Re: Thoughts on Trailing Curtain Sync
On Jul 2, 2010, at 13:53 , John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Or is it something that would require radical hardware revision? For that matter what do the dedicated pins on the Pentax shoe tell the flash? I know what the big one in the center does, and it's obvious which one is ground. Everything you need to know except the actual format and content of the digital signal and the mode format. http://kmp.bdimitrov.de/technology/hot-shoe/index.html Here's a diagram of a circuit to isolate an old high voltage flash from the hot shoe about half way down the page. I know, you didn't ask, but, it can't hurt to have a copy on your hard drive! http://www.flickr.com/groups/strobist/discuss/72157607929201242/ And the Hot Shoe and 5P cable pins, in case you wanted to know. Near bottom of page. http://forums.dpreview.com/forums/read.asp?forum=1036message=28607959 Lots and lots of data about the Pentax AFxxxFGZ flashes compared to others manufacturers. http://knol.google.com/k/pentax-p-ttl-hot-shoe-flash-comparison# also a more technical tome: http://www.jr-worldwi.de/photo/index.html?ist_DS_internalflash.html Joseph McAllister pentax...@mac.com THE SENILITY PRAYER : Grant me the senility to forget the people I never liked anyway, The good fortune to run into the ones I do, and The eyesight to tell the difference. -- 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: Thoughts on Trailing Curtain Sync
On Jul 3, 2010, at 1:56 AM, Bob W wrote: All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. I've found it most effective for my taste at 1/15th second, generally when there's already quite a lot of ambient light in the scene. These pictures from midsummer a few years ago are my most successful and (I think) effective efforts, shot at 1/15th. All shot with an Oly E-1 and Oly flash of some sort. Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html Interesting juxtaposition of Morris dancers and this: http://www.web-options.com/Pick2008/content/_6217916_large.html I can't quite figure out what's going on there such that there are lights in the shadow ring of one of the hula hoops. -- 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. -- Larry Colen l...@red4est.com sent from i4est -- 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: Thoughts on Trailing Curtain Sync
Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html Interesting juxtaposition of Morris dancers and this: http://www.web-options.com/Pick2008/content/_6217916_large.html it's all a continuum I can't quite figure out what's going on there such that there are lights in the shadow ring of one of the hula hoops. aliens -- 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: Thoughts on Trailing Curtain Sync
All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. On Friday, July 2, 2010, Adam Maas a...@mawz.ca wrote: On Fri, Jul 2, 2010 at 9:21 PM, paul stenquist pnstenqu...@comcast.net wrote: On Jul 2, 2010, at 7:05 PM, Adam Maas wrote: On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms jsessoms...@nc.rr.com wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? Very difficult unless certain assumptions about burn time are made, which won't be accurate. You need to fire the flash at just about exactly the burn time before the shutter closes for trailing curtain to work corectly. Most speedlights have a roughly 1ms full-power burn, but at low power levels it can be an order of magnitude shorter as output is normally controlled by burn duration rather than intensity. Olympus did allow this on some OM models, but it only worked because of the low sync speed of the camera's (1/60) so that even if the flash burn time was much shorter than the assumed ~1ms you don't get much exposure after the burn ends. This doesn't work so well with today's high sync speeds. Of course you can shoot trailing curtain synch at low shutter speeds on either the K10 or the K20. I get good results shooting trailing synch on the K10, K20 and K7 at 1/8th or 1/15th. Paul -Adam low shutter speeds work better for non-dedicated flash and rear curtain sync, it's at high sync speeds where the problem occurs becaue the burn time is a much larger portion of the period the shutter is open so a short duration burn triggered early nets you mid-curtain sync rather than rear-curtain sync. With a dedicated flash it's a non-issue because the burn time can be predicted and the flash triggered at the right moment so it cuts off just before the shutter closes. -Adam -- 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. -- Godfrey godfreydigiorgi.posterous.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.
