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The alternative to the ultra-fast long telephoto?
On Thursday, June 14, 2018 at 2:28:51 AM UTC-4, RichA wrote:
Now with cameras and their exceptional high ISO capability, these slower but high-quality telephotos are now good and perhaps, preferable. https://www.dpreview.com/news/7758816413/nikon-developing-compact-and-lightweight-500mm-f5-6-lens The option has been around for "long enough", but one of the ways that the OEMs has functionally obstructed it is through their dSLR specifications. Specifically, when Autofocus capability is disabled when a certain f/stop value is exceeded. If memory serves, the common "upper limit" value had been f/5.6, with some exceptions at f/8 (such as offered only on higher end bodies, and/or only at the center focus point). From a designer policy standpoint, what's needed to really enable this is (enabled by said higher ISO sensitivity) is for the camera to be designed & allowed to (try to) AF at f/8, f/11 and/or even f/16. For example, if we use lens filter diameters as a convenient surrogate, a 200mm f2.8, a 300mm f/4 and a 400mm f/5.6 all have primary apertures of 77mm, whereas when we increment up by one stop (eg, a 300mm f/2.8, 400mm f/4, or 500mm f/5.6) the aperture area needs to double, which is ~120mm. Conversely, if we 'speed up' the dSLR's Autofocus system to allow for an even slower lens, a 500mm f/8 should drop to be only 77mm. -hh |
#2
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The alternative to the ultra-fast long telephoto?
In article , -hh
says... Specifically, when Autofocus capability is disabled when a certain f/stop value is exceeded. Why? If memory serves, the common "upper limit" value had been f/5.6, with some exceptions at f/8 (such as offered only on higher end bodies, and/or only at the center focus point). I have the Olympus 75-300 which is F6.7 at the tele end, but autofocus works also at the tele end. -- Alfred Molon Olympus E-series DSLRs and micro 4/3 forum at https://tech.groups.yahoo.com/group/MyOlympus/ https://myolympus.org/ photo sharing site |
#3
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The alternative to the ultra-fast long telephoto?
In article , Alfred
Molon wrote: Specifically, when Autofocus capability is disabled when a certain f/stop value is exceeded. Why? because it no longer works properly, or is too slow to be useful. If memory serves, the common "upper limit" value had been f/5.6, with some exceptions at f/8 (such as offered only on higher end bodies, and/or only at the center focus point). I have the Olympus 75-300 which is F6.7 at the tele end, but autofocus works also at the tele end. not very well, it doesn't. |
#4
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The alternative to the ultra-fast long telephoto?
On Thu, 14 Jun 2018 22:41:10 +0200, Alfred Molon
wrote: In article , -hh says... Specifically, when Autofocus capability is disabled when a certain f/stop value is exceeded. Why? If memory serves, the common "upper limit" value had been f/5.6, with some exceptions at f/8 (such as offered only on higher end bodies, and/or only at the center focus point). I have the Olympus 75-300 which is F6.7 at the tele end, but autofocus works also at the tele end. Not saying your lens does this but there are those which mis-report the min aperture (which is used for focusing) to the camera body to get around this limitation. I have used a Nikon TC-20 and 1st gen 200-400 f/4 VR on D200/300/7100 and 500. D200 while accepting couldn't hardly focus on the side of a barn. Each focus system has gotten better, though substantially slowed compared to using a TC-14 which is my standard go-to with this lens. Min Aperture of f/8 vs f/5.6. |
#5
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The alternative to the ultra-fast long telephoto?
On 6/14/2018 6:37 PM, me wrote:
On Thu, 14 Jun 2018 22:41:10 +0200, Alfred Molon wrote: In article , -hh says... Specifically, when Autofocus capability is disabled when a certain f/stop value is exceeded. Why? If memory serves, the common "upper limit" value had been f/5.6, with some exceptions at f/8 (such as offered only on higher end bodies, and/or only at the center focus point). I have the Olympus 75-300 which is F6.7 at the tele end, but autofocus works also at the tele end. Not saying your lens does this but there are those which mis-report the min aperture (which is used for focusing) to the camera body to get around this limitation. I have used a Nikon TC-20 and 1st gen 200-400 f/4 VR on D200/300/7100 and 500. D200 while accepting couldn't hardly focus on the side of a barn. Each focus system has gotten better, though substantially slowed compared to using a TC-14 which is my standard go-to with this lens. Min Aperture of f/8 vs f/5.6. With both my D800, and 500, the only usable autofocus at f8, is center point focus. i have a lot of problems with tracking birds in flight at f8, and have resorted to the old fashioned method, hand focus, if I have to use f8. Have you had a similar issue? -- PeterN |
#6
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The alternative to the ultra-fast long telephoto?
