OT: Revisiting 'Digital Cameras'

Not overly relevant to the boot time, the casio takes just as long to boot with a CF card in as it does with a microdrive.

The time to process and store an image post exposure is longer with the microdrive though.

Reply to
Dave Liquorice
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Recently got a pentax istD so's I can use all my old pentax lenses

Reply to
Larry

I recently had a Nikon D70 & it was indeed a great camera, just too big for me!

The Canon G6 is a very good camera & not silly money.

Nige

Reply to
/\/ / & E

nikon 4100 currently on offer at my local asda store 146 ukp

Reply to
Warwick Barnes

You can set it to take as many pics as you want in quick succession and it will store only the last 5, I've used it on many occasions to compensate for the delay between shutter press and picture taking. I look through the viewfinder with one eye and watch the scene with the other and start firing when the car or whatever is about to come into the scene, and stop when it leaves. I usually get at least one useable pic.

As for Martin's pick list, I don't think he's going to get anything that matches without throwing away the "cheap and compact" requirements and going for a digital SLR like a Canon 300D or similar.

Reply to
Ian Rawlings

Digital cameras invariably take the picture to an internal buffer then write it to the card afterwards, media type has no effect on the time delay between pressing the button and the picture being *captured*. Once the picture has been captured, *then* you have to wait for a bit until the image is written to the media. Capturing the image takes as long as it takes the shutter to fire, by definition. When you set the shutter speed to 1/60th of a second, then you are really setting it to spend just 1/60th of a second in capturing the image.

The issue here is the delay between the button being pressed and the image capture starting (a.k.a. "shutter firing"), for example you try to take a pic of a moving car and when it's in the centre of the veiwfinder you press the button only to find that the captured picture is of either a blank track or the back end of a car as it's moved so far since you pressed the button.

Given the advances in electronics over the years, the cynic in me thinks that this delay is no longer necessary but is introduced to keep sales of higher-end cameras up, but I may be being a little over-cynical there.

Fully mechanical SLRs like the Olympus OM4ti (IIRC) and also other traditional film SLRs also suffer from a delay caused by the shutter trigger mechanism, however it's *tiny* compared to the digital problem. Even so you could still get "rt" versions of many film SLRs that went to great pains to minimise this delay and were popular with sports photographers.

A friend of mine has a Canon 300D, and says that the reaction time to button presses is "instantaneous", but one person's instantaneous is another person's wading through treacle. I tried taking pics with my Fuji Finepix 602 at airshows and car races, and even when switching to fully manual (focus and exposure) it was still rubbish. I had to resort to the rapid-fire-and-keep-last-5 mode to avoid getting masses of empty shots. At least the digital camera doesn't cost me a tenner per film including processing though!

It might be worth trying the Canon 300D, it's expensive and large but if my friend is right (and he uses the thing at airshows and is used to high-end SLRs like EOS 3's) then it'll remove the delay and also give you access to some very good optics.

For proper depth-of-field control you *have* to go to an SLR with a "prime" lens, i.e. not a zoom lens, with such a lens you can set the depth of field using the lens barrel markings. With canon kit you can buy old 50mm lenses for less than 100 quid and put them on your super-duper digital, however due to the difference in size between

35mm film and the CCD in most digital cameras, the lens barrel markings will be out so you would have to do a bit of mental maths, like multiply the distances by something like 1.3. Using lens barrel markings is the key to composing a shot that uses focus as part of the composition, not even depth-of-field preview can compensate for it.

In a digital camera, there's nothing to stop the manufacturers from putting in a proper depth-of-field control, e.g. state that you want

1.3 metres to 5 metres in focus and it sets the focus and zoom appropriately, but there's just no demand from the look of it.
Reply to
Ian Rawlings

Wifey recently replaced our aging Finepix. Battery life had got down to about 10 mins!

Pentax Optio 750Z. Bloody brilliant.

Pros: 7 megapixel, pentax lens, loads of control, bells and whistles etc. Does not take standard batteries but battery life seems to be huge, we've charged it just twice since Christmas! AND it comes with an out-of-camera charger as standard. Dunno about robust but the screen flips round like on a camcorder so it doesn't get scratched when in your pocket. Sounds like a cat meowing when you turn it on.

C> It's nearing 'that time' when I'll need to be replacing my trusty

Reply to
Dan Burdge

I tried the 300d & whilst it took great pictures, the build quality ins't great. I got a Nikon D70 & that is a bloody ace camera.

Nige

-- Subaru WRX (The Bitch)

Series 3 Landrover 88" (Albert)

"If you tolerate this then your children will be next"

Reply to
Nige

Sorry, I wasn't referring to the boot time, but the capture time once the shutter has been pressed. Size of memory card and technology used do play a part though, since the file system has to come up before images can be shot/saved.

Reply to
Danny

My Olympus mje-400 has a half way on the shutter what starts up the autofocus and light setting stuff, which takes about a second, and then when you close the button the rest of the way it takes instantly. Works well for moving things but it takes a gentle touch as there is no detent on it. Bike racing you need to focus on the track, watch the display change and then as the right guy comes in sweep through with him and click at the point you focused on. Very easy when you get used to it.

nigelH

Reply to
Nigel Hewitt

Hmm, I doubt it's instant, otherwise you wouldn't need to sweep with him, with a proper film-based SLR like an EOS 3 or even a 20 quid Olympus OM40 you can watch the bike come into frame, wait till he gets to the middle, and take the photo. With that kind of reaction time you can then do fancy effects like motion blur where you *do* sweep with him with a slightly slower exposure than you need so that the bike (which is relatively stationary as you are sweeping with it) comes out sharp while the background is blurred. You can't get that kind of control with the current crop of digital cameras unless you spend mucho dinero on a 400 quid digital version of a film camera that used to sell for 70 quid!

