Aperture question (help)

[ozymay]

So I have a question that is really basic but I cant find the answer anywhere..

What is the difference between just a single aperture number lens and one that goes to another. Example: 2.8 lens compared to a 2.8-4.0 lens etc.

If I extend my lens with just a 2.8 lens will the aperture also get larger? Or will that only happen for a lens with a aperture like 2.8-4.0?

I know its kinda a dumb question but yeah XD

Thanks

 

[Vtec44]

The larger the number = the smaller the aperture. Yes, the aperture opening will stay the same throughout on lenses with a constant aperture, ie f2.8. On lenses with a range, the opening changes depending on the focal length that you're at.

 

[ozymay]

Okay, cool thanks.. for an example I am looking at a 17-50 2.8 lens. It has the 17-50 range but only says 2.8. So it would stay at 2.8 if I extended it at 50mm?

 

[MTVision]

Okay, cool thanks.. for an example I am looking at a 17-50 2.8 lens. It has the 17-50 range but only says 2.8. So it would stay at 2.8 if I extended it at 50mm?

Yes