[ZizZ^]

Like this it doesn't matter at all that it's not sharp on the edges.


Nor does it on photos like this

No offence but those pictures don't say alot. Show me some High resolution Tiff and then we can talk about sharpness...

Corner sharpness doesn't become irrelevant because someone suddenly starts to ignore it.

[normhead]

Corner sharpness doesn't become irrelevant because someone suddenly starts to ignore it.

The reason I posted those photos was because the edges are bokeh. It's not that I am ignoring them, It's that there is no need for them to be sharp and the picture would look exactly the same if the lens was sharp at the edges.

The centre sharpness of the lens is established on the web page linked too. Compare it's center sharpness to any lens you want. From between 24 and 50 mm it compares favourably with any Pentax lens made out there, prime or zoom. After that it has excellent centre sharpness all the way until 135 at f 5.6

[ZizZ^]

The reason I posted those photos was because the edges are bokeh. It's not that I am ignoring them, It's that there is no need for them to be sharp and the picture would look exactly the same if the lens was sharp at the edges.

The centre sharpness of the lens is established on the web page linked too. Compare it's center sharpness to any lens you want. From between 24 and 50 mm it compares favourably with any Pentax lens made out there, prime or zoom. After that it has excellent centre sharpness all the way until 135 at f 5.6

It's True that the centre of this lens is great to excellent but the severe problem lies outside the centre. Unfortunately... Could have been a real winner!

[normhead]

It's True that the centre of this lens is great to excellent but the severe problem lies outside the centre. Unfortunately... Could have been a real winner!

It is a real winner if you use it to it's strength. It's a zoom. You just need that little light that goes on and says, OK, time to switch to the Tammy 90 or 100 WR. ALmost all zoom lenses have strengths and weaknesses. Even with primes. Look at the rating for the 31 ltd. one of the best Pentax lenses of all time and rated as such by people who for the most part don't even shoot Pentax. If you want the best setting for the lens overall you need to use it at F 5.6, but if you want the absolute best edge sharpness then you have to use it at F8. Every lens is like that. You have to learn about the lens to know it's strength. Even looking at the numbers doesn't tell you everything. You have to shoot 1000 pictures with a lens before you really understand it's uses. At least if you're like me and you want to use every lens to maximize it's capabilities. And then after that you need to know where you are going next. If my 18-135 is on the camera and I see a long zoom shot that needs edge to edge sharpness, I'm going to pull out my 60-250. But that's a heavy lens, and I'm probably going to put the 18-135 back on before I start walking again. You use every lens you have for what it's good at. If it's not good at some things that's only a problem if you try to use it for that thing.

I said to my doctor, "it hurts when I do this."
He said "Don't do that."

You buy lenses for their strengths. As long as they do something extremely well, it doesn't really matter what they're bad at, as long as you need that thing they do well. The 18-135 does 22mm to 45 mm really well, center to edge.. and 45 to 135 really well in the center of the frame. And if I didn't have an FA 50mm 1.7 I'd use it up into that range too.

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Last edited by normhead; 11-27-2012 at 03:23 PM.

[zosxavius]

It is a real winner if you use it to it's strength. It's a zoom. You just need that little light that goes on and says, OK, time to switch to the Tammy 90 or 100 WR. ALmost all zoom lenses have strengths and weaknesses. Even with primes. Look at the rating for the 31 ltd. one of the best Pentax lenses of all time and rated as such by people who for the most part don't even shoot Pentax. If you want the best setting for the lens overall you need to use it at F 5.6, but if you want the absolute best edge sharpness then you have to use it at F8. Every lens is like that. You have to learn about the lens to know it's strength. Even looking at the numbers doesn't tell you everything. You have to shoot 1000 pictures with a lens before you really understand it's uses. At least if you're like me and you want to use every lens to maximize it's capabilities. And then after that you need to know where you are going next. If my 18-135 is on the camera and I see a long zoom shot that needs edge to edge sharpness, I'm going to pull out my 60-250. But that's a heavy lens, and I'm probably going to put the 18-135 back on before I start walking again. You use every lens you have for what it's good at. If it's not good at some things that's only a problem if you try to use it for that thing.

I said to my doctor, "it hurts when I do this."
He said "Don't do that."

You buy lenses for their strengths. As long as they do something extremely well, it doesn't really matter what they're bad at, as long as you need that thing they do well. The 18-135 does 22mm to 45 mm really well, center to edge.. and 45 to 135 really well in the center of the frame. And if I didn't have an FA 50mm 1.7 I'd use it up into that range too.

While this lens may suit you and your purposes, some of us need edge to edge sharpness and this doesn't come close to cutting it. If its only good at the wide end and you have a 60-250 already why not use get a 16-45 or better yet a 16-50 and call it a day? None of the pentax zooms that do wide angle are stellar save for the two extreme wa lenses out there. The 16-50 is ok, but not super great. The 16-45 is a bargain and a decent performer. Better across the frame than your lens. If all you shoot is flower and headshots, great. Some of us need more resolution. What if you shoot mostly landscapes? This lens would be a no go in that case.

[normhead]

While this lens may suit you and your purposes, some of us need edge to edge sharpness and this doesn't come close to cutting it.

Because most of the time centre sharp is fine.
I just found a Tamron 17-50 2.8, new for $369 at Prodigal on ebay. As far as I can tell it's just about as good as it gets edge to edge from 17-50, with decent control of CA as well. Next will be the Sigma 8-16 and then the DA 15 ltd. That should give my the best possible edge to edge images available on a K mount from 8 to 250.

But did I ever mention how important it is to have one lens you can just leave on your camera? In windy conditions, you can fill your camera with dust in one lens change. In wet conditions, mist or rain, you'd be an absolutely fool to remove a lens and risk getting water inside your camera body. There are a lot of times you come on something, if your lens range is too narrow, you don't even get a shot off before you've lost your subject. That is why they make walk around lenses, because of the prevalence of those kinds of conditions. They don't make landscape lenses like that because, usually with landscape you have time to change lenses and put on exactly the lens you want.