Are you smarter than a 55-300? For this Bigmos, the answer is no.

Started Jul 4, 2014 | Discussions thread
JeffAHayes Senior Member • Posts: 1,968
Re: Focal length

Leandros S wrote:

Depending on which review you read, the lens is described as soft from 400 or 450mm. So both Paul's soft shots at 500mm and your sharp ones from 267-370mm are "within spec".

Take a look at DxOMark's resolution graph on this matter (mounted on K-3):

It drops to about 2-3 MPix effective resolution beyond 450mm...

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No amount of perceived entitlement can replace actual expertise.

I was thinking something along the same lines, Paul. I have the Sigma 50-500, which I haven't really used enough to tell you whether it's "up to snuff" in my opinion, or not. I finally got a gimbal mount for the lens, which is now attached, but I haven't actually used it on my tripod like that since, and ALL my hand-held 500 mm shots -- even at high shutter speeds -- look about like yours when viewed at full size. But as Breck said, I think it may just be a matter of getting used to the lens and learning how to use it properly. I also think the NEXT time I use it handheld I'll turn off the in-camera shake reduction and turn it on on the lens, as that's supposed to give MORE stabilization than we get from in-camera IS.

But my FIRST thought when looking at your pictures was that you had NONE at 300 mm. In order to do a FAIR comparison against the 55-300, you should shoot some at 300 mm and see what it looks like at THAT focal length. Obviously, of course, you didn't buy it to shoot at 300 mm. But my point is that you're showing shots at a focal length 2/3 BEYOND what the 55-300 can deliver and then upset when they're not "razor sharp" at full pixel resolution. Shots using the 55-300 aren't "razor sharp" at full pixel resolution, either, although I'd say they usually look better than the first one you showed.

But I very much agree with Breck you need to LEARN THE LENS and most likely use the OS on the lens and turn it OFF on the camera (trying to use both at the same time makes them conflict with each other and can create a MESS of a picture). Reviews I've read have pretty consistently said that the in-camera OS provided by Pentax and a couple other brands ranges from 1-2 stops LESS than that which is generally provided by a decent lens-based optical stabilization, so when we have an aftermarket lens that gives us A CHOICE, it's probably better to use the lens' OS -- especially if you're not getting sharp pictures.

Try a few different things -- including a monopod and/or tripod (ALL OS should be turned off if you're using a tripod AND either a timer or some sort of remote release), and see what you get.

Good luck!


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A word is worth 1/1000th of a picture... Maybe that's why I use so many words!

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