do you think there is a problem with my lense?

[dullbird]

Hi Guys

while taking photo's tonight with my tamron lense...

I noticed something odd.

I set the camera up on a tripod and to start with the way I set everything up using the water I didn't have a focal point to focus on automatically (camera was searching as it couldn't see the water)

anyhow I flicked it over to manual focus.....and once I chose my length I went to fine tune and while using the focus ring I noticed that the frame moved....

This is really hard for me to explain...

when touching the focus ring a tiny bit either way...the entire frame moved a fraction off to the left (diagonally) BUT only a fraction!! but enough that I noticed it...and then back again when moving the ring back to its original position.

its only tiny movements on the focus ring because as you can imagine all I'm doing is trying to adjust ever so slightly to get it sharp.

is this a problem in the lense??? common sense tells me its not right, but tech works in wonderful and mysterious ways sometimes

[dmdigital]

Was the lens firmly locked in to the camera mount?

I assume you could see this movement happen in the view finder, sounds rather strange.

The only thing in a lens that could move anything is a loose element or aperture blade and that's not going to cause that effect.

[dullbird]

Yes lens was firmly locked in....

yes I could see the movement in the view finder

I repeatedly moved the fine focus ring backwards and forwards to watch it happening, just to make sure it wasn't just one of those odd things that never occurs again...but it happened everytime.

[Ausfree]

Just a couple of guesses, but I will try,

1) Has the lens been knocked or dropped which could cause one of the lens elements to move.

2) Take the lens off the camera and look thru it from the camera end and move the aperture ring in and out to check if the aperture blades are moving evenly and smoothly. Aperture blades may have moved or may have rust on them which causes uneven or sticky movement.

3) Check around the lens and make sure all the retaining screws are in place and tight particularly the base plate where it mounts onto the camera, also check the lens mount on the camera for looseness.

Hope that helps, Cheers

[dullbird]

Just a couple of guesses, but I will try,

1) Has the lens been knocked or dropped which could cause one of the lens elements to move.

2) Take the lens off the camera and look thru it from the camera end and move the aperture ring in and out to check if the aperture blades are moving evenly and smoothly. Aperture blades may have moved or may have rust on them which causes uneven or sticky movement.

3) Check around the lens and make sure all the retaining screws are in place and tight particularly the base plate where it mounts onto the camera, also check the lens mount on the camera for looseness.

Hope that helps, Cheers

lens has never been dropped

I will have a look at the others tonight...thanks for the ideas

[werdan]

3) Check around the lens and make sure all the retaining screws are in place and tight particularly the base plate where it mounts onto the camera, also check the lens mount on the camera for looseness.

I found the mounting ring on my old Sigma 70-210 was a bit wobbly on the weekend. I carefully removed the chrome bayonet ring from the mounting ring by undoing 4 tiny screws. Underneath the bayonet, I found 2 of 4 screws holding the mounting ring to the main lens body were very loose. After tightening them up and replacing the bayonet, all was good again.

[Chucaro]

Have a look at THIS site if there is any help

Also dpreview forums is a good source of info.
have a look THIS thread to see if it is relevant.

Cheers

[bblaze]

No help to you DB but what tamron lense is it
cheers
blaze

[dullbird]

the 2.8
28 to 75 I think or there and there abouts

[series3]

Hey Dullbird if you are able to take it into Fotoreisel on Kent st in the city and speak to the bloke with the beard he is extremely helpful with this sort of thing; repairs are his specialty. I took a DSLR in with problems with the viewfinder and he was able to diagonose it within 5 minutes.