List of available items- updated 10/13/18

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Prime lenses:
Sony Zeiss SEL35mm f2.8z-Coming soon
Tamron 180mm f3.5 Macro-PREMIUM LENS
Tamron 35-135mm for A mount-Rare -Coming soon
Minolta 28mm f2.8 Crossed X's Prime lens-SOLD

Zoom/Macro lenses:
E Mount to A Mount adapters
49mm,55mm uv & polorizing filters
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Most of the equipment priced here is based on the condition of the item, its value and the price I've had to pay. If you wish to wait for an item that is slightly lower in price, let me know and I will inform you once I have it.
If you wish to see previously sold items click here---> "sold items"

Wednesday, June 5, 2013

Photography: What is Stopping Down?

Photography: What is Stopping Down?

Lenses do not necessarily have uniform sharpness throughout their focal range and across the optical element of the lens (across the area of the photograph) There usually are sharper in the center “Center Sharpness” and a little less so at the corners “Corner Sharpness”. However, “stopping down” is a process that will often allow you to get the lens to provide sharper results. The center sharpness typically reaches its peak 2-3 f stops from the maximum aperture (the lowest f number on your lens). The corner sharpness also increases in sharpness as you stop down, however in most cases, it will continue to get better for several f stops.

So, what is stopping down? Yeah you might have heard some photographers discussing it or seen some lens review mention it. Here it is. Lenses have an opening (aperture), and the maximum size is specified as f-stops. In case of a lens that is 55-200, the specification is f/4-f/5.6. This means that the maximum aperture varies from f/4 to f/5.6, as you increase the focal length. So, the maximum aperture you could choose at 70mm is f/4. However, it decreases to f/5.6 at 200mm (f/4 is larger than f/5.6). This is true of most zoom lenses (variable maximum aperture). Occasionally, you will see some premium zoom lenses with a constant aperture (Sony 16-50mm f/2.8 is an example).

Stopping down is basically using a smaller aperture than maximum allowable aperture. You can control this by selecting Aperture Priority, Program mode, or Manual Mode. Non AF lenses with manual aperture ring allow that control from the lens itself. If you put the camera in “A” mode, turn the dial and you will see aperture size change.

With 55-200, for example, if you want best sharpness, and since max aperture is f/5.6 at 200mm, you might get the best results around f/11.
In lenses, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16 are examples of “Full” f-stops. You might also come across third stops (f/5.6 to f/6.3 to f/7.1 to f/8, for example).

1 comment:

The Geeks said...

Thanks for review, it was excellent and very informative.
thank you :)