Noobie astray: Lens

Garbear1020 · Sep 3, 2008

Hello, I am kinda new to photography and what little I do know I have taught myself so I don't know the technical stuff. I was wondering how a "fixed" MM lens like a Nikion AF-S VR 300MM f/2.8g could sell for thousands where a zoom lens like my 70-300 AF 1:4-5.6G lens is worth maby 150$

I do realize the 300mm has internal focus and VR but I still cant understand how it could be as useful as a "zoom" lens. I think the fixed Zoom would be a pain in the rear when it comes to framing in action shots and.

Also, does a 300mm 2.8g have more "distance" than my 70-300mm

sorry all these lens terms and choices over whelm me if someone has a place i could learn more about the mechanics of a lens and photography i would be more then willing to check it out.

William Petruzzo · Sep 3, 2008

A lot has to do with your aperture of the lens. The second set of numbers after the mm rating. The 300mm lens has a 2.8 constant aperture, meaning that it lets a lot more light through, which uses a lot more glass to do without distorting the image. The 70-300 can get away with a lot less glass, or even use imitation glass, because it doesn't have to worry about so much light coming through.

You would do well to read up on the relationship between Aperture, Shutter Speed and ISO. It will help make the lens market a lot less intimidating. Not to mention make you a more confident photographer.

You might find some useful stuff here in this little online textbook:
http://photo.net/making-photographs/

In fact, photo.net has lots of useful resources. Check it out.

Mitch1640 · Sep 3, 2008

the 300m fixed focal length has better quality optics, i dont really know much about lenses but i heard that primes as they are called are or used to be much better then zooms, in optical quality. i dont think it would have more distanse. also the 2.8 is a much faster lens then the 70-300 4-5.6.

Overread · Sep 3, 2008

300mm is 300mm so the "distance" will be the same for both - however the 300mm prime is in a whole other league of lens to your 70-300mm

First off a 300mm prime of any pricing zone has an advantage of over a zoom lens since it does not have to have as much glass in its construction as the zoom, since it only has to achive a single focal length - hence why they also tend t (though not always) be brighter (larger max aperture) than the zooms.
Further since there is less glass in the equation there is less chance of the lens being soft due to a production error - its rare but does happen (the canon 100-400mm was plagued by this in the early days of its production)
In addition you are comparing a budget range lens (70-300mm) with a top end professional lens - thus the cost is also factoring in better build quality and materials (leading to more weight, but its more durable) and also meaning more expensive glass and glass coatings are used - the end result is that the prime will give you a whole other dimension in sharpness and image quality - the difference between the two is very noticable.
The prime again will also have a focusing advantage - being faster than the zoom

However, as you rightly point out, the prime loses the zoom functionality. Now on a budget zoom its not a gain because your quality of photo is so much less, but there are higher quality zooms where the convenience will outweigh the gain in sharpness. Say you were always in zoos - close to the animals, but with distances being very different from animal to animal - a zoom here would be good for getting the framing right and also helping remove the cage (if that was your desire) hints from the frame without having to crop --- however if you were always shooting in the field you might find yourself always sitting at the 300mm end - then the prime would be the better tool for capturing the shot - the zoom is not helping since its 70-299mm focal range is not being used at all.
hope that helps explain a bit