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Old Aug 13, 2009, 5:48 AM   #1
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Default confused about lense. help please :)

hello everyone,

i own a sony a200 camera and have used it with 18-70mm kit lense for quite a while. I was thinking of buying a new lense for creating extreme bokeh in portraits. I was considering tamron AF 80-210mm 4.5-5.6 or minolta AF 50 mm 1.7.

the question is: would it create good bokeh on zooming into 210mm @ f/5.6 or would it create better bokeh on 50mm f/1.7 ? I've heard that the more you zoom in the more bokeh you create (more blur is created on zooming). So i was just confused about this

any help will be greatly appreciated. Thanks)
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Old Aug 13, 2009, 6:20 AM   #2
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Pretty much there are 3 considerations when reducing the dof (depth of field) in a photo.

Distance from camera to subject, focal length and aperture.

To create a shallower dof you can do one or more of the following.

Get closer to the subject, use a longer focal length, use a wider aperture (smaller f number).

Another thing that will have an affect on the effect is the distance between the subject and the background so try to get the subject away from what is behind it.

Here are a couple of shots that show different extremes.

600mm and f5.6 long way away.

105mm f11 close to subject. Even with a narrow aperture you can get a shallow dof if you are close enough.


OK so now we have the basics you want to work out which focal length is going to be best. A 50mm lens is a good length for portraits on a crop body, so with the option of f1.7 you can do some nice work. For portraits further away then you can use a longer focal length so the zoom might work well but f5.6 is not all that wide when we are talking 210mm, a f4 lens would do better.

Hope that helps out a little.
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Old Aug 13, 2009, 7:27 AM   #3
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Thanks for your reply mark1616

I understand better now. I will probably go for 80-210mm then because I can shoot wildlife a bit and a bit of portrait as well. And costwise, 80-210mm is cheaper than 50mm 1.7!
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Old Aug 13, 2009, 7:38 AM   #4
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You can always get the Minolta 50mm f1.7 pretty cheaply on eBay. I used to have one when I had a Konica Minolta 5D before Sony bough KM.
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Old Aug 13, 2009, 9:37 AM   #5
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Quote:
Originally Posted by shah.apar View Post
And costwise, 80-210mm is cheaper than 50mm 1.7!
There is usually a reason that a lens is less expensive. ;-)

I only found one review of the Tamron 80-210mm f/4.5-5.6 from a KM or Sony dSLR owner, and the reviewer mentioned needing to stop down the aperture to f/11 to get sharp images with it.

http://www.dyxum.com/reviews/lenses/...asp?IDLens=178
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Old Aug 13, 2009, 9:44 AM   #6
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Jim, is it Sony/Minolta or Pentax that has the 'beer can' f4 lens? If it is on Sony mount I believe that is worthwhile.
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Old Aug 13, 2009, 9:51 AM   #7
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That's a nickname for the Minolta 70-210mm f/4

http://www.dyxum.com/lenses/detail.asp?IDLens=48

It's going to sell for quite a bit more than something like that cheap Tamron. Here's an example with hood, caps and case:

http://www.keh.com/OnLineStore/Produ...BCL=&GBC=&GCC=
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