Does my lens need sending in?

jamin100

jamin100

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Name
Ben
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Hey,

I brought a 2nd hand Tamron 28-75 recently and really like it. However I seem to keep missing focus with the lens.
Some images seem fine whilst others seem way off.

Here's an example:
My focus point was clearly on my Daughters face but for me her arm seems to be in focus.

Screenshot2011-02-16at213101.png


Where would be the best place to send this lens? and any idea on price?
 
She might have moved her head a gnats at the last nanosecond.

Or it could be the camera couldn't find anything on her forehead to focus on - no defined edges or contrast change - so it stayed on whatever is was on for the previous shot.
 
Ozei said:
She might have moved her head a gnats at the last nanosecond.

Or it could be the camera couldn't find anything on her forehead to focus on - no defined edges or contrast change - so it stayed on whatever is was on for the previous shot.
Click to expand...

hmmm, ok.
I'll take it out a few more times and see what happens before looking to send it in.
 
jamin100 said:
hmmm, ok.
I'll take it out a few more times and see what happens before looking to send it in.
Click to expand...

Take your wee girl and try to replicate the shot (same focus point on forehead again) - tell her not to move (or she won't get any pudding :)) and see what happens.

With her still in the same position, repeat the shot but focus on one of her eyes.
 
Agreed with the comment above, try do some test on a stationary object, well lit with some decent contrast and detail and see how it fairs. Tripod maybe handy as well.
 
The AF might have latched onto the wisp of hair on her forehead, but she's got fair hair so there's not much contrast against the skin.

My guess with this particular shot is she moved forward at the last split second.
 
jamin100 said:
ok, here's a little test i've just performed with the lens on my D90

Shot at 1/200
ISO 2.8 (wide open)
ISO 200
Onboard flash

Screenshot2011-02-16at221035.png
Click to expand...

Hmm, looks like it's front focussing a tad. The thingy (stamen?) on the right of is more in focus than the one with the AF point.

I'd try it again in daylight with a tripod.
 
PS. Also, if you've got another lens try that too - to rule out a fault with the body.
 
Thanks ill take them to work tomorrow and have a play.

Is front focusing something that can be fixed?
 
jamin100 said:
Thanks ill take them to work tomorrow and have a play.

Is front focusing something that can be fixed?
Click to expand...

Yes - you can tweak the camera to the lens if the body has AF fine tuning, though I'm not sure whether the D90 has it.

If it doesn't, the lens itself can be adjusted by Tamron (or one of their recommended outfits).

Try some more tests first though - it might be something else.
 
ok here are a few shots from today and the test chart as mentioned.

Screenshot2011-02-17at114748.png


Center focus point
Screenshot2011-02-17at114731.png


Side focus point
Screenshot2011-02-17at114647.png


After looking at these and a few others I'm wondering if the center focus point is spot on but the outer ones are maybe off somehow, which I guess would be to with the fact its a cheaper lens?
 
The centre point looks spot on - and the side point doesn't seem far off either. What aperture were you on?

The 5A text on the wall chart looks a tad sharper than the Loctite label - it would be worth trying it again with another lens (if you've got access to one).
 
Last edited:
Hi,

I'm from Sutton Coldfield. Possibly could meet up with you on a sat afternoon or sunday if you want to try on a different body (I have the d300). I should be going into brum - well probably. I need to practice taking pics lol. Of course might depend on the weather.

Alternatively see if there is a recommended repairer around. I haven't found one for nikons locally but the alternative is sending off via jessops and hoping it fixes rather than breaks it.

Have you got any friends with a nikon you could try the lens with..?
 
Ozei said:
The centre point looks spot on - and the other one doesn't seem far off either. What aperture were you on?
Click to expand...

all wide open at 2.8
Im going to take the camera out again next week so i'll report back on how it goes.
 
Ozei said:
On a tripod?
Click to expand...

Only the test chart was on a tripod with the timer release to avoid shake.
The rest were fired handheld at 2.8 1/200 ISO200

I fired off an email to Intro2020 (tamron service center) last night enquiring about the calibration on this lens and also sent them the photo in my first post.

Have just had this back from them:

Dear Mr. Richards.

We recommend to use focus point on centre position.

The optical design for Di takes into consideration the features of digital SLR cameras. However, due to the configuration of digital SLR cameras, even when the autofocus accuracy is within manufacturer's specifications, the focal point may be a little forward or behind the optimum point when shooting with autofocus under some conditions.

Regards
Service Department

So it may be that I need to use the center focus point on this lens and maybe crop to suit composition?
 
jamin100 said:
Im going to take the camera out again next week so i'll report back on how it goes.
Click to expand...

I'd say there's nothing wrong with the lens - i.e. it's just not as sharp at the edges when wide open.

The ideal test is to try the Tamron on another body (as Vince suggests) with both cameras on exactly the same settings (same subject, same framing, same everything, on a tripod). Then repeat with another lens on both bodies (to rule out a fault with your body).
 
jamin100 said:
Only the test chart was on a tripod with the timer release to avoid shake.
The rest were fired handheld at 2.8 1/200 ISO200
I fired off an email to Intro2020 (tamron service center) last night enquiring about the calibration on this lens and also sent them the photo in my first post.

Have just had this back from them:

Dear Mr. Richards.

We recommend to use focus point on centre position.

The optical design for Di takes into consideration the features of digital SLR cameras. However, due to the configuration of digital SLR cameras, even when the autofocus accuracy is within manufacturer's specifications, the focal point may be a little forward or behind the optimum point when shooting with autofocus under some conditions.

Regards
Service Department

So it may be that I need to use the center focus point on this lens and maybe crop to suit composition?
Click to expand...

That could explain it - without a tripod it's not a proper test.
 
The D90 only has one cross-type focus point - the centre one. For any low DOF, focus critical shots I would recommend sticking with the centre point. Another thing worth mentioning is that the Tamron isn't the fastest focusing lens in the world either, but for what its worth I never had any focus problems with it on either my D700 or D90, just a little slow occasionally in low light. Sort of wish I had hung on to it now... ;)
 
jamin100 said:
wouldn't solve the problem of my girlfriend hitting me about the head multiple times for spending £1000 on a lens though :)
Click to expand...

This might work :):

  1. Buy the Nikon 24-70
  2. As soon as it arrives, hand it over to your good lady
  3. Good lady bashes you about the head with it (but you get to borrow it from time to time)
  4. Everybody wins (assuming she hasn't hit you too hard with it)
 
I doubt it, I think the lens would be inserted where the sun doesn't shine and then I'd be beat about the head with it
 
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