Requirements for a blurred background

[BigRuss]

After looking at the great pictures on this forum and failing to replicate them, I've finally decided to join up with a question..

I'm trying to practice portraits so I can get good at them before our new baby comes along. I've got a sony alpha 200 with an 18-70 (3.5-5.6) kit lens and a 75-300 (4-5.6) telephoto zoom. What I really want to do is to get a blurry background. I've read that I need to have as wide an aperture as possible and whilst this blurs the background a bit it's not as much as a lot of the photos I see online.

Can anyone provide any tips for where I am going wrong? Do I need a faster lens? (I was looking at a 50mm f1.4 prime but it's not cheap and I'd rather not spend the money if I can avoid it) or should I try to get the background futher away from my subject? Is there anything else I'm likely to be doing wrong? - I've been using the kit lens at about 35mm f4.

Thanks for any help.

Russ

[tog]

It will help if you're closeish to your subject, with the background is further back. A telephoto lens, instead of the 35mm will make a huge difference, and use it wide open.

[VxDuncan]

The longer the focal length, the more blurring you'll get (in simple terms), so try around 100mm wide open as a good starting point.

The ratio between you and subject and subject and background is critical. Try and make the first a lot smaller than the second.

You should get something pretty good with the long end of the kit lens at F5.6, or even the long zoom (though that may be a bit cumbersome indoors.

An alternative to the F1.4 would be the 50mm F1.8s for £50-60. The difference between F1.4 and F1.8 isn't massive, and to be honest you're gunna want to stop down a 1/3 of a stop on the F1.8 to get a sharp image anyway. For the Nikon's the F1.8 is reported to be better optically than the F1.4 - the fastest you'd want to use either for anything that mattered would be F2 ish.

[BigRuss]

That's brilliant, thanks for the advice.

I'll try the telephoto at 100mm, and try to get the backgrounds further away. I've been trying these indoors and our house isn't that big

Unfortunately I've got a sony and there doesn't seem to be a cheap 50mm lens for it. I found a 50mm 1.7 minolta that'll fit but they are about £130 on ebay at the moment and it seemed to me to make more sense to get a new sony 50mm 1.4 for £210 than worry about buying second hand.

[C&C]

BigRuss said:

Unfortunately I've got a sony and there doesn't seem to be a cheap 50mm lens for it. I found a 50mm 1.7 minolta that'll fit but they are about £130 on ebay at the moment

That's way over what should be the going rate. I'd expect £50 - £60.
One option may be rather than searching for just the lens, look for older Minolta cameras for sale (7000, 5000, 3xi etc...). They often go for less than £100 with a standard lens - on some of these, this is the 50mm f1.7.
An example is this 5000 with 50mm f1.7 part way down the page for under £100 and that's from a dealer:
http://www.mrcad.co.uk/shop/home.php?cat=1545&...
You also get an old film body to play with into the bargain!

Have you looked on the various Minolta/Alpha forums in their classified ads? You should be able to pick up a 50mm f1.7 for £50 - £60, as here (although now sold):
http://www.dynaxdigital.com/index.php/topic,7889.0...

Cheers,

Conrad.

P.S. The Minolta 50mm f1.7 was/is a pretty good lens, and great value at the price you should find it for.