Nikon D90 Back Focusing Issue

[jackgilbert89]

Hey all.

I purchased a essentially as new D90 2nd hand of a user on this website a few months ago and it's been fantastic.Usage has mainly been on a 17-50mm F2.8 Tamron (non-screw driven), some use on 50mm F1.4 AF-D which I sold to get the 85mm F1.8 AF-D. It was working fine focusing accuratley for quite a while.

However something seems to have developed a fault. Essentially the camera/lens will not auto focus accurately.

I have done tests on the 85mm using AF-S, tripod, remote trigger, F2.8 in good light on a focus chart and it is always focusing further back than it should. I know this because I can use live view, and zoom in and the focus is way sharper than when the camera uses AF-S.

The tamron seems to focus fine.

I have tested this using my brother's 50mm F1.4 AF and the problem is still present.

I have tested the 85mm on my brother's D300. It focuses accurately (as does the 50mm)

I have noticed that there is a very very slight rattling in my 85mm, which seems to be a very slightly loose rear element.

There seems to be many other D90 users with similar problems by looking at flickr discussions.

I found an article on the D70 and backfocusing, with a tutorial on correction

Everything seems to point at the camera. Has anyone tried correcting this?

It seems very simple and hard to justify sending to nikon for what will prob be a long time due to post etc.

Other thoughts welcome on this issue!

Thank you!

 

[Flash In The Pan]

I'm a bit puzzled, how can you

have done tests on the 85mm using AF-S

, when you say your 85mm is the AF-D version?

 

[jpw]

I'm a bit puzzled, how can you , when you say your 85mm is the AF-D version?

Must mean AF-S as opposed to AF-A or AF-C mode on the D90...

 

[Naboo32]

Jack, I had the same issue with my D90, straight from when I bought it new.

The short story is that the AF was not calibrated properly and Nikon fixed it free, under warranty.

The long story , is here ... Link ...

Hope you get it sorted .

 

[jackgilbert89]

Thank you Andy. I think I will send it off. I've exams coming up so I shouldn't be taking that many pictures anyway! Will have to reload the film camera though

It just frustrating that they can't see this with bodies straight out of a factory....

 

[Naboo32]

Thank you Andy. I think I will send it off. I've exams coming up so I shouldn't be taking that many pictures anyway! Will have to reload the film camera though

It just frustrating that they can't see this with bodies straight out of a factory....

I agree, it is very frustrating. Still, if all of these cameras were given extensive focus tests before being shipped out of Thailand, you'd be looking at another 50GBP on the price, probably, so it's probably better to send them out untested (and cheaper) and just fix the 0.0005% (made up figure ), which actually go wrong :shrug:.

Since mine was calibrated, it's behaved itself very well and I'm really pleased to own it. Hopefully, you'll feel the same way once yours is fixed .

 

[srichards]

Wages in Thailand aren't that high. It'd probably add £5 to the price if that! I'm sure whatever machine Nikon UK use to test it could be used in Thailand to test a good sample of cameras. If you have a batch showing a higher mis-alignment rate then you'd probably check them all.

Poor QC cheapens the brand image as everyone starts to think Nikons are poor quality because there would be enough people complaining and lots of others that are disappointed with image quality but assume it is them rather than the camera that is at fault.

 

[Naboo32]

Wages in Thailand aren't that high. It'd probably add £5 to the price if that! I'm sure whatever machine Nikon UK use to test it could be used in Thailand to test a good sample of cameras. If you have a batch showing a higher mis-alignment rate then you'd probably check them all.

Poor QC cheapens the brand image as everyone starts to think Nikons are poor quality because there would be enough people complaining and lots of others that are disappointed with image quality but assume it is them rather than the camera that is at fault.

Well, I don't know the exact figures involved (obviously), but I'm sure that if it was only going to cost Nikon 5 quid per unit to have every single one sent from the production line to a testing facility, where they were all fitted with lenses and tested by humans, then Nikon would just do it! That's the kind of testing that I was talking about when I wrote, "If every camera was given extensive focus tests before being shipped out ..." - i.e. a proper inspection/set-up regime :|.

