Autofocus problem at wide angle

[xrdbear]

I have a problem with inaccurate autofocus on my S2 in combination with the 12-24 DX lens. What I would like to know is if anyone else has had a similar problem and been able to resolve it.

Basically if I zoom to 12mm and focus on an object at infinity the lens adjusts to 1m on its focus scale and the resultant shot is indeed out of focus. The same result is produced by focusing manually and using the focus confirmation green dot in the viewfinder. If I focus the lens manually using the distance scale on the lens set to infinity the shot is in perfect focus. There is no error at the 24mm setting and there is a proportionate error at setting in between 12 and 24. Focusing on objects closer than infinity produces errors too.

In another forum various suggestions have been made and the points already covered are:
All the subject is far away so it doesn't matter if the focus bracket position is a bit off.
The appropriate CSM's are disabled.
Dynamic AF selection is OFF.
The batteries are fresh and the contacts clean.

I have sent the camera but not the lens back to Fuji and they report no problems with the AF but were not able to check it with this sort of lens. I have contacted Nikon but they think if it focuses manually fine then there is nothing wrong with it and it must be incompatible with the S2 (thank you Nikon). They will take it in for a check but will charge me for shipping if there is nothing wrong and I will be without the lens for 6 weeks plus.

Unfortunately I live 140 miles from the nearest dealer so I don't have the opportunity to try the lens on another body.

Thanks to anyone who has read this far. All suggestions considered. If you have a Nikon or Fuji body and live on the Isle of Skye then I'd REALLY like to hear from you!

Brian

[JPS]

I'm affraid i can't be of any help concerning a possible malfunction of your lens... I don't have the Nikon 12-24, but the Sigma 12-24 !

I never had any focussing problem, but in any case, i allways shoot MANUAL FOCUSING with this lens, as much as possible at f/8 or f/11, and using the HYPERFOCAL... It allow you to shoot a lot faster, as the S2 doesn't have to "search" for the correct distance, and at f/8, if you set the distance on the lens at about 3 feet, you're sharp to infinity !

...maybe this will allow you to use your lens until you find someone who's got the same lens (to compare on YOUR camera) or any F-mount camera !

Good luck anyway...
:cheers:

[Swampy]

I don't have the lense and may sound silly, but, is there a "limit" switch on the side of the lens? I know there are many lenses that have that and will limit to the upper or lower end of the focusing range very similiar to what you're describing.

[sandman]

I've got the same combination Brian and have found the Nikon pin sharp at all the focal lengths so i can't help , i shoot with the nearest priority off , and center weighted metering most of the time while using that lense .
We have several members on here from Scotland , none from Skye though , but if you send any of them the ferry fare i'm sure they'll jump over to help you out. :lol: (sorry i forgot you got a bridge now).

(another) Brian.

P.S. I've put this on the D70 and got sharp results as well , could try as JPS suggested and try manual focusing to see if it makes a difference.
BTW theres no limit switch on the 12-24 Bryan

[HulaMike]

I would have to agree with Brian. My Nikkor 12-24DX is very sharp throughout its range. I tend to use center weighted metering most of the time as well, don't know if this has an effect or not. But I also override AF most of the time with a manual adjustment, one of the wonderful features of the newer AF-S lenses and so I suppose I'm in both camps really. I auto focus and then tweak the focus manually depending on the focus point.

Perhaps yours is a poor sample.

[xrdbear]

I've got the same combination Brian and have found the Nikon pin sharp at all the focal lengths so i can't help , i shoot with the nearest priority off , and center weighted metering most of the time while using that lense .
We have several members on here from Scotland , none from Skye though , but if you send any of them the ferry fare i'm sure they'll jump over to help you out. :lol: (sorry i forgot you got a bridge now).

(another) Brian.

P.S. I've put this on the D70 and got sharp results as well , could try as JPS suggested and try manual focusing to see if it makes a difference.
BTW theres no limit switch on the 12-24 Bryan

I'll have to see if I can locate one of these members! I'd cheerfully pay the bridge toll. Hopefully I will have the camera back in the next few days and see if the Royal mail has managed to correct the problem by accident ;o)

As I mentioned in the original post I can focus the lens perfectly well manually. Although it is difficult in the small viewfinder I can use the distance scale which is perfectly accurate at all focal lengths. That is why I think the body is to blame. I could live with this for landscape photography but then again £750 is a lot for a lens.

I seem to remember that where the depth of field (the region in front of the lens) is very large for a short focal length lens, the depth of focus (the region behind the lens) is very small. It may be that the very short focal length of 12mm combined with the small light circle places great demands on the accuracy of the autofocus beyond its normal standard of adjustment. I have found 2 other references to this problem in other forums but they never seem to have been resolved and the participants haven't revealed their e-mail addresses.

