01-16-2017, 12:17 AM
@ Wim: You are hardly the one I would challenge when it comes to macro work! Not if you run around with the 65mm MPE!
I did forget to mention in the above comment that you are indeed correct, many lenses do no focus correctly with tubes attached. What makes this tolerable is the fact that your higher magnification at least allows you to see more details, if you have good lighting.
The same thing could be expected with anything changing depths of field, such as close-up lenses. Which is why (Just guessing) close-up lens work better further away from the subject. Because the size of the focus steps will be off, hence Canon's advice, that AF even using their doublet closeup lenses is not recommended. Now, it comes down to scale. Is there enough difference to make a difference.
Let me throw in one example why I think the answer is maybe yes. Even decent quality adapters from Pentax, Nikon, M42, and Tamron Adaptall-2 to EOS. Often loose infinity focus. This is regardless of the quality of the lens in question. It can only be the adapter, and the adapter is not off by very much! One that looks identical to the eye, might give perfect results. So, it just makes me wonder, that's all.
Of course I don't need to understand perfectly how the system works. But one speculates on one's hobby. It's human nature.
I did forget to mention in the above comment that you are indeed correct, many lenses do no focus correctly with tubes attached. What makes this tolerable is the fact that your higher magnification at least allows you to see more details, if you have good lighting.
The same thing could be expected with anything changing depths of field, such as close-up lenses. Which is why (Just guessing) close-up lens work better further away from the subject. Because the size of the focus steps will be off, hence Canon's advice, that AF even using their doublet closeup lenses is not recommended. Now, it comes down to scale. Is there enough difference to make a difference.
Let me throw in one example why I think the answer is maybe yes. Even decent quality adapters from Pentax, Nikon, M42, and Tamron Adaptall-2 to EOS. Often loose infinity focus. This is regardless of the quality of the lens in question. It can only be the adapter, and the adapter is not off by very much! One that looks identical to the eye, might give perfect results. So, it just makes me wonder, that's all.
Of course I don't need to understand perfectly how the system works. But one speculates on one's hobby. It's human nature.