Tracking Focus with A700 - using 100-200mm f4.5

[sulhan]

Hi Everyone,

Here's some results from a resent test shoot on Birds in Flight using the Alpha A700. To makes things a little "challenging" i have used a Minolta 100-200mm f4.5 lens. This lens is "known" to be slow in AF (i'll share with you my thoughts on why its"slow"). Too bad its the longest lens I have got during my vacation.

The photos are off the camera no processing except for the last image with slight sharpening to bring our some detail.

All shots taken at Maximum open wide aperture at f4.5. Shutter apeed at 1/2500.
First Shot:


Cropped of First Shot:

Cropped of First Shot Sharpened:


Second Shot:


Cropped of Second Shot Sharpened:


Taking the shots of the swallows flying at full speed is not an easy task. It looks like even with a "slow" f4.5 aperture lens the tracking is very positive.

The tracking is made possible by the the "just nice" depth of field that separates the background from the subject (separation). All these factors come into play for the succesful shot:
- AF tracking resposne of the Camera ( Only S mode was used here but the "time-out - i.e focus lock" duration is just nice to cater for tracking motion)
- Sharpness of the lens at wide open - to be able to resolve the shubject and provide good contrast for AF system to work.


Why the lens is labelled as "slow "- in terms of AF.
The 100-200mm f4.5 is rather slow as the number of turns of the AF spindle required for it to rack between nearest focus distance and infinity takes 5+ turns AF spindle from end to end.
Although the 5+ turns it needs, the just nice shallow depth of field allows locking of subject better as the AF system doesn't overshoots off focus easily. Yes its right to say its slow to get from close distance to infinity, but due to its depth of field its able to lock focus fast.

What could have been better is incorporating a focus limitter on old lens like these. Then things would be much better.

Rgds,
Sulhan

[Zenten]

I personally find that the AF tracking of A700 only so-so ....................

[tankm]

so-so in what way ? in comparison to ?

Originally Posted by Zenten I personally find that the AF tracking of A700 only so-so ....................

[eow]

not fair comparsion...tan u had all the best original lenses of minolta and sony u can buy...zenten use all the best value for money 3rd party lenses...so the findings will not be a same one

[tankm]

no leh... still don't have the CZsss.

Just curious why the remark on "so-so" without other detail ? Not saying that the A700 has the best focus tracking in the market as well, it's not. However it's adequate for most cases and usage. I don't get to use alot of other brand, hence will be good to know from those who did.

In sulhan post, he's not using those expensive lens either and not those fast af gearing. In his case the slow af gearing is beneficial.

Originally Posted by eow not fair comparsion...tan u had all the best original lenses of minolta and sony u can buy...zenten use all the best value for money 3rd party lenses...so the findings will not be a same one

[eow]

Originally Posted by tankm no leh... still don't have the CZsss. Just curious why the remark on "so-so" without other detail ? Not saying that the A700 has the best focus tracking in the market as well, it's not. However it's adequate for most cases and usage. I don't get to use alot of other brand, hence will be good to know from those who did. In sulhan post, he's not using those expensive lens either and not those fast af gearing. In his case the slow af gearing is beneficial.

Base on some publications the af of the A700 is the fastest in good lighting, when the light fall, so will be it af performance,so there will be a lag in the afc...Our friend is expecting 1Dmk3 or D3 performance at $2k pricing. Based on what i had used and had seen.
no af system is omnipotent.
I do see an oof shot from nikon D3 pairing with nikon 85mm 1.4 user when we shoot side by side
I do see an canon 40D pairing with tamron 18-200mm hunt badly in broad daylight
A professional shooter who switch to A700 from canon 1dmkIIn....due to better noise ctrl and better Acquisition in area of low contrast (not to be confuse with afc)

[Zenten]

Originally Posted by tankm so-so in what way ? in comparison to ?

Originally Posted by eow not fair comparsion...tan u had all the best original lenses of minolta and sony u can buy...zenten use all the best value for money 3rd party lenses...so the findings will not be a same one

Just a personal opinion, yup, when I make comparisons, it will still be similar 3rd party lenses used ......... A700 usually ends up with more OOF shots ....................... Peace.

[eow]

which lenses in particular?

[Zenten]

Originally Posted by eow which lenses in particular?

Sigma 24-135mm. Tokina 80-200mm. Eow, when you giving up photography maybe can hand over your prized possessions?

[eow]

Originally Posted by Zenten Sigma 24-135mm. Tokina 80-200mm. Eow, when you giving up photography maybe can hand over your prized possessions?

The tokina 80-200 is a slowwwwww lenses...even my 75-300 can beat it flat
likewise my 18-70 can beat the 24-135mm.

likewise.... i sorry to announce i had not missed any critical shot with my 18-250mm due to af tracking.
u should reconsider yr lens lineup

[Zenten]

Originally Posted by eow The tokina 80-200 is a slowwwwww lenses...even my 75-300 can beat it flat likewise my 18-70 can beat the 24-135mm. likewise.... i sorry to announce i had not missed any critical shot with my 18-250mm due to af tracking. u should reconsider yr lens lineup

What is the moral of the story ? If using Sony system must use only Sony lenses so that pics will not be OO7.

You got your Oly yet?