| Author |
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JM
Guest
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 Posted:
Wed Oct 26, 2005 4:40 am Post subject:
When to use smaller aperture? |
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My Olympus C5050 offers a max aperture of f1.8, and I usually shoot at that
or very close to it. With those settings I'm very comfortable setting the
shutter speed on the fly for the specific conditions. Given the difficulty
of learning the relationship of aperture to shutter speed even when the
aperture is static, what are some reasons for decreasing the aperture? In
other words, what types of situations might benefit from decreasing the
aperture and making the subsequent changes to the shutter speed?
thanks,
jm
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Charles
Guest
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| Posted:
Wed Oct 26, 2005 4:40 am Post subject:
Re: When to use smaller aperture? |
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On Wed, 26 Oct 2005 02:55:02 GMT, "JM" <jm@yahoo.com> wrote:
| Quote: | My Olympus C5050 offers a max aperture of f1.8, and I usually shoot at that
or very close to it. With those settings I'm very comfortable setting the
shutter speed on the fly for the specific conditions. Given the difficulty
of learning the relationship of aperture to shutter speed even when the
aperture is static, what are some reasons for decreasing the aperture? In
other words, what types of situations might benefit from decreasing the
aperture and making the subsequent changes to the shutter speed?
thanks,
jm
When you want more depth of field. |
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Matt Ion
Guest
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| Posted:
Wed Oct 26, 2005 4:40 am Post subject:
Re: When to use smaller aperture? |
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JM wrote:
| Quote: | My Olympus C5050 offers a max aperture of f1.8, and I usually shoot at that
or very close to it. With those settings I'm very comfortable setting the
shutter speed on the fly for the specific conditions. Given the difficulty
of learning the relationship of aperture to shutter speed even when the
aperture is static, what are some reasons for decreasing the aperture? In
other words, what types of situations might benefit from decreasing the
aperture and making the subsequent changes to the shutter speed?
|
Actually, the relationship is pretty easy to understand: each "stop" in
aperture represents a doubling or halving of the light allowed through:
f/4 is one stop wider than f/5.6 and will let in twice the light; f/8 is
one stop smaller and will let in half the light. Each doubling or
halving of shutter speed is also a "stop" and will have the same effect.
F/5.6 at 1/200s will give the same exposure as f/4 at 1/400s (twice
the opening, half the shutter speed) or f/8 at 1/100s (half the opening,
twice the speed).
If you would normally shoot something at f/2 (close to your camera's
aperture, for easy calculation, since "standard" stops are f/1, f/1.4,
f/2, f/2.8, f/4... are we seeing a pattern here?) at 1/200s, then to
shoot it f/2.8 you would use 1/100s, and for f/4, you'd shoot for 1/50s.
As others have already noted, a smaller aperture will give you greater
depth of field, and to some degree and up to a point, better sharpness.
---
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Barry L. Wallis
Guest
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| Posted:
Wed Oct 26, 2005 4:40 am Post subject:
Re: When to use smaller aperture? |
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JM wrote:
| Quote: | My Olympus C5050 offers a max aperture of f1.8, and I usually shoot at that
or very close to it. With those settings I'm very comfortable setting the
shutter speed on the fly for the specific conditions. Given the difficulty
of learning the relationship of aperture to shutter speed even when the
aperture is static, what are some reasons for decreasing the aperture? In
other words, what types of situations might benefit from decreasing the
aperture and making the subsequent changes to the shutter speed?
|
Finally, a question I can answer. :-)
The smaller the aperture the greater the depth of field. In other words,
with a smaller aperture objects at more varying distances will remain in
focus.
--
- Barry |
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JM
Guest
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| Posted:
Thu Oct 27, 2005 4:41 am Post subject:
Re: When to use smaller aperture? |
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I don't take any offense at all. However, the basic nature of the question
belies how much I actually know about photography, or, more specifically,
taking pictures with my C5050. I'm by no means an advanced photographer,
but I do know the basics of aperture and shutter speed. Don't take this to
mean my purpose was to mislead; rather, I wanted to see the variety of
answers to a "simple" question. While I anticipated almost all of the
answers, there were a couple of posts that jogged the old brain.
