wide aperture vs postprocessing for shallow DOF

[WT21]

I hear about many people buying very expensive lenses in order to produce a shallow DOF in the portraits and i would like to ask if there is a difference in obtaining the same effect with a little post processing in photoshop. I am thinking of buying the sigma 50mm 1.4 for my canon 40D buy i am thinking if at the end the result will be the same and i will be throwing money for no reason. I am not a pro so i dont make money from my pics and i am not rich either to buy expensive glass easily.

Another thing that i would like to add is that with a smaller aperture you get sharper image and by postprocessing the background you get both a very sharp image and a shallow DOF, while from what i read many lenses are not very sharp when they are wide open.

I know that the real thing is always bettr than faking it...but at the end of the day...is there a really huge difference?

Thank you in advance,

Bezbozny.

Shoot with a longer FL than 50mm. Try 100, 135 on a crop. background blurs quite nicely.

 

[c2cal]

I'd be interested to see just how good it could be faked, understanding the limitations presented by others.

 

[biochemiker]

I find it very unlikely that such a minor scratch will affect image quality. Check out this link to see how little image quality is affected by lens damage...

http://www.lensrentals.com/news/2008.10.30/front-element-scratches

 

[Bezbozny]

Thank you very much for the link... I had already seen this and i agree with you. I shot a couple of pictures and i don't see and problems. But the fact remains that this is a brand new lens. It shouldn't have this crack. If i had caused this i wouldnt worry and wouldn't send it for repair. And even though the lens is cheap it does not mean that people are supposed to accept it in this condition. Lets say that you go to buy a new car and there is a tear in the back seat. Even though this wont affect the performance of the car, it does not mean that you have to accept it.

 

[PicPocket]

Thank you very much for the link... I had already seen this and i agree with you. I shot a couple of pictures and i don't see and problems. But the fact remains that this is a brand new lens. It shouldn't have this crack. If i had caused this i wouldnt worry and wouldn't send it for repair. And even though the lens is cheap it does not mean that people are supposed to accept it in this condition. Lets say that you go to buy a new car and there is a tear in the back seat. Even though this wont affect the performance of the car, it does not mean that you have to accept it.

All that... and besides that, even if a small crack in glass may not affect pictures, it definitely makes the glass weaker and more dust prone. There is no reason to happily live with it

--
PicPocket
http://photography.ashish-pragya.com

 

[photonius]

Thank you very much for the link... I had already seen this and i agree with you. I shot a couple of pictures and i don't see and problems. But the fact remains that this is a brand new lens. It shouldn't have this crack. If i had caused this i wouldnt worry and wouldn't send it for repair. And even though the lens is cheap it does not mean that people are supposed to accept it in this condition. Lets say that you go to buy a new car and there is a tear in the back seat. Even though this wont affect the performance of the car, it does not mean that you have to accept it.

well, even if you don't see the problem, you can think of it this way, the size or the area affected versus the whole diameter, so perhaps it's 2% or 5% max? so 2-5 % of the light rays will not be focused properly, causing loss of contrast. Since it is at the edge, when stopping down, light might not even travel through that part of the lens - but that depends on the light path.

Just think of mirror lenses. They have a big hole right in the middle, still works, but they have less contrast. You your case, the bad spot, rather than being black, will cause scattering of the light path. If you happen to shoot against the sun and the major part of the rays go through that area, you might get rather bad flare and stuff.

So, while you probably will not notice it under most circumstances, exchange the lens.

--
Life is short, time to zoom in ©