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#11
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D750 -CRASH- and subsequent testing.
On Tue, 9 Aug 2016 16:34:12 -0700 (PDT), RichA
wrote: On Tuesday, 12 July 2016 23:31:23 UTC-4, Eric Stevens wrote: A few months ago I had a fall while carrying my camera. I came down hard but the camera which I was carrying came down even harder on concrete. It was a hell of an whack. I think the Manfrotto tripod shoe on the bottom took the bulk of the impact. RichA will no doubt be disappointed to learn that all those fancy carbon-fibre parts on the body of the camera remained intact as did the magnesium metal frame. How hard could the impact have been if the camera sustained no damage, not even a dent or ding? I dropped a specialized tripod the other day onto hardwood. The head of the tripod which was held in-place with 3 small allen-head set-screws rotated slightly to the point where the allen screw channels (in aluminum) were bent sideways, ruining the threading so I have to re-tap the holes and put in slightly larger screws to fix the problem. The tripod weighs about 20lbs. The camera was in my hand which I shot out to try and break the fall. I remeber the sensation: the tripod shoe crunching grit as I came down. As I said, it was a hell of a whack. -- Regards, Eric Stevens |
#12
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D750 -CRASH- and subsequent testing.
On Wed, 10 Aug 2016 10:06:35 +1200, Eric Stevens
wrote: On Tue, 12 Jul 2016 21:01:45 -0700, Bill W wrote: On Wed, 13 Jul 2016 15:31:25 +1200, Eric Stevens wrote: A few months ago I had a fall while carrying my camera. I came down hard but the camera which I was carrying came down even harder on concrete. It was a hell of an whack. I think the Manfrotto tripod shoe on the bottom took the bulk of the impact. RichA will no doubt be disappointed to learn that all those fancy carbon-fibre parts on the body of the camera remained intact as did the magnesium metal frame. All of the body of the camera has continued to function properly since the fall but I have had doubts about Tamron 24-70 f/2.8 lens with which it fas fitted at the time. I have had no worries about its mechanical functioning but I was concerned that the impact may have displaced or distorted key parts of the lens' internal mechanism. I have just put the lens through a series of primitive tests to see how well it is working optically. AF fine tuning (focus calibration) has ended up at +1 which would be quite acceptable in a new lens, so no worries there. I was more concerned about sharpness and definition. I made a panel of a number of fine-detailed objects and made a number of test shots. A jpg of one of these may be found at https://dl.dropboxusercontent.com/u/...R--7502179.jpg This shot and the versions below were all made at 24mm, f/2.8 and a distance of about 4' (1.2m). Focussing was autofocus. Not being satisfied with the relatively coarse screen resolution for a 24MP image I also made an image for 100% printing of an A2 sized image. Those game enough to take on 244MB file can find it at https://dl.dropboxusercontent.com/u/...R--7502179.tif These images are straight off the camera via LR and the only processing is correction of lens distortion. I would be grateful for any comments on the quality of the image. Is it what one would expect from that camera and lens combination? For those interested the original raw file, it may be found at https://dl.dropboxusercontent.com/u/...3/_7502179.NEF I must add, I was not responsible for emptying all those bottles. A friend dropped his FF Nikon, and said it sounded like an eggshell when it hit the ground. His crack was visible, but you might have one that's not. He said the IQ was off after that, and I think he gave up on the camera. Bodies were not available at the time. I offered him $100. I figure I can fix anything, but he declined. Anyway, you might want to send/take it in to get checked. We all know how critical dimensions are in those things. After reading allresponses I decided to send the lens in for testing. I have just received an account by email which among other things says: "Dismanted lens. Supplied and fitted new front cam barrel and rollers. These were stretched causing optics to mis-align. Reassembled, recalibrated lens and checked." I was right: it wasn't working properly although there was nothing obvious I could put my finger on. The bottles are still set up in my room and I will be interested to compare results whan the lens returns. I'm surprised you didn't have the camera checked, too. If you still think there's a problem, there are some critical angles/distances involved in the PDAF. But I think that if there is a problem with that, you will have OoF problems across the entire image in every shot. In fact, if your PDAF shots are as good as your CDAF shots, you are probably good to go. |
#13
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D750 -CRASH- and subsequent testing.
