Photoclubalpha

Lens review that shows that the AF motor is faster in the body, than in the lens.

http://www.dpreview.com/lensreviews/pen ... /page3.asp

This time on Pentax.

I am starting to think, let's not even bother with in lens motors, bar a few exceptions..bit more noise, but don't really care. Slow AF, do care!

Thoughts??

The designer is always pressed to deliver on three things: scheduile, cost, and performance. Pick any two.

I don't care how fast or slow an auto-focus is, be it in-lens or in-body ... well, as long as it doesn't take ages to focus. The only issue that really matters is how accurate it is. Sure, I prefer faster AF over slower just like anyone---but not at the expense of accuracy. Faster is better only if it's at least as accurate. More accurate is better no matter what.

Unfortunately, most hobbyist photographers (as well as camera testers) don't get their priorities right. They don't care about accuracy; they will look at AF speed only and will always favour the faster-focusing gear over the slower without taking accuracy into consideration---which is stupid. As an inevitable consequence, manufacturers don't care about accuracy in their entry-level and mid-level stuff because that wouldn't sell. Cheap and fast sells. So we have affordable and fast-focusing gear that suffers from back-focusing or front-focusing more often than not.

That's why all Sony DSLR cameras are worthless toys---except the A900. And that's not due to 24 MP or full-frame image format. It's due to the A900's reliably accurate auto-focus with all AF lenses under all circumstances.

-- Olaf

01af wrote:...all Sony DSLR cameras are worthless toys---except the A900. And that's not due to 24 MP or full-frame image format. It's due to the A900's reliably accurate auto-focus with all AF lenses under all circumstances.
-- Olaf

Sigh.

01af, I never suggested AF accuracy should be sacrificed for AF speed.

If anything, reading that Pentax lens review..it is that lens, not the 50mm that is causing AF issues (FF/BF on various bodies, so they say)

Not sure I can agree on the A900 being the "only body" with worthy AF. There are some issues on other bodies, but let's not forget, if ALL bodies had AF adjustments in camera, then none would have any issues.

Funny thing is my film 7 is both accurate and fast (in the majority of situations I have used it in)

bfitzgerald wrote:I never suggested AF accuracy should be sacrificed for AF speed.

No, you didn't. I was just ranting on the issue in general.

bfitzgerald wrote:Not sure I can agree on the A900 being the "only body" with worthy AF.

Well ... last year I tried to buy an A700 twice but had to return both for a refund due to inaccurate AF (it was fine with some lenses but not with others). By that time I was very seriously considering to sell all my Minolta stuff and switch to Nikon. Then the A900 finally came along and solved the AF accuracy problem and thus enabled me to keep my prized Minolta lenses.

bfitzgerald wrote:Funny thing is my film 7 is both accurate and fast (in the majority of situations I have used it in).

Yes ... it's a well-known fact that the pinnacle of Minolta's AF performance (both in terms of speed and accuracy) was reached with the Dynax 9 and Dynax 7. After that, it went downhill. Particularly the AF performance in the Konica-Minolta Dynax 7D and Dynax 5D was really poor---despite the fact the Dynax 7D was based upon the Dynax 7. They do not share the same AF module.

-- Olaf

01af wrote:
Yes ... it's a well-known fact that the pinnacle of Minolta's AF performance (both in terms of speed and accuracy) was reached with the Dynax 9 and Dynax 7. After that, it went downhill. Particularly the AF performance in the Konica-Minolta Dynax 7D and Dynax 5D was really poor---despite the fact the Dynax 7D was based upon the Dynax 7. They do not share the same AF module.

-- Olaf

Well it's open to debate on a few points. I had this before with the 60 film review I did..and it was suggested that the 5d has the same AF sensor as the 60, frankly aside from one being 35mm FF, and one APS (which pretty much rules that out), the cameras do not perform the same!

The film 5 is not far off the 7, and the 60 feels very similar to the film 5..and I have used both a lot. They don't have the double cross sensor of the 7, but if you can shoot f2 with a 50mm and nail it (in low light) with the 5 and 60, then that says something to me.

The 5d isn't a complete disaster AF wise, by far the biggest complaint is predictive focus, or rather lack of..not something I do much myself, but the points have been raised. Speed wise it's not too bad. Funny thing is, whilst the A200 smokes it for speed in good light, Sony (unwisely IMO) downgraded the spec to EV 0 fro EV -1. End result is, A200 is a bit of a dog in low light (slower than any other body I have). Add to that the AF sensor issue with the central point (I remain convinced the sensor is covering a much larger area than any other body I have, I can work around it..but it's a valid point)

So a mixed bag on some fronts. AF accuracy wise, the 5d has proved more consistent in low light, even if it's no demon for tracking. A200 is good at tracking, in good light. All my film bodies are pretty strong all round. I'll let A700 and 900 users comment on AF for those bodies.

Well I've use the KM5D a fair bit and I don't have any great complaint with normal use, I find acceptably fast and very accurate, it is probably nowhere near fast enough for sports though, ie. zoomed in on speeding subjects filling the frame...
I've never really tried the camera set up for predictive AF on a moving subject (Wide AF area + AF-C + Continuous advance + shutter = AF priority + JPEG Fine + ISO800 ...aim in the general direction of moving target and hold shutter button fully down) so I can't comment on how good it would handle that...
Greg

01af wrote: Well ... last year I tried to buy an A700 twice but had to return both for a refund due to inaccurate AF (it was fine with some lenses but not with others). By that time I was very seriously considering to sell all my Minolta stuff and switch to Nikon. Then the A900 finally came along and solved the AF accuracy problem and thus enabled me to keep my prized Minolta lenses.

-- Olaf

Any evidence that Nikon AF is better?

Youpii, comparing the A700 to the D90 - my impression is that if you are using the centre AF point with 3.5-4.5 and 4-5.6 type lenses then there is little practical difference. If you choose to focus with one of outer focus points then the D90 certainly appears to be quicker and more precise.

I have found that with the presentation of AF and exposure info in the viewfinder then Nikon does a better sales job on the photographer. But on the other hand in practice I find the Nikon matrix exposure metering to be less consistent than the Sony/Minolta models I have used. This relates specifically to Nikons general market models both film and digital rather than their pro models. Same general complaint with D70 and D90 as well as F70, F80 and F90.