[ephophex]

When autofocusing, my 60-250mm does not proceed directly to the correct distance. Rather, it will proceed swiftly through the range; pause; then proceed to the correct distance. Sometimes, there is an additional pause. In all cases, these pauses are *very* brief. I've posted two video to illustrate this. The first is at normal speed

Youtu.be

Youtu.be

. The second is a slow motion

Youtu.be

Youtu.be

version, where it's clear there are brief pauses at ~4m and ~10m. It's also noteworthy that there are very slight sticking points when manually turning the focus ring, but not at the same points (sticking is at 1.2m and 5.0 m).

This is noticeable when racking through large distances, and much less so for smaller distance adjustments, as might be expected. In either case, focus seems to be achieved pretty quickly.

Now, the somewhat shameful confession: this has been happening for years; but I didn't really question it (don't ask me why!) until I got a D FA 70-200mm, and noticed that it just kinda proceeds directly to the scene of the crime with no dilly-dallying.

My questions for the owners of this lens: do you see anything like this? If not, any thoughts on what's happening here? It seems to be independent of the body it's mounted on (K-5, K-3II), and independent of focal length.

---------- Post added 08-04-18 at 03:57 PM ----------

One more video for good measure, showing a bit more chatter:

You Tube

You Tube

---

Last edited by ephophex; 08-04-2018 at 02:00 PM.

[BigMackCam]

Is the focus target, distance and lighting exactly the same in all instances - i.e. when this happens, and when it doesn't?

I haven't noticed the behaviour on my own copy, but in all honesty I've only ever used it out in the field, with the camera to my eye. I've never thought of it as a particularly fast-focusing lens, but never found it dreadfully slow either. Certainly not one for fast-moving sports, but otherwise quite acceptable.

If I get time tomorrow, I'll give mine a try. I haven't used it for a couple of months, but I'll be taking it with me it for a short break in early August, so I ought to check it's functioning properly anyway

[ephophex]

Is the focus target, distance and lighting exactly the same in all instances - i.e. when this happens, and when it doesn't?

I haven't noticed the behaviour on my own copy, but in all honesty I've only ever used it out in the field, with the camera to my eye. I've never thought of it as a particularly fast-focusing lens, but never found it dreadfully slow either. Certainly not one for fast-moving sports, but otherwise quite acceptable.

If I get time tomorrow, I'll give mine a try. I haven't used it for a couple of months, but I'll be taking it with me it for a short break in early August, so I ought to check it's functioning properly anyway

It seems to be independent of all of these factors. Except in the case of small adjustments (i.e., from, say, 4m to 5m), it always happens.

If yours has the same behavior, you won't actually have to look at the distance scale - there's an audible chatter as it slows, then accelerates. And you know, I'd concur - I've shot with it for years, and it never seemed *awful* in the AF speed department. I mean, it was no 40mm Ltd or anything; but it was swift enough. It's worth noting that it always achieves focus, even if the path it takes is not as direct as it might be.

Thanks for the feedback, AND for checking yours if time permits.

[UncleVanya]

I can try tomorrow as well.

[ephophex]

I can try tomorrow as well.

Many thanks, UncleVanya.

[BigMackCam]

I've just tested mine on the K-3.

Setting the lens to minimum distance then focusing on a distant subject, mine frequently focuses in two stages - one long, and one short (occasionally followed by fine tuning). Sometimes, it takes three stages like yours, and sometimes just one, with fine tuning.

The same thing happens when I set the lens to infinity and focusing on a short-range subject, but it's somewhat less noticeable.

Whether it takes one, two or three stages (followed by fine tuning) seems to depend on the focus target I choose and lighting, which isn't at all surprising.

I hadn't noticed this behaviour previously, but in all honesty I've never watched the distance window when focusing. Also, I typically pre-set the focus ring to infinity or minimum focus distance depending on whether my subject is nearby or distant. I first got into that habit using the HD DA55-300 screw-drive model, where it's pretty much essential if you want reasonably quick AF acquisition. Doing this on the 60-250 significantly reduces the AF time, and I've noticed that it seems less prone to the stepping you've demonstrated.

