Re: Using the 645z for Astrophotography
Fascinating. Thanks for the link, PJ. Alan C -Original Message- From: P.J. Alling Sent: Sunday, October 05, 2014 8:16 PM To: pentax-Discuss Mail List Subject: Using the 645z for Astrophotography at the Luminous Landscape and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml -- I don't want to achieve immortality through my work; I want to achieve immortality through not dying. -- Woody Allen --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Using the 645z for Astrophotography at the Luminous Landscape
and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml -- I don't want to achieve immortality through my work; I want to achieve immortality through not dying. -- Woody Allen -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
P.J. Alling wrote: and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I wouldn't have any money left over for the $500 astro mount. I was surprised to find that there don't seem any lenses faster than f/2.8 available for the 645. Doing some quick web search, there don't even seem to be any manual focus lenses faster than f/2.8 available. -- Larry Colen l...@red4est.com (postbox on min4est) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: > > > P.J. Alling wrote: >> and wonder of wonders it's got some interesting information for free. >> >> http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml > > Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I > wouldn't have any money left over for the $500 astro mount. > > I was surprised to find that there don't seem any lenses faster than f/2.8 > available for the 645. Doing some quick web search, there don't even seem to > be any manual focus lenses faster than f/2.8 available. > There are adapters that support the use of Hassleblad etc. on the 645. Maybe you can find the faster glass you need by going that route? stan > >> >> > > -- > Larry Colen l...@red4est.com (postbox on min4est) > -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin wrote: > > On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: >> >> P.J. Alling wrote: >>> and wonder of wonders it's got some interesting information for free. >>> >>> http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml >> >> Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I >> wouldn't have any money left over for the $500 astro mount. >> >> I was surprised to find that there don't seem any lenses faster than f/2.8 >> available for the 645. Doing some quick web search, there don't even seem >> to be any manual focus lenses faster than f/2.8 available. >> > > There are adapters that support the use of Hassleblad etc. on the 645. Maybe > you can find the faster glass you need by going that route? I always assumed that there isn't faster glass because there doesn't need to be. The DoF on medium format is already razor thin compared to 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious focusing problem? Or ridiculously OOF portraits? In other words, we have what's practical to sell, as with other formats. Or am I way off base? -- -bmw -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
Using the term "astrophotography" is sort of like using the term "Dr." or "PhD". It implies something that can be rather broad without revealing the particulars. Frankly, I think that calling Milky Way shots, (particularly with landscape sillouettes or light painting )"astrophotography" is a stretch. But to each, their own. In any event fast lenses are really only important if you must limit your shutter speed, as we often need to do in terrestial photography. In astrophotography, with a motorized, polar-aligned platform, your shutter speed is limited only by your motorized/guided accuracy or periodic error built into the gears. It makes little difference if you are shooting at f2.8 or f/10 (as with using many of the popular Schmidt-Cassegrain telescopes for lenses). Most good apochromats for astrophotography are around f/5.5 or f/6. Most photographic lenses need to be stopped down 1 or two stops for best performance, particularly off-axis. So the wide open "speed" of the lens only determines at what focal ratio that one or two stops down is going to BE. A *scope* made for imaging has no such aperture iris and is made to shoot "wide open" because that is your only choice. Stacking images in post-processing allows you to take your longest guided/polar-aligned images and reduce noise, effectively pulling out more detail. A lens that performs well when stopped down to f5.6 is plenty good for astrophotography, though a lens that is fine at wider apertures might be even better. The DA* 200mm f2.8 is, by all accounts, one of the Good Ones, for deep space objects like nebula, galaxies & star clusters. On Mon, Oct 6, 2014 at 3:26 PM, Larry Colen wrote: > > > P.J. Alling wrote: >> >> and wonder of wonders it's got some interesting information for free. >> >> >> http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml > > > Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I > wouldn't have any money left over for the $500 astro mount. > > I was surprised to find that there don't seem any lenses faster than f/2.8 > available for the 645. Doing some quick web search, there don't even seem > to be any manual focus lenses faster than f/2.8 available. > > >> >> > > -- > Larry Colen l...@red4est.com (postbox on min4est) > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and > follow the directions. -- Photographers must learn not to be ashamed to have their photographs look like photographs. ~ Alfred Stieglitz -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