Re: Thoughts on Trailing Curtain Sync
John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Non-dedicated flashes fire when they are told to. It doesn't mstter whether that is at the beginning, the end or halfway through exposure. On the face of it, some coding telling the camera to fire any connected flash at the end of exposure would be a comparatively simple task. So simple that I must go and see if it will work already Or is it something that would require radical hardware revision? For that matter what do the dedicated pins on the Pentax shoe tell the flash? I know what the big one in the center does, and it's obvious which one is ground. -- 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: Thoughts on Trailing Curtain Sync
mike wilson wrote: John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Non-dedicated flashes fire when they are told to. It doesn't mstter whether that is at the beginning, the end or halfway through exposure. On the face of it, some coding telling the camera to fire any connected flash at the end of exposure would be a comparatively simple task. So simple that I must go and see if it will work already OK. With KX and AF280T, it's no go. Trailing curtain seems to be a PTTL-only mode, as the RTF preflashes. Some illogicality there.. There is no trailing curtain mode on the DL2. Or is it something that would require radical hardware revision? For that matter what do the dedicated pins on the Pentax shoe tell the flash? I know what the big one in the center does, and it's obvious which one is ground. -- 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: Thoughts on Trailing Curtain Sync
All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. I've found it most effective for my taste at 1/15th second, generally when there's already quite a lot of ambient light in the scene. These pictures from midsummer a few years ago are my most successful and (I think) effective efforts, shot at 1/15th. All shot with an Oly E-1 and Oly flash of some sort. Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html -- 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: Thoughts on Trailing Curtain Sync
Hi John, I think it could be done in _software_ to make it work for any flash, but it would require a bit complicated menu to give the camera the required information about P-TLL or center contact only or expected burn time. In the Z-1 time I measured burntime of several flashes at hand, they all were much faster than the 1ms mentioned by Adam. It requires additional measures in the design to increase the burntime, I have seen that some Metz designs have that. It could also be in _Hardware_: In the past I measured the trigger pulse of my (P)Z-1 (Pentax hi end 35mm camera). The trailing edge of the trigger pulse was the right timing information for the rear curtain sync. So the pulse width of the triggerpulse changed with shutterspeed. And on the flash the decission could be for first or second curtain sync. I made even a small interface circuit to get rear curtain sync with non dedicated flashes. I donot know if my K20 has the same info in the rear sync. I think it would not harm other use if it was there. When I'll be retired, I might find time to measure this. Groeten, Jos John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Or is it something that would require radical hardware revision? For that matter what do the dedicated pins on the Pentax shoe tell the flash? I know what the big one in the center does, and it's obvious which one is ground. -- 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: Thoughts on Trailing Curtain Sync
Last sentence should be read as: I donot know if my K20 has the same info in the _flash trigger pulse_. Jos from Holland wrote: Hi John, I think it could be done in _software_ to make it work for any flash, but it would require a bit complicated menu to give the camera the required information about P-TLL or center contact only or expected burn time. In the Z-1 time I measured burntime of several flashes at hand, they all were much faster than the 1ms mentioned by Adam. It requires additional measures in the design to increase the burntime, I have seen that some Metz designs have that. It could also be in _Hardware_: In the past I measured the trigger pulse of my (P)Z-1 (Pentax hi end 35mm camera). The trailing edge of the trigger pulse was the right timing information for the rear curtain sync. So the pulse width of the triggerpulse changed with shutterspeed. And on the flash the decission could be for first or second curtain sync. I made even a small interface circuit to get rear curtain sync with non dedicated flashes. I donot know if my K20 has the same info in the rear sync. I think it would not harm other use if it was there. When I'll be retired, I might find time to measure this. Groeten, Jos John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Or is it something that would require radical hardware revision? For that matter what do the dedicated pins on the Pentax shoe tell the flash? I know what the big one in the center does, and it's obvious which one is ground. -- 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: Thoughts on Trailing Curtain Sync