On Tue, 09 Aug 2016 20:32:09 -0700, Bill W
wrote: On Wed, 10 Aug 2016 10:06:35 +1200, Eric Stevens wrote: On Tue, 12 Jul 2016 21:01:45 -0700, Bill W wrote: On Wed, 13 Jul 2016 15:31:25 +1200, Eric Stevens wrote: A few months ago I had a fall while carrying my camera. I came down hard but the camera which I was carrying came down even harder on concrete. It was a hell of an whack. I think the Manfrotto tripod shoe on the bottom took the bulk of the impact. RichA will no doubt be disappointed to learn that all those fancy carbon-fibre parts on the body of the camera remained intact as did the magnesium metal frame. All of the body of the camera has continued to function properly since the fall but I have had doubts about Tamron 24-70 f/2.8 lens with which it fas fitted at the time. I have had no worries about its mechanical functioning but I was concerned that the impact may have displaced or distorted key parts of the lens' internal mechanism. I have just put the lens through a series of primitive tests to see how well it is working optically. AF fine tuning (focus calibration) has ended up at +1 which would be quite acceptable in a new lens, so no worries there. I was more concerned about sharpness and definition. I made a panel of a number of fine-detailed objects and made a number of test shots. A jpg of one of these may be found at https://dl.dropboxusercontent.com/u/...R--7502179.jpg This shot and the versions below were all made at 24mm, f/2.8 and a distance of about 4' (1.2m). Focussing was autofocus. Not being satisfied with the relatively coarse screen resolution for a 24MP image I also made an image for 100% printing of an A2 sized image. Those game enough to take on 244MB file can find it at https://dl.dropboxusercontent.com/u/...R--7502179.tif These images are straight off the camera via LR and the only processing is correction of lens distortion. I would be grateful for any comments on the quality of the image. Is it what one would expect from that camera and lens combination? For those interested the original raw file, it may be found at https://dl.dropboxusercontent.com/u/...3/_7502179.NEF I must add, I was not responsible for emptying all those bottles. A friend dropped his FF Nikon, and said it sounded like an eggshell when it hit the ground. His crack was visible, but you might have one that's not. He said the IQ was off after that, and I think he gave up on the camera. Bodies were not available at the time. I offered him $100. I figure I can fix anything, but he declined. Anyway, you might want to send/take it in to get checked. We all know how critical dimensions are in those things. After reading allresponses I decided to send the lens in for testing. I have just received an account by email which among other things says: "Dismanted lens. Supplied and fitted new front cam barrel and rollers. These were stretched causing optics to mis-align. Reassembled, recalibrated lens and checked." I was right: it wasn't working properly although there was nothing obvious I could put my finger on. The bottles are still set up in my room and I will be interested to compare results whan the lens returns. I'm surprised you didn't have the camera checked, too. If you still think there's a problem, there are some critical angles/distances involved in the PDAF. But I think that if there is a problem with that, you will have OoF problems across the entire image in every shot. In fact, if your PDAF shots are as good as your CDAF shots, you are probably good to go. PDAF? CDAF? What are you talking about? -- Regards, Eric Stevens |
#14
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D750 -CRASH- and subsequent testing.
In article , Eric Stevens
wrote: I'm surprised you didn't have the camera checked, too. If you still think there's a problem, there are some critical angles/distances involved in the PDAF. But I think that if there is a problem with that, you will have OoF problems across the entire image in every shot. In fact, if your PDAF shots are as good as your CDAF shots, you are probably good to go. PDAF? CDAF? What are you talking about? phase detect and contrast detect autofocus. |
#15
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D750 -CRASH- and subsequent testing.
On Wed, 10 Aug 2016 09:34:23 -0400, nospam
wrote: In article , Eric Stevens wrote: I'm surprised you didn't have the camera checked, too. If you still think there's a problem, there are some critical angles/distances involved in the PDAF. But I think that if there is a problem with that, you will have OoF problems across the entire image in every shot. In fact, if your PDAF shots are as good as your CDAF shots, you are probably good to go. PDAF? CDAF? What are you talking about? phase detect and contrast detect autofocus. I checked focus before I sent the lens away. I eventually made an adjustment of +1. That suggests that everything is in it its correct place. -- Regards, Eric Stevens |
#16
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D750 -CRASH- and subsequent testing.
On Thu, 11 Aug 2016 08:44:20 +1200, Eric Stevens
wrote: On Wed, 10 Aug 2016 09:34:23 -0400, nospam wrote: In article , Eric Stevens wrote: I'm surprised you didn't have the camera checked, too. If you still think there's a problem, there are some critical angles/distances involved in the PDAF. But I think that if there is a problem with that, you will have OoF problems across the entire image in every shot. In fact, if your PDAF shots are as good as your CDAF shots, you are probably good to go. PDAF? CDAF? What are you talking about? phase detect and contrast detect autofocus. I checked focus before I sent the lens away. I eventually made an adjustment of +1. That suggests that everything is in it its correct place. It's likely enough, and you'll be sure after the lens comes back. BTW, CDAF is what's used in live view. |
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