Attention Tamron 24-70 VC owners

Started Jul 28, 2012 | Discussions thread
amateurtony
Forum MemberPosts: 93
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Re: Problem #2: Aperture lever miscalibration
In reply to Horshack, Jan 26, 2013

I too recently bought this lens (1 week ago). I found it has the lever miscalibrated also. I can tell from running the tests suggest here as well as actually physicall looking at the aperture blades moving. When I move the lever handle, the aperture blades do not immediately move. It only moves after I move the lever about 1mm then does the aperture blades make a noticeable movement.

HERES THE GOOD NEWS! ITS EASY TO FIX!

Being somewhat handy myself, I decided to see if I can manually calibrate it myself so I don't have to waste time sending it anywhere. After spending an hour (learning, reading http://www.lensrentals.com/blog/2013/01/24-70mm-f2-8-lens-teardown-comparison) and then finally got the courage to do it, spent about 10 minutes getting it fixed.

HERES HOW!

Disclaimer: Try at your own risk! I take absolutely NO responsibility for what you do with this information. You CAN break your lens. Don't blame me if you try it.

Tools: Philips screwdriver, smallest possible. flat head may work too, its what I used.

Philips screwdriver, small size, but bigger than the first one.

Being handy with tools is a plus.

Note: Do not touch the rear lens element throughout this entire process please. You don't want to dirty it up.

Step 1: The mount is metal and inside that mount is the plastic rear with the electrical contacts. There are 4 tiny screws holding this plastic ring in place. Theres also 1 tiny screw that sticks out of the metal mount (ignore this one, don't take it out). Take those 4 screws holding the inner plastic piece out with a tiny eyeglass screw driver. You'll need the smallest possible screw driver you can find to do it. It can also be screwed in quite tight, so be careful not to strip it. The 2 that connects to the electrical contacts are ever so slightly longer than the other two screws, so just remember and keep that separate.

Step 2: Once unscrewed, carefully take the plastic piece on out. The electrical contact piece is free from the plastic ring, but is attached to the lens. Do not take out this electrical contact piece! Just take the ring out.

Once the ring is out, you will see the aperture lever arm attached with 2 screws. These screws are what you need to adjust. Loosen these two screws so you can adjust the lever arm. They are designed to be movable so that it can be calibrated!

step 3: The way I did the calibration is this: loosen the screws

Pull the lever arm on the mount to the end so it contacts the stopper. Keep it in this position with your left thumb the entire time, this is your maximum aperture state. Now you want to move the bottom piece of the arm using the screws. I push the arm ever so slightly at the screws until the aperture blade starts moving. It helps to see the aperture blade if you take the lens cap off, and keep the shade petal on. Once you see the aperture blade start moving, move the screws back slightly so its JUST back to the maximum aperture, and tighten the screws! This part is trick, as you tighten the first screw, the arm will move slightly, so make sure to carefully do this part to prevent moving the arm at all. If you see any movement of the aperture blades, then your maximum aperture will not be 2.8 anymore. If the blades move, just loosen the screws ever so slightly again and adjust again. Do this step right or else you will not have the best results!

Once you get the screws tighten, just fit the plastic ring and electrical contact back the way it was before and screw it back together. You're almost done!

Test the camera and aperture to see if everything works, and if the aperture is correct now!

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