more about Canon extender 2x III

[Bill Yeung]

Hello, all:

more question around the extender 2x.
I understand the loss of 2 stop.
what I am more concern is the slower down of the auto-focus speed.
I am enjoying the 7 fps of 7D in figure skating. if 2x extender only slower down to a quater of the auto-focus speed. Am I only left around 3 or less of fps?
IF it is the case, no matter how reasonable the extender is, still can't fit in my purpose for indoor ice rink situation.
Again, I know, indoor light, no flash, big contrast background is all challenging and I gradually understand why no many people like to follow this route. They rather go outdoor and take some excellent exposure soccer, baseball........ shot!!
Is not the $ 600 concern me, it is just don't want to bring it home and found out after one photo session and put it aside!!
you folks sure will have more input in saving me from falling into this pain.

thanks

Bill

[Colin Southern]

I am enjoying the 7 fps of 7D in figure skating. if 2x extender only slower down to a quater of the auto-focus speed. Am I only left around 3 or less of fps?

Hi Bill,

No and yes and maybe!

A 7FPS camera is always potentially capable of 7FPS, but the key word there is POTENTIALLY. Auto-Focus speed comes into it (AF speed is influenced mostly by the maximum aperture of the lens, and that aperture is effectively reduced when using teleconverters, so it does slow down). Having said that, AF speed is usually OK so long as the lighting is good -- but having said THAT, I shoot with a 1 series camera that has a far superior AF to other series anyway, so keep that in mind.

What will potentially slow your frame rate down though is the shutterspeed; off the top of my head, the max frame rates they quote only apply when your shutterspeed is 1/1000th sec or faster ... so if your shutterspeed drops to something like 1/80th sec there's no way it's going to do 7 of those a sec (too many other things it has to do).

Then again, what are your alternatives? Even something like a 400mm F2.8 is likely to give you issues with not being able to fit the young lady in the frame when she's close to you; so I don't think there's a perfect solution for you at any cost (other than carrying several cameras and tripods!).

[Bill Yeung]

Colin:
you can see I am posting different posts and thread around my issue of 200mm, 400mm, aperture.....
I am in the process of digesting the many ideas around it.
very likely, 1 series is the next level I will go for, it is only next year or sooner.
sure, we never have a perfect solution in such a challenging situation.
(1) 400mm f2.8 (good at 400mm, miss the close distance)
yes, 400mm f 2.8 work perfect if she is 40 ft away and fit the frame perfectly (40 ft is the furthest side of the rink), of course i should not dream in take her in when she is in the closest side of the rink. But, do it mean that it pretty sure will do the "perfect" job in 400mm length because of the f2.8.
also, the dream may be a long one in seeing the price tag.
(2) 200mm in 70-200mm (Good at close distance, miss the long reach)
It is just the same I can only get good photos with my 70-200mm on the closest side of the rink while it is on the 200mm.
(3) 70-200mm with 2x extender III ( Afraid will blur both the long and close shot!!)
What I afraid is option (3) will only give me down grade pictures no matter in 140-400mm.
It will give me a final yes if your conclusion is:
(4) Bill , you can live with the 70-200mm + 2x extender III, and I can only guarantee these will do better when you go up to 1 series.

see whether it is your voice around this.

thanks for all the patience.

Bill

[Colin Southern]

Hi Bill,

What camera are you shooting with, and what's it's maximum ISO?

[Bill Yeung]

Colin:

auto ISO (100-3200) ; ISO 100 - 6400 ; H1 (12800)

Your advise, please.

Bill

[Colin Southern]

Colin:

auto ISO (100-3200) ; ISO 100 - 6400 ; H1 (12800)

Your advise, please.

Bill

Hi Bill,

Basically, ISO is your only variable (for a given lens), as you're always going to want to have the biggest aperture and the highest shutterspeed. So my suggestion is to just experiment with the ISO at the highest settings, and see what setting a relatively uncropped frame that's correctly exposed gives you acceptable quality (if you don't already have the EF70-200mm F2.8L IS USM II lens and EF2.0x III Teleconverter, you might like to restrict the camera to an aperture of F5.6 to see what shutterspeeds you would get at various ISOs).

[Bill Yeung]

Colin:

I now have 70-200 F2.8 IS USM II, that's why tempting to add the 2x extender.
yes, I did try with the 70-200mm with F 5.6. Sounds like acceptable.
By imagination, the extended 400mm ( more on my cropped sensor) should be bog enough to fill the frame.
It is only the slower fps and auto-focus out of my imagination. Because some review may said that it can slower down the auto-focus to more than half...
It is scary !!
ISO. I think with F 5.6, my highest ISO is 1600, and I already noticed some noise on the skater's face on the attached picture.

Bill