If the softness from the 14-24 is due to the misfocus, does that mean the sharp images he provided from his 24-70 and 24G was badly misfocused as well?
honorerdieu wrote:
I'm confused by some of the response to the OP.
If the softness from the 14-24 is due to the misfocus, does that mean the sharp images he provided from his 24-70 and 24G was badly misfocused as well?
Extending your question further, if some lenses focus well on a body without fine tuning does that mean all lenses will focus well on that same body without fine tuning? That's why either Live View must be used when evaluating the sharpness of a lens or AF tuning the lens you're evaluating, although PDAF isn't consistent enough even on a tuned body+lens to evaluate sharpness.
snapsy wrote:
Extending your question further, if some lenses focus well on a body without fine tuning does that mean all lenses will focus well on that same body without fine tuning? That's why either Live View must be used when evaluating the sharpness of a lens or AF tuning the lens you're evaluating, although PDAF isn't consistent enough even on a tuned body+lens to evaluate sharpness.
You have point there, but I strongly doubt that fine tuning an AF on a lens shot at 24mm with such great DOF at f/4, f/5.6, and f/8 is really a great factor.
honorerdieu wrote:
You have point there, but I strongly doubt that fine tuning an AF on a lens shot at 24mm with such great DOF at f/4, f/5.6, and f/8 is really a great factor.
Very slight differences in focus can have pretty dramatic effects on the measured resolution, including and sometimes especially at infinity. I posted a link describing slrgear's experiences previously on the thread: http://www.slrgear.com/articles/focus/focus.htm. For my own personal experience the 14-24mm is very temperamental on the D800 if the focus is not perfect. I have a thread about it here: http://forums.dpreview.com/forums/read.asp?forum=1021&message=42026957
honorerdieu wrote:
I'm confused by some of the response to the OP.
If the softness from the 14-24 is due to the misfocus, does that mean the sharp images he provided from his 24-70 and 24G was badly misfocused as well?
AFAIK, lenses and bodies can be slightly off. When sold new and sent out to stores, they have a slight variance that is within the company's acceptable range. Lets say within +/- 2. You have a camera body and three lenses. The camera is +2, lens A is -2, lens B is -1, and then on your third lens, C is +2 and all of a sudden your focus is quite off, so much that you notice soft pictures.
According to my depth of field calculator, at 24mm and ƒ/8 when focusing on the wall, about 6 feet in front of wherever the plane of focus ended up should be in focus and everything behind it should be. If this lens focuses that poorly on all copies, which I doubt, I will reject it outright.
I'm also being conservative with my numbers, guessing I was about 12 feet from the wall when focusing and excluding ƒ/11, which I also shot and was soft.
Please let me know if I've got this horribly wrong. I have no interest in reading that slrgear site. If the softness I'm seeing is really the result of normal lens behaviour, I find that totally unacceptable. And maybe a little ridiculous.
The only point that will be pin sharp will be the point on which you have focused. The rest of the image might be 'sharp' but not as sharp as the point at which you focused.
You need to show us an example so we can judge what is acceptable and what is not
Your D700 has a pixel pitch of about 8.45 μm, while your depth of field calculator probably assumes an acceptable circle of confusion of 1/1500 the diagonal of the frame, or about 0.029 mm. Dividing 0.029 mm by 8.45 μm gives about 3.4, or an acceptable blur circle of about 3.4 times the pixel pitch. That's fine for lots of real-world photographic use, but it's wholly inadequate for testing a lens.
Dudewithoutape wrote:
AFAIK, lenses and bodies can be slightly off. When sold new and sent out to stores, they have a slight variance that is within the company's acceptable range. Lets say within +/- 2. You have a camera body and three lenses. The camera is +2, lens A is -2, lens B is -1, and then on your third lens, C is +2 and all of a sudden your focus is quite off, so much that you notice soft pictures.
Bond wrote:
Keith B., it must suck to be so busy as not to have enough time even to determine if a product is functioning 100% the way it ought to. At nearly $2Gs, I like to make sure things are working as well as possible.
I use first, test later only if I think I'm detecting a problem in normal use. I thought my 14-24 maybe was decentered. Shot tests, looked like maybe...hard to tell. Took to Nikon(El Segundo). They shot tests, and provided me with their tests on a CD. Their tests, on a full wall chart(nice to have) showed me that the lens was not as good at f/2.8 as it was stopped down. Duh. Since I shoot 98% hand held, tripod tests aren't the whole story anyway.
Btw, I bought my 14-24 when it cost $1470.
IMO, you need a better target for testing sharpness. There are many targets you can download from the internet or buy a LensAlign if you are anal about your lenses. I use the LensAlign so I don't have to rely on my eyesight.
Well fortunately a new batch of 14-24s arrived just days before the trip I bought the lens for in the first place. Apparently they're becoming more difficult to get in stock.
Anyhow, i'm awfully glad I opted for the exchange. The replacement copy seems to auto-focus to my satisfaction. Here's a quick comparison. Luckily I was able to spare the 3 minutes it took to take these new shots before my vacation.
