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Old Jul 17, 2005, 10:28 PM   #1
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This one is technical:

When you havefor example, anf/1.4 aperture in your lens does it means that you can shoot images with a magnification ratio of 1:4, does the aperture of the lens affects magnification??????:O

Thanks for your replies!

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Old Jul 18, 2005, 2:52 PM   #2
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The f/ stop is a ratio between light and lens focal distance. It doesn't express magnification.

Lower numbers let more light reach the sensor (or the film. in traditional photography). Lenses with lower numbers are called "faster," because you can take exposures of shorter time duration when they are wide open.

Wikipedi has a good discussion at http://en.wikipedia.org/wiki/F-number.
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Old Jul 19, 2005, 12:03 AM   #3
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THANK YOU! So lenses with larger openings say a f/1.2 aperture will let me take photos with better light in low light situations or at faster shutter speeds at absolute darkness...if I can take photos at faster shutter speeds that means that I will not have to use the lowest shutter speeds so often so I will be able to take better handheld photos right? I still don't see myself buying a tripod...yet. I'm concentraring on lenses right now, in fact I have these ones in mind: let me know what you think of them:

http://cgi.ebay.com/ws/eBayISAPI.dll...%3AIT&rd=1

http://cgi.ebay.com/ws/eBayISAPI.dll...%3AIT&rd=1

I'm planning on using the reverse mount technique...will keep on researching!




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Old Jul 19, 2005, 12:34 AM   #4
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the links to the 2 lenses you posted are not addon lenses

they are primary replacement lenses for a Pentax camera
with a bayet K Mount


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Old Jul 19, 2005, 9:22 PM   #5
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I know, is just that I want to construct a camera like hauer54's, Look:

http://www.stevesforums.com/forums/v...mp;forum_id=50

Also, I think (correct me if I'm wrong please) that if I have alarger aperture, taking photos at night (when the camera "asks" for the slowest shutter speeds, which I don't like to use because my photos come out all blurry :roll:...my hands can't seem to stop shaking when I press the shutter, still practicing :G) the will be easier because more light will pass to the lens.

My biggest interest in the lens is to use it in reverseto take macro photos, like hauer54 did... From what I've read, the lens has a very good reputation.

I'll keep on the research! :|
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Old Jul 19, 2005, 11:58 PM   #6
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When using a reversed lens for macro photography, the aperture of your camera, not the add-on lens, is normally what controls the light. The usual way is to set the add-on to full open, and use the appropriate camera setting.

To get good macro images with this type of setup, you will almost certainly need a tripod or some other solid rest. When you magnify the image, whether with telephoto or close-up lens, you also magnify the camera shake. Even with a tripod, it is a good idea to use either a remote release or the self-timer, to avoid movement from pressing the shutter release.

Depth of field is drastically reduced by this method, so focus is critical. Flat surfaces work well, but anything with three dimensions will have fore-and-background out of focus.

Using a reversed 50mm f/1.4 lens from my manual 35mm camera, attached to my Dimage 7hi, I can get some fairly good magnification.

brian

PS: Those are 1mm marks on a machinist's steel rule.

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Old Jul 20, 2005, 11:40 AM   #7
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nice shot of the rule

I'll have to see what my closeup lenses can do

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Old Aug 14, 2005, 9:52 PM   #8
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Wow that's quite nice, it's almost microscopic! I can't do that with my +1,+2,+4+10 diopters!
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