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Nogin

Hi Ryan & Mel

If you don't want the inconvenience and cost of an SLR and lenses, (I have a Canon 40D with a couple of Sigma EX lenses cost around 2k), look at the Panasonic FZ50 & FZ18 both have fantastic lenses and will cover most shooting requirements, where they fall down compared to an SLR is the low light performance. I know because I also have an FZ50 which I use as a carry round camera. To get the zoom capability of the panasonics on my SLR I would require another much larger and heavier lens.

Regards Nigel

Boff

Hi,

having been a "classical slide-photographer" for many years, using a Nikon SLR, I am currently on the verge of abandoning the good old analogue technique and stepping over to a digital SLR camera. (I already have a compact digicam for some years, too, which is used on all occasions in which I formerly used negative films to make prints.)

Now, with any camera, there are several items where "size can only be substituted by more size". Wink

These are:

The lens diameter:
The diameter of the lens not only defines an upper limit for the amount of light that enters the camera. It also determines the diameter of the so-called

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, and so the maximum possible resolution of the camera. (This is why it does not make any sense to exceed 6 megapixels with compact digicams, as I had explained in another thread.).
So, the larger the lens diameter, the better the camera operates in low-light conditions, and the better the resolution is.
The detector size:
Instead of a film a digicam has an electronic detector, a so-called CCD-chip. This CCD forms an array of millions of tiny, light-sensitive cells, the pixels. Their number is often (mis)used as a quality criterion. However, the smaller these pixels are, the less light hits them during exposure, so the signal-to-noise ratio and the sensitivity decreases. The only way of increasing sensitivity and signal-to-noise ratio while maintaining the resolution is therefore to make bigger detectors. Which requires bigger cameras.
The lens-detector distance:
As seen before, "big is beautiful" for the CCD chip. However a big chip helps nothing if it is not completely covered by the image projected by the lens. As the image is divergent, the easiest way of getting a bigger image is to move the detector away from the lens. The alternative would be to use a lens with a shorter (inner) focal length, but this would increase optical aberration.
Of course, it is possible to compensate a lot of optical aberrations by image processing software. And in fact, that is exactly what compact digicams do internally. But for optimal image quality it is always better to avoid an aberration in the first place than compensating it afterwards.
Last but not least: Battery life:
As an SLR camera has a lot more moving parts than any compact camera, the strain on the battery is much higher. Which requires bigger batteries to maintain uptime.

All these issues are pure physical reasons why big is better with cameras. In addition, if you change lenses frequently then the lens mount should be sturdy and reliable, to avoid wear and tear. And, as any enthousiastic photographer will confirm, a big camera can just be better held steady in critical situations.

An alternative for somebody who wants more than a compact camera can offer, but not the hassle with a whole bunch of lenses, can be a so-called

2kias

Have just ordered the Panasonic Lumix 55 from my friend who has his own camera shop. No SLR but great zoom and crystal clear picture on 3.5" screen.
He recommended it. Have a look on the Jessops site. They have got some

Pixelpusher

Gerhard.....

I think your #1 point is missing something. While the diameter of the diagphram - not the lens - is significant in determining the amount of light entering the camera, so is the focal length of the lens. This is why we have Apertures settings which are the ratio of diameter to focal length.

A scene that requires an exposure of say f5.6 at 1/60s will be the same for any lens and camera - at the same ISO. If you look at Compact cameras they have similar Aperture ranges but have to resort to wider angled lenses because of their size constraints.

It's true that putting more pixels on a small sensor creates challenges with signal to noise ratios but these are much better addressed these days than a couple of years ago. Both the electronics and noise reduction algorithms have been improved. Where many cameras start to show increased noise is when the ISO setting is bumped up and this varys from make to make.

Colin

ActiveCampers

THought I'd better reply... Wink

Thanks everyone - very interesting (!!) reading.... Lots of ideas and information for me to absorb

Boff

Pixelpusher

In fact the problem of Diffraction Limiting can be even greater with Digital Sensors since a single pixel only records a single colour and the composite RGB pixel has to be made from adjacent pixels.

It's also likely that other lens defects will be more apparent than just the Airy Disc issue.

Colin

bigfoot

Some more information from CBC Canada,which may help or cloud the issue-you choose.

Boff