4 Jul
2011
4 Jul
'11
2:53 p.m.
On 04/07/2011 20:20, Dave Caroline wrote:
Tony Im just in the pocess of jury rigging a better
close up experiment
http://www.collection.archivist.info/archive/fiche_experiments/50mm_canon_l…
was yesterdays experiment, some exposure error hence noise and also
thats hand held
next is to bolt stuff to a stand so I can increase exposure time and
reduce shake at the same time
I think I need a higher resolution sensor in the camera though
I don't think you need higher resolution, just more magnification.
> Can you use 'traditional' closeup methods
(extension tubes, bellows, etc)
> with digital SLR cameras? If so, that's what I would be looking at using.
To answer Tony's question, in general, yes of course you can use rings,
bellows, and all the other things with digital SLRs. I suspect he knew
that, maybe he was asking if Dave has access to those things.
Dave, can you get hold of a set of extension rings? or a bellows unit?
That'll get you better magnification. And use a shorter focal length
with tubes or bellows; that increases the magnification. A good trick
if you can do it is to turn the lens round. Firstly that's because
camera lenses are optimised for a short distance between lens and
film/sensor and a longer distance between lens and subject; here the
situation is reversed so the lens will usually work better back to
front. Secondly, you can often get the lens closer to the subject when
it's reversed, especially with a retrofocus lens (ie a "wide angle"
lens). Don't try to focus by turning the focussing ring (or moving the
bellows in and out if you have one); you've possibly already discovered
it's easier to set the magnification and then move the whole unit back
and forth to get the focus. Ideally, stop the lens down about halfway
or just a bit more; that's when most lenses are at their sharpest.
--
Pete Peter Turnbull
Network Manager
University of York