[meteorite-list] Meteorite Photography (Must read!)

From: Dark Matter <freequarks_at_meteoritecentral.com>
Date: Wed, 27 Jan 2010 12:10:55 -0700
Message-ID: <822da19a1001271110q3468c030if929d8f9e44afaa4_at_mail.gmail.com>

Hmm, where to start....

How about a couple general points:

First, a smaller aperture is a bigger number as it represents a ratio
of lens diameter to aperture opening. I believe that is expressed
backward in the previous post. Further a doubling or halving of the
shutter speed or ISO is the same as a one stop increase or decrease in
aperture.

Sports photogs use fast lens because in the Shutter speed/aperture/ISO
equation, more light = higher usable shutter speed at the same ISO.

Tele lenses compress the image FOV and have a narrower DOF than normal
or wide lenses.

The DOF works both ways-in front of prime focus and behind it.

A stopped down tele lens still has a short DOF and the background
would only be in focus if the DOF contained infinity.

 A lens wide open i.e. 2.8 can not be sharper than the lens stopped
down. Isolated elements in the photo are not the same as sharpness.

Macro lenses are designed to be flat field so when moving to the macro
world, the playing field changes, especially when using extension
tubes, bellows, or the like.

The optical physics are straight forward, but often mixed with human
interpretation of an image. But in the end, physics is physics.


-Martin




On Wed, Jan 27, 2010 at 11:14 AM, Meteorites USA <eric at meteoritesusa.com> wrote:
> Erik is right, The higher f-stop of 22 will increase depth of field, not
> sharpness of focus. Though it's related, it's not quite the same. Your focus
> is not controlled entirely by f-stop, only the DOF and amount of light allow
> into the camera.
>
> This is why sports photographers use a low/large f-stop lens like f2.8
> lenses. The reason is simple, the smaller aperture only allow focus on a
> small area of the subject, blurs out the background and has a very shallow
> DOF which focuses (at distance) in the perfect zone, making the player seem
> in sharp focus. Simply stopping down to f22 you would be able to see
> everything behind the player, distracting the subject, and it would not be
> as sharp.
>
> The distance to the subject also plays a large part in DOF focus. DOF can be
> measured in percentages to give a better idea of the range of focus. If
> point A were 2 inches in front of your subject, and point D was the
> background, then points B to C would be the area in which your the photo
> would be in focus and directly related to your f-stop number. Shallower is
> sharper, sharper is smaller, i.e. f.2.8 is will be sharper than f22.
>
> When photographing meteorites, or anything, it's the same thing.
>
> Regards,
> Eric
>
>
>
> On 1/27/2010 5:50 AM, al mitt wrote:
>>
>> Hi Erik and all,
>>
>> I'd think just the opposite would be correct. A higher f-stop (f 22, 18
>> etc.) would create a better depth of field and the more open your iris is on
>> your camera (lower f stop, 1.8, 2.0 etc.) the less focused your items would
>> be. I think you just stated it backwards. Best!
>>
>> --AL Mitterling
>> Mitterling Meteorites
>>
>> ----- Original Message ----- From: "Erik Fisler" <erikfwebb at msn.com>
>> To: "meteorite-list" <meteorite-list at meteoritecentral.com>
>> Sent: Tuesday, January 26, 2010 3:51 PM
>> Subject: [meteorite-list] Meteorite Photography (Must read!)
>>
>>
>>
>> The third thing is auto-blending. For those of you who have SLR's you will
>> notice that shooting at a higher F-stop like F1.8 or F2.8 is a lot sharper
>> than shooting at a lower F-stop like F22. The problem is, you might have to
>> drop your F-stop to make sure the whole meteorite is in focus.
>>
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Received on Wed 27 Jan 2010 02:10:55 PM PST