Sony 16-80mm - how much slop, twitch, clunk?

[drok]

Hi all,

I'm new to the forum and after just purchasing the 16-80za for my A100, I felt I should chime in too to get a better understanding of the quality of lens that I have.

I'm fairly new to digital photography and this is the first "high quality" lens that I have purchased. I don't think I have much of the aforementioned "slop", "twitch", or "clunk" with my copy (are those technical terms?? ). My concern is with the AF. If I am on the wider side of the range and use the AF, it doesn't seem to nail the focus. Similar to how David said he needs to zoom in first, lock focus, and then zoom out...this is what I seem to need to do. See cropped comparison below (please note I haven't adjusted WB or applied sharpening:

Without zooming in first:

With zooming in first

Should I be satisfied with this? Or should I look to get a second copy? Like I said, this is the first time I've purchased a lens of this calibre and I have little experience in testing these things out and knowing what is worthwhile complaining about. Any comments or suggestions on how to further test would be greatly appreciated!

Cheers,
Drok

[springm]

I don't have an A100, but I remember to have had AF problems with my D7D in low tungsten light: especially with wide angle positions, the AF was not reliable. Maybe it is this kind of effect you see here, and not a problem originating from this lens

Markus

[David Kilpatrick]

This is not a lens issue, it's a problem with very short focal lengths and camera calibration. I corrected this on both my A100 and A700 using the manual (adjusting the screws) method which I do not advise to anyone concerned about their warranty, or unsure about pulling sticker/covers off the bottom of the camera and accessing the setting screws.

David

[drok]

Thanks for your responses! Although I bought my A100 used without the warranty, I think I'll take David's advice as I still don't feel that I'm quite ready to trust myself with that sort of adjustment. Maybe in the future though...

Cheers,
Drok

[Dr. Harout]

I don't remember exactly where but have posted somewhere mentioning the same issue with the 16-105. Might they be variofocal lenses instead of real zoom ones?

And Drok, welcome to the forum.

[smills]

This is not a lens issue, it's a problem with very short focal lengths and camera calibration. I corrected this on both my A100 and A700 using the manual (adjusting the screws) method which I do not advise to anyone concerned about their warranty, or unsure about pulling sticker/covers off the bottom of the camera and accessing the setting screws.

David

David,

I have a CZ16-80 mated to an A700 (v4) with severe backfocus issues at the wide end. At 80mm it's just about perfect, but as you zoom out the backfocus gets progressively worse right up to 16mm, where it's practically unusable.

Assuming I can adjust the focus screws so that at 16mm it focuses correctly, will the longer focal lengths suffer? Most of my other lenses are not anywhere as bad - my KM 28-75, Sigma 24mm f1.8, 85mm G, beercan, and 300mm f4 all seem to focus pretty well, and I'd rather have all of those working well than just the CZ.

On the other hand, my Tokina 17mm f3.5 does noticeably backfocus (although not nearly as bad as the CZ at 16mm) which seems to point to a wide-angle focusing problem with my A700.

Also, the thought occurred to me that I should send in the CZ 16-80 for calibration, because my copy is definitely not parfocal - I can't do the zoom in/focus/zoom out trick and achieve proper focus at 16mm (it's still backfocused).

Any advice you have would be appreciated - when it's focused correctly the Zeiss is an awesome lens, but I just can't trust the AF with it and my eyes aren't good enough to reliably manual focus the wide end.

-Stephen

[David Kilpatrick]

First, the Zeiss is not parfocal, but it's parfocal enough to improve closer-up shots (portrait or group distance) at medium focal lengths by zooming in/back.

Second, all AF sensors have problems with ultra wide angles of high contrast. Phase contrast detection works by seeing frequency and contrast, and with ultra wide lens, larger objects get turned into smaller frequencies - and if the contrast is high, the AF sensor can say 'yes!' to the focusing even when it is significantly far from reaching the perfect focus point. Combine this with any imaging sensor/AF module collimation errors being most noticeable at short focal lengths and wide apertures, and you get the typical result of 17mm f2.8, 16mm f3.5 etc not focusing very well.

The irony is that the better the lens, the worse the focus (the AF detects 'good enough' too soon) and the more you notice the error on enlarging the pic.