Thanks for the interest. I'll try and post any more news as I get it.

Brian

[Tom V]

I have the S2 and the Nikkor 12-24, which focuses just fine.

It's baffling how the S2 can AF at 24 but not 12. .... maybe...

Image detail is smaller at 12mm than it is at 24mm. Maybe the AF sensor has something partially obscuring it (dust or smudge, or misalignment of some sort), causing it NOT to correctly AF if the subject detail is too small?
:beerchug:

[xrdbear]

I have the S2 and the Nikkor 12-24, which focuses just fine.

It's baffling how the S2 can AF at 24 but not 12. .... maybe...

Image detail is smaller at 12mm than it is at 24mm. Maybe the AF sensor has something partially obscuring it (dust or smudge, or misalignment of some sort), causing it NOT to correctly AF if the subject detail is too small?
:beerchug:

Interesting thought. I've only had the camera and lenses for 2months and I'm not sure if the problem was there from the start as I've not taken that many pictures at max aperture and 12mm. If it is just the same on its return I'll see if I can get some air on the AF sensor. I've seen in other forums dirt on the sensor causing problems but it seemed to cause errors irrespective of the lens.

Any beer going spare?

Brian (on a windy wet night in the Western Isles)

[xrdbear]

Well, I got the camera back today. 24hrs from Bedford to Isle of Skye. Well done Royal Mail (this will only be appreciated by UK readers).

Camera is no different apart from a lot more dust on the CCD :(
Removed this with 'Sensor Brush' completely and blew a lot of air across the AF sensors.
No different.

I've done some more tests and noted that if the lens is set to 12mm, f4, AF and pointed at anything (and on mains power) repeated half presses of the shutter produce quite a wide scatter of focus distances. Zooming out to wider than 15mm this does not happen and the focused distance stays the same. Must indicate something but I don't know what.

Frankly I think I give up at this point until I can find a another body to try the lens out on. I can live with focusing manually. It only really causes a problem at apertures wider than f8 and focal lengths wider than ~18mm.

[Tom V]

Well, I got the camera back today. ....

Camera is no different apart from a lot more dust on the CCD :(
....

Shipping the camera around often causes dust to land on the sensor. Even cameras cleaned by Fuji, and shipped back to the owner, arrive with a new arrangment of dust.

As for the AF problem, I cannot fathom a reason the lens could be at fault. That leaves the camera.

[tombrayne]

Hi -

I've jumped thru hoops with this behavior since I got my S2 in Sept. 2002. I also went thru all the custom functions to make sure the camera was properly set up. Camera finally went back to Edison, NJ this spring for inspection (at no cost - thanks to my Fuji pro rep). It came back with "Focus Adjusted" and yes lots of sensor crud at no charge. Unfortunately also with no change. I experience the "front focus at widest angle" behavior with all my zooms: Sigma 12-24, Nikkor 17-35AFS, 28-70AFS and 80-200AFS with the problem diminishing in severity the longer the lens I use (barely perceptible on the 80-200). I've also torn out remaining hair with 2 pals (also commercial shooters) who have S2s. Our conclusion: it is what it is. The only solution is to zoom tight, focus & lock, zoom back & recompose, then shoot. Surely a PITA, but it's the only thing that works. Our determination: "It's digital" - an all encompassing term that explains ANY bad voodoo you might experience. Seriously, we don't know if it's the ever-so Professional N80 platform for the S2, the APS sensor size (compared to 35mm film), or the prevailing wind direction. We've just learned to live with it & make the thing work. By the way the Sigma is a replacement for the Nikkor 14 (2 samples) which it blows out of the water (course the Sigma was the only acceptable sample of the 6 my dealer had in stock). Not up to my Nikkor zooms though better than Nikkor 12-24 zooms we tested.

Good luck.

TB

[xrdbear]

Hi -

I've jumped thru hoops with this behavior since I got my S2 in Sept. 2002. I also went thru all the custom functions to make sure the camera was properly set up. Camera finally went back to Edison, NJ this spring for inspection (at no cost - thanks to my Fuji pro rep). It came back with "Focus Adjusted" and yes lots of sensor crud at no charge. Unfortunately also with no change. I experience the "front focus at widest angle" behavior with all my zooms: Sigma 12-24, Nikkor 17-35AFS, 28-70AFS and 80-200AFS with the problem diminishing in severity the longer the lens I use (barely perceptible on the 80-200). I've also torn out remaining hair with 2 pals (also commercial shooters) who have S2s. Our conclusion: it is what it is. The only solution is to zoom tight, focus & lock, zoom back & recompose, then shoot. Surely a PITA, but it's the only thing that works. Our determination: "It's digital" - an all encompassing term that explains ANY bad voodoo you might experience. Seriously, we don't know if it's the ever-so Professional N80 platform for the S2, the APS sensor size (compared to 35mm film), or the prevailing wind direction. We've just learned to live with it & make the thing work. By the way the Sigma is a replacement for the Nikkor 14 (2 samples) which it blows out of the water (course the Sigma was the only acceptable sample of the 6 my dealer had in stock). Not up to my Nikkor zooms though better than Nikkor 12-24 zooms we tested.