Furthermore, I was interested to see where the DOF effect "ranked" in the
answers, and, as I suspected, it is quite high. That is significant to me,
because it reinforces my view that where my particular camera is concerned
the aperture settings are not crucial. Honestly, in "normal" shooting (if
there is such a thing ; ), my aperture/shutter speed selection does not bear
significantly on the photograph. As most people pointed out, a camera like
the C5050 has substantial DOF throughout its FL. For special effect,
however, I do make use of many different settings.
Thank you for your input. It is appreciated. And you can bet that I'll
heed your suggestion to read more about photography ; )
jm
"Dave Cohen" <dave@example.net> wrote in message
news:H_M7f.499$m81.201@newsread1.news.atl.earthlink.net...
| Quote: | This is not meant to in anyway offend, but if one needs to ask such a
basic question, I would suggest getting an introductory book on
photography. Film or digital probably shouldn't make too much difference
for starters. Try the local library. The benefit of doing this is you'll
find answers to other questions you haven't thought to ask yet.
The great benefit of digicams is you can do a lot of experimenting at no
cost, so have fun.
Dave Cohen
"Joseph Meehan" <sligojoe_Spamno@hotmail.com> wrote in message
news:cJL7f.159132$lI5.143385@tornado.ohiordc.rr.com...
JM wrote:
My Olympus C5050 offers a max aperture of f1.8, and I usually shoot
at that or very close to it. With those settings I'm very
comfortable setting the shutter speed on the fly for the specific
conditions. Given the difficulty of learning the relationship of
aperture to shutter speed even when the aperture is static, what are
some reasons for decreasing the aperture? In other words, what types
of situations might benefit from decreasing the aperture and making
the subsequent changes to the shutter speed?
thanks,
jm
You use a smaller aperture for greater DOF, but you also use a smaller
aperture for a longer exposure time.
--
Joseph Meehan
Dia duit
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Hunt
Guest
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| Posted:
Fri Oct 28, 2005 4:41 am Post subject:
Re: When to use smaller aperture? |
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In article <0H68f.1883$AS6.1317@newsread3.news.atl.earthlink.net>,
dave@example.net says...
[SNIP]>
| Quote: | "Dave Cohen" <dave@example.net> wrote in message news:H_M7f.499
Thanks for your reply, but now I have a problem. For both this post and one
I did a few days ago for another post, I'm getting a reply to a response I
posted, but my submission isn't being displayed by my reader. Obviously it
got posted or I couldn't be getting replies. Anyone have any ideas why this
should happen. I'm using OE news reader and this doesn't happen all the
time. My post shows up in messages sent.
Dave Cohen
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David,
News readers differ. Basically, what you are seeing is your news reader not
showing articles. This could be because of something in your Options, like: "
Do not show 'read' articles... " or it could be that you have set your NR to
only show so many articles. In this NG, I see 29,000 article headers on my
news server, but chose to only open the most recent 500. I see some of my RE:
articles, but not the originals. My reader signifies "new" articles with an "
N." You may have to check something like "show all headers." It could also be
that your news server purges articles over X days old.
First check your Options in the NR, then go to your news server's Web site,
and look for their policies re: purging. Usually in non-binary NG's, the
articles stay around for quite a while, but on some servers, they only last
for a few days.
Hunt |
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Ron Hunter
Guest
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| Posted:
Fri Oct 28, 2005 4:41 am Post subject:
Re: When to use smaller aperture? |
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JM wrote:
| Quote: | I have some rather nice pictures of flowers in which the ones in the
foreground are sharp, and ones only a few inches away are blurred.
Everything depends on the settings used by the camera, and the lens and
sensor installed.
did you use the camera's macro mode(s)?
jm
I used 'close-up' setting. Not the same as macro, technically, but it |
does well. In bright light, the DOF is considerable, but in heavy
shade, the lens opens more and the DOF drops off.
