Tanya asks:
> She claimed that his number one tip was to shoot EVERYTHING in landscape
> photography at f22 to ensure maximum depth of field. Ok, so here is my
> question, (and please forgive me if I am wwaaaaay off track here), but when
> you are shooting, say a lake, or a beach scene at 6.30 at night and you need
> more light, doesn't it make sense to shoot as wide open as possible?
Depends if you're using a tripod. I did some half-hour night-sky exposures
the other night with the 15mm on a tripod. I was going to try one while lying
back with the camera on my chest to see how my breathing/heartbeat
affected the star trails but I'd have needed a couple of hours and I didn't want
to freeze :)
I shoot most of my landscapes around f/5.6 to f/11 to maximise lens
resolution where applicable. The resolution of a lens is generally best at
these apertures and actually decreases towards f/22 because of diffraction.
If you want to see this quantified take a look at:
http://www.takinami.com/yoshihiko/photo/lens_test/index.html
and have a browse through the numbers.
If I need more depth of field I'll stop down further and use the hyperfocal
distance, until I run out of handholdable shutter speeds when I face the
question: "am I too lazy to get the tripod?". Yesterday when I faced with this
decision the tripod was a 30-minute round trip of hilly walking away. I looked
at my lens focussing scale and moved back by a metre instead :) I also use
mirror lockup (yes, handheld) to get an extra stop of shutter speed below the
"1/focal length" rule-of-thumb.
> The
> lady I spoke to argued the point of depth of field with me, but unless I am
> reeeeally mistaken, I thought that the theory behind a lens which focuses at
> "infinity" meant that after your subject is a certain distance away from the
> lens (eg. 8 metres on my Vivitar 28/2) the focusing switches to infinity
> which basically means that everything is in focus anyways?
Correct, although it depends on the aperture you're shooting at.
You can get even more DOF using what's known as the hyperfocal distance.
I don't put all my faith in the lens focussing scale though, as the "cutoff"
point between "in focus" and "not in focus" is not abrupt and some lenses
will indicate a "wider" zone of "sharpness" than others for a given focal length
and aperture. When using this method I always try to keep at least one stop
"in reserve" by focussing with the f/8 scale when set to f/11, for example.
This gives me a little extra margin in case the lens manufacturer has a
different definition of "acceptably sharp" to my own opinion.
If DOF is important (I'm talking desired DOF which is not necessarily
maximum) then I would strongly recommend a camera with DOF preview. I
find it absolutely indispensable, not only for a rough check of my hyperfocal
distance, but particularly for my macro work when I'm most often shooting
around 1:2 magnification at about f/4-5.6 (a DOF of about a couple of
millimetres). It really helps on those ultra-rare portraits I've been known to
take as I can see just how my background is going to look (although you
don't get to see the effect of your flash on those highly reflective things you
didn't see:).
> I mean, if that
> is not the case, than what is the use of having a "fast lens" when only a
> miniscule amount of your shot will be in focus?
Handheld exposures in low light. I've been known to use my 24mm f/2.0
wide open because of bad light and slow film. My 15mm f/3.5 has been
known to frustrate me because it's so darn slow :) (nevermind the 200/4 or
400/5.6 - I can't afford a 200/2.8 yet and couldn't even carry a 400/2.8)
Also, "selective" focus can be very effective in the right situation. Usually
that situation is when you have no option but to shoot at f/2.0 :)
BTW I'm making the assumption that everyone's talking about 35mm gear.
Larger formats tend to require smaller apertures to get the same DOF,
because the lenses are longer for the same angle of view. The principles are
exactly the same but the numbers are different. f/22 can be pretty useful for
6x7 or 4x5 landscapes.
> I am sure that I sound really backward and totally clueless to even very
> basic photography rules on this, but if her friend is truly an "expert" then
> wouldn't he be correct in his f22 theory? And if he is, can somebody please
> elaborate on this for me, cause I have definitely lost the plot
> somewhere....
Don't worry, I'm absolutely clueless about taking photos of people. I do my
best to exclude them from my pictures :)
> Oh, btw, Merry Easter!! (Well, some people say "Happy Christmas" you know!)
> 8-)
I just got back from a long weekend at Lake Tekapo... to 403 new email
messages!
Cheers,
- Dave
David A. Mann, B.E.
email [EMAIL PROTECTED] * http://www.digistar.com/~dmann/
"Why is it that if an adult behaves like a child they lock him up,
while children are allowed to run free on the streets?" -- Garfield
-
This message is from the Pentax-Discuss Mail List. To unsubscribe,
go to http://www.pdml.net and follow the directions. Don't forget to
visit the Pentax Users' Gallery at http://pug.komkon.org .