Not off-base at all Bruce. Scale it up and look at the fastest lenses for 4x5 or 5x7 film cameras. Same reasoning. On Mon, Oct 6, 2014 at 8:33 PM, Bruce Walker wrote: > On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin > wrote: >> >> On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: >>> >>> P.J. Alling wrote: and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml >>> >>> Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I >>> wouldn't have any money left over for the $500 astro mount. >>> >>> I was surprised to find that there don't seem any lenses faster than f/2.8 >>> available for the 645. Doing some quick web search, there don't even seem >>> to be any manual focus lenses faster than f/2.8 available. >>> >> >> There are adapters that support the use of Hassleblad etc. on the 645. Maybe >> you can find the faster glass you need by going that route? > > I always assumed that there isn't faster glass because there doesn't > need to be. The DoF on medium format is already razor thin compared to > 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious > focusing problem? Or ridiculously OOF portraits? > > In other words, we have what's practical to sell, as with other > formats. Or am I way off base? > > -- > -bmw > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- Photographers must learn not to be ashamed to have their photographs look like photographs. ~ Alfred Stieglitz -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On 10/6/2014 9:33 PM, Bruce Walker wrote: On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin wrote: On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: P.J. Alling wrote: and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I wouldn't have any money left over for the $500 astro mount. I was surprised to find that there don't seem any lenses faster than f/2.8 available for the 645. Doing some quick web search, there don't even seem to be any manual focus lenses faster than f/2.8 available. There are adapters that support the use of Hassleblad etc. on the 645. Maybe you can find the faster glass you need by going that route? I always assumed that there isn't faster glass because there doesn't need to be. The DoF on medium format is already razor thin compared to 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious focusing problem? Or ridiculously OOF portraits? In other words, we have what's practical to sell, as with other formats. Or am I way off base? Not just DOF, but an f2.0 135mm would be quite large and heavy if built to cover the 645 format, yet it would be the equivalent of a Portrait lens say 85mm on 35mm, (75mm actually). Fast glass makes in any focal length on 645 need a tripod, whereas Pentax build a system to be equally good as a hand held field camera, as well as at home on a tripod in a studio. Traditionally medium format lenses have been fairly slow. There are exceptions, but they are exceptions. -- I don't want to achieve immortality through my work; I want to achieve immortality through not dying. -- Woody Allen -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On Oct 6, 2014, at 10:38 PM, P.J. Alling wrote: > On 10/6/2014 9:33 PM, Bruce Walker wrote: >> On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin >> wrote: >>> On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: P.J. Alling wrote: > and wonder of wonders it's got some interesting information for free. > > http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I wouldn't have any money left over for the $500 astro mount. I was surprised to find that there don't seem any lenses faster than f/2.8 available for the 645. Doing some quick web search, there don't even seem to be any manual focus lenses faster than f/2.8 available. >>> There are adapters that support the use of Hassleblad etc. on the 645. >>> Maybe you can find the faster glass you need by going that route? >> I always assumed that there isn't faster glass because there doesn't >> need to be. The DoF on medium format is already razor thin compared to >> 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious >> focusing problem? Or ridiculously OOF portraits? >> >> In other words, we have what's practical to sell, as with other >> formats. Or am I way off base? >> > Not just DOF, but an f2.0 135mm would be quite large and heavy if built to > cover the 645 format, yet it would be the equivalent of a Portrait lens say > 85mm on 35mm, (75mm actually). Fast glass makes in any focal length on 645 > need a tripod, whereas Pentax build a system to be equally good as a hand > held field camera, as well as at home on a tripod in a studio. Traditionally > medium format lenses have been fairly slow. There are exceptions, but they > are exceptions. > Bruce, not to disagree with your point at all, but FYI a 645 135mm lens on the 645z would have an effective field of view equivalent to a 110mm lens on a 35mm film camera. The “crop factor” is 0.8. So taking (many of) the actual lenses available, the 645z has: X 645 lens => equivalent to Ymm focal length on 35mm 25 => 20mm 35 => 28mm 45 => 35mm 55 => 44mm 75 => 60mm 90 => 72mm 120 => 96mm 150 => 120mm 200 => 160mm I think you were basing your comparison on actual 6x4.5 film vs. 35mm film. One other point about lens speed: the importance of wide apertures has seriously diminished (except for very specialized niche applications that call for shallow DOF) - the ability to shoot clean shots at ISO6400 or 12800 really makes “fast” lenses a relic of the good old days when we had a choice of either Kodachrome as God intended it to be at ISO 25 or of that new Kodachrome 64 that was a serious compromise in quality. Though I must admit that I prefer a fast lens to a slower one for the simple reason that I have a brighter image to focus and compose. Stan -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
