Re: Utterly off-topic: digital cameras

[Large chunks snipped]

In message <87zmebp4f9.fsf@xxxxxxxxxxxxxxxxxxxxxxxx>, Gareth McCaughan
<Gareth.McCaughan@xxxxxxxxx> writes
Mike Davis wrote:
Yes, I just checked (the F30 has a rather limited lens - f5.6 at long
end of a 4x zoom).

3x zoom, surely? Am I right in thinking that this doesn't matter
so much given the apparent extreme sensitivity of their sensor,
or are there other reasons for wanting a wide aperture? (It makes
a difference to depth of field, AIUI, but naively that seems
unlikely to be a big deal at the long end of the zoom. I won't
be surprised if you tell me that's all wrong.)

(I'm sure you know this!)
The main reason for a large[1] aperture is to let in light. That means
faster shutter speeds (less movement blur). The majority of amateur
photos are ruined by camera shake caused by too low a shutter speed.
High shutter speeds also stop subject movement or enable lower
sensitivity (less digital noise or less film grain).

[1] 'Large', of course, means 'big hole' for the large apertures
have the smallest numbers (being reciprocals). eg f2.8 allows
in 4x the light of the smaller f5.6 aperture.

The long end of the zoom (even 3-4x) still gives quite a limited dof at
say, 2m and f2.8.

eg http://www.flickr.com/photos/watchman/200358912
taken from about 1.5m. - try getting that at 10cm!!

Nice picture!

Thanks (you should have seen the 60 where the butterflies 'quivered' or
the focus was wrong!)
[snip]

I always use my camera with auto-focus switched off. I focus manually[1]
...
[1] This can mean either of two things:-
a) triggering the autofocus mechanism by hand (checking that it
has set it correctly) or
b) using the controls on the camera to focus in and out until it
is right, or, of course..
c) a combination of the two.

I strongly suspect that with a compact camera where the only
way to do (b) is via (I'm guessing, never having used manual
focus on a compact digital camera) a 2-way switch, (b) is just
unbearable. I do (a) all the time, but sometimes opportunities
pass too rapidly, or involve things changing distance too fast,
for the 2-stage thing to work well.

OK, if you do a), I don't think there's more to be said.

re wide angle 28mm equiv.)
No, not *really* important. Just annoying. :-) The S9000 sounds
nice, but I can't quite see why anyone would buy it when they
could get a D50 for about £30 more.

12x zoom compared with 3x zoom?

Have a look at the Panasonic Lumix DMC-FX01 it has IS and a 28mm lens -
I think it meets many of your criteria except for an eyelevel vf.

Looks very nice, but I think I'd want a bit more control than
it seems to offer. (I didn't list that among my annoyances,
because the C-3000Z is actually pretty good in that department.)

Yes, I guessed so.

[snips]
So some Image Stabilisation could be valuable - I rave about mine on the
Panasonic FZ5 (now FZ7) - and better than high ISOs which are always
noisy.

Quite possibly, yes.


2. What sized prints do you want to end up with? (What's the largest
you've had from your 3.1Mp Olympus?)

I've never made prints from it :-). (But I *have* zoomed in
close to things on-screen, and I would like the option of
being able to make prints if and when I acquire sufficient
round tuits.)

I can't see any real need for anything much greater than 3 Mp frankly.
If, for prints, you are willing to do post processing then all you need
is a sharp (not 'sharpened'), well exposed, picture. Don't get carried
away by the megapix claims - it's mostly hype.

I'm pretty good at resisting hype.

I guessed! ;-)

I can see some value
in having more than 3MP, but none (for almost all purposes)
in having (say) 10MP as some insane compacts now do.
I suspect the point at which having more stops being
beneficial for me is somewhere around 5, though that's
based largely on handwavy guesswork; most of the cameras
that seem promising to me on other grounds have 6ish,
and that's fine.

Indeed.

