1.4X Teleconverters (Page 3): No, it was stopped them into an F8. It's easy to figure out, 2×4 = 8. If you were using a 1.4 X that it would be 1.4×4=5.6. It is simple math but many...

oldtool2 Loc: South Jersey

waapl01 wrote:

With a 2x teleconverter wouldn't u be only only be able to stop down to a 6.3 if the lens was initially an f4 lens?

No, it was stopped them into an F8. It's easy to figure out, 2×4 = 8. If you were using a 1.4 X that it would be 1.4×4=5.6. It is simple math but many don't realize the process.

Jim D

waapl01

I thought it was 2 stops in the line of of f stops after 4 normally 5.6 then 6.3 then 8 etc. That would be 3 stops not 2, and 200 mm would then become 400mm. At the time I was playing with this I had a 3.5-5.6 lenses on my camera and was viewing the next f stops (2) that were available in my camera. I didn't try it with a lens that was a f4 stopped lens. Not sure if it would have mattered I understand the formula now. Thanks for the help!!

Benttree Loc: GA.

danielb59

Daniel, as well by using 1.4X with a lens other than a manufacturer did designed it use for you'll fine in most of the cases your camera/lens auto-focus do not function, or it is very slow and/or it "hunt".

wingclui44 Loc: CT USA

waapl01 wrote:

I thought it was 2 stops in the line of of f stops after 4 normally 5.6 then 6.3 then 8 etc. That would be 3 stops not 2, and 200 mm would then become 400mm. At the time I was playing with this I had a 3.5-5.6 lenses on my camera and was viewing the next f stops (2) that were available in my camera. I didn't try it with a lens that was a f4 stopped lens. Not sure if it would have mattered I understand the formula now. Thanks for the help!!

6.3 is half stop between 5.6 & 8.
The traditional aperture full stop scale as following:
1.0;1.4; 2.0; 2.8; 4.0; 5.6; 8.0; 11; 16; 22; 32; 45; 64; 90; 128..

Grammieb1 Loc: New Orleans

Benttree wrote:

danielb59

Daniel, as well by using 1.4X with a lens other than a manufacturer did designed it use for you'll fine in most of the cases your camera/lens auto-focus do not function, or it is very slow and/or it "hunt".

I have a 70-200 4 & the AF is a little slower with 1.4 added, but it still works fine & doesn't hunt. Canon made it by design that the teleconvertors slow down the af when in use. This affects all the lenses that use it including the 70-200 2.8 ll which I own as well. The 4 works very well with the 1.4 teleconvertor. The advantage with the 2.8 is that the 2xs can be used as well. Bab

oldtool2 Loc: South Jersey

wingclui44 wrote:

6.3 is half stop between 5.6 & 8.
The traditional aperture full stop scale as following:
1.0;1.4; 2.0; 2.8; 4.0; 5.6; 8.0; 11; 16; 22; 32; 45; 64; 90; 128..

:thumbup: :thumbup:

birdpix Loc: South East Pennsylvania

danielb59 wrote:

I did consider the 2X converter. However, with a 2 stop loss in light, this lens would only allow manual focus. At least with the 1.4X I think I could use AF as long as I had the lens set at F4. Again, my original question was concerning the cost/benefit of the canon vs tamron vs kenko converters.
Thanks,

You are correct in that the 2.0 TC will not autofocus on an f/4 lens except with certain of the Canon higher end Cameras. The 1.4 will AF with that lens regardless of the f/stop used as it focuses at the widest aperture available and then stops down to take a photo. Adding the 1.4 would make the widest aperture f/5.6.

I have a Canon 70-200 f/4 NON IS version and I use the Canon 1.4 TC occasionally and it works very well on my Canon 7D with little loss in image quality. I can't speak to the IQ using the Kenko or Tamrom converters.

imagemeister Loc: mid east Florida

danielb59 wrote:

I just purchased a used canon 70-200 f4 IS lens on... (show quote)

This is for the Tamron TC naysayers........

Canon 70-200 2.8 II W/Tamron SP 2X, 50D

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Canon 80-200 2.8 W/Tamron SP 2X - Nancy Wilson

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