Tamron SP 35-80 01A front element removal

[kansalliskala]

I got this today and it is in "kind of " condition. Want to keep the lens because it is starting to get rare nowdays. Asked for partial refund because wasn't really EX++ that the seller stated ..

Lens is usable, that is if you are Superman OR use only under 50 mm focal lenghts OR use 80 mm only macro. The back tubes stick now and the but this is typical for this lens I think.

The problem occurs when the front element group that is used for focusing reaches the 1:10 mark on the barrel, it is the same on every focal lenght. Then it almost sticks and makes a screech.

The front element threads connect to the floating element in the middle so threads are or, the front element just gets stuck to "something" in the barrel.

So here is the question: how does one remove the front element?

[peterqd]

[Nesster]

The CF (Continuous Focus) function is something I still get a kick out of, 24 years later. As you focus closer, the lens is supposed to start zooming automatically, at the closest focus, till you reach 80mm at max magnification.

I'd have to play with mine to report exatly where what is happening... I do know the mechanism had some slop from new - and now I appreciate why. Probably the ones that were tighter developed these problems.

There is a resistance along the way, though on mine it's always been more a feel than a real obstacle. If interested I'll report in detail from home.

[kansalliskala]

I tried to open the front element: there are six screws under the focusing rubber band. When you open them the focusing ring turns freely. Then I tried to open the ring that keeps the focusing ring - or perhaps the whole front element assembly. But I couldn't get the ring turning, basically because I didn't know whether it is right or left handed or should it even turn.

But as I tried to get it out with my 'hit it with a hammer method' and turned it pretty much then the focusing ring did start to turn more freely.

Now it is usable, just a little screech. I think it was just sand (the lens is from Nevada) or someone had opened it and put it back wrong. Have to start using it so I see if it is any good.

[Nesster]

Hope it remains usable.

Here's how mine works - I've had this since new and -touch wood- it continues to work the way it did back in '85.

@35mm closest focus is 3ft
Then as I focus closer the lens zooms out:
@40mm closest focus is 1.5ft
@50mm closest focus is slightly over 1ft
it reaches the very closest focus at a bit over 60mm

Between 65 and 70mm the lens is physically at its shortest, and there's an easy spot for the zoom ring - at the other focal lengths there's more resistance as the ring's moving the lens lengthwise. Also, at closest focus, there's a null spot in the zoom between 65 and 70mm.

The CF (Continuous Focus) mechanism works by the lens zooming out with minimum focus distance - focus closer and it zooms. The reverse does not work - zooming wider doesn't make the focus turn.

Focusing down from infinity, there's a Clonk sound, at 80mm around 7-10 feet, closer to infinity at shorter lengths. The Clonk doesn't always occur.