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Old Nov 16, 2010, 7:01 PM   #1
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Hi all,
I need some professional opinions on these two shots, one with my old 50mm f/1.7 Minolta lens, and the other with the new Sony 28-75mm f.28

Do I need a $900.00 lens?
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Old Nov 16, 2010, 8:29 PM   #2
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Not a professional, but to my eyes, the 50mm f/1.7 looks a bit sharper. Not unusual though considering that zoom lenses at max zoom tend to show some softness. Do you need a $900? Perhaps not, but I think the question is if you want one??? If you are looking for a less expensive mid range fast zoom, you might look at the Sigma 28-70 f/2.8 which retails for about $600 http://www.amazon.com/Sigma-24-70mm-...9957290&sr=1-4

The reviews seem favorable.
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Old Nov 17, 2010, 3:45 PM   #3
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A zoom will do things your lovely old prime won't. It also makes some compromises because it's a zoom. The bigger question is do you mind giving up the zoom capability to become a prime shooter? Some people will say yes, some no. I'm using a lousy work monitor so I don't see any quality difference, just the distance factor (you were closer with the 50 lens - does it have a closer focusing range?).

Do I need that expensive prime lens I have my eye on? No. Do I want it? Sure do! And I'm hoping that one of these days I'll have enough money to buy it.
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Old Nov 17, 2010, 4:23 PM   #4
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What was your focus point?

It's tough to judge from your photos.... (and they have no EXIF information to give us any clues as to the active focus points).

But, if you were 2 feet away from your subject when using the 50mm lens, you would have been able to capture an area around 10 inches wide (and I'm not sure you were that far away).

See this DOF calculator (chances are, your DOF was only around an inch in front of and behind your focus point if you were two feet away, so anything further away or closer is going to get softer).

http://www.dofmaster.com/dofjs.htmll

IOW, if you're filling the frame that much with a smaller subject, your Depth of Field is going to be very shallow. So, focus on what you want to be sharper if that's the technique you want to use, making sure that you're carefully selecting the focus point (not letting the camera do it for you). ;-)

Also, even if you move the camera a fraction of an inch after locking focus with a half press before pressing it down the rest of the way to take the photo, focus point can shift (as it's not uncommon for shooters to lean a bit after locking focus). So, for macros, using a tripod is a good bet.
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Old Nov 17, 2010, 5:07 PM   #5
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I had the camera on a tripod about 4 feet from the subject and the iris was the focus point.
The exif is printed on the photos for the most part and both were at f11.

I left the camera position set and just swapped the lens.

Wanted to see how my old Minolta lens fared against the new Sony.

The Sony 28-75mm I know is a little more versitile than the fixed 50mm.
I also took a shot with my Sony 18-250 at the same settings and it compared very favorably to the 50mm and the 28-75.

Thanks for the input.
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Old Nov 17, 2010, 10:27 PM   #6
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If there is an edge in detail and contrast, I'd give it to the 50, but there is enough difference in lighting that it is really tough to say. The size difference in the shots could also be adding to the 50's edge. You would probably see more difference at wider apertures. But both shots look good. I wouldn't can either lens, though.

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Old Nov 17, 2010, 11:04 PM   #7
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I am really trying to talk myself out of getting the Zeiss 24-mm f/2.8.

I have no plans to go to a FF camera. May get the new A580 and put the Minolta 50mm on it and later get the Sony 70-200mmG f/2.0 for indoor and outdoor sports for use on the A700.

I hate it when lens/camera lust consumes me.
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Old Nov 18, 2010, 6:53 AM   #8
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You were also "filling the frame" more with the 50mm (flower represented a larger percentage of the frame), meaning more pixels were representing it.

When stopped down that much with those lenses, that's about as good as you're going to do from an optical quality perspective (I wouldn't spend money on another lens intending to get better results with those types of shots, unless you wanted to get very close and fill the frame more with a Macro lens (and I'd lean towards a longer lens so you could fill the frame more from further away without blocking lighting). For example, a 100mm or 150mm macro of some flavor.

If you don't plan on filling the frame more (so that your filling the frame more with a smaller area to get more detail -- for example, just the center of the flower petal), things like lighting, focus distance and focus point would make a bigger difference. ;-)
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Old Nov 18, 2010, 1:12 PM   #9
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from your sample photos, I think you need to take another sample away from the object coz its hard to compare in that closer range..
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Old Nov 19, 2010, 12:27 PM   #10
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Fill the frame with a single flower on both of them and open that apertrure to 2.8 on both, you will see the difference.
Its hard to compare the IQ at f11 as most lenses weakpoints are diminshed by then.
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