Even though the videos from this channel are usually absolutely great, I would refrain from trying to remove the front lens. It is a centering element and therefore adjusted (centered) using a special tool: a collimator. The mark @9:25 is not enough to get the lens back to its original position and I would even go so far to say repositioning is impossible to do at home with decent results. Image quality will suffer after putting the front lens element back without proper centering. Just to clarify for those who want to know more: This type of adjustment has nothing to do with the front lens adjustments of like the Canon 17-55mm 2.8 or the Canon 17-85mm. The position you mark there is the factory adjusted optimal position for division of autofocus movement across the zoom range. What I mean here is a centering adjustment. Compare the adjustment sections of the Nikon DX 17-55mm or Nikon Micro 105mm 2.8 repair manuals (available online) for the 1st lens group alignment to learn more.
@@pluto149 Marking the eccentric collars is fine. Results are usually ok when done right, I'd prefer finer markings though. The front lens is a different thing. Once the screws are loosened a bit, you can slide the lens around horizontally to align it with the optical axis of the other lens groups. You need a collimator for that. If you don't adjust the front lens, image results are very likely blurred - especially in the corners.
thank you so much for this man!! :D
You're welcome!
Even though the videos from this channel are usually absolutely great, I would refrain from trying to remove the front lens. It is a centering element and therefore adjusted (centered) using a special tool: a collimator. The mark @9:25 is not enough to get the lens back to its original position and I would even go so far to say repositioning is impossible to do at home with decent results. Image quality will suffer after putting the front lens element back without proper centering.
Just to clarify for those who want to know more: This type of adjustment has nothing to do with the front lens adjustments of like the Canon 17-55mm 2.8 or the Canon 17-85mm. The position you mark there is the factory adjusted optimal position for division of autofocus movement across the zoom range. What I mean here is a centering adjustment. Compare the adjustment sections of the Nikon DX 17-55mm or Nikon Micro 105mm 2.8 repair manuals (available online) for the 1st lens group alignment to learn more.
The front glass is held with 3 screws that seem fixed. The more questionable thing was the calibrated screw he marked with marker. Am I wrong.
@@pluto149 Marking the eccentric collars is fine. Results are usually ok when done right, I'd prefer finer markings though. The front lens is a different thing. Once the screws are loosened a bit, you can slide the lens around horizontally to align it with the optical axis of the other lens groups. You need a collimator for that. If you don't adjust the front lens, image results are very likely blurred - especially in the corners.
good
Thank you for your comment!
Now send it to canon to put it back together
...or view my video about assembling this lens.