Progress eh ;-)

Reply to
Ian Rawlings

*shrug* I sweep because I need to frame it. The problem is me. Digital camers do have a 'shutter' time. It is the period over which the CCD integrates light but involves no moving parts. If I am using the flash with the half push the delay is imperceptable.

It works for me.

nigelH

Reply to
Nigel Hewitt

great. I got a Nikon D70 & that

There is the EOS 10D which is virtually identical (in fact slightly higher) spec but not in a stupid reflective plastic body!

Reply to
Tim Hobbs

My first air-show photos were taken on a camera which you can now get on eBay for around thirty quid. 135mm lens maybe the same again.

There's a digital camera which will take the same lenses, sold for a couple of thousand.

But that 85mm f2 is still a damn fine lens, 70 years after the optics were designed.

Reply to
David G. Bell

On or around Sun, 20 Feb 2005 08:31:32 +0000, Tim Hobbs enlightened us thusly:

great. I got a Nikon D70 & that

mind, none of these are much like what Martyn was after.

Reply to
Austin Shackles

Some of them *do* have moving shutter parts, which puzzled me ;-) It's mostly the lower-end cameras that don't use mechanical shutters, I did find out the reason for this but it escapes me now. I think it's something to do with the colour response of the CCD when it's activated being different to when it's been going for a while or sommat, so more expensive cameras keep the CCD going most of the time and use a mechanical shutter. That's from memory though. I know that all the digital SLR cameras use mechanical shutters, even my Fuji Finepix S602Z has a mechanical shutter. Can't remember if my tiny Minolta has or not.

But yes, all current cameras have an exposure time, which on film and some digital cameras is how long the shutter is open for, and on some digital cameras is the time that the CCD is active for.

Is it a fairly recent camera? Maybe they've improved, my digital cameras are all at least 2 years old now. There's no good reason to have long delays between button presses and the beginning of the exposure, not with modern technology. The fact that my S602Z still has a delay even with manual-everything is just inexcuseable!

Reply to
Ian Rawlings

Prime lenses (i.e. non-zoom) haven't really improved optically as there's not much to them so an old prime lens is pretty much as good as its new counterpart, apart from autofocus. Zoom lenses are another matter, old zooms are pretty crummy compared to new ones, but most people don't worry too much about the quality as they're good enough for most purposes.

I still have an F1.4 50mm Olympus lens on an old OM2-SP, the last camera I ever used to take serious photos. I used to have 4K's worth of Canon autofocus lenses, flash guns, motor power boosters etc but I always took better pictures on the old OM2-SP, so flogged the canon gear on ebay as I never took good pictures with it. The Canon pro-series 100-400 lens was the best zoom lens I'd ever used though, great piece of kit.

Reply to
Ian Rawlings

It only plays a part in how long it takes to save the image, *not* how long it takes to shoot it. The image saved to card is a formatted image, either TIFF or jpeg usually, and no CCD outputs a TIFF or JPEG. The image is saved in raw pixel values to an internal buffer then is written to the card as a TIFF or JPEG file.

Reply to
Ian Rawlings

OK, I've dug up an explanation of why higher-end digital cameras use mechanical shutters, and here it is, quoted verbatim;

---------------------------------------- A digital camera captures its image in several steps, depending on the camera mode, and the exact technology of the detectors, the process of capturing a picture is something like:

1) open the shutter for framing, focus, exposure, and white balance calculation. 2) close the shutter, and charge all the CCD detectors to a known state. 3) open the shutter for a fixed time, and record the image by bleeding off an amount of charge in each pixel that is proportional to the light intensity. 4) close the shutter, and extract the digital image by sequentially connecting each pixel to an A/D converter, and storing the resulting digital value in the camera's internal memory. 5) color convert, sharpen, and compress the image before transferring it to permanent memory.

Steps 2 and 4 must be done in darkness, for obvious reasons. Step 4 in particular is relatively slow, since each pixel must be read sequentially, converted to a digital value, and then stored in memory. Add to that the constraint that all the pixels should be exposed simultaneously to avoid distortion of moving objects, and the fact that the shutter can be extremely small for most digital cameras, and a mechanical shutter is an excellent solution.

Some low-resolution digital cameras do indeed use an electronic shutter. The shutterless design works well for low resolution images where motion distortion is acceptable, such as the Casio wrist watch camera and web. These cameras are really digital video cameras, and the data rate is slow enough to simply scan each pixel through an A/D converter in real time.

In principle, as technology improves, the same idea could be extended to higher resolution cameras, but a mechanical shutter will probably always offer a quantum leap in image quality over sequentially scanned images of the same resolution.

Reply to
Ian Rawlings

True enough, but to be fair the G6 is what he needs & I'm gonna take mine to show him tomorrow. It is easily the best 'amalgamation' of SLR & compact types available.

Nige

-- Subaru WRX (The Bitch)

Series 3 Landrover 88" (Albert)

"If you tolerate this then your children will be next"

Reply to
Nige

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