[Damian.T]

Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

As I slowly get used to my K20 I'm getting a little frustrated with the 18-50mm DA lens that came with it as I'd gotten accustomed to my old Olympus C765 ultrazoom camera with it's 38 -380mm ability.

My dilemma is that I want two new lenses, a wide angle and a zoom. I want them for off road motorsport, views, static indoor and outdoor car shows and action shots, in possible wet and miserable conditions. However, I don't have hundreds to spend!

I want a zoom, but do I need it up to 380mm? I know, how long is a piece of string? My local camera shop has two lenses on offer:

DA 50-200mm f/4.0-5.6ED WR @ £139.

DA 55-300mm f/4.0-5.8EP @ £169.

I like the 50-200mm option as it's WR, and therefore when I'm on a Lancashire moor mid winter taking pics of Land Rovers playing in the mud, it won't break! However, the 55-300mm will get me nearer to the 380mm I'm used to.

Next is the wide angle lens, and judging by it's own thread on here the Sigma 10-20mm, is an awesome piece of kit, however, it isn't 'WR'. Do Pentax offer a similar lens that's as good for around £400 with the 'WR' stamp? Having asked that, I've just been through the Pentax DA12-24mm thread, and that looks good too, but around £200 more expensive. Is it that much better?

So now I'm totally lost on what to buy, can I have the thoughts of the educated collective please...?

Oh, and if makes a difference, my pics can end up on double page spreads and front covers of magazines... my little old Olympus did me proud, and now it's the Pentax turn!

[Ira]

The 55-300 is much more highly regarded than the 50-200, so that's an easy choice. And 300 is plenty long.

For wide, the superb and expensive 12-24 will get you as wide as you need, and the Sigma 10-20 is great as well. But that still lives you a gap--to be filled in at a later date by something like the Tamron 28-75 or similar.

But as always, it all boils down to money.

[Cuchulainn]

Remember too that the 38-380mm is equivalent field of view, so in that money, the 55-300 goes to 450mm and the 50-200 to 300mm.

[Damian.T]

Remember too that the 38-380mm is equivalent field of view, so in that money, the 55-300 goes to 450mm and the 50-200 to 300mm.

Whoa, hang on, that kind of info flies straight over my head!! What is this 'equivalent field of view' that you speak of?

[agsy]

On cameras with APS-C sensor the FOV is 1.6 x the lens equivalent mm.

[Flickeroo]

Remember too that the 38-380mm is equivalent field of view, so in that money, the 55-300 goes to 450mm and the 50-200 to 300mm.

Whoa, hang on, that kind of info flies straight over my head!! What is this 'equivalent field of view' that you speak of?

I won't get into specifics, because I myself don't quite understand it completely. But it has to do with the size of the sensor on the camera. Thus the image sent by through the lenses are adjusted according to the size of the sensor. It's called sensor crop. You can look at other threads for more details.

The way I wrap my head around it is by the following example (I'm also using approximates for simplicity, some discussions on this forum go into the technical details in depth) :

If you stand 10 feet or 3 meters away from a window and you look through it, you'll see the outside world in a certain field of view. If your window is bigger, you'll see a wider field of view of the outside world.
A full frame sensor on a DSLR will give you a truer perspective of a 50mm long lens. Film cameras were all full frame, so it's our standard focal length.
A smaller sensor will give a more "zoomed in" perspective, as if you're looking through a smaller window at 10 feet away. On a Pentax DSLR, a 50mm lens approximately comes up with the equivalent of 75mm on a full frame sensor.
An Olympus DSLR 4/3 sensor, being smaller still, will give you the equivalent of 100mm for a 50mm lens. I believe the Olympus you were refering to wasn't a DSLR and was giving you the perceived equivalent focal lenghts.

In summary, if you take a picture on your K20d at 50mm, and you want to have the same field of view on a full frame camera or film camera, you need to have a focal length of 75mm. That's the perceived focal length.


So Cuchulainn was doing the calculations for you in giving you the approximate perceived focal lengths of these lenses on your K20d.

I hope this helps, and doesn't confuse you even more...

[axl]

Whoa, hang on, that kind of info flies straight over my head!! What is this 'equivalent field of view' that you speak of?

