Dslr Tamron lens selection?
I have a very little confusion regarding dslr lens. I'm not too noob nor a professional. I hv nikon D5100 with kit lens 18-55mm. I want to upgrade my lens. The thing making me confuse is that f-stop means aperture or focal length, the more smaller F number, the more bokeh(blurred background) effect you get. But i have seen lenses with F-stop like 4-5.6 and their sample images hv very smooth creamy bokeh effects that look near to f1.8 or siniliar results. How it is possible? I mean f2.8 or less than this seems to be doing the job but how they does it with f5.6 lens?
I already know the technique of distance between subject and background. More difference means more blurness.
I want a tamron lens for every day to day photography like event or wedding stills etc.
The lens i hv found based on my knowledge and experience is Tamron A17 Af 70-300mm F/4-5.6 Di LD MACRO. Is this the right choice?
you can suggest me other lenses as well, coz i dnt want to regret later.
Larger apertures make is easier to blur the background, because your depth of field is very narrow. But the difference between f/4 and f/2.8 is one stop of light. There are a lot of things you can do to help through the background out of focus.
Yes, you can increase the amount of space between your subjects and the background, but you can also focus in front of your subjects, so they are in back of what would be an acceptable focus range. You can also do stuff in the computer. Smoothness relies on a number of things, and you can create so nice smooth bokeh with round filters. Higher end lenses tend to have better bokeh because they have more blades in the aperture, giving a smoother imaging circle. But that is not a universal, and you can shoot through a round cutout filter to give that same smoothness.
As for the lens, that sounds like a terrible choice for events and weddings. It is long and slow. The choice for a single lens would be a f/2.8 24-70 or 28-80. Sigma and Tamron make them, and I'm sure Nikon has one as well. Tokina used to make one, so maybe you can find a used Tokina.
As a complement to that lens, you would go wider, with a 16-35mm f/2.8.