Teleconverter question

Z

Zilog

Messages
275
Edit My Images
Yes
Why do Sigma and Nikon quote different f stop reduction for the same magnification?

Nikon 1.4x reduce by 1 f stop
Nikon 2x reduce by 2 f stop

Sigma 1.4x reduce by 1.2 f stop
Sigma 2x reduce by 2.8 f stop

I would have thought they would be the same as there doing the same thing.
 
How bizarre - would imagine the Sigma specs are an error..
 
Very strange. It says on there web site it takes my Sigma 70-200mm F2.8 and 1.4x turns it in to a 98-280mm f4 and 2x takes it to 140-400mm f5.6. It also says my 50-150mm f2.8 to 70-210mm f4 and 100-300mm f5.6. Guess some one messed up on the web site.
 
Zilog said:
Why do Sigma and Nikon quote different f stop reduction for the same magnification?

Nikon 1.4x reduce by 1 f stop
Nikon 2x reduce by 2 f stop

Sigma 1.4x reduce by 1.2 f stop
Sigma 2x reduce by 2.8 f stop

I would have thought they would be the same as there doing the same thing.
Click to expand...

It's down to the glass. It's the old you get what you pay for. If it's speed you want you'll need to get the Nikon one. My Nikon X2 drops my 70-200 2.8 to 5.6...
 
18-270 said:
It's down to the glass. It's the old you get what you pay for. If it's speed you want you'll need to get the Nikon one. My Nikon X2 drops my 70-200 2.8 to 5.6...
Click to expand...


Oh for christ sake

Once and for all there is no difference !!!

When this 70 - 200 2.8 HSM lens is used with the optional 1.4x EX DG APO , it becomes a 98-280mm F4 AF telephoto zoom lens 1 stop loss

or with 2x EX DG APO Tele Converters a 140-400mm F5.6 AF telephoto zoom lens respectively. A 2 stop loss

I have

a 1.4 Sigma - 1 Stop
a 2 X Sigma - 2 stops

a 1.4 Nikon - 1 Stop
a 1.7 Nikon - 1.7 Stop
and
a 2X Nikon - 2 Stops

Both the 1.4s are excellent the 1.7 very good and both 2 x not bad.

The Nikon TCs are better built and so they should be at nearly £300 a pop :thumbsdown:



Rant over



and breathe :bonk:
 
tbm said:
Anyone care to bring T-Stops into this discussion? :D
Click to expand...

T-stops are sometimes used instead of F-stops for exposure purposes, surly more for VERY old cinematographic use!!! The advances in lens tech over the last say... 40 years omits measure in T-Stops, but full marks for being a smart alec LOL :thumbs:
 
You must log in or register to reply here.
Back
Top