Originally posted by Cloudy Wizzard As I just told Tom
here I recently (monday evening) bought a Pentax zoomlens from a seller on Ebay (local Belgian).
since this is my first lens (not counting the 18-55 kit lens) I have some questions and I hope some here are able to answer them for me (but I'm quite sure they will).
The seller calls it a "SMC PENTAX- ZOOM A 1:4 70-210mm , 32 tot 4" in as good as new condition. So I've been looking at the lens review section here on the forums and I'm happy to see that most (of not all) reviewers would recomend this lens so I guess it's a fairly good one.
now here are the questions I have about it :
1. what do the reviewers mean with "zoom creep" or plain "creep" ? is that something to worry about ?
2. I assume this lens has the standard K Bayonet mount (will fit on my K100D Super without trouble) ??
3. What's the focal lenght when used on my K100D since I've heard that the 70-210 is for 35mm film and that it's different when used on a dSLR camera (and how do you calculate this ? so I can do it myself in the future).
4. I see it has a manual aperture ring and an A on that ring so I can eighter manually set the aperture with the aperture ring (to 22 for example) or put the ring in A and have the camera set the aperture ? correct ?? (I think I've set the menu of my K100D to allow manual aperture setting with the aperture ring).
5. How does this lens compair to the newer DA lenses like the :
Pentax SMC-DA 50-200mm F:4.0-5.6 ED and the new
Pentax SMC-DA* 50-135mm F:2.8 ED IF SDM
or in other words, if I have the Pentax A 70-210mm would there be a good reason (so not because of LBA) to get eighter of both of the above lenses aswell ?
I've been reading that the cheapest (Pentax SMC-DA 50-200mm F:4.0-5.6 ED) is a good overall lens but I would think that the 70-210 would cover most of the range of that one with a similar speed.
The more expensive DA* lens on the other hand has a smaller focal lenght but is faster with a lower aperture 2.8 instead of 4/5.6
A lot of questions I know but I'm trying to learn something about this lens.
I bought this lens not too long ago, perhaps I can answer your questions. If you want any pictures from this lens, let me know.
1. This means that the sliding mechanism that is used for zooming the lens has become worn and depending on how bad it is, the lens may shift focal length a little bit on extreme angles or may not even hold the desired focal length. My A 70-210 has a little bit of zoom creep and it hasn't bothered me at all.
2. Yup, mounts perfectly.
3. The crop factor of our cameras is 1.5, (technically 1.53x). Thus the 70-210 becomes a 105-315.
4. Your correct but there's a catch. With the A lens you can control the aperture of the lens from the camera body. Using the aperture ring on the camera
is allowed but the lens cannot communicate what aperture you have manually set it to. This can lead to exposure problems. Since your prospective lens is an A lens, my suggestion is to change the aperture from the body.
5. I'll say this, if your considering the DA* 50-135, get it. Out of the trio of tele zooms you have presented it is by far the better one. It is also very expensive at ~900 US. However, if your choice at present lies between the 50-200 and 70-210 it's a toss up. They're both very good in terms of IQ. My A 70-210 has very sharp and I've heard equally good things about 50-200.
There are four main differences that can sway your decision one way or the other.
Focal range - The DA is slightly wider, do you need it?
Auto Focus - One lens is MF one is AF.
Constant Aperture - The DA variable between 4-5.6 where as the A is a constant F4.
Weight - The A series zoom is heavy. The DA is lightweight.
I ended up selecting the A 70-210. Good luck with your choice.
-Rajiv
Edit: To focus with a one touch zoom. You push-pull to change the focal length and twist to focus on your subject.
Last edited by TFTM; 11-21-2007 at 09:23 AM.