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'AF point expansion' query re. birds in flight (1 Viewer)

D

davpen

Well-known member
Hello. I've never used Canon gear before but am considering getting a 70D (or possibly a 7D), mostly for getting record shots of birds passing over our visible migration watchpoint.

My question is: with the AF point expansion feature on the 7D, is it necessary to get the single point to focus on the bird in the first place, ie before the surrounding points come into play? Reason I ask is that I don't think I could do this very often with fast flying passerines, and I'd probably end up using Zone AF anyway, and hoping for the best.

This is one of the reasons why on balance I'm leaning towards the 70D (with its supposedly slightly better high ISO capabilities) over the 7D.

Am I doing the right thing?

Cheers,

David
 
davpen said:
Hello. I've never used Canon gear before but am considering getting a 70D (or possibly a 7D), mostly for getting record shots of birds passing over our visible migration watchpoint.

My question is: with the AF point expansion feature on the 7D, is it necessary to get the single point to focus on the bird in the first place, ie before the surrounding points come into play? Reason I ask is that I don't think I could do this very often with fast flying passerines, and I'd probably end up using Zone AF anyway, and hoping for the best.

This is one of the reasons why on balance I'm leaning towards the 70D (with its supposedly slightly better high ISO capabilities) over the 7D.

Am I doing the right thing?

Cheers,

David
Click to expand...
Yes, with single point expansion you first have to pick the bird up with the single point and then the surrounding points will come into play if you lose it on the single point - I always set a slow Sensitivity speed in this mode so that if you lose the bird altogether it would give you time to get back on with the focus going wildly out on something in the background. With Zone AF on the 7D I always found it best to set a fast sensitivity speed so it passed from one point to another quickly. I found that single point expansion was best where there were cluttered backgrounds but ZoneAF was fine for uncluttered backgrounds although with ZoneAF it is a bit hit and miss as to whether or not you nail the birds eyes or not as it could just as likely focus on its wings !! . Hope this helps :t:
 
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Thanks Roy. Yes, that does help. I think with the kind of birds in flight photography I'm hoping to be doing, there'd be virtually no chance of focussing on the eye anyway. I suspect I'll be lucky to get the bird in the viewfinder in the first place. With this in mind, I think I'd usually be using Zone AF rather than AF point expansion. Hence I'm still leaning towards the 70D, but would welcome any other opinions.

David
 
davpen said:
Thanks Roy. Yes, that does help. I think with the kind of birds in flight photography I'm hoping to be doing, there'd be virtually no chance of focussing on the eye anyway. I suspect I'll be lucky to get the bird in the viewfinder in the first place. With this in mind, I think I'd usually be using Zone AF rather than AF point expansion. Hence I'm still leaning towards the 70D, but would welcome any other opinions.

David
Click to expand...
I don't know your budget David but it may be worth hanging on a while for the 7D2 to hit the market although it will probably be at least double the price of the 70D.
 
Haha! Hmm, I've seen that mentioned, but I doubt I'd be able to justify the cost. The 70D is already pushing at my limits as it is. Maybe I'll get the 2 when the 3 comes out.

David
 
Just to clarify things the 70d whilst a perfectly capable camera for bif doesn't work in the same way as I understand the 7d does. You either have single focus point or a central group any of which will focus on what it thinks is the most relevant feature. This works very well for birds against the sky but I tend to use single point when there's a background. The high iso is I think a bit overstated, it's only minimally better than my 50d. Other features such as the flip out touch screen are brilliant and it does have more pixels.
 
ncf15 said:
Just to clarify things the 70d whilst a perfectly capable camera for bif doesn't work in the same way as I understand the 7d does. You either have single focus point or a central group any of which will focus on what it thinks is the most relevant feature. This works very well for birds against the sky but I tend to use single point when there's a background.
Click to expand...
The central group as you call it is ZoneAF I guess where you have a selectable group of nine AF points - I do not know about the 70D but on the 7D I always used a fast AI servo sensitivity speed when using this as it passes AF from one point to another faster than the if you use a slow or medium AI servo sensitivity. As you say this is a good choice if you have an uncluttered background like the sky. If I have a cluttered BG then I use single point expansion (just the single point on the 70D) but I then change the AI servo sensitivity setting to slow so that if you lose the bird then the Camera will give you some time to get back on it before going wildly out of focus on something in the BG.
 
Thanks both. I'm still wavering between the 7D and 70D. Basically, I'm still trying to come to a conclusion re the potential usefulness of AF point expansion for the kind of BIF pics I'm hoping to take. Weighed against that are a few reports I've read that the AF of the 70D is slightly more accurate and stable, and possibly even a touch faster, and that the metering is more reliable.
 
davpen said:
Thanks both. I'm still wavering between the 7D and 70D. Basically, I'm still trying to come to a conclusion re the potential usefulness of AF point expansion for the kind of BIF pics I'm hoping to take. Weighed against that are a few reports I've read that the AF of the 70D is slightly more accurate and stable, and possibly even a touch faster, and that the metering is more reliable.
Click to expand...

Same dilema Davpen. The 7d is a proven reliable camera with many users getting many great results. However the technology in the 70d I think has surpassed the 7d. The sensor & the processor are updated & the focus system is all but comparable.... with a slightly more attractive price. The body build however just doesnt feel quite as robust to me...still undecided & waiting just to see how much out of range 7d mk2 is... due out by 15th Sept I think.
I should also add that using a 40d Ive not had spot AF or AF Expansion so perhaps dont know what I'm missing (decent BIF shots would be the obvious answer I guess!!)
 
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7D is just £595 with 3 year warranty from Hdew - http://www.hdewcameras.co.uk/canon-7d-digital-slr-camera-body-494-p.asp

The 70D is £605 with 3 year warranty - http://www.hdewcameras.co.uk/canon-eos-70d-camera-body-1348-p.asp

Hdew supplied my 5D3 a couple of years back with faultless service. These will be grey imports, but from a trusted UK supplier with all the consumer protection afforded by such.

I doubt a new 7D2 would be anywhere close on price. The 7D was £1699 at launch, although I paid around £1200 for mine from Jessops a few months later. Still, <£600 for a new 7D with warranty is bargaintastic IMHO. :)
 
gazpic said:
Same dilema Davpen. The 7d is a proven reliable camera with many users getting many great results. However the technology in the 70d I think has surpassed the 7d. The sensor & the processor are updated & the focus system is all but comparable.... with a slightly more attractive price. The body build however just doesnt feel quite as robust to me...still undecided & waiting just to see how much out of range 7d mk2 is... due out by 15th Sept I think.
I should also add that using a 40d Ive not had spot AF or AF Expansion so perhaps dont know what I'm missing (decent BIF shots would be the obvious answer I guess!!)
Click to expand...

Gareth, someone on dpreview has just been talking about this. He has extensive experience using the 7D for migrating birds in Texas and at Cape May. He also uses the 70D, which he says now gives him more keepers than the 7D. He obviously still likes the 7D, but reckons the 70D is a 'smoking good camera' for birds in flight, including passerines, and seems to prefer it overall.

Tim, thanks for the links. I see they've got a good deal on the 400mm f5.6 as well, albeit without the 3 year guarantee.

David
 
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