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#31
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dj_nme writes:
Bill Tuthill wrote: Mike Henley wrote: I'm not sure what that means but it says one of the features of this pop-up flash is that you don't get that lens shadow in the close-up shots. Here are images with one of them of the flash (it does seem to reach up higher than usual pop-up flashes) http://www.dcresource.com/news/newsitem.php?id=2878 Yes, that looks quite good. It's unusual because the SLR mirror swings to the side, so I suppose this is why there isn't the normal SLR mirror hump in the middle, on which popup flash is usually set. That lump on top of an SLR camera usually houses the pentaprism (some oddball SLRs have a fixed mirror box or porroprisms). The mirror that you can see from the front (with the lens off) reflects the image up into the prism. And of course, Olympus has experience with SLR's with odd finders; remember the Pen F? This setup is somehow reminiscent of that. And I think the both use mirrors rather than a prism. I wonder how bright the viewfinder will be, with side-swing mirror? Personally I don't like photographing via LCD. I don't think that it will make much difference to the brightness of the finder. But the fact that it uses mirrors rather than a prism will have some effect; Canon 300D has a rather dim finder because of this, as I recall. Because it is an SLR, the mirror and shutter block light to the image sensor until the shutter is fired. No live LCD preview on this camera. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. |
#32
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#33
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Stephen H. Westin wrote:
dj_nme writes: Bill Tuthill wrote: Mike Henley wrote: I'm not sure what that means but it says one of the features of this pop-up flash is that you don't get that lens shadow in the close-up shots. Here are images with one of them of the flash (it does seem to reach up higher than usual pop-up flashes) http://www.dcresource.com/news/newsitem.php?id=2878 Yes, that looks quite good. It's unusual because the SLR mirror swings to the side, so I suppose this is why there isn't the normal SLR mirror hump in the middle, on which popup flash is usually set. That lump on top of an SLR camera usually houses the pentaprism (some oddball SLRs have a fixed mirror box or porroprisms). The mirror that you can see from the front (with the lens off) reflects the image up into the prism. And of course, Olympus has experience with SLR's with odd finders; remember the Pen F? This setup is somehow reminiscent of that. And I think the both use mirrors rather than a prism. Not true. The E-Volt uses a porroprism (according to the press release), like the Pen-F. I haven't used a Pen-F, so I don't know if it had a good viewfinder. I wonder how bright the viewfinder will be, with side-swing mirror? Personally I don't like photographing via LCD. I don't think that it will make much difference to the brightness of the finder. But the fact that it uses mirrors rather than a prism will have some effect; Canon 300D has a rather dim finder because of this, as I recall. It uses a porroprism, which is a series of triangular prisms put together to flip the image around like a pentaprism. I think it ends up being wider, but much less tall as a pentaprism for the same job. If memory serves correctly, an early full-frame 35mm SLR used a porroprism in the same way. I read a reference to this camera on camera history page, but it didn't have a great deal of detail (just a name that I've unfortunately forgotten) just stating that it used a porroprism in it's finder. There must be a good reason why no other full-frame SLR has them in their design. Perhaps bulk? Or the need to assemble it from pieces, rather than a solid hunk of glass? I dunno. |
#34
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dj_nme writes:
Stephen H. Westin wrote: dj_nme writes: Bill Tuthill wrote: Mike Henley wrote: I'm not sure what that means but it says one of the features of this pop-up flash is that you don't get that lens shadow in the close-up shots. Here are images with one of them of the flash (it does seem to reach up higher than usual pop-up flashes) http://www.dcresource.com/news/newsitem.php?id=2878 Yes, that looks quite good. It's unusual because the SLR mirror swings to the side, so I suppose this is why there isn't the normal SLR mirror hump in the middle, on which popup flash is usually set. That lump on top of an SLR camera usually houses the pentaprism (some oddball SLRs have a fixed mirror box or porroprisms). The mirror that you can see from the front (with the lens off) reflects the image up into the prism. And of course, Olympus has experience with SLR's with odd finders; remember the Pen F? This setup is somehow reminiscent of that. And I think the both use mirrors rather than a prism. Not true. The E-Volt uses a porroprism (according to the press release), like the Pen-F. I haven't used a Pen-F, so I don't know if it had a good viewfinder. Right you are. The Canon 300D and Nikon D70 seem to use pure mirrors, and controversy has ensued, e.g. http://www.photo.net/equipment/nikon/D70/. Well, the d70 seems to have a prism: http://www.nikonusa.com/template.php?cat=1&grp=2&productNr=25214. snip It uses a porroprism, which is a series of triangular prisms put together to flip the image around like a pentaprism. I think it ends up being wider, but much less tall as a pentaprism for the same job. So the only extra loss is the extra air-glass interfaces. If memory serves correctly, an early full-frame 35mm SLR used a porroprism in the same way. I read a reference to this camera on camera history page, but it didn't have a great deal of detail (just a name that I've unfortunately forgotten) just stating that it used a porroprism in it's finder. There must be a good reason why no other full-frame SLR has them in their design. Perhaps bulk? Or the need to assemble it from pieces, rather than a solid hunk of glass? I dunno. Alignment, additional reflections and loss. Space and packaging, certainly. -- -Stephen H. Westin Any information or opinions in this message are mine: they do not represent the position of Cornell University or any of its sponsors. |
#35
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"Stephen H. Westin" wrote in message ... But the fact that it uses mirrors rather than a prism will have some effect; Canon 300D has a rather dim finder because of this, as I recall. Can anyone quantify how much light is lost by a pentamirror as compared to a prism? And how that compares to the dimness resulting from using a ~f4 zoom rather than a ~f2 fixed lens? - Len |
#36
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"Stephen H. Westin" wrote in message ... But the fact that it uses mirrors rather than a prism will have some effect; Canon 300D has a rather dim finder because of this, as I recall. Can anyone quantify how much light is lost by a pentamirror as compared to a prism? And how that compares to the dimness resulting from using a ~f4 zoom rather than a ~f2 fixed lens? - Len |
#37
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(Stephen H. Westin) wrote in message . ..
