Nubi question about 16-45 DA

fccwpe · 06-19-2009, 10:25 PM

I have read loads of reviews and I am confused. Some people say the the Pentax 16-45 f4.0 fixed is really great at f8.0 or f22 etc. How does one change a fixed aperture? Maybe I am not looking at the obvious?

imtheguy · 06-19-2009, 11:21 PM

Its only "fixed" in that the lens keeps the same maximum aperture of f/4 through its entire zoom range of 16-45mm unless you change it. You can manually (with the camera, there is no aperture ring on the lens) change to a smaller aperture like f/8 or f/11 at any focal length from 16-45mm. Most zooms can not keep the same maximum aperture throughout the zoom range.

Hope that helps.

**Ash** · 06-19-2009, 11:40 PM

People generally prefer a zoom with a 'fixed' wide open aperture, that is, the biggest aperture the lens can achieve throughout its focal range.

Like the Tamron 28-75. At 28mm, it can be set at f/2.8, and at 75mm also at 28mm.
Contrast that with the Sigma 17-70. At 17mm, it can be set at f/2.8, but the widest aperture it can achieve at 70mm is f/4.5, which is less flexible when wanting to limit depth of field (range of in-focus parts of image). Sorry if I'm explaining this poorly.

Ultimately, it depends what you're looking for in a lens: the 16-45 is a stellar lens, but f/4 is its largest aperture. The DA* 16-50 can open up to f/2.8 throughout its focal range, and so adds that much more versatility. The choice is yours as to what you're looking for in a lens.

**rparmar** · 06-20-2009, 03:35 AM

You'll be happy with the DA16-45mm. Not only is it cheaper and lighter than the faster weather-sealed lens, but it is actually sharper too. No compromises in IQ here!

I use it at f/4 without problem, though as with any lens would prefer to stop down a couple notches to increase resolution.

Peter Zack · 06-20-2009, 03:43 AM

The DA16-45mm is a great lens, even wide open at f4 (when many lenses doen't perform well wide open). As the others have said, it's a fixed f4 through the focal range (wide open) as opposed to a variable lens like the ones that say 55-300mm f4-5.6 and so on. Not that these variable lenses aren't good. Just limiting in a couple of areas that many would like to avoid if possible.

06-19-2009, 10:25 PM	#1
fccwpe Veteran Member Join Date: Mar 2009 Location: Perris, CA Photos: Gallery Posts: 380	Nubi question about 16-45 DA I have read loads of reviews and I am confused. Some people say the the Pentax 16-45 f4.0 fixed is really great at f8.0 or f22 etc. How does one change a fixed aperture? Maybe I am not looking at the obvious?

06-19-2009, 11:40 PM	#3
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	People generally prefer a zoom with a 'fixed' wide open aperture, that is, the biggest aperture the lens can achieve throughout its focal range. Like the Tamron 28-75. At 28mm, it can be set at f/2.8, and at 75mm also at 28mm. Contrast that with the Sigma 17-70. At 17mm, it can be set at f/2.8, but the widest aperture it can achieve at 70mm is f/4.5, which is less flexible when wanting to limit depth of field (range of in-focus parts of image). Sorry if I'm explaining this poorly. Ultimately, it depends what you're looking for in a lens: the 16-45 is a stellar lens, but f/4 is its largest aperture. The DA* 16-50 can open up to f/2.8 throughout its focal range, and so adds that much more versatility. The choice is yours as to what you're looking for in a lens. Last edited by Peter Zack; 06-20-2009 at 03:38 AM.

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06-19-2009, 11:21 PM	#2
imtheguy Site Supporter Join Date: Mar 2009 Location: Virginia Beach Photos: Gallery \| Albums Posts: 2,950	Its only "fixed" in that the lens keeps the same maximum aperture of f/4 through its entire zoom range of 16-45mm unless you change it. You can manually (with the camera, there is no aperture ring on the lens) change to a smaller aperture like f/8 or f/11 at any focal length from 16-45mm. Most zooms can not keep the same maximum aperture throughout the zoom range. Hope that helps.

06-20-2009, 03:35 AM	#4
rparmar Site Supporter Join Date: Jan 2008 Photos: Gallery Posts: 8,823	You'll be happy with the DA16-45mm. Not only is it cheaper and lighter than the faster weather-sealed lens, but it is actually sharper too. No compromises in IQ here! I use it at f/4 without problem, though as with any lens would prefer to stop down a couple notches to increase resolution.

06-20-2009, 03:43 AM	#5
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	The DA16-45mm is a great lens, even wide open at f4 (when many lenses doen't perform well wide open). As the others have said, it's a fixed f4 through the focal range (wide open) as opposed to a variable lens like the ones that say 55-300mm f4-5.6 and so on. Not that these variable lenses aren't good. Just limiting in a couple of areas that many would like to avoid if possible.