Lens question

RoBoToKilroy · Jan 30, 2007

Hi all. Call me a supernoob but i have a question: where are the aperture/f-stops??

This is a SMC Pentax-FAJ 28-80mm F3.5-F5.6 -AL- Auto Focus Zoom lens that i'm looking at on eBay.
I'm trying to get a wide angle lens for my Pentax k-1000. I've found a few 28mm lenses (those are primes right? lol), but I'd rather have something like 28-70mm, so that i don't have to change back and forth to another lens. Anyway, yea, i'm a noob -.- ..Any help appreciated!

Don Simon · Jan 30, 2007

The aperture is - inside the lens! There is no aperture ring on this lens however, it is designed for the fully-auto series of SLRs on which aperture was controlled on the body. Therefore on the K1000 you will only be able to shoot 'wide-open' i.e. at full aperture. That's not the only reason not to buy this lens though; a 28mm 'prime' will almost certainly be better than a 28-80mm at 28mm. Changing lenses is after all one of the advantages of an SLR, and you can get plenty of wide primes for a very good price, so I would take another look at that option.

shingfan · Jan 30, 2007

i dont know why...but i always reply without finishing the enitre post......pls ignore

Big Mike · Jan 30, 2007

Welcome to the forum.

Firstly, that is an auto focus lens...and the K1000 is a manual focus camera...I'm not certain if the two are compatible.

The aperture is the hole in the lens, which is usually adjustable. It's very similar to the pupil of any eye...in that it can open wide or close down small.

When looking at a lens, the maximum aperture is listed. So for that lens above, the maximum aperture is F3.5-F5.6. That means that at the wide end of the zoom, the max is F3.5 and at the long end, the max is F5.6. (smaller number is bigger aperture).

The aperture is measured in terms of F numbers or F stops. The F number is a ratio of the focal length to the actual width of the aperture hole.

RoBoToKilroy · Jan 31, 2007

ZaphodB said:
The aperture is - inside the lens! There is no aperture ring on this lens however, it is designed for the fully-auto series of SLRs on which aperture was controlled on the body. Therefore on the K1000 you will only be able to shoot 'wide-open' i.e. at full aperture. That's not the only reason not to buy this lens though; a 28mm 'prime' will almost certainly be better than a 28-80mm at 28mm. Changing lenses is after all one of the advantages of an SLR, and you can get plenty of wide primes for a very good price, so I would take another look at that option.

:lmao: Yes, the aperture is inside the lens. You got me

Zaphod and BigMike: I had a feeling that there is no ring because the lens is auto, but what about other lenses that say AF but DO have an aperture ring?

Zaphod, how come a prime will be better? Is it because primes are designed specifically for their focal length? I don't want to sound like a newbie, but i was going for a 28-80mm so that i don't have to carry around that many lenses. (I use my camera for family moments and the like. Like a point and shoot really. I Don't have time for as much artsy photo as i'd like ...not to say that candid shots can't be artsy, but that's another debate.)

Mike: Yea, i was concerned about this lens working on my pentax. I know the mount is the same, but since the lens is designed for automatic it probably won't work well. And thanks for the welcome! I've been lurking around a little bit (lol) trying to learn more stuff, and there's a lot of good info around. btw, dare you explain to me what an aperture is?! I am offended sir that you think i'm that amateurish!

haha, just kidding. It's good to look over more basic detail once in a while. I still can't figure out ratios, but that's just because math isn't my strong point. :\

Anyway, thanks for the replies!