Photoclubalpha

On a recent trip to London for 5 days, I was rather concerned and surprised to find that after the third or fourth day, my CPL and lens hood was wobbling on my Tammy 17-50.

An immediate panic investigation revealed that optically, the lens is as excellent as it ever was - the optics are secure and there's no wobble from the front element or the zoom extension. It's just the very front plastic bit that surrounds the front element, that carries the filter screw thread on the inside, and the bayonet hood mounting on the outside.

I'm surprised that it's happened as I treat my kit very carefully - I never so much as set a camera or lens down hard against a table, and when being carried out and about it lives in Kata bags which are almost armour plated. The lens is less than a year old.

Am I right in thinking I just need to call the UK distributor (Intro2020?) who will need to fix it? Not sure whether it's safe to leave or not - I've got visions of reversing/unreversing the hood one day and finding the front plastic bezel has stayed attached to the hood!

The Tamron has a six-year warranty, call Intro2020. They are very good with repairs. Sounds to me as if bus-seat vibration has got your lens even through the bag... it's probably just unscrewed itself a bit.

David

Thanks David. 6 years eh? Excellent.

If only my car had a 6 year warranty too!

We don't get the 6 year tamron warranty in Australia

Sometimes during cleaning I feel or hear a little shift at the front of my lens, too...let us know what you find out about yours, please!

Heh, I will do, when I find the time at work to phone the distributor!

This happened to my copy as well, I fixed it myself, http://forums.dpreview.com/forums/read. ... e=29066929

"It's not too hard but take at your own risk. You need to prise the plastic surround from just inside the filter ring, there's a small notch you can lever a small screwdriver into. Work your way around the ring to disengage the retaining tabs. Underneath are three screws you can tighten. Then you can then replace the plastic surround.

"Be careful not to break the plastic cover, and don't slip and scratch your front element. Also, don't over tighten the screws or you'll strip the threads and/or the head."

Many thanks for the link and explanation. That certainly makes sense. Not sure I fancy having a go at it myself though - knowing me, I'll slide a screwdriver neatly across the front element or something!

I haven't used my 17-50 for a while, but i checked it today and it is very loose. I'm sure it wasn't when i reversed the hood and stashed it in my bag last time i used it, so it must have happened from vibrations while I've been travelling.

OK, so i pulled the front of my lens apart this afternoon to tighten the screws, but i found that in fact the screws hadn't come loose. The reason for the looseness of the plastic surround is a little more complex than screws coming loose, and i will try to explain here because i need some advice. The front element of the lens is mounted on three ramps spaced evenly around its circumference, such that if the front element is rotated it is lifted away from or lowered towards the lens body depending on which way it is turned. The plastic surround with the three screws acts as a clamp to hold the front element in place once it is set to the right height by rotating either way. If the front element then turns in the way which lowers it towards the lens body, the pressure is released from the plastic surround and it is free to wobble, exactly what had happened to mine. So the screws hadn't come loose, but rather vibration had caused the front element to rotate and caused the plastic surround to come loose.

My question is this, how critical is it to get the front element exactly back to where it was before it came loose? What effect would i notice if it was too close or too far from the next element in the lens?

I'll be watching this thread with interest, my Tamron 17-50 just arrived in the post this morning. Any chance you could post a pic of what you're describing Tony?

Ewannawe wrote:I'll be watching this thread with interest, my Tamron 17-50 just arrived in the post this morning. Any chance you could post a pic of what you're describing Tony?

Ewan, I've put my lens back together now. I just took a guess at where the front element should be, so I'll test the lens when i get some spare time and see how it looks. It is only a couple minute job to pull it apart again, so i could do this to get some photos, and i definitely will if someone can tell me where it should be set. Don't worry too much about your lens, just try not to expose it to vibrations or bumps.
Tony