Equivalent field of view is used to measure lenses of different formats against each other in numbers of known standard. In our case the standard is 135 format that is commonly known as 35mm film (yes, the normal film most of us were using 10 or so years back.) Or FF - full frame. This is used because it was the most popular format for interchangable lens systems back in the days. The numbers for your previous superzoom you have given above refer to this too. There is no way superzoom camera would have lens of actual focal length of 38-380mm. These numbers refer to lengths of lenses you would need to use on 135 format to see what you see on your superzoom. As such if you want to compare the lenses you are planning to buy to your superzoom, you have to multiply them by 1.5 (rounded value) to get numbers you can use for comparison.
So you are looking for 38-380 equivalent.
Sigma 10-20 gives you 15-30 so still way wider than you superzoom could do. 18-55 gives you 28-80, covering the wide to normal part of your previous camera. The telephoto lenses are 50-200 which stands for 75-300 and 55-300 which stands for 80-450. So the former brings you quite close to what you had and the second goes comfortably over it.
Now optically the 55-300 is reputed as best budget lens in that sector for K mount. But if you really need WR than it's no brainer IMO.
Is DA12-24 £200 better than Sigma 10-20? In short: No. In long: depends which version of 10-20 are you looking at. The old 10-20/4-5.6 EX DC is a terrific lens and practically equals DA12-24 in many aspects. Therefore I'd happily recommend you to save 200. The new 10-20/3.5 EX DC HSM is however inferior to both old version and DA12-24 and I would not recommend you buying it.
Final advice, for Pentax lenses check out srsmicrosystems (just google them). Probably the best UK stockist of Pentax and very often beating others on prices.

Hope this lengthy reply helped

Regards
Peter

[Flickeroo]

Axl's reply was much more detailed and probably made more sense than mine...

[sterretje]

On cameras with APS-C sensor the FOV is 1.6 x the lens equivalent mm.

It's usually 1.5 times Canon is the exception with 1.6 times if I'm not mistaken.

[JeffJS]

As I slowly get used to my K20 I'm getting a little frustrated with the 18-50mm DA lens that came with it as I'd gotten accustomed to my old Olympus C765 ultrazoom camera with it's 38 -380mm ability.

My dilemma is that I want two new lenses, a wide angle and a zoom. I want them for off road motorsport, views, static indoor and outdoor car shows and action shots, in possible wet and miserable conditions. However, I don't have hundreds to spend!

I want a zoom, but do I need it up to 380mm? I know, how long is a piece of string? My local camera shop has two lenses on offer:

DA 50-200mm f/4.0-5.6ED WR @ £139.

DA 55-300mm f/4.0-5.8EP @ £169.

I like the 50-200mm option as it's WR, and therefore when I'm on a Lancashire moor mid winter taking pics of Land Rovers playing in the mud, it won't break! However, the 55-300mm will get me nearer to the 380mm I'm used to.

Next is the wide angle lens, and judging by it's own thread on here the Sigma 10-20mm, is an awesome piece of kit, however, it isn't 'WR'. Do Pentax offer a similar lens that's as good for around £400 with the 'WR' stamp? Having asked that, I've just been through the Pentax DA12-24mm thread, and that looks good too, but around £200 more expensive. Is it that much better?

So now I'm totally lost on what to buy, can I have the thoughts of the educated collective please...?

Oh, and if makes a difference, my pics can end up on double page spreads and front covers of magazines... my little old Olympus did me proud, and now it's the Pentax turn!

Actually in terms of 35mm vs APC-C Crop factor, the 55-300 will get you to a 450mm field of view. Somebody else probably mentioned that but I wanted to make the point again. I'll guarantee that your Olympus lens is not a 380mm lens but that is the cropped 35mm equiv.

I can't offer a compare between the sigma and the Pentax wide angle zooms. I think they are two completely different lens. If you're asking which to buy, I'll offer my invite to the club I'm in, the DA12-24. For no other reason than I own one and love it. I don't know of any ultra wide lens that is weather sealed (for Pentax). An inexpensive option may be something like this if it really concerns you.

New Camera Rain Coat Cover for DSLR Sony Olympus Pentax - eBay (item 250688849705 end time Oct-27-10 00:55:20 PDT)

Not necessarily that one but something similar.

[Damian.T]

What a helpful bunch you guys are.. good answers, thanks! I get what you mean now by equivalent field of view.

I just need search down the back of the couch for any lost change, it's going to be an expensive week!

[Impartial]

So to boil down your choices on the long side, the 50-200 will give you WR, a lower price, and slightly less "reach" at the long end than your Olympus. (300 vs. 380 in 35-mm equivalent Field of View). The 55-300 will cost a little more, is a better-regarded lens optically, and gives a slightly more "reach" (450 vs. 380 35mm equivalent FOV). Neither is a bad choice, and you are looking at either 20% less or 20% more reach than your Olympus, depending on what you choose.

At the wide end there is no dedicated wide-angle WR lens, though the DA* 16-50 is a well-regarded lens, better for indoor or fast-action work than the kit, and it goes 2mm -- over 10% -- wider than the kit, which is already wider than your Olympus. So you might thinking about saving up for one of those, unless you are already drawn to Ultra Wide Angle photography . . .

[Damian.T]

Oooo, the DA 16-50mm... I haven't considered that, but then I already have the DA 18-55mm that came with the K20. Is there much difference?

[JeffJS]

Oooo, the DA 16-50mm... I haven't considered that, but then I already have the DA 18-55mm that came with the K20. Is there much difference?

You're kidding, Right?

[Damian.T]

You're kidding, Right?

Errmm, no!

Please take into account that I'm a newbie to all this and will more than likely ask ridiculous questions!