Manual focus indication: 300/f4+2x on 7D

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12-02-2009, 11:03 PM
Amit Kalele

Manual focus indication: 300/f4+2x on 7D

HI All,

I am new to canon system. I got the above combination (7d , 300/f4 and 2x tc) recently. My problem is when I put 2x tc on 300/f4, i am not able to get the focus indication of any sort while doing MF. No beep, no green light on view finder. I have enabled the C fn III - 10 also, beep is also enabled. Lens is on MF.

Is this expected? In that case how to make sure the focus is correct? BTW IS works fine with 2x tc.

Regards
Amit
12-02-2009, 11:14 PM
arash_hazeghi

AF sensors of 7D are deactivated at slower than f/5.6 you cannot AF or use MF confirmation. You can buy third party TCs and tape one of the contacts to "fool" the camera and force it to AF/confirm but the performance will be very inconsistent.
12-02-2009, 11:18 PM
Amit Kalele

Hi Arash,

Thanks for your quick response, I was aware that AF will not work, but if one cant get a MF confirmation, makes life really hard. Anyway thanks for your inputs.
12-02-2009, 11:22 PM
Roger Clark

Amit,
You can always use live view to focus. Also consider getting a 1.4x TC. You have a lot of resolution with the small pixels on the 7D and a 2x TC is not gaining much additional resolution that a 1.4x will give.

Roger
12-02-2009, 11:46 PM
Amit Kalele

Quote:

Originally Posted by rnclark

Amit,
You can always use live view to focus. Also consider getting a 1.4x TC. You have a lot of resolution with the small pixels on the 7D and a 2x TC is not gaining much additional resolution that a 1.4x will give.

Roger

Hello Roger

Thats a good suggestion, never occurred to me, will try today itself. Yes 1.4x tc works fine. I was just wondering whether no MF confirmation with 2x tc is some missed setting or some tech fault.
12-03-2009, 01:02 AM
Roger Clark

Quote:

Originally Posted by Amit Kalele

Hello Roger
I was just wondering whether no MF confirmation with 2x tc is some missed setting or some tech fault.

Amit
A slower f/stop is more difficult to see find the best focus point. If you have an old film camera with microprism focusing screen and a manual lens, stop the lens down to f/8 and see how easy/difficult it is to focus. It's the same with modern AF systems. The phase detect focus system has more difficulty with the narrow angles of the light from the lens.

Roger
12-03-2009, 01:32 AM
Amit Kalele

Quote:

Originally Posted by rnclark

Amit
A slower f/stop is more difficult to see find the best focus point. If you have an old film camera with microprism focusing screen and a manual lens, stop the lens down to f/8 and see how easy/difficult it is to focus. It's the same with modern AF systems. The phase detect focus system has more difficulty with the narrow angles of the light from the lens.

Roger

Yeah agree with you. I think i will stick to 1.4x at best.

BTW 7D viewfinder is terrific, even with 2x on 300/f4 it appears quite bright compared to my earlier cameras F80 and D70s.

Thanks for your reply Roger. It was really helpful.
12-03-2009, 10:29 PM
Amit Kalele

Quote:

Originally Posted by rnclark

Amit,
You can always use live view to focus.

Roger

Hi Roger, tried using live view and it works out fine. Thanks for the pointer.
12-05-2009, 05:23 AM
Sabyasachi Patra

Amit,
Some good suggestions already given. I had earlier tried the 2x couple of times with the 300 f4 IS and never used it again. I will use it again, If I have only the 300 f4 and see a Yeti (legendary snowman). Ofcourse, in that case, what ever lens or camera you use wont matter. As that image will be bought by all the agencies. :D

With the 1.4xII TC the 300 F4 IS gives great results. The live view feature is great for manual focussing, provided you don't keep it on for a while.

Cheers,
Sabyasachi