Higher-end compact or SLR for me?

On Fri, 30 Nov 2007 22:44:26 -0500, Neil Harrington wrote:
>> There are a few exceptions, though; a 50mm f/1.8, for example, is the
>> cheapest lens nikon sells, is fast, very light and very sharp when
>> stopped down. A 85mm f/1.8 is also a potentially useful lens (for
>> portraits, for instance). Neither of these autofocuses on the d40.
>
> Right. However, I have both the 50/1.8 and the 85/1.8 and they do
> manually focus easily on the D40 with the little focus indicator in the
> viewfinder. Too bad it's down there in the corner, but short of
> replacing the screen it's the best available solution I suppose.
>

I gather the 50/1.8 is largely designed for portraits and other uses where
fast autofocus wouldn't be as critical. Do you find it's still fun to use?

> Also a difference in sync speed -- 1/500 for the D40, 1/200 for the
> D40x.

What exactly is sync speed? I read somewhere that it's something pros
care about but newbies don't understand, but that's all I got

Dan

"Daniel Lenski" <dlenski RemoveThis @gmail.com> wrote in message
news:pk54j.78381$Um6.59638@newssvr12.news.prodigy.net...
> On Fri, 30 Nov 2007 22:44:26 -0500, Neil Harrington wrote:
>>> There are a few exceptions, though; a 50mm f/1.8, for example, is the
>>> cheapest lens nikon sells, is fast, very light and very sharp when
>>> stopped down. A 85mm f/1.8 is also a potentially useful lens (for
>>> portraits, for instance). Neither of these autofocuses on the d40.
>>
>> Right. However, I have both the 50/1.8 and the 85/1.8 and they do
>> manually focus easily on the D40 with the little focus indicator in the
>> viewfinder. Too bad it's down there in the corner, but short of
>> replacing the screen it's the best available solution I suppose.
>>
>
> I gather the 50/1.8 is largely designed for portraits and other uses where
> fast autofocus wouldn't be as critical. Do you find it's still fun to
> use?

I do, but frankly I've used it only a few times on the D40 -- mostly out of
curiosity to see how well it could be used focusing manually. It works well
for that if you're not in too much of a hurry, but I use it mostly on my D80
on which of course it does autofocus. I haven't yet used it for
portraiture, mostly for available light shooting where that f/1.8 aperture
is a delight.

What it was originally *designed* for of course was use as a normal lens on
a 35. On a Nikon DSLR with the usual 1.5x lens factor it's equivalent to
75mm on a 35, which is sort of an odd focal length -- somewhat too long for
a normal but a bit short for a portrait lens, though that's mostly a matter
of personal taste anyway.

>
>> Also a difference in sync speed -- 1/500 for the D40, 1/200 for the
>> D40x.
>
> What exactly is sync speed? I read somewhere that it's something pros
> care about but newbies don't understand, but that's all I got

Sync speed (more fully, flash sync speed) is the fastest shutter speed on a
camera with a focal-plane shutter, such as a typical SLR or DSLR, at which
you can use flash. (There are some exceptions for certain kinds of flash,
but I won't go into those here.)

Focal-plane shutters are located just in front of the sensor (or film), and
work by moving two curtains in front of it. These nowadays are made of thin
metal strips but are still called curtains. The first curtain moves out of
the way, exposing the sensor to light from the lens, then the second curtain
moves to cover it again, ending the exposure. For an exposure of 1/100
second for example, the second curtain would be released 1/100 second after
the first. When flash is used, usually it is fired at the moment the first
curtain is fully open, so the exposure is made over the whole sensor.

But at higher shutter speeds, the second curtain has started to move before
the first curtain has completed its travel. This means that the entire
sensor cannot be exposed at the same instant, because exposure is being made
by the space or slit between the shutter curtains which travels over the
sensor. This would be a major problem for conventional electronic flash.

So sync speed, *generally speaking*, is the highest shutter speed at which
the second curtain has not yet started to move before the first curtain has
finished its travel. This is usually not higher than about 1/200 second,
though this varies somewhat between cameras.

In a few cases, however, the camera is able to get a higher sync speed by
switching the sensor on and off in a substantially shorter time than the
shutter is actually open, and coordinating this with the firing of the
flash. This is how the D40 gets its exceptionally high sync speed of 1/500
second.

Why doesn't the D40x do the same? Presumably because its sensor, which
obviously is different from the D40's, just cannot be switched on and off
that fast.

Neil