08-16-2010, 06:44 AM
[quote name='Brightcolours' timestamp='1281870027' post='1784']
You didn't stop down the Canon 100mm lens to see how exposure might be different that with normal electrical communications, the whole idea about your retest.
Anyway, the answers have been there all along, explaining on how the focal length can change differently for each lens, and other factors.
If you want to go about it more scientifically, you will have to measure/calculate the focal lengths for both lenses at the different focus distances, and actually measure the exposure instead of "trusting the camera metering".
As pointed out, the Canon macro and that Mamiya are very different beasts, design wise.[/quote]
Stopping down was not relevant in this case as I only compared them wide open. Given the theory and the similarity between the lenses I expected similar results. What surprised me was that the differences were huge, not marginal.
[quote name='Brightcolours' timestamp='1281870027' post='1784']
However, we are not discussing those lenses, we were talking about the Canon 90mm TS-E and Nikon 85mm PC. And you, without real reason, "seriously doubt" that you will see the same order of light loss shooting each at 1:2 magnification, because with one you have to put an extension tube on.
However, the one without extension tube DOES extend itself in a similar manner, inside, when focussing closer.
So, you can do two things. Either believe that indeed you will see light loss also with the Nikon (you did note that light loss with both of your very different macro lenses after all, even if your methods were not optimal), or you won't believe it. It will not change the outcome, though.[/quote]
I searched and could not find a direct comparison between the two. I'd be much more relaxed <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' /> if I see one to corroborate for this.
You didn't stop down the Canon 100mm lens to see how exposure might be different that with normal electrical communications, the whole idea about your retest.
Anyway, the answers have been there all along, explaining on how the focal length can change differently for each lens, and other factors.
If you want to go about it more scientifically, you will have to measure/calculate the focal lengths for both lenses at the different focus distances, and actually measure the exposure instead of "trusting the camera metering".
As pointed out, the Canon macro and that Mamiya are very different beasts, design wise.[/quote]
Stopping down was not relevant in this case as I only compared them wide open. Given the theory and the similarity between the lenses I expected similar results. What surprised me was that the differences were huge, not marginal.
[quote name='Brightcolours' timestamp='1281870027' post='1784']
However, we are not discussing those lenses, we were talking about the Canon 90mm TS-E and Nikon 85mm PC. And you, without real reason, "seriously doubt" that you will see the same order of light loss shooting each at 1:2 magnification, because with one you have to put an extension tube on.
However, the one without extension tube DOES extend itself in a similar manner, inside, when focussing closer.
So, you can do two things. Either believe that indeed you will see light loss also with the Nikon (you did note that light loss with both of your very different macro lenses after all, even if your methods were not optimal), or you won't believe it. It will not change the outcome, though.[/quote]
I searched and could not find a direct comparison between the two. I'd be much more relaxed <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' /> if I see one to corroborate for this.