dj_nme writes: Stephen H. Westin wrote: dj_nme writes: Bill Tuthill wrote: Mike Henley wrote: I'm not sure what that means but it says one of the features of this pop-up flash is that you don't get that lens shadow in the close-up shots. Here are images with one of them of the flash (it does seem to reach up higher than usual pop-up flashes) http://www.dcresource.com/news/newsitem.php?id=2878 Yes, that looks quite good. It's unusual because the SLR mirror swings to the side, so I suppose this is why there isn't the normal SLR mirror hump in the middle, on which popup flash is usually set. That lump on top of an SLR camera usually houses the pentaprism (some oddball SLRs have a fixed mirror box or porroprisms). The mirror that you can see from the front (with the lens off) reflects the image up into the prism. And of course, Olympus has experience with SLR's with odd finders; remember the Pen F? This setup is somehow reminiscent of that. And I think the both use mirrors rather than a prism. Not true. The E-Volt uses a porroprism (according to the press release), like the Pen-F. I haven't used a Pen-F, so I don't know if it had a good viewfinder. Right you are. The Canon 300D and Nikon D70 seem to use pure mirrors, and controversy has ensued, e.g. http://www.photo.net/equipment/nikon/D70/. Well, the d70 seems to have a prism: http://www.nikonusa.com/template.php?cat=1&grp=2&productNr=25214. snip It uses a porroprism, which is a series of triangular prisms put together to flip the image around like a pentaprism. I think it ends up being wider, but much less tall as a pentaprism for the same job. So the only extra loss is the extra air-glass interfaces. If memory serves correctly, an early full-frame 35mm SLR used a porroprism in the same way. I read a reference to this camera on camera history page, but it didn't have a great deal of detail (just a name that I've unfortunately forgotten) just stating that it used a porroprism in it's finder. There must be a good reason why no other full-frame SLR has them in their design. Perhaps bulk? Or the need to assemble it from pieces, rather than a solid hunk of glass? I dunno. Alignment, additional reflections and loss. Space and packaging, certainly. So, for the simple (simplicity-seeking) mind, what are you saying? The E-Volt is good or bad for this? |
#38
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Stephen H. Westin wrote:
snip So the only extra loss is the extra air-glass interfaces. If memory serves correctly, an early full-frame 35mm SLR used a porroprism in the same way. I read a reference to this camera on camera history page, but it didn't have a great deal of detail (just a name that I've unfortunately forgotten) just stating that it used a porroprism in it's finder. There must be a good reason why no other full-frame SLR has them in their design. Perhaps bulk? Or the need to assemble it from pieces, rather than a solid hunk of glass? I dunno. Alignment, additional reflections and loss. Space and packaging, certainly. Perhaps. I have two accessory viewfinders for my RF cameras, a Leica Vidom multifinder and a Steinheil multifinder. Both use a porroprism to flip the image around. Considering that the objective lens is so tiny on the Steinheil version (2mm, 4mm or 6mm diameter depending on focal length), the image seen through it is suprisingly bright. I could only assume, given that a typical APS or 135 sized lens usually has an objective element that is at least 10 (or 20 or 30) times the diameter as this, then I would expect the viewfinder on such an SLR camera to be more than sufficiently bright and clear. Alignment of the porroprism elements would seem like a pretty good reason against using it a mass-produced item. Perhaps Olympus has found a short-cut to manufacture them? |
#39
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Leonard wrote:
"Stephen H. Westin" wrote in message ... But the fact that it uses mirrors rather than a prism will have some effect; Canon 300D has a rather dim finder because of this, as I recall. Can anyone quantify how much light is lost by a pentamirror as compared to a prism? And how that compares to the dimness resulting from using a ~f4 zoom rather than a ~f2 fixed lens? If there are two similar cameras from the same maker (one prism, the other mirror), look at the AF or metering performance at the low end. Difference will be close to the loss difference between the mirror and the prism versions. -- -- rec.photo.equipment.35mm user resource: -- http://www.aliasimages.com/rpe35mmur.htm -- e-meil: there's no such thing as a FreeLunch.-- |
#40
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"Alan Browne" wrote in message .. . Leonard wrote: Can anyone quantify how much light is lost by a pentamirror as compared to a prism? And how that compares to the dimness resulting from using a ~f4 zoom rather than a ~f2 fixed lens? If there are two similar cameras from the same maker (one prism, the other mirror), look at the AF or metering performance at the low end. Difference will be close to the loss difference between the mirror and the prism versions. ? Does not the AF system operate on the other side of the focus screen? Anyway, I looked it up. You lose about half a stop of finder brightness, assuming that the mirrors are ordinary cheap ones (and they surely are, otherwise why not have a prism). - Len |
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