Canon 2x extender

Not sure what is going on here if it is because I am only using a version one 2x extender or what but all my images look bad.
Using a canon 1D mark III just back from CPS having the AF fixed, and a 300 f4 IS

Am I missing focus or any ideas? Is it worth scrapping this extender and getting the version 3? Is the version 3 that much better?

Or am I just pixelpeeping?

A 2X extender slows down the focus speed a lot and also softens the image. I don't own one for this reason. I've used an older version and the newer version with the same results on a 500mm f/4L lens and a 1D4 body. I think it's safe to say it's not you or the version of the extender you're using.

Guaranteed someone will post an image that goes against my opinion on the 2X extender though.

What about the 1.4x extender? Should I grab one of those?

Or should I scrap the extender and get one of the Sigma 150-600s

I use a version II and III 1.4 extender on my 500mm f/4L about 95% of the time and although it does slow the focus speed down a bit it's manageable for in-flights and I don't see a difference in image quality. Just remember the more you crop the more you're going to see a drop in image quality. I cannot say yes or no on your lens question....I've never used one of those lens's.

I have not seen any folks posting about a version one extender so cannot comment on them. The version two was current when I bought mine (a 1.4x).
The version two 2x extender did not enjoy a reputation for fine IQ. When the version threes came out the opinion was that if you had a 1.4x II you would not see much improvement at all if you bought a version III. But if you were shooting with a 2x II that moving up to a version III 2X would be a big improvement. This was all before the release of the current (II) super-teles.
I suspect the version I 2x is a source of your problems. The version II 2X did not have the quality of the version II 1.4x. The IIIs both work well on the current (II) super-teles.

Thanks I may rent a version 3 2x to test it out prior to making any purchase

I had a 2Xi and tried using it on my new 7Dii with my 400DO f/4, which gave me 800mm that would auto-focus with the center point, wow. The results were quite poor and I discovered that the 2X version i electronics do not support MFA, which my rig needed. So, I bought a 2Xiii. In addition to the MFA capability, I think the optic quality is also improved. I do have to stop it down to get a sharp image, but I had to do that with my 1.4Xiii as well. I can tell you that the difference between 560mm focal length and 800mm focal length is quite significant when photographing small birds. It also requires careful technique and faster shutter speeds when handholding. I need a lot more practice. These are two images from my very first outing at Brazos Bend SP with the 2Xiii. Both are considerable crops. When our weather improves, I will be trying this setup some more, probably stopped down a bit more. I have added some additional mfa, as well.

Admittedly this was shot with a Canon 300 F2.8 L IS but it is one of the very first (3rd or 4th) images that I took with this lens. This was using the Canon 2 x Mk3 extender, frankly I found the Mk2 useless as I was better off shooting with the 1.4 and cropping - expensive lesson!
2 x extenders are for emergency use only, especially if you don't have an F2.8 lens. However, in good to very good light, the Canon 2 x Mk3 can get you decent shots that would be otherwise unobtainable.
Note the image attached is just a RAW file converted and scaled - no processing/cropping/sh​arpening etc.

Thank you, I will probably just pick up a 1.4x

I've used the 2xIII with the 70-200mm f/2.8II and have been very satisfied with the results. I certainly don't think it's only for emergencies. Works well on static subjects, not very useful for BIF or sports action.

Big Ugly wrote in post #17450137
I've used the 2xIII with the 70-200mm f/2.8II and have been very satisfied with the results. I certainly don't think it's only for emergencies. Works well on static subjects, not very useful for BIF or sports action.

Perhaps I overstated the "Emergency" bit but they are not ideal on any lens. However they can be useful when there is no alternative. Decent shots can be taken with the Canon 2 x Mk3 and the 300 F4 L IS but conditions need to be just right. The 1.4 extender is much more flexible regarding lighting and offers faster AF and this is the better option with the 300 F4 in my opinion though the 2 x will work the 1.4 generally works better.

johnf3f wrote in post #17450216
Perhaps I overstated the "Emergency" bit but they are not ideal on any lens. However they can be useful when there is no alternative. Decent shots can be taken with the Canon 2 x Mk3 and the 300 F4 L IS but conditions need to be just right. The 1.4 extender is much more flexible regarding lighting and offers faster AF and this is the better option with the 300 F4 in my opinion though the 2 x will work the 1.4 generally works better.

You pretty much said what I was trying to say and I would have to agree that if I owned a 2X extender it would only be used in rare situations where I had time to experiment with a cooperative subject. In the right conditions I think any extender will produce decent images even with the 2X extender....I've seen some amazing captures when a 2X extender was used.

I often experiment with the 1.4 and 1.5 extenders I currently own and sometimes in the right conditions I'm amazed at the results but it's not something I do on a regular basis...I'd rather use the raw lens but sometimes reach is necessary.

This image was taken using 3 extenders and an extension tube.

I don't consider the 2x to be a substitute for a prime, but it does give me very good results under certain conditions. If I have good light and stop it down to f/8 the 70-200II/2xIII combo approaches my 400mm f/5.6, and allows me to shoot at much slower shutter speeds. Maybe I was blessed with a copy that is unusually sharp and compatible with my 70-200. My 1.4x does not work well at all on the 70-200, but works very well on a 500mm.

Big Ugly wrote in post #17450665
I don't consider the 2x to be a substitute for a prime, but it does give me very good results under certain conditions. If I have good light and stop it down to f/8 the 70-200II/2xIII combo approaches my 400mm f/5.6, and allows me to shoot at much slower shutter speeds. Maybe I was blessed with a copy that is unusually sharp and compatible with my 70-200. My 1.4x does not work well at all on the 70-200, but works very well on a 500mm.

I think we are probably on the same wavelength - just putting it differently!
I am quite happy with the way my 2 x Mk3 performs on my 300 F2.8 L IS but my 600 F4 was significantly better - though bigger/heavier and more expensive!
On smaller aperture lenses the 2 x becomes even more of a compromise - but if there is no alternative it is FAR better than nothing!

Tim Barnhart wrote in post #17450029
Thank you, I will probably just pick up a 1.4x

I think you will be very pleased. I think there is one here on the POTN classifieds for $170, if I am not mistaken.