Sorry Bruce, P.J. - I misattributed your post, P.J., to Bruce. stan On Oct 7, 2014, at 12:32 AM, Stanley Halpin wrote: > > On Oct 6, 2014, at 10:38 PM, P.J. Alling wrote: > >> On 10/6/2014 9:33 PM, Bruce Walker wrote: >>> On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin >>> wrote: On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: > P.J. Alling wrote: >> and wonder of wonders it's got some interesting information for free. >> >> http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml > Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, > I wouldn't have any money left over for the $500 astro mount. > > I was surprised to find that there don't seem any lenses faster than > f/2.8 available for the 645. Doing some quick web search, there don't > even seem to be any manual focus lenses faster than f/2.8 available. > There are adapters that support the use of Hassleblad etc. on the 645. Maybe you can find the faster glass you need by going that route? >>> I always assumed that there isn't faster glass because there doesn't >>> need to be. The DoF on medium format is already razor thin compared to >>> 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious >>> focusing problem? Or ridiculously OOF portraits? >>> >>> In other words, we have what's practical to sell, as with other >>> formats. Or am I way off base? >>> >> Not just DOF, but an f2.0 135mm would be quite large and heavy if built to >> cover the 645 format, yet it would be the equivalent of a Portrait lens say >> 85mm on 35mm, (75mm actually). Fast glass makes in any focal length on 645 >> need a tripod, whereas Pentax build a system to be equally good as a hand >> held field camera, as well as at home on a tripod in a studio. Traditionally >> medium format lenses have been fairly slow. There are exceptions, but they >> are exceptions. >> > > Bruce, not to disagree with your point at all, but FYI a 645 135mm lens on > the 645z would have an effective field of view equivalent to a 110mm lens on > a 35mm film camera. The “crop factor” is 0.8. So taking (many of) the actual > lenses available, the 645z has: > > X 645 lens => equivalent to Ymm focal length on 35mm > > 25 => 20mm > 35 => 28mm > 45 => 35mm > 55 => 44mm > 75 => 60mm > 90 => 72mm > 120 => 96mm > 150 => 120mm > 200 => 160mm > > I think you were basing your comparison on actual 6x4.5 film vs. 35mm film. > > One other point about lens speed: the importance of wide apertures has > seriously diminished (except for very specialized niche applications that > call for shallow DOF) - the ability to shoot clean shots at ISO6400 or 12800 > really makes “fast” lenses a relic of the good old days when we had a choice > of either Kodachrome as God intended it to be at ISO 25 or of that new > Kodachrome 64 that was a serious compromise in quality. > > Though I must admit that I prefer a fast lens to a slower one for the simple > reason that I have a brighter image to focus and compose. > > Stan > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
Stanley Halpin wrote: One other point about lens speed: the importance of wide apertures has seriously diminished (except for very specialized niche applications that call for shallow DOF) - the ability to shoot clean shots at ISO6400 or 12800 really makes “fast” lenses a relic of the good old days when we had a choice of either Kodachrome as God intended it to be at ISO 25 or of that new Kodachrome 64 that was a serious compromise in quality. I take it that you've never tried photographing dancers at a social dance: tango, lindy hop, west coast, blues etc. Nor have you probably ever tried photographing martial artists taking a belt test, or any other athletic activity where people are moving fairly quickly in indoor lighting and you can't use a flash. Yes, what we can get out of sensors at ISOs above 6400 these days is really amazing, but trust me, the need for fast glass for reasons other than shallow dof has not gone away. -- Larry Colen l...@red4est.com (postbox on min4est) -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On Oct 7, 2014, at 04:10 , Larry Colen wrote: > Stanley Halpin wrote: > >> >> One other point about lens speed: the importance of wide apertures has >> seriously diminished (except for very specialized niche applications that >> call for shallow DOF) - the ability to shoot clean shots at ISO6400 or 12800 >> really makes “fast” lenses a relic of the good old days when we had a choice >> of either Kodachrome as God intended it to be at ISO 25 or of that new >> Kodachrome 64 that was a serious compromise in quality. >> > > I take it that you've never tried photographing dancers at a social dance: > tango, lindy hop, west coast, blues etc. Nor have you probably ever tried > photographing martial artists taking a belt test, or any other athletic > activity where people are moving fairly quickly in indoor lighting and you > can't use a flash. > > Yes, what we can get out of sensors at ISOs above 6400 these days is really > amazing, but trust me, the need for fast glass for reasons other than shallow > dof has not gone away. > I agree that for dim-light action photography, you just can't beat a fast lens. I was surprised at my last series of concert photos, though, that I shot with the F70-210. I forgot to set the "program mode" for SPEED and had left it at MTF. Upon reviewing all of my (pretty decent-looking) images after the show, I found that almost every shot was taken at f/8! That would have been absolutely unimaginable in the film days. (example, if you care) http://charles.robinsontwins.org/photos/2014/lily_allen/content/K5__4431_large.html -Charles -- Charles Robinson - charl...