Good luck.

TB

Thanks Tom, I now feel better and worse at the same time! I'll go and have a lie down.

I'd begun to suspect this was the case. Quick question, do any of your pals have the D70 and do they have the same problem?

Personally I don't really like the jpegs my S2 is producing. All attempts to get it to produce good daylight colour balance out of the camera seem to be doomed, the cyan skies are the worst aspect. I'm shooting RAW all the time to avoid it. I'm also rather dissapointed in the general AF performance. I got the machine hoping it would be much better than my E20 at AF but it isn't and the E20 had reliable colour.
Because of all this I'm prepared to cut my losses and make a change but I need some more research first.

Brian

[tombrayne]

Hi Brian -

This focus voodoo really is no fun. Sometimes I think I can focus more quickly with my old Sinar F+ and a loupe. No one I'm acquainted with is shooting with a D70. I can check with another pal who uses a D100, Sigma 12-24 (4 of us on that train now) and 28-70AFS & get his take on things. As to the jpgs - dunno, never shoot 'em, except for silly lens & sensor cleaning tests. The upside is that properly exposed RAF files that have been accurately focused with the zoom/lock/recompose routine just knock the crap out of most anything out there. The EX converter is gawdawful slow, but once you get the hang of it it produces a wonderful tif that with a few tweaks in PShop is a thing of beauty.

I was involved in a 48 hr documentary project over the summer and as one the administrators and editors (along with the other S2 boyz and the D100 guy) have had the singular delight of wading thru approx 10K raw files and maybe 4K of film scans. To our slightly jaundiced eyes, the Fuji RAF files are the best looking of the bunch right out of the camera - and we saw files from Nikon D1X, D2H D100, Canons from D60 to 1Ds and some Oly stuff. Yesterday we printed one of my files, shot with the Sigma and blended from 4 different conversions of the same RAF at 16 X24 thru an Epson 4000. The print absolutely beats the pants off anything I could have done with one of my Hblads & Provia 100. Scary sharp & no noise - did I mention beautiful color? We'll be outputting another shot w/ 28-70AFS in the next day or so. At 8X10 - very scary sharp.

To make a short story long - don't give up. The S2 has a jewel of an imager housed in a crappy body that yields some of the best files I've seen. Learn to live w/ it quirks & you've got a weiner.......er winner. We can't wait for a demo of the S3 - even with the "upgraded" N80 platform, we're thinkin the extra 1 1/2 - 2 (?) stops dynamic range and 14 bit files are going to give the new Hi-mp cameras a good run for the money.

Good luck. Hang in there.

TB

[xrdbear]

For anyone interested in the latest on this saga here it is. My new D2H has arrived, my... isn't it heavy!

This has enabled me to try the 12-24 on another body. Against all my expectations it appears that *my* focus problem at 12mm is the lens and not the body. The lens performs just as badly on the D2H. In fact pointing at my pinboard at the end of the room and half pressing the shutter over and over again produces an impressive scatter of focus distances between .5 and 2m. I think it is actually worse.

Tomorrow therefore the lens goes back to Nikon UK. Wish me luck, I gave them a call and they reckon that they are turning around this lens in under 10 days.

The other lenses are working just fine. I'm impressed with the D2H focus motor. It is focusing my 80-400 VR maybe 3 times as fast as the S2.

Brian

[xrdbear]

Well, the lens is back from Nikon. They could find no fault with the lens.
I guess I have to give up and assume that there is some kind of generic AF problem with ultrawide/DX lenses which Nikon and Fuji can't solve but not everyone experiences. My last gasp effort is to mail the Nikon European Support center about it. It really is depressing to have shelled out £850 for an AF-S lens that I have to focus manually or stop down to f11 all the time. I guess I just have to be thankful that the CCD on the S2 and the metering on the D2H haven't failed yet. Do I sound depressed? Should I just stop reading the forums? Should I have another drink? :guzzle: :guzzle: :guzzle:

Brian