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MTF Charts for f/4 Lenses with 2xTC
- By AlanF
- Canon Lenses
- 5 Replies
As some posters have written that their f/4 600mm II is soft with a 2xTC, I checked the Canon MTF charts. But, I am now mystified. The black lines on the charts are for wide open and the blue stopped down to f/8. For the f/4 500 and 600s with a 2xTC the wide open is f/8. So, why are there still separate blue and black lines?