@visi.com Minneapolis, MN http://charles.robinsontwins.org http://www.facebook.com/charles.robinson -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On 10/7/2014 12:32 AM, Stanley Halpin wrote: On Oct 6, 2014, at 10:38 PM, P.J. Alling wrote: On 10/6/2014 9:33 PM, Bruce Walker wrote: On Mon, Oct 6, 2014 at 9:23 PM, Stanley Halpin wrote: On Oct 6, 2014, at 4:26 PM, Larry Colen wrote: P.J. Alling wrote: and wonder of wonders it's got some interesting information for free. http://www.luminous-landscape.com/techniques/pentax_645z_astrophotography.shtml Excellent link, though I'm afraid that if I were to spend $10K on a 645Z, I wouldn't have any money left over for the $500 astro mount. I was surprised to find that there don't seem any lenses faster than f/2.8 available for the 645. Doing some quick web search, there don't even seem to be any manual focus lenses faster than f/2.8 available. There are adapters that support the use of Hassleblad etc. on the 645. Maybe you can find the faster glass you need by going that route? I always assumed that there isn't faster glass because there doesn't need to be. The DoF on medium format is already razor thin compared to 35mm and APS-C and perhaps a 1.4 on a 645z would create a serious focusing problem? Or ridiculously OOF portraits? In other words, we have what's practical to sell, as with other formats. Or am I way off base? Not just DOF, but an f2.0 135mm would be quite large and heavy if built to cover the 645 format, yet it would be the equivalent of a Portrait lens say 85mm on 35mm, (75mm actually). Fast glass makes in any focal length on 645 need a tripod, whereas Pentax build a system to be equally good as a hand held field camera, as well as at home on a tripod in a studio. Traditionally medium format lenses have been fairly slow. There are exceptions, but they are exceptions. Bruce, not to disagree with your point at all, but FYI a 645 135mm lens on the 645z would have an effective field of view equivalent to a 110mm lens on a 35mm film camera. The “crop factor” is 0.8. So taking (many of) the actual lenses available, the 645z has: X 645 lens => equivalent to Ymm focal length on 35mm 25 => 20mm 35 => 28mm 45 => 35mm 55 => 44mm 75 => 60mm 90 => 72mm 120 => 96mm 150 => 120mm 200 => 160mm I think you were basing your comparison on actual 6x4.5 film vs. 35mm film. One other point about lens speed: the importance of wide apertures has seriously diminished (except for very specialized niche applications that call for shallow DOF) - the ability to shoot clean shots at ISO6400 or 12800 really makes “fast” lenses a relic of the good old days when we had a choice of either Kodachrome as God intended it to be at ISO 25 or of that new Kodachrome 64 that was a serious compromise in quality. Though I must admit that I prefer a fast lens to a slower one for the simple reason that I have a brighter image to focus and compose. Stan Well yes I am, basing it on film vs film. From the past the future is determined. Most lens design in the past was based on existing lenses being modified from other formats. Just for example why was 135mm the most popular long lens for 35mm film for such a long time? It's a funny focal length. Doesn't match any particular rule that I ever heard. Well it was the "normal" focal length for larger a film format. There were lots of good 135mm designs to base the new Long Lens design on. So it became a defacto standard. Faster short telephotos were designed, but the 135mm focal length was now engrained in the photographers mindset, so they were designed in 135mm. n So really why aren't there "fast" lenses for medium format? Well in addition to DOF, there's size, cost, for lack of a better word, (not that there isn't a better word, but I can't think of one). "tradition". -- I don't want to achieve immortality through my work; I want to achieve immortality through not dying. -- Woody Allen -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
On Oct 7, 2014, at 10:24 , P.J. Alling wrote: > > Just for example why was 135mm the most popular long lens for 35mm film for > such a long time? It's a funny focal length. Doesn't match any particular > rule that I ever heard. Well it was the "normal" focal length for larger a > film format. There were lots of good 135mm designs to base the new Long Lens > design on. So it became a defacto standard. Faster short telephotos were > designed, but the 135mm focal length was now engrained in the photographers > mindset, so they were designed in 135mm. n > Cool information! I never knew this (but have wondered from time to time). -Charles -- Charles Robinson - charl...@visi.com Minneapolis, MN http://charles.robinsontwins.org http://www.facebook.com/charles.robinson -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
Re: Using the 645z for Astrophotography at the Luminous Landscape
Charles Robinson wrote: >On Oct 7, 2014, at 10:24 , P.J. Alling wrote: >> >> Just for example why was 135mm the most popular long lens for 35mm film for >>such a long time? It's a funny focal length. Doesn't match any particular >>rule that I ever heard. Well it was the "normal" focal length for larger a >>film format. There were lots of good 135mm designs to base the new Long Lens >>design on. So it became a defacto standard. Faster short telephotos were >>designed, but the 135mm focal length was now engrained in the photographers >>mindset, so they were designed in 135mm. n > >Cool information! I never knew this (but have wondered from time to time). IIRC, 135mm was the longest focal length that was compatible with Leica's rangefinder-coupling mechanism, so it was the longest focal length lens offered by Leica. Other manufacturers just followed along making that a standard focal length even though they also offered longer lenses. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
