Nice and close. But did you actually get within the normal MFD of the lens? At the 400mm end with the barrel extended, the subject without an extension tube will only be ~60-70cm away from the end of the lens.
arbitrage wrote:
Nice and close. But did you actually get within the normal MFD of the lens? At the 400mm end with the barrel extended, the subject without an extension tube will only be ~60-70cm away from the end of the lens.
I was at 800mm, not 400mm. And the MFD of the lens is irrelevant if the MAD of the subject is greater than that.
Imagemaster wrote:
I was at 800mm, not 400mm. And the MFD of the lens is irrelevant if the MAD of the subject is greater than that.
MAD = Minimum Approachable Distance.
Yes that is what I was asking, was the MAD (from end of the lens) less than the (MFD - lens length) thus making the extension tube needed? I also know you were at 800, doesn't change the MFD. My comment was that when the lens is extended to the 400mm mark (ie 400, 560, 800), the remaining distance from the front element to the subject gets very short (as the MFD is measured from the sensor) and is already under 1m before accounting for the extended lens length.
arbitrage wrote:
Yes that is what I was asking, was the MAD (from end of the lens) less than the (MFD - lens length) thus making the extension tube needed? I also know you were at 800, doesn't change the MFD. My comment was that when the lens is extended to the 400mm mark (ie 400, 560, 800), the remaining distance from the front element to the subject gets very short (as the MFD is measured from the sensor) and is already under 1m before accounting for the extended lens length.
Yes, I only use tubes when I can't get closer than the MFD of the lens I am using.