It's been a couple of months or more since I last used this lens, but taking shots of distant rooftops for this test, I'm blown away by the detail it records, even wide open. From f/5.6 onwards, it's silly sharp And what beautiful out-of-focus rendering...

[aaacb]

I used to have a 60-250 and it used to do something similar. It worked just fine until I sold it, and was tracking sports well, so I always thought it was just that point to point focus was slow (from very close to very far or the other way around).

[ToddK]

Setting the lens to minimum distance then focusing on a distant subject, mine frequently focuses in two stages - one long, and one short (occasionally followed by fine tuning). Sometimes, it takes three stages like yours, and sometimes just one, with fine tuning.

I just tested mine and had the same result as BigMackCam. However, it seemed much smoother going from long to short focusing.

[BigMackCam]

I just tested mine and had the same result as BigMackCam. However, it seemed much smoother going from long to short focusing.

I agree. If I look closely, I notice some stepping, but it's definitely smoother.

[ephophex]

I've just tested mine on the K-3.

Setting the lens to minimum distance then focusing on a distant subject, mine frequently focuses in two stages - one long, and one short (occasionally followed by fine tuning). Sometimes, it takes three stages like yours, and sometimes just one, with fine tuning.

The same thing happens when I set the lens to infinity and focusing on a short-range subject, but it's somewhat less noticeable.

Whether it takes one, two or three stages (followed by fine tuning) seems to depend on the focus target I choose and lighting, which isn't at all surprising.

I hadn't noticed this behaviour previously, but in all honesty I've never watched the distance window when focusing. Also, I typically pre-set the focus ring to infinity or minimum focus distance depending on whether my subject is nearby or distant. I first got into that habit using the HD DA55-300 screw-drive model, where it's pretty much essential if you want reasonably quick AF acquisition. Doing this on the 60-250 significantly reduces the AF time, and I've noticed that it seems less prone to the stepping you've demonstrated.

It's been a couple of months or more since I last used this lens, but taking shots of distant rooftops for this test, I'm blown away by the detail it records, even wide open. From f/5.6 onwards, it's silly sharp And what beautiful out-of-focus rendering...

@BigMackCam, I really appreciate the tests! So, based on your experiences, as well as those of @ToddK and @aaacb (thanks, all!), it sounds like the behavior of mine is completely normal. I also see that the multi-step focusing movement is much less noticeable in the long-to-short direction.

I've used it over the years primarily for shooting motorsports, and I generally would pre-focus on the target spot; so speed wasn't an issue. It also rarely had to rack from near to infinity; so this wasn't so noticeable.

And I have to agree, BMC - it's a fantastic performer, made all the more impressive by the fact that it's relatively compact and light (I'm looking at you, D FA 70-200mm).

[tonezime]

What AF mode are you all using? I've noticed some lenses behave quite differently in auto select mode compared to manual select, for example. I thought the DA* 55 had terrible autofocus until I took my camera out of SEL EX.

[BigMackCam]

What AF mode are you all using? I've noticed some lenses behave quite differently in auto select mode compared to manual select, for example. I thought the DA* 55 had terrible autofocus until I took my camera out of SEL EX.

In my test, I used a single centre focus point and AF.S to limit other variables.

[ephophex]

What AF mode are you all using? I've noticed some lenses behave quite differently in auto select mode compared to manual select, for example. I thought the DA* 55 had terrible autofocus until I took my camera out of SEL EX.

I'm also using AF.S and single point.

[UncleVanya]

And while I was unable to get to this test that is how I use mine as well. AF.S and single center point.

[Scorpio71GR]

Seems fairly normal to me. My copy will briefly hesitate during a long focus throw. The SDM motors were never known for their lighting speed. My old Tamron 70-200 2.8 blows the my 60-250 away in focus speed. But I like the 60-250 too much to care. Between the two lenses, the 60-250 is always the one I grab first.