How to calibrate 7Artisans and TTArtisan lenses to your digital camera
7Artisans & TTArtisan lenses are sold at the Photo Rumors Online Store
A reader sent me detailed instructions on how to calibrate 7Artisans or TTArtisan lenses to your digital camera (thanks Frank Filippone):
I post this for anyone who now needs or will need this instruction. If your lens focuses fine, ( the RF focuses correctly) don't fiddle with it. If it is out of focus, continue.
This whole process will take you less than an hour. Less if you do not screw up like I did.
Please review this video:
However this is a written explanation of how to do it.... the audio is in Chinese. Watch the video a few times.
My 75 F1.4 7Artisans lens was bought used. I do not know if the last owner had the lens calibrated to HIS camera or if the lens was not set properly from the factory. But it needed to be done on my camera. It was way off.
Perform this on a bright day where there is lots of light. It makes the process easier.
First of you will need the calibration chart from the manufacturer. (Did not get one? Make one up from a piece of paper and an X for the focus spot, in the middle of the page, and some vertical lines before and after it. Mount to wall. Tape works, Blue 3M tape will not leave marks or remove paint. Scotch tape, the clear stuff, WILL remove the paint. Use clear tape at your own risk!!!
You will need the screwdriver for the calibration that came with your lens. (Ditto did not get? The proper tool is a flat screwdriver, 0.025 inches or 1mm wide. Get one of Amazon or eBay).
Get camera ( I used my M240) and mount lens. Tripod is required. You want to be 78 inches or so ALONG the wall, and about 45 inches AWAY FROM the wall to the focus spot. This will create a 30 degree angle from wall to target X to make the focusing work easiest. You do not need to go crazy setting this up perfectly. Approximately is good enough.
Set lens to WIDE OPEN.
Focus using your RF to find the correct focus. (I used a 1.4x VF magnifier to make things easier. Not required). If you have an EVF attachment, (the Visoflex) turn it on. If not use Live View (LV) and check to see WHERE the image of the focus spot is most correct. Is best focus BEFORE or PAST the focus spot? Remember this relative position. ( Don't worry how much, this is an iterative process, you will be doing this several times to get it right.)
Remove lens from camera. Go to quiet spot with lots of light and is clean. A kitchen table or countertop is fine. Lens facing upside down so you are looking at the camera mount side of the lens.
The following is what you must do:
The bottom of the lens has a ring inside. It is painted black on my lens. It is inside the chrome lens mount. It has 3 holes...... as far as I can tell, there are 2 screws in the holes. The third hole has no screw in it. Find the right holes. Take your finger and hold in place the ring, so that it does not move during the next step. This is pretty important.
The ring moves REALLY easily.
Take your screwdriver and GENTLY turn the screws counterclockwise to loosen it . DO NOT REMOVE IT!!! 1/2 to 1 1/2 turns is more than sufficient.
( Your finger is holding the ring from rotating, so that you know your starting place.) Now that the screws are loose, the ring can rotate. Go back to which way your lens focused... if it focused PAST the focus spot, then turn the ring about 5mm or 1/4 inch (circumferentially) as if you were UNSCREWING a screw (Lefty loosey, righty tighty). To do this, you will need to loosen your finger grip on the ring. The ring moves REALLY easily. If you loosen and the ring moves out of place without your "permission", you just need to tighten the screws and start over again on the camera, I did it twice.
If your lens focuses in FRONT OF the focus spot, you turn the ring CLOCKWISE. Everything else is the same.
Tighten the screws. GENTLY. Apparently, if you tighten too much, it will affect the lightness of the focusing ring overall.
Proceed to mount to your camera, and repeat this process.
When you get this right, (It took me 4 tries) you are done. The lens is calibrated to your camera.
If you want to do this with a film camera, the process is the same but you need to inspect your FILM each time you want to make a correction to the lens. You can still do it, but it will take you time and a bunch of film to get right.
Note that I own several of the TTA and 7A lenses. This was the only lens I have that was not spot on, right out of the box.... new or used. It is unlikely you will need these instructions.
7Artisans & TTArtisan lenses are sold at the Photo Rumors Online Store with free international shipping