03-16-2011, 07:00 AM
[quote name='boren' timestamp='1300208815' post='6822']
Most user reviews in dyxum.com say that the Tamron 60/2.0 is slow to focus. The Canon 60/2.8 on the other hand is known to be one of the faster-focusing macro lenses around (at least according to user reviews in fredmiranda.com). Testing the Tamron on the EOS-7D will give you a better point of comparison.
The kit lenses are a similar story. One of the users at dyxum.com had this to say about the Sony 18-55 SAM: "Extremely poor auto-focus (slow and unreliable in anything but good light)". This is from a user who also used the following lenses: Sony 16-105, Sony 18-70, Minolta 17-35, Minolta 20-35, Minolta 24-50. He has enough experience to compare its performance. Another user had this to say about the lens: "slow to almost none af in low light". Among the 44 review at fredmiranda.com I couldn't find a single one that complained the the Canon 18-55 IS is slow to focus. In fact, quite a few of them raved about its fast and accurate AF.
Bottom line: SAM motors are very different than SSM motors. The former are a marketing trick. They are slow and noisy and were only released to the market by Sony as a cheap answer to "those in the know" (e.g. salesmen and Canikon FUD-spreading fanboys) that claim screwdrive AF is a disadvantage. Tamron isn't known for fast focusing lenses and the 60/2.0 is a typical example, if not the worst. Both Canon lenses you've used are much better, and this means that your findings, as interesting as they may be, are not really valid. At least not as a comparison of the AF capabilities of these cameras.
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1. I guess it all depends on your PoV. As I have many lenses with ring-USM, IF design and non-rotating front filter I can not define the AF of the 18-55 IS as fast. However, that of the 18-55 SAM was much worse.
2. The problem was less AF speed per-se but the inability to lock focus fast. In simple words: They hunted a lot. That is why I suspect that more than it's the lens' fault, it's a body related issue e.g. AF algorithm. The fact that I saw the same issue with both lenses only strengthens my suspicion.
3. I agree with you that the best way of testing this is with the same lenses in different mounts e.g. Tamron 60/2 in SA and EF mounts but as I said, I'm no lens tester. I'm just a user. All these lenses and bodies were bought from my personal budget for my personal use. On paper, the A33 had many advantages. In practice, it disappointed.
4. I must confess that the Tamron 60/2 in SA mount was a dream combination of mine for a very long time. I love fast aperture and I love stabilization. The 7D + 60/2.8 combo gives me none of these. Again, I witnessed that theoretical advantages do not always translate to practical ones.
Most user reviews in dyxum.com say that the Tamron 60/2.0 is slow to focus. The Canon 60/2.8 on the other hand is known to be one of the faster-focusing macro lenses around (at least according to user reviews in fredmiranda.com). Testing the Tamron on the EOS-7D will give you a better point of comparison.
The kit lenses are a similar story. One of the users at dyxum.com had this to say about the Sony 18-55 SAM: "Extremely poor auto-focus (slow and unreliable in anything but good light)". This is from a user who also used the following lenses: Sony 16-105, Sony 18-70, Minolta 17-35, Minolta 20-35, Minolta 24-50. He has enough experience to compare its performance. Another user had this to say about the lens: "slow to almost none af in low light". Among the 44 review at fredmiranda.com I couldn't find a single one that complained the the Canon 18-55 IS is slow to focus. In fact, quite a few of them raved about its fast and accurate AF.
Bottom line: SAM motors are very different than SSM motors. The former are a marketing trick. They are slow and noisy and were only released to the market by Sony as a cheap answer to "those in the know" (e.g. salesmen and Canikon FUD-spreading fanboys) that claim screwdrive AF is a disadvantage. Tamron isn't known for fast focusing lenses and the 60/2.0 is a typical example, if not the worst. Both Canon lenses you've used are much better, and this means that your findings, as interesting as they may be, are not really valid. At least not as a comparison of the AF capabilities of these cameras.
[/quote]
1. I guess it all depends on your PoV. As I have many lenses with ring-USM, IF design and non-rotating front filter I can not define the AF of the 18-55 IS as fast. However, that of the 18-55 SAM was much worse.
2. The problem was less AF speed per-se but the inability to lock focus fast. In simple words: They hunted a lot. That is why I suspect that more than it's the lens' fault, it's a body related issue e.g. AF algorithm. The fact that I saw the same issue with both lenses only strengthens my suspicion.
3. I agree with you that the best way of testing this is with the same lenses in different mounts e.g. Tamron 60/2 in SA and EF mounts but as I said, I'm no lens tester. I'm just a user. All these lenses and bodies were bought from my personal budget for my personal use. On paper, the A33 had many advantages. In practice, it disappointed.
4. I must confess that the Tamron 60/2 in SA mount was a dream combination of mine for a very long time. I love fast aperture and I love stabilization. The 7D + 60/2.8 combo gives me none of these. Again, I witnessed that theoretical advantages do not always translate to practical ones.