[thunderbrick]

I bought a cheap Sigma 140-400 (or similar) for my wife's D80.  I was very impressed by the quality of it's images.    Would I prefer a Nikon brand?  Hell, yeah, but the Sigma holds its own and won't break the bank.

[rklein]

Current camera is a D5100 with the the supplied  18-55mm f/3.5-5.6 AF-S DX VR Nikkor Zoom Lens.
Im looking for a lens thats shorter in length and lighter for casual shooting and have come across these two:
http://www.amazon.com/Nikon-50mm-NIKKOR-Digital-Cameras/dp/B004Y1AYAC
http://www.amazon.com/exec/obidos/ASIN/B00005LEN4/kenrockwellcom

Could someone please look at the specs and tell me what Im missing going with the less expensive lens?
Should I also be considering lenses from Tamron and Sigma?
Would I be better off with a 35mm fixed lens instead?

My suggestion would be to go back and look at the pictures that you have taken with the 18-55 lens.  You should have a "history" showing the focal length of each picture you shot.  That will tell you which prime to buy.  DO NOT go on other's recommendations on which focal length is better or worse.  What works for them might not work for how you shoot.  However, since your camera is a DX type, I would also agree with others that you "probably" would be better served by buying either a 28mm or 35mm prime.

I recently picked up a Nikon D600 with the Nikon 24-85mm f/3.5-4.5 G AF-S.  Since then, I have acquired the Nikon 50mm f/1.8 G.  I am saving up for the AF-S NIKKOR 16-35mm f/4G ED VR.  I will combine this last lens with Lee's Big Stopper filter system.  However, I rented the 16-35mm f/4 for 4 days to make sure that this lens would work for my type of shooting. (it did in a big way  ) 

Regards,

Randy

[low.pfile]

Emil,
There's already some good information in the previous posts.

But, we do not know WHAT you photograph and HOW. if you are shooting family gatherings, the answer will be different that if you hare taking travel landscape photos, which will be different than close-ups of pottery, etc.

The main thing to determine first is which focal length will work best for YOU. As rklein states above if you are using a photo organizing program like Lightroom you can automatically see the the breakdown of the photos in your library.

Another idea would be to take your 18-55 lens and using some gaffers tape, tape the zoom ring at 24mm, and take photos for a day or two (without zooming). Do the same at 30, 35, and 50mm. as these are the standard focal lengths that you can get from Nikon and others.

Similarly you can turn your camera's Auto Focus Mode to Manual and see if you live with a Manual focus only lens [there are arrows and a Dot to confirm focus in the viewfinder] the Nikon AF-D lens like to the less expensive 50mm lens you mentioned in your first post.

When I had my D5100 I really liked my Nikon 20mm AF-D lens which gives a 30mm Field of View for Full Frame (which is what is used as the lens designations). Though, with it I had to manual focus because it the D5100 does not have an internal focus motor.

After you determine which Focal Length is best for you then start shopping for the lens. Good luck.

[Emil]

Wow! Many thanks to all who responded
Much appreciated.

I think I'll go with the 35mm and from what you guys taught me, its better in low light , is close to the perspective of the human eye and is physically smaller than the 50mm

Thanks again