interesting - they were taken above ground.


Yes - I bought a Canon A630 a lttle while ago and it does have a varying aperture (and hence varying Depth of Field) unlike the Nikon I mentiond previously.
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Postby hunter » Feb 9, 2007 12:36 pm

This apparently has something to do with the max length time of receptivity of the CCD in the camera, and no one at the camera co. could envison a reason you would want to have a camera exposure longer than two minutes

it turns out the B setting is only for 2 minutes max.


2min is pretty good, my Rebel XT goes for 30 seconds although I might be able to get around that with a remote. The max time has very little to do with the camera people not understanding a bulb setting. CCDs have a fundamental problem with noise generated by the electronics of the CCD itself(actually caused by the CCD heating up).
This effect is cumulative for a single photo which means the longer your exposure the more noise you get in it. The max setting is based on how long the CCD can record before the noise starts to show up in your picture. The max time keeps getting longer so maybe in a few years...

If your curious: http://www.astrophys-assist.com/educate/noise/noise.htm a ways down the page under primary sources of noise.

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Postby bigalpha » Feb 9, 2007 12:56 pm

hunter wrote:...(actually caused by the CCD heating up)....


So, you just need to keep that CCD cool, and you can eliminate/reduce noise?
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Postby hunter » Feb 9, 2007 2:00 pm

So, you just need to keep that CCD cool, and you can eliminate/reduce noise?


That's pretty much it. The problem is that it is kind of like trying to keep a car engine cool while driving at max rpm(you need to rebuild the engine. You can get research type CCD's that can record for a long time but the cost is high enough I don't think you can get one in a commercial SLR. People keep getting better at making electronics so I'm just figuring it will trickle down at some point...

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Postby Realms » Feb 9, 2007 2:19 pm

I use a Pentax istD DSLR (uses all my K-1000 lenses...grin...) and have done exposures in excess of 5 min. Even at 5 minutes the noise hasn't beena big issue. The images are still clean and i'm happy with it. I just throw it in bulb mode and click my caver rated remote ;-)

Good stuff
never stop imagining what could someday come to pass...
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Postby Teresa » Feb 9, 2007 6:38 pm

hunter wrote:
This apparently has something to do with the max length time of receptivity of the CCD in the camera, and no one at the camera co. could envison a reason you would want to have a camera exposure longer than two minutes

it turns out the B setting is only for 2 minutes max.


2min is pretty good, my Rebel XT goes for 30 seconds although I might be able to get around that with a remote. The max time has very little to do with the camera people not understanding a bulb setting. <snip>
James


Did you not understand a statement made with tongue firmly in cheek when I made it? Sorry :oops: Of *course* the reason has nothing to do with what camera cos. do or do not understand, and everything to do with the electronics (and marketing) of the situation. (Though fewer and fewer digital cameras are made by camera cos. these days.) Even I knew about the noise issue; however, digital camera manufacturers listen to their marketers, not necessarily to the technicians. For every hundred thousand people who wants stop action of little Johnny running the bases, there is maybe one who wishes to stand in the cold or the dark with a shutter open for minutes on end. Bingo.

That's also why they've quit making cameras which a left handed person can operate without great difficulty--'one handed operation' means 10% of the population can probably not keep hold of the camera in a reasonable fashion, much less operate it. I've been appalled to see the digicams going the way of videocams (which I cannot operate, under any circumstances--it takes too much coordination with my off hand.)
But I will sit down and be quiet, now.
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Postby hunter » Feb 12, 2007 12:50 pm

Did you not understand a statement made with tongue firmly in cheek when I made it?

Sorry about that Teresa, I was in a rush and should have spent more time on my reply. I understood your comment but felt it was worth explaining the actual technical issue and the fact that it is improving as electronics get better. (especially in a "New to Digital Cameras" thread)

For every hundred thousand people who wants stop action of little Johnny running the bases, there is maybe one who wishes to stand in the cold or the dark with a shutter open for minutes on end. Bingo.

Yes, but at least in the cameras/posts I discussed we are talking digital SLRs which always have a bulb setting because there is a demand. I think the time restriction is really based on a conservative assesment of what the sensor can do.

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Postby rcoomer » Feb 27, 2007 2:08 pm

Bulb settings are still around and usable on the DSLRs. I've done 20 minutes plus on star trails on a Canon Digital Rebel, and a 20D. You do have to have the proper locking camera remote to use it though. Standing there holding the shutter would get pretty tiring. :grin:

But that's also the magic of digital. Many people do all night start trails by stacking lots of shorter exposures in photoshop to keep the noise levels low. So if you stack 10 - 15 second exposures, you have a 2.5 minute exposure. . .
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stacking photos

Postby Dave Bunnell » Mar 3, 2007 9:49 pm

Even if you do have the ability for a long time exposure, which I have on my Nikon D70S with a locking remote, shooting sequential frames for big room or long passage shots and then "stacking" them, as Rob mentions in the last post, is a great technique compared to the old film camera method of covering the lens while people walk around and flash.

When I do large areas that will require repositioning of flashes one or more times, I just capture each frame separately. Then when people move to a new flash position, I don't have to worry about covering up the lens. And best of all, if a flash somewhere along the way isn't properly hidden from the camera, it just messes up one frame and not a photo you've spent a long time and lots of flashes making.

It also gives you great material for making dissolve presentations.

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Postby wendy » Mar 28, 2007 6:05 pm

Well I've waited long enough and the A630 is $50 cheaper now than when this thread started, I figure I'll wait 2 more weeks and I'll get it.

Is everyone that has it still happy with this camera?
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Postby NZcaver » Mar 28, 2007 10:22 pm

wendy wrote:Well I've waited long enough and the A630 is $50 cheaper now than when this thread started, I figure I'll wait 2 more weeks and I'll get it.

Is everyone that has it still happy with this camera?

Wendy,

Not sure if this is even cheaper for you, but Beach Camera (an online store) currently has the A630 for $212 with free shipping to the lower 48 states.

http://www.beachcamera.com/shop/product ... u=CNPSA630

Normally I wouldn't do a company's advertising for them, but in this case I've bought 2 other cameras from them so far without a hitch. This is more than can be said for a lot of online stores, so I've heard.

And as for the flash/slave settings discussed earlier in this thread, I suspect you may be able to set the A630 to fire your slave flashes directly. The features and menus on it look similar to my A540 - so when you get your camera try selecting manual mode, turn the flash on and select the lowest power level (if you have this option) and see if you only get a single flash. If so, it should trigger your regular slave(s) without giving too much fog/dust/etc flashback from the camera's built-in flash.
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