The solution is first to get the A700 collimated to the 16-80mm, and ask them to do so at 16mm - or they will set the lens to 50mm, and do it at that setting. Personally, I would just adjust the set screws for the AF module. I know it does no harm, the results are easily assessed, and as long as you remember to turn the screws an equal amount (all together) and always to limit your turn to 1/6th of a turn at a time maximum, you can fine tune the focus easily. It does not affect longer lenses except to improve their results marginally.

But before doing so, test the 16mm length from two directions. Test it focusing from infinity, and from close-up. If the two results are different, it's because you have picked too good a focus target. One secret with accurate focusing is to pick a low contrast, difficult target and NEVER one with lines or patterns. A face is a good target. Concrete, tarmac or grass are not good because they have patterns which can coincide. Fences, brick walls, cladding, roofs etc are the worst possible targets as they have geometric repetition and a major focus error can appear to be perfect focus to the AF sensor. Also, avoid solid coloured targets in blue or red. The focus distance is colour sensitive unless the lens is apochromatic. A good target would be a fruit like an apple, a suede coat, a rough painted wall, a gravestone with lettering.

David

[Bengeo]

I finally got my 16-80mm and it seems to be fine. No slops, twitches or clunks. Got it from Warehouse Express and they did their Price Beat Guarantee to bring the price down to £453.99 with free delivery.

Andy

[Dr. Harout]

Congratulations Andy and have a nice shooting.

[rogprov]

I used my 16-80mm at a wedding earlier in the year and was shattered to find that the focussing was all wrong when later looking at the shots on the computer screen. Of course they'd looked fine on the camera LCD and, as I had no reason to suspect a problem, I didn't magnify the image to check closely.

I sent the lens off to Sony under warranty and it was back in about a week fully repaired and at no cost to me. Their service note indicated that the "4th lens block was misoperating" and had been replaced. I must say it does seem extremely good now

[edrice]

My copy of the lens is from the first month release to the the USA market. It has been working fine. I used it first on the A100. It is now on the A350. I strongly recommend the lens. If you use the A350, it needs the CZ or G glass to be worth using. The difference on the A700 or A100 is not as great, but better then the kit lenses. I recommend exchanging the lens for another. It might mean waiting for the replacement to be shipped. The IQ is worth it.

I had the exact same experience - ordered it the week it came out for my A100 and now use it on the A350 and never had any issues at all, except for maybe the vignetting even with a slim polarizer. It's just been a dream lens.

Ed

[_Oliver_]

I got this lens a few weeks ago, and I'm not really sure if I got a "good" copy or not. I do not notice any image quality flaws (no decentering etc.), but there is noticable wobble when I extend the lens all the way to 80mm, and during autofocus at 80mm, the image jumps slightly in the viewfinder. On the other hand, the zoom mechanism seems to be decent, there are no suspicious noises when shaking the lens slightly, and I've been very impressed with all the images I got out of the lens so far.

So as the lens is somewhat of a mixed bag right now (mechanical issues vs. very satisfying image quality) I'm not sure about sending the lens in for repair; I don't want to risk getting an even worse copy back.

Any opinions on this would be appreciated.

And I hope it's ok to append this to this existing thread.

Oliver

[Dr. Harout]

And I hope it's ok to append this to this existing thread.
Oliver

Sure Oliver and welcome to the forum.

[aster]

Hello Oliver,

Welcome to the forum!
I think a good copy of this lens really shouldn't wobble at any point while zooming. I understand your frustration but my copy is only a couple of months old and it was firm and stable with no sounds from the beginning. Final decision to send the wobbling copy back is yours naturally but you still have that wonderful chance of getting an excellent copy. Everyone deserves to get a good copy especially if a Carl-Zeiss lens.

Good luck,
Yildiz

[Yagil Henkin]

No mechanical problems at all, very sharp, focuses well. I guess Mr. Kimka or whatever is his name did a good QC job that Day.
BTW, I now use Sigma EX UV filter. I've found out that it does not vignette as far as I can see, It's good quality and it is much thinner than my standard Hoya HMC which it replaced. Not too expensive, too. As for polarizer - I use a 77mm B+W with step-up ring. If I put it in front of the sigma filter, it may vignette a bit in some conditions - so I just take off the UV when I put the polarizer on.