kezeka wrote:
I would call into question the AF accuracy complaint when it comes to extenders since there are no motors within the extender. Clearly, I am no lens designer and do not know how extenders impact the AF calculations but it would seem to me that they would not modify the AF motor in the lens' ability to focus nor the cameras ability to convey that information. There is a possibility that the electronic connection between lens and body could be bad but I believe that extenders literally just connect the leads from the body to the leads on the lens.
I'll probably buy one of these in the next month or so and let everyone know how it works out. I have used the mk III 2.0x tc on my 70-200 II before and wasn't pleased with its performance anyway so I might as well try out a different one before picking up a mk III used. ...Show more →
Thanks kezeka, I was making a general claim about third party glass, not this extender in particular.
For example, my siggy 50 1.4, not art, and siggy 85 1.4 both gave me af issues, after 18-24 months.
I cannot speak specifically about the extender in question, just third party lenses. And of course, just my experience.
kezeka wrote:
I would call into question the AF accuracy complaint when it comes to extenders since there are no motors within the extender. Clearly, I am no lens designer and do not know how extenders impact the AF calculations but it would seem to me that they would not modify the AF motor in the lens' ability to focus nor the cameras ability to convey that information. There is a possibility that the electronic connection between lens and body could be bad but I believe that extenders literally just connect the leads from the body to the leads on the lens.
A good TC (e.g., OEM Nikon) will be coded to inform the camera of it's existence and factor. In some of the older cameras that was very simple, but entails a chip nowadays. The 3rd party TCs may not have any coding, but depends on what the manufacturer decides to do. If the camera does not know there is a TC attached, the AF may have a higher miss rate.
With today's optical software it is easy to copy lenses, you start with the physical measurements diameter and radius. Make a reasonable guess for the glass properties, measure the mtf etc at infinity and a reasonable distance. Input all of the above, into the computer and let it rip over the weekend, then presto you have a design. Well almost you still need tha AF software hardware easy to reverse engineer from vivitar ef lenses, the figure out some of the mechanical stuff. The last thing you ever want to do is patent your lens because you are required to give the glass composition. Btw you can buy the raw glass from Hoya.
Sorry for the delay but I'm seeing some weird behavior with this and want to get a better understanding of it before I present anything. So far what I've seen it that the images with the teleconverter on the 70-200ii are razor sharp in the center and reasonably good at the borders at short focus distances but the shots are just downright mushy at reasonably long focus distances. I'll report back when I have a better understanding of what's going on but I only have ~20 minutes of daylight per day to play with until the weekend.
Any updates and test shots to share whumber? I am interested in this YN-2XtcIII. I am particularly interested in AF speed and accuracy as well as sharpness. I would love to see and hear a direct comparison with the Canon version when someone is able to have both side by side. Thanks in advance.
I'm pretty sure the copy I received must have been defective so I'd rather not post the results I have now as it seems like they could give an unfair reputation. It gave excellent results when I tested in a studio environment but the results were quite awful outdoors at more realistic subject distances. I'm in the process of exchanging it for another copy at the moment and will post up some results when the replacement comes. If the next copy exhibits the same behavior then I'll feel comfortable enough that it's not just a freak occurrence.
whumber wrote:
I'm pretty sure the copy I received must have been defective so I'd rather not post the results I have now as it seems like they could give an unfair reputation. It gave excellent results when I tested in a studio environment but the results were quite awful outdoors at more realistic subject distances. I'm in the process of exchanging it for another copy at the moment and will post up some results when the replacement comes. If the next copy exhibits the same behavior then I'll feel comfortable enough that it's not just a freak occurrence.
whumber wrote:
I'm pretty sure the copy I received must have been defective so I'd rather not post the results I have now as it seems like they could give an unfair reputation. It gave excellent results when I tested in a studio environment but the results were quite awful outdoors at more realistic subject distances. I'm in the process of exchanging it for another copy at the moment and will post up some results when the replacement comes. If the next copy exhibits the same behavior then I'll feel comfortable enough that it's not just a freak occurrence.
Thanks looking forward to hearing and seeing more on this...
EB-1 wrote:
Have you tried it on a long tele lens?
EBH
Unfortunately no, I don't have anything longer than 200mm in EF mount. As an aside, for some good news I should have an actual Canon 2x III to compare against by the time I get the Yongnuo replacement so hopefully the comparison should be a bit more useful now.
whumber wrote:
Unfortunately no, I don't have anything longer than 200mm in EF mount. As an aside, for some good news I should have an actual Canon 2x III to compare against by the time I get the Yongnuo replacement so hopefully the comparison should be a bit more useful now.
whumber wrote:
Unfortunately no, I don't have anything longer than 200mm in EF mount. As an aside, for some good news I should have an actual Canon 2x III to compare against by the time I get the Yongnuo replacement so hopefully the comparison should be a bit more useful now.
Actual testing should be far superior to couching the whole thing like the previous page. Any idea when you will have all of the TCs in by?
kezeka wrote:
Actual testing should be far superior to couching the whole thing like the previous page. Any idea when you will have all of the TCs in by?
Probably not for at least another week at best. I ordered the original one through Amazon but I think it shipped from somewhere in China as delivery took a bit over a week.
Edit: Actually scratch that. It seems they have some that are being distributed directly through Amazon's network now so I may be able to order one of those and turn this around much faster.
Edit: Actually scratch that. It seems they have some that are being distributed directly through Amazon's network now so I may be able to order one of those and turn this around much faster.
Good news. Can't wait and again thanks for any examples that you take the time to provide.
Sorry for the long delay, it took longer than expected to get both the teleconverters together. I'll post some shots later tonight as well as my thoughts but it seems like the new Yongnuo 2X is at least as sharp, if not a bit sharper, than the actual Canon 2.0x III that I have.
