Re: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
Monday, November 8, 2004, 12:39:45 AM, Alan wrote: AC Many people have reported some Sigma lenses took longer to lock focus (tend AC to hunt more). It seems that the distance and focal length data are required AC for AF as well, and those data are held by a chip inside the AF lenses. Probably. I had problems with a Sigma 1.8/28 (the old version, not the EX one) in Nikon mount, it consistently frontfocused. On several bodies. I previously thought that impossible, but apparently there is now so much chips in lenses and cameras that even what looked like a closed loop system (check focus, rotate by some computed amount from FL and distance, recheck focus) can get buggy. But it was from a period when Sigma lenses were quite buggy. Nowadays, they make the software in them better I heard. Good light! fra
Re: Opinions about 80-200 f2.8 zooms
Hi Larry, Welcome out of lurker's shadows. :-) The Pentax lens is getting very hard to find these days, and is hideously expensive new. It's gone out of production. I have little experience with shooting at sports arenas, so take my thoughts on this with a suitable measure of salt. When photographing my kids playing soccer, I find that *istD AF can be too slow on moving targets. Especially when set to automatic selection of focus point. What I usually do is to manually select focus point depending on which team has the ball, or which direction the game is going. It kinda pre-determines the composition a bit, so I'm not sure if it is the best way to get good shots, but it has increased the percentage of in-focus shots for me...:-) best, Jostein - Original Message - From: Larry Cook [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, November 06, 2004 2:07 PM Subject: Opinions about 80-200 f2.8 zooms I have been following the list for the past couple of months and have found it to be both interesting and informative about Pentax, cameras and lenses, photography in general and other subjects. As my initial foray into the list I would like to solicit opinions about 80-200 f2.8 AF zooms. Specifically I am wondering if procuring an 80-200 AF lens is worthwhile for taking pictures of my son's soccer. Currently I have a Tokina 100-300 f4 ATX (manual focus) and a Tokina 80-200 f2.8 ATX (manual focus) that I like a lot and both can take very good pictures with my *istD. However, there are times when my ability to focus is insufficient because of the quick action involved and I wondered if an AF model would be significantly better. Since all of my lenses save one (16-45 DA) are MF I have no good way to judge whether I would see a significant improvement focusing in the fast pace and questionable night lighting found at high school soccer games. So what is the opinion of people that have used both? Is it worth buying an AF lens to get improved focusing? And if it is, is there any reason not to get the Tokina 80-200 ATX Pro? Or is the Pentax 80-200 FA* superior enough to justify the added expense assuming one could be found? I have searched the archives for this information and haven't yet been able to answer my questions adequately. Thanks, Larry Cook www.cook-imaging.com http://www.cook-imaging.com
Re: Opinions about 80-200 f2.8 zooms
This one time, at band camp, Jostein [EMAIL PROTECTED] wrote: The Pentax lens is getting very hard to find these days, and is hideously expensive new. It's gone out of production. I have been pondering this also. I have decided to go with the Sigma 70-200mm 2.8 as it offers much the same as the pentax and is less than half the price. Can pick these babies up new for a little over $1000.00 Australian dollars ( $US720.00 ). The equivalent Pentax lense, if you can find one, is listed at $AUD3800.00. The istD auto focus is slooow, so you need to be on your game a little. I will be using this for indoor dance photography. Kind regards Kevin - Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote.
AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
To those that have responded to the original thread, thanks very much for the replies. However, the replies from Kevin and Jostein, brought up a question that I had been wondering about myself while pondering lens options. What determines AF performance? I though that I had, in the past, read lens reports that talked about how poor or good a lens' AF performance was and then Kevin and Jostein talk about the *istD's slow AF performance. So which is responsible for the AF performance? Is it the lens? the camera? or both? and how does each influence the AF performance? Inquiring minds want to know Thanks, Larry Cook This one time, at band camp, Jostein [EMAIL PROTECTED] wrote: The Pentax lens is getting very hard to find these days, and is hideously expensive new. It's gone out of production. I have been pondering this also. I have decided to go with the Sigma 70-200mm 2.8 as it offers much the same as the pentax and is less than half the price. Can pick these babies up new for a little over $1000.00 Australian dollars ( $US720.00 ). The equivalent Pentax lense, if you can find one, is listed at $AUD3800.00. The istD auto focus is slooow, so you need to be on your game a little. I will be using this for indoor dance photography. Kind regards Kevin - Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote. --
RE: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
So which is responsible for the AF performance? Is it the lens? the camera? or both? and how does each influence the AF performance? Inquiring minds want to know Both. Some AF lenses have lighter and smoother AF mechanisms might AF faster. Some AF bodies have stronger AF motor might AF faster. Some AF bodies have better algorithms might lock focus and track moving subjects better. Alan Chan http://www.pbase.com/wlachan
Re: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
So which is responsible for the AF performance? Is it the lens? the camera? or both? and how does each influence the AF performance? Inquiring minds want to know Both. Some AF lenses have lighter and smoother AF mechanisms might AF faster. Some AF bodies have stronger AF motor might AF faster. Some AF bodies have better algorithms might lock focus and track moving subjects better. Good answer. I could not have said it better. (Actually, I could not even say it that good, but that's another matter... - g) Fred
AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
So the answer is that the camera possess the algorithms for AF but the performance is based both on the algorithms and how responsive the lens mechanism is? If that is correct then a lens that seems to hunt more than another is not directly at fault? It is the camera algorithms not being able to adequately handle the responsiveness of the lens? Interesting. Of course you would still want to avoid such a lens because it is the system as a whole that is important and therefore an unresponsive lens that causes the camera to hunt is still a bad thing regardless of which component is actually at fault. Larry Cook So which is responsible for the AF performance? Is it the lens? the camera? or both? and how does each influence the AF performance? Inquiring minds want to know Both. Some AF lenses have lighter and smoother AF mechanisms might AF faster. Some AF bodies have stronger AF motor might AF faster. Some AF bodies have better algorithms might lock focus and track moving subjects better. Alan Chan http://www.pbase.com/wlachan