On Thu, 14 Jun 2018 23:52:57 -0400, PeterN
wrote: Too be honest my use with the TC-20 and 200-400 f/4 is minimal the limitations as you have mentioned. Also makes the AF slow as molasses. Finally, since I hand hold It's very tough to get a sharp images. I've convinced myself it is better to stick with the TC-14 in the end. I do miss the "nearest subject" option of the D200 though. With both my D800, and 500, the only usable autofocus at f8, is center point focus. i have a lot of problems with tracking birds in flight at f8, and have resorted to the old fashioned method, hand focus, if I have to use f8. Have you had a similar issue? |
#7
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The alternative to the ultra-fast long telephoto?
On 6/16/2018 2:51 PM, me wrote:
On Thu, 14 Jun 2018 23:52:57 -0400, PeterN wrote: Too be honest my use with the TC-20 and 200-400 f/4 is minimal the limitations as you have mentioned. Also makes the AF slow as molasses. Finally, since I hand hold It's very tough to get a sharp images. I've convinced myself it is better to stick with the TC-14 in the end. I do miss the "nearest subject" option of the D200 though. I gotta say, that's one thing I do not miss at all. You could rarely get a shot like this with closest focus. Too many weeds in the way. https://www.dropbox.com/s/qbknjnxve7be85n/4.jpg?dl=0 With both my D800, and 500, the only usable autofocus at f8, is center point focus. i have a lot of problems with tracking birds in flight at f8, and have resorted to the old fashioned method, hand focus, if I have to use f8. Have you had a similar issue? -- PeterN |
#8
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The alternative to the ultra-fast long telephoto?
On 6/16/2018 11:39 PM, PeterN wrote:
On 6/16/2018 2:51 PM, me wrote: On Thu, 14 Jun 2018 23:52:57 -0400, PeterN wrote: Too be honest my use with the TC-20 and 200-400 f/4 is minimal the limitations as you have mentioned. Also makes the AF slow as molasses. Finally, since I hand hold It's very tough to get a sharp images. I've convinced myself it is better to stick with the TC-14 in the end. I do miss the "nearest subject" option of the D200 though. I gotta say, that's one thing I do not miss at all. You could rarely get a shot like this with closest focus. Too many weeds in the way. https://www.dropbox.com/s/qbknjnxve7be85n/4.jpg?dl=0 Sent the wrong link https://www.dropbox.com/s/cqdavyowtoj5wi9/20180615_NickersonBeach%20Birds_7580.jpg?dl=0 With both my D800, and 500, the only usable autofocus at f8, is center point focus. i have a lot of problems with tracking birds in flight at f8, and have resorted to the old fashioned method, hand focus, if I have to use f8. Have you had a similar issue? -- PeterN |
#9
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The alternative to the ultra-fast long telephoto?
On Sat, 16 Jun 2018 23:39:41 -0400, PeterN
wrote: On 6/16/2018 2:51 PM, me wrote: On Thu, 14 Jun 2018 23:52:57 -0400, PeterN wrote: Too be honest my use with the TC-20 and 200-400 f/4 is minimal the limitations as you have mentioned. Also makes the AF slow as molasses. Finally, since I hand hold It's very tough to get a sharp images. I've convinced myself it is better to stick with the TC-14 in the end. I do miss the "nearest subject" option of the D200 though. I gotta say, that's one thing I do not miss at all. You could rarely get a shot like this with closest focus. Too many weeds in the way. https://www.dropbox.com/s/qbknjnxve7be85n/4.jpg?dl=0 It was a selectable option, so if you didn't need it no harm. |
#10
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The alternative to the ultra-fast long telephoto?
On 6/17/2018 2:02 PM, me wrote:
On Sat, 16 Jun 2018 23:39:41 -0400, PeterN wrote: On 6/16/2018 2:51 PM, me wrote: On Thu, 14 Jun 2018 23:52:57 -0400, PeterN wrote: Too be honest my use with the TC-20 and 200-400 f/4 is minimal the limitations as you have mentioned. Also makes the AF slow as molasses. Finally, since I hand hold It's very tough to get a sharp images. I've convinced myself it is better to stick with the TC-14 in the end. I do miss the "nearest subject" option of the D200 though. I gotta say, that's one thing I do not miss at all. You could rarely get a shot like this with closest focus. Too many weeds in the way. https://www.dropbox.com/s/qbknjnxve7be85n/4.jpg?dl=0 It was a selectable option, so if you didn't need it no harm. I know. Since I never used it, I never missed it. OTOH, when shooting critters through cages, the extension of the minimum focus length s something I regularly use. It is also great for shortening the time for focus lock. But on my cameras, it is lens function. -- PeterN |
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