[suraswami]

Hi,

Bought this Sigma 135-400 APO DG Lens from Adorama. Lens was rated very good and not that expensive. But sharpness is not that great with the K-3. Not sure if I need more practice considering its heavier lens than Pentax 55-300.

Sigma APO 135-400mm F4.5-5.6 DG Lens Reviews - Sigma Lenses - Pentax Lens Review Database

Should I keep it? What's your thoughts?

Here are some pictures.

[luftfluss]

I'm seeing back-focusing on most of these shots.

You might want to try focusing manually on stationary targets in an effort to ascertain if the lens provides adequate sharpness.

[suraswami]

I'm seeing back-focusing on most of these shots.

You might want to try focusing manually on stationary targets in an effort to ascertain if the lens provides adequate sharpness.

that's my thought too. I also didn't use spot metering, if that will make any difference.

unfortunately i broke my hand and will take a while before i can get back.

here are other samples

[luftfluss]

that's my thought too. I also didn't use spot metering, if that will make any difference.

unfortunately i broke my hand and will take a while before i can get back.

here are other samples

Oy, best wishes for a quick recovery!

The pics you just posted look better. When you are back at it, you might need to engage in some AF calibration.

In my experience, it can take a few months to really learn long tele lenses. I've started with a new-to-me lens and thought uh-oh this isn't going to work out well and after a while everything starts clicking and I realize the problem wasn't the lens it was me.

[C_Jones]

I have s Sigma 150-500 DG OS. It has done quite well for me. One thing I make sure to do is check what aperture works for which distance I am shooting. For example I checked my lens at 500 mm by focusing on a road sign at a reasonable distance and found that the detail started to show when the aperture was at F8 . A good shutter speed of about 250 or 320 for things such as the herons or egrets walking in the water may help along with using your in camera shake reduction if you do not have "OS" (optical stabilization) on your lens. The shake reduction and OS help, especially when zoomed out, but if you do have both (in camera and on lens), do not use them at the same time to avoid conflict.

[suraswami]

I have s Sigma 150-500 DG OS. It has done quite well for me. One thing I make sure to do is check what aperture works for which distance I am shooting. For example I checked my lens at 500 mm by focusing on a road sign at a reasonable distance and found that the detail started to show when the aperture was at F8 . A good shutter speed of about 250 or 320 for things such as the herons or egrets walking in the water may help along with using your in camera shake reduction if you do not have "OS" (optical stabilization) on your lens. The shake reduction and OS help, especially when zoomed out, but if you do have both (in camera and on lens), do not use them at the same time to avoid conflict.

Thanks, the lens don't have OS. Shutter speed was at 1/500 and iso 400.

beyond 300mm, every little shake feels like earth quake lol.

BTW bought the lens for $89+shipping.

[C_Jones]

Thanks, the lens don't have OS. Shutter speed was at 1/500 and iso 400.

beyond 300mm, every little shake feels like earth quake lol.

BTW bought the lens for $89+shipping.

You're welcome. I know exactly what you mean about zooming out. In your case, since you do not have the lens OS, you may want to use the in camera SR (shake reduction) like I mentioned before.

Good luck.

[suraswami]

You're welcome. I know exactly what you mean about zooming out. In your case, since you do not have the lens OS, you may want to use the in camera SR (shake reduction) like I mentioned before.

Good luck.

Yes SR is on.