Re: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
- Original Message - From: Larry Cook Subject: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms) So the answer is that the camera possess the algorithms for AF but the performance is based both on the algorithms and how responsive the lens mechanism is? If that is correct then a lens that seems to hunt more than another is not directly at fault? It is the camera algorithms not being able to adequately handle the responsiveness of the lens? Interesting. Of course you would still want to avoid such a lens because it is the system as a whole that is important and therefore an unresponsive lens that causes the camera to hunt is still a bad thing regardless of which component is actually at fault. Unresponsiveness or hunting can be induced by a variety of external factors that have nothing to do with the equipment, as well. Trying to focus on a low contrast subject that gives the AF nothing to latch onto will cause hunting. Low light levels will cause hunting, and this problem will be exacerbated by a slower lens. Some third party lenses won't work as well with some cameras as first party lenses. Consumer market equipment may not be a responsive as pro market equipment. It isn't possible to get a camera/lens combination that will perform 100% flawlessly 100% of the time. I think it is a good idea to focus manually whenever auto focus isn't required. This way, you will have that skill in place for when you need it. William Robb
Re: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
I understand that circumstances can stymie focusing but what I was concerned about were reviews that talk about a particular lens' inabilty to focus well or that it hunts more than another lens. Currently I have all manual focus lenses and I am trying to determine if an AF lens would be better to photograph my son's soccer games and sort of veered off into how AF works. Larry Cook So the answer is that the camera possess the algorithms for AF but the performance is based both on the algorithms and how responsive the lens mechanism is? If that is correct then a lens that seems to hunt more than another is not directly at fault? It is the camera algorithms not being able to adequately handle the responsiveness of the lens? Interesting. Of course you would still want to avoid such a lens because it is the system as a whole that is important and therefore an unresponsive lens that causes the camera to hunt is still a bad thing regardless of which component is actually at fault. Unresponsiveness or hunting can be induced by a variety of external factors that have nothing to do with the equipment, as well. Trying to focus on a low contrast subject that gives the AF nothing to latch onto will cause hunting. Low light levels will cause hunting, and this problem will be exacerbated by a slower lens. Some third party lenses won't work as well with some cameras as first party lenses. Consumer market equipment may not be a responsive as pro market equipment. It isn't possible to get a camera/lens combination that will perform 100% flawlessly 100% of the time. I think it is a good idea to focus manually whenever auto focus isn't required. This way, you will have that skill in place for when you need it. William Robb
RE: AF Performance (Was: Re: Opinions about 80-200 f2.8 zooms)
Many people have reported some Sigma lenses took longer to lock focus (tend to hunt more). It seems that the distance and focal length data are required for AF as well, and those data are held by a chip inside the AF lenses. Alan Chan http://www.pbase.com/wlachan So the answer is that the camera possess the algorithms for AF but the performance is based both on the algorithms and how responsive the lens mechanism is? If that is correct then a lens that seems to hunt more than another is not directly at fault? It is the camera algorithms not being able to adequately handle the responsiveness of the lens? Interesting. Of course you would still want to avoid such a lens because it is the system as a whole that is important and therefore an unresponsive lens that causes the camera to hunt is still a bad thing regardless of which component is actually at fault.
Opinions about 80-200 f2.8 zooms
I have been following the list for the past couple of months and have found it to be both interesting and informative about Pentax, cameras and lenses, photography in general and other subjects. As my initial foray into the list I would like to solicit opinions about 80-200 f2.8 AF zooms. Specifically I am wondering if procuring an 80-200 AF lens is worthwhile for taking pictures of my son's soccer. Currently I have a Tokina 100-300 f4 ATX (manual focus) and a Tokina 80-200 f2.8 ATX (manual focus) that I like a lot and both can take very good pictures with my *istD. However, there are times when my ability to focus is insufficient because of the quick action involved and I wondered if an AF model would be significantly better. Since all of my lenses save one (16-45 DA) are MF I have no good way to judge whether I would see a significant improvement focusing in the fast pace and questionable night lighting found at high school soccer games. So what is the opinion of people that have used both? Is it worth buying an AF lens to get improved focusing? And if it is, is there any reason not to get the Tokina 80-200 ATX Pro? Or is the Pentax 80-200 FA* superior enough to justify the added expense assuming one could be found? I have searched the archives for this information and haven't yet been able to answer my questions adequately. Thanks, Larry Cook www.cook-imaging.com http://www.cook-imaging.com
Re: Opinions about 80-200 f2.8 zooms
Hi Larry. Welcome aboard. I snipped your post a tad. Cannot speak for the Pentax version as i dont have one, yet, but i do a lot of equestrian work with my Nikon f2.8 and it works out very well.I;'d have to say atleast 97-98% usable,well focused shots from it. If i am following a Dressage rider around the ring,i keep it on AF-C and shoot at will. I think for soccer you should find a huge difference from the mf lenses.You allready say you have mf f2.8 lenses so that should give you a good idea what you can get in low light. I do have some problems in ~really~ low light, but nothing that bothers me. Dave Brooks . Since all of my lenses save one (16-45 DA) are MF I have no good way to judge whether I would see a significant improvement focusing in the fast pace and questionable night lighting found at high school soccer games. So what is the opinion of people that have used both? Is it worth buying an AF lens to get improved focusing? Thanks, Larry Cook www.cook-imaging.com http://www.cook-imaging.com
