Question regarding lenses

[Huston]

Hi guys, I am new here, but hope to post here frequently.
What's the different between a lens like this: SAL-70200G | 70-200mm f/2.8 Telephoto Zoom Lens | Sony | Sony Style USA

And this: SAL-70300G | 70-300mm f4.5-5.6 Telephoto Zoom Lens | Sony | Sony Style USA

We currently own a 75-300 zoom lens, and spotted this online: Sun Zoom F:4.8 85-210mm, for Minolta "Mint" for sale - TradeMe.co.nz - New Zealand
And was wondering what the difference is?

Sorry for the all the links, but I appreciate your help.

 

[white]

So you're looking at them both and you want to know why one is a thousand dollars more expensive? The aperture. The 70-300mm has a max aperture of 4.5 at the 70mm end, and 5.6 at the 300mm end.

The 70-200mm has a constant 2.8 aperture. Probably better craftsmanship, too.

 

[table1349]

Beyond aperture, the difference is in the optical quality and build quality. Every zoom lens is a compromise. You give up some image qualities, for the convenience of a zoom. The less you give up, the more expensive the lens. One thing that effects that compromise/quality/cost triangle is focal range. The bigger the focal range the more compromise. This comes from a cost standpoint. Technically we have the abilities to make an 18 - 400mm f2.8 lens with good image quality. But how many consumers would be willing to pay a 15K, 20K or higher price tag for the lens that would be big and heavy as well.

 

[burstintoflame81]

The difference is uhhhhh about a grand.


I think this has already been explained. The f/2.8 has a wider aperture, better glass for less distortion, better contrast, and better color. it will also allow for better Bokeh due to the wider aperture. Although depending on your subjects position, teles usually provide that adequetly anyway. If you can afford the f/2.8 get that. I have a Canon 70-300 f/4-5.6 and love it so far. But I only shoot long distance outdoors in adequate light in Arizona, not too many rainy overcast days here. If you shoot a lot of indoor sports the 2.8 will allow a faster shutter speed and lower ISO.