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09-06-2007, 07:47 AM   #1
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K100D + kit lens question

Hi all,

I'm a totally new comer to photography. I've just got my K100D + 18-55mm + 50+200mm today. I'm trying to learn how to use the machine, and have some questions.

I'm trying to setting large aperture at long focal length, but the machine does not let me do that. For example f/3.5 at 55mm (18-55mm) or f/4.0 at 200mm (50-200mm). Is that normal to this K100D + lens?

I want to take shallow depth of fields of subjects about 5-10 meters from the camera with these lens. How can I do that?

Thanks!

09-06-2007, 07:54 AM   #2
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Those zoom lenses have F markings showing a range, like 3.5-5.6. The 3.5 refers the the shortest focal length, which in your case would be 18 mm, and the 5.6 would refer to the longest focal length (55, 200 whatever the lens tops out at). As you increase the focal length, you won't get 3.5 anymore but something like 4 or 4.5, depending on the lens of course.
09-06-2007, 08:09 AM   #3
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QuoteOriginally posted by VF-19 Quote
Those zoom lenses have F markings showing a range, like 3.5-5.6. The 3.5 refers the the shortest focal length, which in your case would be 18 mm, and the 5.6 would refer to the longest focal length (55, 200 whatever the lens tops out at). As you increase the focal length, you won't get 3.5 anymore but something like 4 or 4.5, depending on the lens of course.
Exactly... on my kit lens it's worked out to somewhere around the following:

f/3.5 18mm
f/4 25mm
f/4.5 35mm
f/5 45mm
f/5.6 55mm

Hope that helps answer your question.

It annoys me to no end, though I haven't got a particularly good reason for it, and so I am shopping for a constant aperture lens.
09-06-2007, 08:21 AM   #4
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Aperature priority

QuoteOriginally posted by dauvit Quote
Hi all,

...

I want to take shallow depth of fields of subjects about 5-10 meters from the camera with these lens. How can I do that?

Thanks!
Try using the aperture priority mode and selecting the widest aperture available, ie f3.5 or 5.6 depending on focal length.

09-06-2007, 11:21 AM   #5
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Original Poster
Thanks for your help. It clears my question of aperture / focal length relation.

About Depth of Field, I've just found an online DOF calculator which seems to be helpful to me to vision the DOF ranges of f-stop-focal length relationship.

Thanks!
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