20D w/ 70-200 2.8 IS w/2x tele getting soft results?

[nick_breedlove1]

I've got the 20D and I'm using the 70-200 2.8. I get razor sharp

results with that lens...kinda scary how detailed things are. I put

the 2x extender (made by Canon) on and my results are soft to say

the least, that detail is gone...of course I know it doubles the f-

stop and requires more light, but come on, looks like someone

smeared a bit of vaseline on my lens. Has anyone else ran into this

problem? Maybe I'm expecting too much.

 

Thanks

Nick

[phyrpowr]

My Kenko 2x, or anybody's for that matter, will cause noticable loss of sharpness and contrast, but "vaseline" effect....no.

 

Can you post "with" and "without" shots?

[frank_dzambic]

You left out the most important detail. Are you using a tripod?

[nick_breedlove1]

I wish I had a sample, but I trashed them off the comp after being dissatisfied. Not using a tripod, but the shutter speed was like 1/500th of a second, so I shouldn't need one and that is with IS turned on. Maybe the term vaseline was a little bit much. Its just soft.

[frank_dzambic]

Well, a sample shot would be helpful.

 

However, 1/500 with IS turned on should be a fast enough shutter speed with that lens and TC combination. That doesn't mean that your hands might not have been particularly shaky that day, even more than the IS could correct for.

 

TC's will soften an image somewhat, when compared to the lens without the TC attached--especially a 2X TC. But, unless you shoot comparison shots on a tripod, it's hard to say. What can I say....I'm a firm believer in tripods. At least that would rule out camera shake.

 

Other than camera shake, and the inherent loss of quality with a 2X TC, I can't really think of any other possibilities.

[john schroeder]

Try turning the I.S. off when you use the tele. I've been told that I.S. can get confused and cause soft images under certain conditions. I don't know if this is true, but it's not like you're wasting film. I have never used that combination of optics. I could just be that it dosn't work well. I would also try a shot wide open and another stopped down a few EV's. Just to see what happens at different apetures.

[david_haynes]

Nick,

 

I have the same camera/lens, as well as the Canon 1.4x and 2x converters.

 

It's a well-documented fact that the 1.4x converter is a much better performer than

the 2x. In fact, I'm hard pressed with the 20D to see any drop off of quality with the

1.4xTC.

 

That is not the case with the 2xTC. It does degrade the image with this lens, but it can

be managed somewhat. I'm more pleased with the 2xTC on my 400 f/5.6L and 180 f/

3.5L macro than this zoom, however.

 

If it comes down to a choice of using the 2x or shooting without and cropping, I still

think there's an advantage in using the TC.

 

In my experience, using the 70-200 f/2.8 IS plus 2xTC, the best image quality comes

when you stop the lens down two stops from wide open - from f/2.8 to f/5.6. But

once you add the TC factor of 2x the f/5.6 becomes f/11, so unless you're shooting in

direct sun it's best to use support. Remember, this lens on the 20D with converter is

now equal to a 640mm tele in 35mm format.

 

I'm never tested turning the IS on or off with the TC, but I can see how that could also

be a factor. I also do not understand why the 2x works so well on the 180 macro -

still very crisp!

 

For me, I carry the 2xTC with me most of the time for "emergency" shots that might

arise when I don't have a longer lens along. I don't hesitate a bit about using the 1.4x,

but the 2x is only used when nothing else is available.<div></div>

[ralph_jensen]

I notice a real difference in sharpness between my 1.4x and my 2x when comparing their

effect on my 70-200. The 1.4x looked great; the 2x was fairly disappointing by

comparison.

 

(Of course, in the pre-digital days, we wouldn't be complaining about such things -- or

not as much -- but the ability to instantly zoom into the pixel level makes us pickier!)

 

The 2x affects sharpness so much that I thought about selling it, but when you need the

reach it's still better than shooting without it and then enlarging to that size (and yes, I

tested that principle, which I'd read but never believed).

[ralph_jensen]

"If it comes down to a choice of using the 2x or shooting without and cropping, I still think

there's an advantage in using the TC."

 

That's what I was trying to say (David and I posted at the same time).

[digitmstr]

posting that fly picture after the mention of vaseline was quite the pun...

 

:D

[david_haynes]

FYI, here's a photo I took today with the 400 f/5.6 and 2xTC<div></div>

[david_haynes]

... and a 100% crop of the above image

[david_haynes]

And here's a 100% crop of same view shot at ISO 100...<div></div>

[david_haynes]

I just noticed the ISO 800 crop showed as a link instead of a photo on this page. I

made smaller and am trying again...