Got a 800mm f/8 mirror for testing ... - Printable Version +- Opticallimits (https://forum.opticallimits.com) +-- Forum: Forums (https://forum.opticallimits.com/forumdisplay.php?fid=4) +--- Forum: Just Talk (https://forum.opticallimits.com/forumdisplay.php?fid=17) +--- Thread: Got a 800mm f/8 mirror for testing ... (/showthread.php?tid=3434) |
Got a 800mm f/8 mirror for testing ... - Klaus - 01-18-2011 [quote name='mst' timestamp='1295338020' post='5602'] That was my first thought, too. You'll probably have to find something to replace the tripods with ... something made of concrete comes to my mind <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' /> -- Markus [/quote] That's not really a problem. Got a 800mm f/8 mirror for testing ... - mst - 01-18-2011 [quote name='Klaus' timestamp='1295339362' post='5604'] That's not really a problem. [/quote] Well, it would be with the D3x. However, the camera is probably special in this regard ... -- Markus Got a 800mm f/8 mirror for testing ... - genotypewriter - 01-18-2011 [quote name='Klaus' timestamp='1295127442' post='5559'] Well, it's way beyond normal testing parameter. We can provide reliable tests till 400-500mm maximum. Beyond it's a gamble. [/quote] Watch out for those cars <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='' /> Got a 800mm f/8 mirror for testing ... - anyscreenamewilldo - 01-18-2011 [quote name='arv' timestamp='1295164290' post='5566'] . . . . Most interesting would be to look at well PP images <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' />. [/quote] - you called? . . . yes i know, i'm off with the pixies, but i can't help looking in from time to time - so . . . someone else's 500 mirror, so light and compact for carrying around - two points of view = - smoothie bg - - but on the other hand here is the honourable henry heron- after me getting fat eating all those donuts - - and before pigging out - Got a 800mm f/8 mirror for testing ... - Yakim - 01-18-2011 [quote name='Klaus' timestamp='1295127442' post='5559'] Well, it's way beyond normal testing parameter. We can provide reliable tests till 400-500mm maximum. Beyond it's a gamble. [/quote] Ha! Since when you were afraid of a challenge? <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' /> And afterwards, go for the Minolta/Sony 500/8 AF lens. Seriously, why not test mirror lenses? Many people are interested in these lenses as cheap telephoto lenses. It'll be nice to see how they really perform. FWIW, I had a Nikon 1000/8 once and it was very good on my 40D but eventually I got fed up of shooting the moon. http://www.fredmiranda.com/forum/topic/626335/2 http://photo.net/canon-eos-digital-camera-forum/00ROFu Go Klaus, Go! Got a 800mm f/8 mirror for testing ... - Guest - 01-18-2011 Hi Klaus I'm very interesting to this test because I have this lens and I'm not pretty happy with its performance although I knew -prior buying it- that I would normally expect quite mediocre results and I have tried hard to get usable results. Thus, I'm curious what results you'll get from your side as also as the quality of the sample photos. The key is to have a very stable tripod, Mup, wireless triger and super-extremely careful focusing. This lens is able to focus very close thus you can use the imatest chart for resolution testing but I believe that close focus is not its strong point and the results will be disasterous. I believe its best performance is around 300 meters away. I would be interesting to see whether the T-mount adapter makes any difference regarding its space from the sensor, given that the focusing ring has a lot of space past infinity in order somebody to use a quite thicker T-mount to increase sensor distance from the lens. I find that the best use for this lens is videography which does not require much resolution from a lens but the 800mm focal length is wow for some video applications e.g. sunset, wildlife, moon. Got a 800mm f/8 mirror for testing ... - mst - 01-18-2011 [quote name='dimitris' timestamp='1295361382' post='5624'] This lens is able to focus very close thus you can use the imatest chart for resolution testing but I believe that close focus is not its strong point and the results will be disasterous. [/quote] On full frame, the test distance would be 32 meters (40 x focal length). Even more on APS-C, of course. So, not really "close focus" (what's the MFD of this lens?). -- Markus Got a 800mm f/8 mirror for testing ... - Brightcolours - 01-18-2011 [quote name='mst' timestamp='1295362324' post='5625'] On full frame, the test distance would be 32 meters (40 x focal length). Even more on APS-C, of course. So, not really "close focus" (what's the MFD of this lens?). -- Markus [/quote] 3.5 meters http://www.syopt.co.kr/eng/product/manual_zoom_800F80mirror.asp Got a 800mm f/8 mirror for testing ... - Klaus - 01-18-2011 [quote name='mst' timestamp='1295362324' post='5625'] On full frame, the test distance would be 32 meters (40 x focal length). Even more on APS-C, of course. So, not really "close focus" (what's the MFD of this lens?). -- Markus [/quote] We can't really go too close anyway because we have to keep a certain quality level on the chart in relation to print pixel magnification. Got a 800mm f/8 mirror for testing ... - genotypewriter - 01-18-2011 [quote name='anyscreenamewilldo' timestamp='1295353829' post='5616'] so . . . someone else's 500 mirror, so light and compact for carrying around - two points of view = - smoothie bg - [/quote] That Sony/Minolta 500 AF is a very good lens. Wish Sony's low light was as good as Canon's or Nikon's. GTW |