Nikon D50 autofocus problem

[fastcaterham]

I've had my Nikon D50 for aboput a year and half now. I'm not a serious photographer, it gets used a handful of times a month mainly at motorsport events.
When I took the camera to rally gb on the last day it started struggling to autofocus on cars in high speed sections. Thinknig it was to do with the conditions and seeing as it was towards the end of the day I just decided to stop taking photos. I used the camera again at few rallies after this with no problems and had virtually forgotten. Now last event I went to I couldn't get the camera to autofocus on moving objects at all. Its all fine with stationary objects but cannot seem to cope with anything over about 30 mph.
Does anybody have any ideas? I'm going to feel a bit silly taking it into the shop where I bought it (that I can't get to for a few weeks anyway) and saying it won't autofocus then knowing full well when he tries it in the shop it will work fine.
The problem is with the kit 15-55mm lens by the way.
Has anybody had similar problems/knows an easy fix before I go to the trouble of taking it to the shop and being without it for ages?

[andy-xr]

Does it have AF-C as an option?

[angryS3owner]

I have to admit my D50 is start to struggle with focusing and I'm getting the odd error too (when you really don't want it), that said it's probably 3-4 years old now and has been through a fair bit. I'm guessing it's not worth trying to get Nikon to take a look as it'll end up costing as much as a new one?

[Dogsey]

andy-xr said:

Does it have AF-C as an option?

Yes it does, it's fairly well buried in the menus though. I've just switched my D50 to AF-C and it's certainly improved the accuracy of focusing on moving objects.

[andy-xr]

See how you go with that then, Continuous is as it says on the tin, but not much good for statics.

Have you got the AF assist on or off? In AF-A or S on my D80 it does need the mini spotlight to help it out from time to time

[Simpo Two]

AF needs a certain amount of light and subject detail/contrast to work. If for example the AF point is on the middle of a plain car door, it will simply hunt back and forth trying to find something to lock on to. The AF assist light is not going to make any difference on a rally stage.

Possibly time to check all the settings carefully and revisit the manual. When my camera does something stupid the cause is usually the loose nut behind the viewfinder...

[andy-xr]

I dont think the light works in AF-C anyway to be honest, it'd be landing planes as well as focussing

[fastcaterham]

Thanks for the quick replies. I have had af-c selected and had the af area mode in dynamic area. I don't think its a setting related problem as such because on the last occasion I simply borrowed a lenses from my friend who also has a D50 and that worked fine without changing any of the settings instantly. The lenses was different but if I remember rightly the standard nikon lenses only with a slightly different zoom range.

[Simpo Two]

fastcaterham said:

I have had af-c selected and had the af area mode in dynamic area.

That sounds right for the job.

Are you saying that the camera worked with your friend's lens but not your own? That would imply a lens problem. What lenses exactly? AF-S or screw drive?

[fastcaterham]

Yes I should have made that clearer. Everything worked fine when I swapped lenses on the day, I think having looked at some lenses on the internet that it was a Nikkor DX 18-70mm that I ended up using. Obviously at the end of the day I had to give it back. I have since used my kit lens for static shots and it has worked fine.
I suppose thinking logically (something I'm not very good at!) that does indeed point to a lenses problem rather than something with the camera itself.
I don't know if it helps but I have never had any sensors or anything cleaned as I didn't think I'd used it enough to warrant it yet.

[Simpo Two]

fastcaterham said:

Yes I should have made that clearer. Everything worked fine when I swapped lenses on the day, I think having looked at some lenses on the internet that it was a Nikkor DX 18-70mm that I ended up using. Obviously at the end of the day I had to give it back. I have since used my kit lens for static shots and it has worked fine.
I suppose thinking logically (something I'm not very good at!) that does indeed point to a lenses problem rather than something with the camera itself.
I don't know if it helps but I have never had any sensors or anything cleaned as I didn't think I'd used it enough to warrant it yet.

It won't be anything to do with the sensor, so don't worry about that. The 18-70mm is not a particularly expensive or 'pro' lens by any means, rather just a good kit lens (I got one with my D70). So it looks as if your own lens is iffy, or at least, isn't talking to the camera body properly. However it does work on static shots, which is curious.

I can only suggest you do some more tests and try to define exactly what's not working. My 18-70mm isn't for sale as I keep it for backup, but I do have an identical-looking Nikkor 24-85mm in mint condition if you're interested.

[fastcaterham]

Thanks for all the help. Yes I think what I'll perhaps do is when i get a chance borrow my friends lens then go and stand on a bridge over the motorway or something and try and try and suss where exactly the problem lies.
Thanks for the offer of buying your lenses but to be honest I'm not financially in the position to go buying new lenses at the moment being a poor student which is exactly why the lenses playing up is really annoying!
Thanks for everyones help anyway.

[andy-xr]

Simpo Two said:

Nikkor 24-85mm in mint condition if you're interested.

If it's the F2.8-4 they're impossible to get hold of at the moment, I've cancelled an order I had on hold for the last 5 weeks and went with the Sigma 24-70 F2.8 instead

[Simpo Two]

No, it's ths one: www.bythom.com/2485lens.htm

The body is identical to the 18-70mm, but soon after production began they got swamped by demand for the 18-70 (to go with the D70) and so made that instead. The 24-85mm is not DX-specific; ie it will work on DX and also full frame (FX) cameras.

[VxDuncan]

the first hing I'd try would be to take the lens off and clean the contacts twixt lens and camera. How you do that is open for debate, but I'd start with a simple wipe with a cotton t-shirt or something being careful not to get and dirt or fibres into the mirror box of the camera. Clean the camera contacts as well as the lens. As for the issue, try removing any polarising or other filters, and test in good strong sunlight on a good moving subject, even a kid on a bike in the garden will do. As said before, in dim, low contrast conditions the camera will struggle.

Typically the camera uses contrast detection at each AF point, and will work down to around F5.6 (ish), as your lens will be F5.6 zoomed in, then it's not going to be bathed in light anyway. Try to use the centre AF point also, typically they are more sensitive.