Which long telephoto zoom?

I am contemplating buying a long telephoto zoom to g with my *ist DS, mainly for wildlife purposes, especially birds at wetland reserves. Curently I have a Sigma 70-300 APO Macro Super which is pretty good but fully extended is prone to camera shake even tripod mounted because it has no tripod mount on the lens (hardly expected on such a lens). I also have an older sigma 400/5.6 AF which does have a tripod mount. However it is not very sharp. I would like the extra reach of 400 or 500

Pentax do not do anything that fits the bill (except perhaps the 500 4.5 preset which ocasionally crops up for sensible money, but I would like autofocus really. The Pentax 400 5.6 F would be nice but is very rare on the second hand market) The choice thus seems to be
Sigma: 135-400, 170-500, 50-500
Tokina: 80-400

I'm most tempted by the Sigma 50-500 and that would be within budget. I know it has had very good reviews and is due in the lates DG version for Pentax pretty soon. It also means I can cover the full range with two lenses, as I have the 16-45.

However the Tokina 80-400 is half the price, half the weight, has good reviews, and its latest incarnation has a tripod mount. Given the Sigma has been measured at around 460 (rather than 500) the difference at the long end is relatively small. Furthermore it has a 72mm filter diameter, which is the same as my old Sigma 400 - so less filters/adaptors to buy.

Anybody any experience with either of these, especially the Tokina? I'm fairly sure the Sigma would perform well but I don't want to spend more than I need.

Hmm. Talking to myself. Always a bad sign!

Perhaps I will make the question more general.

I want to get a long lens (400mm+) for use on my Pentax bodies - primarily the *istDS. I don't want to spend a sackload of cash as I don't have it. However I can probably budget £800 sterling if necessary. I would be happy to pay less! Zoom would be useful. Autofocus is essential. Obviously the faster the better but I won't get a fast long lens for this money. Image quality, especially sharpness, is, of course, the primary consideration.

Principal use will be birds at nature reserves and wetlands.

Any helpful suggestions welcome!

Tony, something like this might fit the bill - esp. when you take into account the 1.5x focal length conversion on an *ist DSLR.

http://www.tamron.de/index.php?id=106&kc_prid=452&L=2

I much prefer Tamrons to Sigmas and there are quite a few available on eBay, not all models are available for Pentax though!

If you really want to save money, you could look for an adaptall2 manual focus lens, say a 75-250 f3.8/4.5, which is reasonably fast and a fine performer and add to that the Pentax 1.7x AF adapter.
I know that's not an ideal option but the results would be pretty good and you'd save a small fortune!

If you fancy a fixed focal length, in preference to a zoom when using the AF adapter, there are plenty of good Tamron and Pentax lenses that would do an excellent job and perfectly usable on an *istDS.

Thanks for that

I already have the Sigma 70-300 APO Macro Super which is fine for some purposes (I got some good shots on the Farne Islands handheld but sat down and bracing elbows on knees), but fully extended prone to camera shake even on a tripod. I would like a lens with a tripod mount as that gives much better balance. I do own an older sigma 400 5.6 AF lens which can produce passable results and is nice to use on a tripod, but being the non APO version it is quite soft.

Maybe I should wait for a Pentax 400/5.6 to come up on ebay. Might be waiting quite a long time though. Can you still get it new does anyone know? How much is it??

If sharpness is a major consideration, you should avoid zooms with a huge zoom range. Ten times is asking for trouble.

If you had £200, I'd suggest a second-hand Pentax-M 300mm with the 1.7 AF convertor. For £500, I'd suggest a second-hand F or FA 300mm f4.5 with the same convertor or the 1.4 convertor.

But for £800, I'm stumped. I don't know enough about non-Pentax lenses to be able to say anything useful, and the Pentax 400mm and 600mm AF lenses are outside the budget and very rare.

Good luck

G

The Sigma 170-500 performs well, provided that have something to hold it steady. Good on MZ5N, and even better on *istDS. However don't attempt to use 1.5TC with it as loose the AF!
Holding it steady is the real issue
* Tripod often too cumbersome
* Monopod only useful if wedged against something.
* Beanbag works quite well
* In theory a 'car door tripod bracket' should work, but never tried it.

Look at the s/h market. Should be able to pick one up for less than £350.

Worth trying the 70-300 with a beanbag

My instinct is to avoid the 50-500. Yes, it got good reviews, but how often would you really need full range? And it weighs a lot!

Thanks. I intend to use it on a tripod anyway so that is not an issue. The weight of the 50-500 does put me off, and as you say, I'm not likely to use the shorter end of the zoom.

So it is probably between this and the 135-400 (which I can fit my Cokin P filter system on)

Thanks for the help everybody!

I recently bough a SIGMA 100 to 300 mm F4 IF EX APO (that's F4 at 300mm) to replace my beaten up 100 to 300 mm Pentax FA. I use these lenses on my *istD and Z1.

The sigma lens is a cracker! Very well made and optically outstanding. It has a very well balanced tripod mount. Focusing is internal as is zooming. A delight to use, given a monopod or tripod!

Picked up a mint Sigma 170-500 for £279 from Ffordes. Not had chance to try it properly yet but initial tests look promising. I'll take it down to Arundel (wildfowl reserve) in the near future!

I agree with Ken on the EX 100-300

I also have this lens and am very pleased with results, especially sharpness.

It is very well built

Well, I've given the Sigma 170-500 its first field test at the WWT in Arundel. Quite please with the results, a crop of a swan displaying taken at full stretch at f13 and 1/1000 at 400ASA printed at 200dpi onto A4 looks pretty good to me at least. Not quite 'you can see every feather' but the day was slightly hazy.

The lens handles pretty well, though the zoom is the 'wrong way round'. The tripod mount could be further forward - it is still a bit front heavy (maybe I need a heavier camera body!). Autofocus is pretty good, the internal focus is a boon for this.

Not bad for £279!

My Manfroto MN360 head is good for this sort of work. Set the horizon level and leave the other two dimensions (pan and tilt) slightly loose and I get good support while shooting and yet can still quickly relocate to anoher subject.

If you're getting camera shake on a tripod, the tripod needs to be tightend up or you're using too small of a tripod. Make sure the tripod is resting on a firm surface if at all possible, putting a tripod on bouncy spongy grass will not do you a whole lot of good!