--
Ron Hunter rphunter@charter.net |
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David Littlewood
Guest
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| Posted:
Sat Oct 29, 2005 12:19 am Post subject:
Re: When to use smaller aperture? |
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In article <11m4sggnh3b04a3@news.supernews.com>, Lorem Ipsum
<Lorem@ipsum.xxx> writes
| Quote: |
"David Littlewood" <david@nospam.demon.co.uk> wrote in message
news:v46BgckDglYDFwhx@dlittlewood.co.uk...
In article <11m4kr57dnen6f9@news.supernews.com>, Lorem Ipsum
Lorem@ipsum.xxx> writes
You are confusing "complex" with "correct. It's actually no more complex
than your incorrect version, just more, well, correct.
If you don't believe me, try looking it up in an optics book.
Come on, you can answer the question.
I repeat: It is not true that the smaller the actual (not relative)
aperture, the more profound is diffraction? Ordinary, small digital-sensor
cameras have little lenses, therefore they have little apertures, and
therefore their lenses are more susceptible to the effects of diffraction
at ordinary, working apertures.
It's not true. I said this in my first answer, go back and read it. The |
diffraction limited resolution of a lens depends on relative aperture,
not on absolute aperture. Note that "resolution" always refers to the
resolution on the primary image, irrespective of any further use which
may be intended.
There, not too complex.
What causes imaging systems with tiny lenses and tiny sensors to show
lower resolution in final output is that the tiny image has to be
magnified more.
David
--
David Littlewood |
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Roger N. Clark (change us
Guest
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| Posted:
Sat Oct 29, 2005 4:40 am Post subject:
Re: When to use smaller aperture? |
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Lorem Ipsum wrote:
| Quote: | "David Littlewood" <david@nospam.demon.co.uk> wrote in message
news:v46BgckDglYDFwhx@dlittlewood.co.uk...
In article <11m4kr57dnen6f9@news.supernews.com>, Lorem Ipsum
Lorem@ipsum.xxx> writes
You are confusing "complex" with "correct. It's actually no more complex
than your incorrect version, just more, well, correct.
If you don't believe me, try looking it up in an optics book.
Come on, you can answer the question.
I repeat: It is not true that the smaller the actual (not relative)
aperture, the more profound is diffraction? Ordinary, small digital-sensor
cameras have little lenses, therefore they have little apertures, and
therefore their lenses are more susceptible to the effects of diffraction
at ordinary, working apertures.
David is correct. Diffraction is constant in terms of linear diameter in the |
focal plane for a given f/ratio. For example, at 5000 angstroms, the diffraction
spot diameter is 2.2 microns at f/2, and 8.9 microns at f/8. What makes the
larger lens have more resolution is the longer focal length means that the
diffraction spot in the focal plane subtends a smaller angle. See:
http://www.clarkvision.com/imagedetail/scandetail.html#modulation
Note that at f/8 the diffraction spot size is larger than 8 microns at green
and red wavelengths. That has impacts to image sharpness for small
diameter pixel cameras (like P&S cameras).
Roger |
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David Littlewood
Guest
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| Posted:
Mon Oct 31, 2005 5:10 am Post subject:
Re: When to use smaller aperture? |
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In article <dk3coh$27e7$1@agate.berkeley.edu>, Ilya Zakharevich
<nospam-abuse@ilyaz.org> writes
| Quote: | [A complimentary Cc of this posting was sent to
David Littlewood
david@nospam.demon.co.uk>], who wrote in article
E6KrgsmDnnYDFwlW@dlittlewood.co.uk>:
What causes imaging systems with tiny lenses and tiny sensors to show
lower resolution in final output is that the tiny image has to be
magnified more.
This is very misleading. In a certain range of sensor sizes, there is
"practically" NO DIFFERENCE between resolution of digital cameras with
different sensor sizes.