3. How small ie. pocketable do you want it to be?
[snip]

I've generally been happy enough with the results of the C-3000Z's
autofocus, but then I haven't often wanted to photograph people
behind railings, birds sat in front of zebras, etc. You're clearly
right that such issues can arise, though. I've more often wanted
to adjust the shutter speed or aperture. The aforementioned FX01
falls down there.

I think "rules out" is too strong; again, I've survived the last
5 years with a non-pocketable camera. Given compelling enough
reasons for buying another, I would. But pocketability is
certainly a plus.

[Post-processing:]
Of course. You will need prints of the baby for family, but as long as
they are smaller than A4, any of the cameras you are considering will
do.

Right.

Frankly, the lens is the important thing, if it's woolly at the edges
not really sharp, then the amount of noise doesn't matter that much.

What's actually going on, optically, to produce that woolliness?
(I ask because I'd naively have thought it ought in principle
to be post-processable away, but that would exacerbate noise.)

Compromise in design.

That's what's going on in engineering, to produce whatever-it-is
that's going on optically, to produce the woolliness. It's the
middle stage I was wondering about. For instance, if that
woolliness is roughly equivalent to a gaussian blur whose
amount of spread varies across the image (worse in the corners),
it should be somewhat reversible digitally, given a bit of trial
and error.

Actually, you *could* build a software filter that sharpens
progressively more from the centre to the outside, but every combination
of focus distance, zoom, and aperture would require different parameters
for each for this to work. I wouldn't bet on it. (Remembering your
expertise, is that a challenge?)

Ideally I'd like both; the inability to compose shots with the
LCD is a drawback to DSLRs.

Yes. - Don't confuse pro-sumer digicams with true D-SLR (which have
internal mirrors); the internal digital screen is pretty good.

The C-3000Z's optical viewfinder shows an area substantially
smaller than the actual image, and whose centre is substantially
offset. It's almost unusable for composition. I expect modern
cameras are better.

I'm not sure what makes you suspect that I might be confusing
DSLRs with "prosumer" digicams; I'm fairly sure I'm not.

I don't - but the discussion had polarised between automatic 'compacts'
and DSLRs, and I was reminding you that there's a range of cameras 'in
between' - of a type I'm very happy with.

The main
advantage of the true SLR is interchangeable lenses. I don't think your
pocket or criteria require those.

I'd thought they were also supposed to be (for the most part)
much better in dynamic range, fast response, and so on.

Yes, can be but (as I know for the past 40 years) changing lenses isn't
part of that 'fast response'. The other revelation to me was the lack of
dust in digital - even though some DSLRs now have dust 'releasers' - it
is still a practical risk!

I'd thought DSLRs were generally thought to have an advantage
in dynamic range too, on account of having much larger sensors;
and (slightly to my surprise) they seem to be less power-hungry
and therefore provide better battery life.

Yes all that, perhaps, but I'm taking 300+ photos a day on one battery
with my Panasonic FZ5, - frankly until you meet the limits of a compact
camera I don't think you need worry too much.

Fair enough. I've met some of the limits of my existing one,
and my difficulty is that I don't know which of those limits
are now well inside the limits of modern compact digicams.
It sounds, from what you're saying, as if most of them are.

Just to add that the external screen uses more battery power than an
internal screen does.


I don't feel any need for interchangeable lenses now, still
less for a wallet-hole the size of a good lens. But I might
change my mind later...

In this industy competition is so great that things can only get better.
You are young enough to wait! ;-)

You may well be right, though I suspect the most fundamental
limits may be in the optics, which aren't improving so fast.

I'm not sure. There have been fantastic improvements in optics (mass
produced aspherical components and very high refractive glasses) and in
digital technology (note that if you zoom a prosumer digital camera it
needs to be refocused due to digital correction) in the last 10 years,
that mean that the lenses I have in my camera give a performance that
was inconceivable 10 years ago.

Mike

[The reply-to address is valid for 30 days from this posting]
--
Michael J Davis
http://www.trustsof.demon.co.uk
<><
For this is what the Lord has said to me,
"Go and post a Watchman and let
him report what he sees." Isa 21:6
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