[Adam]

OK, sounds logical. Hmm. I did focus manually on infinity. Are the distance scales more or less exact on this lens?

You can't really go by the distance scale, especially on a zoom like the 55-300mm. Your best bet is to verify focus through the viewfinder or (better yet) live view magnification if you're on a tripod.

Adam
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[geedee]

You can't really go by the distance scale, especially on a zoom like the 55-300mm. Your best bet is to verify focus through the viewfinder or (better yet) live view magnification if you're on a tripod.

Ok, thanks!

[Azergoth]

Hi!

Could you try this "trick"? It's a little complicated, but should be a great indication about the lens.

1) In photoshop or gimp, create grayscale image of exactly the resolution (amount of pixels) as your screen
2) Fill the entire image with black (ctrl-A then fill --> black)
4) Zoom approximatively in the middle (the ruler can be helpful) and select only one pixel (should be a little square)
5) Fill that signal pixel with pure white
6) save as bmp of other lossless format (otherwise, the white pixel will be lost)

7) Display the image in full screen. Now, only one single pixel should be lit, the rest being totally black.
8) Take a picture of this one single pixel:

--> Be as far as you can in the room (several feet/meters)
--> on a tripod
--> wide open (f/5,8 ISO100, try not to overexpose the white pixel. In my case, it was about 1 second)
--> mirror lock up mode
--> no shake reduction
--> center the pixel and focus in live view

A shorter way is to shoot any kind of LED or little light, but I'm not sure about the result...

[kh1234567890]

Could this be a matter of micro adjustment and how should I fine tune it to properly focus on distances near to infinyty?

Most likely. Set up the micro adjustment at infinity - use a contrasty distant building, tree etc. as your target. Then with the camera on a tripod and the lens wide open and at 300mm shoot a series of frames at different adjustment settings. Defocus the lens for each shot. Then pixel peep the shots and narrow it down to the best setting. Try a few more shots at this to be sure. Do not use rulers, test charts etc. - they won't be far enough.

[Azergoth]

Most likely. Set up the micro adjustment at infinity - use a contrasty distant building, tree etc. as your target. Then with the camera on a tripod and the lens wide open and at 300mm shoot a series of frames at different adjustment settings. Defocus the lens for each shot. Then pixel peep the shots and narrow it down to the best setting. Try a few more shots at this to be sure. Do not use rulers, test charts etc. - they won't be far enough.

... I would suggest to use LiveView: center point focus or x10 magnification...

[jeallen01]

FWIW see here https://www.pentaxuser.com/forum/topic/pentax-smc-da-55-300mm-v-sigma-70-300...g-os-39721/p-1
OTOH, when I go to airshows (etc.) I use my Sigma 100-300 F4!

BTW, those shots with the 55-300 were with a very early version, and handheld