Go to dpreview, and compare, e.g., resolution charts of Canon EOS 350D
with KM A200. The sensor sizes differ 3x in linear scale. The
smaller sensor is used with 7x zoom, the larger one with the prime.
But what is the result? The resolutions are within 5% of each other.
[Note that with firmware demosaicer, Canon performs slightly better.
But used with Adobe demosaicer A200 gives better resolution than 350D
with Canon's one. So the question of applied DSP may be more
important than the sensor formfactor.]
Hope this helps,
Ilya
|
Ilya, perhaps I did not make the point clearly enough, but I thought I
did. We were talking about the limits of resolution which are imposed by
the lens, and combined with the effect of image magnification for
different formats.
Whatever the ability of lens designers to reduce aberrations, there is a
limit to lens resolution which is governed by diffraction. This
resolution is defined in cycles per mm, line pairs per mm, or whatever
you want.
Thus, there is a limit to how much resolution can be on any sensor,
however big it is, whatever its own intrinsic resolution may be, and
whatever lens is used to create it. This is a law of physics, and
unavoidable.
It follows that if you have put this amount of resolution on two sensors
(both having more than sufficient resolution to capture the detail) one
of which requires a magnification of 20x to create the desired final
output, and the other of which requires a magnification of 5x to create
the final output, then the latter will give a final product which shows
more resolution than the former.
Whether or not you follow this, it is the hands-on practical experience
of tens of thousands of workers in formats larger than 35mm that this is
indeed a real, practical and observable fact. It is why tens of
thousands of workers still use large formats, and get results which blow
away 35mm film and similar sized digital formats.
If a given test were to show that images created from sensors or film of
different sizes showed similar resolution, this would be demonstrating
that some other quality limitation was reducing them to a lowest common
denominator. This is of course perfectly possible (for example,
limitation by sensor resolution, with the smaller sensor having a closer
pixel pitch, but neither approaching the diffraction limit). That is
most probably what the test you quote is observing. If so, it is not
particularly interesting, and is completely non-responsive to the point
I made.
However, there is also the possibility that you have been confused by
the terminology of the test report. If you measure the resolution of a
lens/sensor system in terms of cycles per mm on the recorded image,
without reference to the magnification up to the final product, then
clearly (if other things are equal) they would show similar resolution.
Only when the smaller one is magnified to give the same output will this
relative degradation show up. I suggest you go back and read the report
carefully.
David
--
David Littlewood |
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Ilya Zakharevich
Guest
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| Posted:
Tue Nov 01, 2005 3:35 am Post subject:
Re: When to use smaller aperture? |
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[A complimentary Cc of this posting was sent to
David Littlewood
<david@nospam.demon.co.uk>], who wrote in article <oTC88WXglqZDFw6t@dlittlewood.co.uk>:
| Quote: | Did you read my posting? Dave made a blanket statement. I had shown
that this blanket statement does not work *without further
qualifications*.
[It turns out that these further qualifications make his statement
irrelevant to the preceeding discussion, but this is not related to
this subthread, right?]
(1) My name is David, not Dave
|
My apologies!
| Quote: | (2) The qualification "other things being equal" was clearly set out a
couple of lines away from your selective quote.
|
....and this qualification qualified some absolutely unrelated to the
discussion at hand: whether larger magnification (from sensor to final
image) always produces worse result (assuming enough resolution of the
sensor to cover the performance of the optics).
| Quote: | (3) Your points are the ones which are utterly without relevance to the
point under discussion, backed up by spurious and distorted comparisons,
and lacking the basic comprehension required to follow the thread of an
argument.
|
How come my comparisons are "spurious and distorted" if you did not
even look at the images in question?
My points are very simple:
a) A lot (probably at least half - by some calculations did done on
this newsgroup) of the time the large format is used it is not
used to get higher resolution, but for other purposes;
b) There are simple physics laws governing when a smaller sensor
will give *exactly* the same quality of the image is a larger
sensor (I listed them many times here);
c) There are simple economy factors which govern when the situation
needed in "b" is economically feasible, and practically relevant.
