[gatorguy]

I don't understand this conclusion. Why wouldn't it work with the other focusing screen?
BTW, lots of precision equipment needs calibration to work best. If the lens works within the calibration range, it works as designed and should not be considered a "dog."

It's a split-screen Katz Eye, and in just now looking the viewfinder will not show it as focused on that screen with the -7 adjustment in camera.

[gatorguy]

OK so that was easily dealt with. B&H was great. Called them, explained the issue with needed focus adjustment. The rep said "Oh wow, I absolutely understand that wouldn't be acceptable for a new lens. We'll be happy to exchange it and I'm issuing the FedX label while we're on the phone"

Eezzy, peezy.
Thanks B&H.

[simple1]

OK so that was easily dealt with. B&H was great. Called them, explained the issue with needed focus adjustment. The rep said "Oh wow, I absolutely understand that wouldn't be acceptable for a new lens. We'll be happy to exchange it and I'm issuing the FedX label while we're on the phone"

Eezzy, peezy.
Thanks B&H.

Late to this but I’d add kudos to B&H for easy returns/exchanges. My new D FA 150-450 was having a problem focusing beyond 300mm - took less than 3 minutes to process an RMA. No hassles.

[ZombieArmy]

It's because B&H is basically a pro and prosumer establishment. They are lenient on exchanges and RMAs because it allows them to keep high margin clientele. It's why I even shop for general electronics there when I can.

[JensE]

Back to the original question, I found my KP to be somewhat inconsistent or imprecise with several lenses. E.g., focusing from opposite directions, e.g. makes my D-FA50mm overshoot. I.e., you'd need different settings, depending which way you de-focus the lens - between +5 and +7 on this lens. It just very fast, too fast for precision. Above the macro range, the focus throw of the D-FA50mm macro is very short. The lens focuses consistently on my K-1, btw. Both the KP and K-1 do need focus adjustments. The KP varies more, 7 lenses ranging from +1 (F50/1.7) to '7.5' (DA40/2.8), averaging +6. For the K-1, it's around +3 to +5 for all 6 or 7 lenses, which I tested, 4 of them tested on both cameras. I had the K-1 in service in Germany, it came back with clearly the wrong registration distance (progressively larger deviation from focus scales towards shorter focal length). Sending it in again, together with my FA31 and FA77 for reference, focus scales are now spot-on, still AF needs +4 on both.

[RocksandRocks]

Not to resurrect a dead thread, but I prefer that to starting another. My KP has been having a somewhat inconsistent time dealing with the DA* 300 (purchased used but in excellent condition).

My DA* 300 appears to even be less sharp than my 55-300 PLM at times! Looking more closely though, it seems like the focus is just missing. I only autofocus set to spot center, back-button and recompose if necessary, if that matters. Chalking it up to needing a fine tune adjustment, I tested the lens at 40x the focal length using the dot tune method. For my first try, I ended up getting very responsive confirmations f/+2 t/+10, or rather maxing out the range (pretty large range as well). The second go-around gave me the range f/0 t/+10. With such a wide range, I took some photos and I could hardly tell the difference, and settled on +4. Does this seem like a normal result? Has anyone else had this experience? Is my copy no great shakes or am I just being a deranged pixel-peeper?

[pschlute]

My DA* 300 appears to even be less sharp than my 55-300 PLM at times!

The DA* 300 is one of the sharpest telephotos made by Pentax. Unless your lens is a bad copy, you have focus issues.

I suggest the following:

1. Check the lens by focussing using a tripod in LV zoomed 100%. If the image is in sharp focus you know your lens's optics are OK.

2. Do a robust test using PDAF on an unambiguous target. Make the lens AF focus 10 times from closest focus distance. Then 10 times from infinity. Report your findings back here with pictures if needed, and we can analyse from there.

[RocksandRocks]

The DA* 300 is one of the sharpest telephotos made by Pentax. Unless your lens is a bad copy, you have focus issues.

I suggest the following:

1. Check the lens by focussing using a tripod in LV zoomed 100%. If the image is in sharp focus you know your lens's optics are OK.

2. Do a robust test using PDAF on an unambiguous target. Make the lens AF focus 10 times from closest focus distance. Then 10 times from infinity. Report your findings back here with pictures if needed, and we can analyse from there.

Thanks for the help! I took your advice and did more stringent testing, and since adjusting the focus, I've have been obtaining much better images in the field. My focus adjustment resulted in about the same as what I had originally "concluded", so that gave me some confidence. Also, I timed the autofocusing for each focusing test and I fear that the SDM motor may be starting to weaken, as they were not as consistent as I was expecting. Sometimes snappy, sometimes quite slow, focusing just a bit slower when I first turn it on. I don't think I would have ever noticed if I didn't do this with so much attention paid, so I'm not going to worry about that aspect of it for now.

I also have been doing some digging in my photo library to see if there has been a common thread in pictures I'm not thrilled with, and it seems that I have been too confident in my handholding capabilities and using too slow of a shutter speed. I see that I have more keepers in my library if the shutter speed is above 1/400. I'm usually walking/hiking while using it, so my unsteady hands and movement from physical activity exasperated my blurry issues separate from issues inherent to the lens.


More often than not, at least for me, its not the arrow but the archer