What they probably do have, is just what you were talking about - a limited/sample test programme. This would help to identify batch errors, although I'm not sure if mis-aligned AF sensors are likely to be affected in that way, as I get the impression that this is more of an (human) assembly problem, rather than a component issue . Anyway, that will already be factored into the selling price and probably won't amount to very much, per unit.

I stand by my original assertion though, which is that it is probably better for the consumer to have limited testing done on their products (with the possibility of free adjustments for any sub-par units), rather than forcing every customer to pay a premium to be 99.9% certain of avoiding any such problems :shrug:.

As you said, reputation is important to a brand like Nikon and so I expect that they do go to great lengths to balance QC and retail price .

 

[StewartR]

I stand by my original assertion though, which is that it is probably better for the consumer to have limited testing done on their products (with the possibility of free adjustments for any sub-par units), rather than forcing every customer to pay a premium to be 99.9% certain of avoiding any such problems :shrug:.

Well said, that man!

Makes a refreshing change from the "I've got one dead pixel out of 12,000,000 which proves that the QC is inadequate" brigade.

 

[srichards]

AF alignment being off is a bit different though. A few dead pixels aren't noticeable. A couple of moaners on watchdog and that's Nikon's reputation down the toilet. It doesn't matter whether it is an entirely fair criticism or not.

I wouldn't expect it with budget cameras but with the mid range onwards I'd expect better build quality and QC.

How sensitive is the equipment is to knocks etc from travelling by couriers. Is the alignment even wrong at the factory anyway? Could be they're all perfect when they leave and some just get knocked out of alignment by transportation?

 

[Flash In The Pan]

Well, I don't know the exact figures involved (obviously), but I'm sure that if it was only going to cost Nikon 5 quid per unit to have every single one sent from the production line to a testing facility, where they were all fitted with lenses and tested by humans, then Nikon would just do it!

Nikon's factory in Thailand produces 300,000 dslrs - per month, so an extra £5 spent per unit (or to put it another way, nearly a third of the average factory worker's weekly wage over there) would cost Nikon an extra £18 million every year.

 

[Naboo32]

Nikon's factory in Thailand produces 300,000 dslrs - per month, so an extra £5 spent per unit (or to put it another way, nearly a third of the average factory worker's weekly wage over there) would cost Nikon an extra £18 million every year.

See, somebody knows the facts .

What I actually meant when I said that Nikon would just 'do it' if it was only going to cost an extra 5GBP per unit, is that they would add that onto the selling price of the unit, so it wouldn't be reducing their profits or 'costing them' anything.

Like I said though, I'm no expert on big business .

 

[Flash In The Pan]

See, somebody knows the facts .

What I actually meant when I said that Nikon would just 'do it' if it was only going to cost an extra 5GBP per unit, is that they would add that onto the selling price of the unit, so it wouldn't be reducing their profits or 'costing them' anything.

Like I said though, I'm no expert on big business .

You would think so, but ultimately it doesn't work that way. There's a famous example of Ford, back in the 70s, discovering that their Pinto model had a fatal design flaw that could cause the car to explode.

Ford calculated it was cheaper in the long run to pay compensation for the predicted number of casualties than redesign the car, so did nothing.

For a company like Nikon it's probably far more cost effective to repair any faulty units that are returned than spend what would probably be nearer a penny per unit it would cost in adding a pre-shipment test into the process.

 

[Naboo32]

You would think so, but ultimately it doesn't work that way. There's a famous example of Ford, back in the 70s, discovering that their Pinto model had a fatal design flaw that could cause the car to explode.

Ford calculated it was cheaper in the long run to pay compensation for the predicted number of casualties than redesign the car, so did nothing.

For a company like Nikon it's probably far more cost effective to repair any faulty units that are returned than spend what would probably be nearer a penny per unit it would cost in adding a pre-shipment test into the process.

Well, I learn something new every day on here - it's great!

Cheers Graham, have a Happy New Year !

 

[Mark G]

Is this a problem that can suddenly arise or would it be an issue from new. I did some shots this weekend that all seem more than a little oof and the focus point is behind the subject. But all of my other shots from before this weekend seem fine.