It turns out that the current state of the part "c" makes the
difference between APC format and 2/3'' format almost negligible in
the situation when a photography is optimized for resolution.
Hope this helps,
Ilya |
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Ilya Zakharevich
Guest
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| Posted:
Tue Nov 01, 2005 3:40 am Post subject:
Re: When to use smaller aperture? |
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[A complimentary Cc of this posting was sent to
Lorem Ipsum
<Lorem@ipsum.xxx>], who wrote in article <11md71egooud382@news.supernews.com>:
| Quote: | Did you read my posting? Dave made a blanket statement. I had shown
that this blanket statement does not work *without further
qualifications*.
So you make up qualifications that have nothing to do with the real world.
Way to go. NOT.
|
I see it's time to refresh your latin a little bit...
http://en.wikipedia.org/wiki/Reductio_ad_absurdum
Hope this helps,
Ilya |
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Ilya Zakharevich
Guest
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| Posted:
Tue Nov 01, 2005 3:48 am Post subject:
Re: When to use smaller aperture? |
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[A complimentary Cc of this posting was sent to
David Littlewood
<david@nospam.demon.co.uk>], who wrote in article <kDE$YvX5nqZDFw6B@dlittlewood.co.uk>:
| Quote: | What metric do you use? For me, an excellent 35mm lens is one which
can produce MTF 50% at 40lp/mm corner-to-corner.
|
Of course, I should have qualified this that it is the
"resolution-wise quality" which I meant. It goes without saying that
there are many other facets of the lens qualility.
| Quote: | So, what makes the Mamiya 6 lenses close to that?
Practical hands-on experience comparing them with a sizeable collection
of Canon L lenses, Contax lenses, and Schneider and Rodagon LF lenses.
|
Sorry, but this sounds too vague. Comparing in which way? Images in
focus at the "sweet" f-stop with the same magnification
negative-to-print, or what? Manufactures data does not match your claim.
| Quote: | Sure, judge yourselves. But anyone who would look would not indulge
in this discussion: these images speak better than words:
If you go for best resolution, then you get practically identical
(resolution-wise) images from APS format (with prime lens) and 2/3''
format (with 7x zoom).
Since the comparison was not the one under discussion, no.
|
Well, maybe I'm blind, but I was answering this paragraph of yours:
| Quote: | What causes imaging systems with tiny lenses and tiny sensors to show
lower resolution in final output is that the tiny image has to be
magnified more.
|
Why do you think that "the comparison was not the one under
discussion"?
Puzzled,
Ilya |
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Lorem Ipsum
Guest
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| Posted:
Tue Nov 01, 2005 4:35 am Post subject:
Re: When to use smaller aperture? |
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"Ilya Zakharevich" <nospam-abuse@ilyaz.org> wrote in message
news:dk5vm7$30o7$1@agate.berkeley.edu...
| Quote: | [A complimentary Cc of this posting was sent to
Lorem Ipsum
I just can't fathom where you are coming from.
Likewise. What is your point, really? Are you going to say that *in
the examples above*, the produced image from 6x6 is going to be better
than one of 35mm?
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The examples you gave have nothing to do with reality!
| Quote: | First, rationalize your input; why F/90 for the 6x6?
Did you read my posting? Dave made a blanket statement. I had shown
that this blanket statement does not work *without further
qualifications*.
|
So you make up qualifications that have nothing to do with the real world.
Way to go. NOT. |
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Lorem Ipsum
Guest
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| Posted:
Tue Nov 01, 2005 4:36 am Post subject:
Re: When to use smaller aperture? |
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"Ilya Zakharevich" <nospam-abuse@ilyaz.org> wrote in message
news:dk6098$30u5$1@agate.berkeley.edu...
| Quote: | What metric do you use? For me, an excellent 35mm lens is one which
can produce MTF 50% at 40lp/mm corner-to-corner. Some Leica lenses
can do it.
|
Bullshit. I don't believe you even make pictures. |
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