p.1 #3 · Is there a technical reason why TC’s are 1.4 and 2.0x?
1.4 squared is 2 and 2 squared is 4. A 1.5x would be 1.17 stops darker rather than one stop with the 1.4x. Humans like round numbers.
Nikon made a 1.7x. It would be nice to have more options, but there are fewer in the MILS era.
p.1 #7 · Is there a technical reason why TC’s are 1.4 and 2.0x?
Choderboy wrote:
Nikon made 1.5X and 1.7X TCs.
Olympus has 1.25X built in TC in their 150-400 Pro lens.
Kenko and Vivitar make 3X TCs.
I'm sure there are others.
So 1.4 and 2X are by far the most common but others exist.
Round numbers sounds like a reasonable explanation.
I recall the TC16A at 1.6x, but the only "TC" I found in 1.5x was a front mounted setup for an all in one. Is that what you mean or is there an SLR 1.5x TC?
p.1 #8 · Is there a technical reason why TC’s are 1.4 and 2.0x?
Many seem rounded up a noticeable amount. The Kenko 1.4X and 1.5X Tele Plus MC4s use the same optics and are more like 1.3X. I know I had 1.7x once. I still have a Kenko 3x.
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p.1 #9 · Is there a technical reason why TC’s are 1.4 and 2.0x?
Choderboy wrote:
Nikon made 1.5X and 1.7X TCs.
Olympus has 1.25X built in TC in their 150-400 Pro lens.
Kenko and Vivitar make 3X TCs.
I'm sure there are others.
So 1.4 and 2X are by far the most common but others exist.
Round numbers sounds like a reasonable explanation.
Actually, a 1.7X TC is half-way between a 1.4X and a 2X TC and results in a stop and a half loss of light. The 1.7 is probably 1.67 or the square root of 2.8, just like a 1.4X TC is probably 1.41 or the square root of two. Just think of the math as following the square root of the typical apertures. The square root of 2 is 1.4X and that results in a one stop loss of light. The square root of 4 is of course 2 and a 2X TC results in a 2 stop loss of light.
Olympus' 1.25X TC doesn't follow this pattern and the light loss isn't an even number in the same way as it results in a little less than 2/3rds of a stop, and a 3X TC would of course be the square root of 9 and would result in the loss of 3 and third stops of light.
Having the TCs result in an easily understood loss of light was important for getting exposure right back in the film days, but is probably less of an issue with digital. The typical TCs, however, are of course carry overs from the film days.
p.1 #10 · Is there a technical reason why TC’s are 1.4 and 2.0x?
I meant a 'standard' TC between camera and lens but my googling was less than thorough.
Nikon do make a front mount 1.5x but the standard type was actually a Kenko.
EB-1 wrote:
I recall the TC16A at 1.6x, but the only "TC" I found in 1.5x was a front mounted setup for an all in one. Is that what you mean or is there an SLR 1.5x TC?