From: paul stenquist On Jul 2, 2010, at 7:05 PM, Adam Maas wrote: On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms jsessoms...@nc.rr.com wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? Very difficult unless certain assumptions about burn time are made, which won't be accurate. You need to fire the flash at just about exactly the burn time before the shutter closes for trailing curtain to work corectly. Most speedlights have a roughly 1ms full-power burn, but at low power levels it can be an order of magnitude shorter as output is normally controlled by burn duration rather than intensity. Olympus did allow this on some OM models, but it only worked because of the low sync speed of the camera's (1/60) so that even if the flash burn time was much shorter than the assumed ~1ms you don't get much exposure after the burn ends. This doesn't work so well with today's high sync speeds. Of course you can shoot trailing curtain synch at low shutter speeds on either the K10 or the K20. I get good results shooting trailing synch on the K10, K20 and K7 at 1/8th or 1/15th. Paul But you can only do so with the on-board flash or a dedicated Pentax flash like the AF-540FGZ. The regular hot-shoe contact (or the PC contact on the K20) ONLY sync with the front curtain. The trailing curtain sync does not work with the AF-540FGZ in wireless mode, you have to use the Hot-shoe Adapter F and F5P cable to get it use trailing curtain sync off camera. I was wondering whether the main contact tripping only on the front curtain is hard-wired into the cameras or is it something Pentax could change in the firm-ware? Could Pentax tell the camera when the on-board flash mode is set for trailing curtain, trip the hot-shoe/PC contact with the trailing curtain as well, or would it require a physical change to the wiring inside the camera? It would be useful to have the camera trigger the hot-shoe/PC on the rear curtain so I could use trailing curtain sync with pocket wizard type radio slaves. Obviously, if the AF-540FGZ can do trailing curtain sync when mounted on the shoe, some information is being communicated through one of the contacts that tells the flash when the trailing curtain begins to close. How is the information formatted and what connector does it come through? If I knew that, I might be able to bread-board my own adapter. -- 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: Thoughts on Trailing Curtain Sync
From: mike wilson mike wilson wrote: John Sessoms wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? E.G. like with a radio-sync transmitter or Vivitar 285HV? Dedicated flash like the AF-540FGZ has its own circuitry to talk to the camera and can be set to trailing curtain sync. Is this something they could do with a firmware update? Non-dedicated flashes fire when they are told to. It doesn't mstter whether that is at the beginning, the end or halfway through exposure. On the face of it, some coding telling the camera to fire any connected flash at the end of exposure would be a comparatively simple task. So simple that I must go and see if it will work already OK. With KX and AF280T, it's no go. Trailing curtain seems to be a PTTL-only mode, as the RTF preflashes. Some illogicality there.. There is no trailing curtain mode on the DL2. The non-dedicated flash fires when the main hot-shoe contact triggers. I'm asking how the camera controls when that main hot-shoe contact triggers. Could a camera software change make it trigger the main hot-shoe/PC contact on the trailing curtain when the on-board flash is set to trailing curtain? Or would it require physical changes to the wiring inside the camera? The K10 and the K20 allow you to set the on-board flash to trailing-curtain. The AF-500 (which worked with the *ist-D) and the AF-540FGZ have trailing curtain sync built into the flash. On the K10 and the K20, with the on-board flash set to trailing curtain, the main hot-shoe pin triggers on the front curtain. Same for the K20's PC sync. Is this main pin trigger on front curtain hard-wired into the camera, or is this something that could be changed by a firm-ware update? -- 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: Thoughts on Trailing Curtain Sync
On Sat, Jul 3, 2010 at 1:56 AM, Bob W p...@web-options.com wrote: All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. I've found it most effective for my taste at 1/15th second, generally when there's already quite a lot of ambient light in the scene. These pictures from midsummer a few years ago are my most successful and (I think) effective efforts, shot at 1/15th. All shot with an Oly E-1 and Oly flash of some sort. Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html Thanks for the photos ... good stuff! The trigger lead time is shorter than I wrote. A 125 second flash burn is 8 ms and that's a long burn; they probably do trigger with 30 ms lead, not 300. :-) -- Godfrey godfreydigiorgi.posterous.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.
Re: Thoughts on Trailing Curtain Sync
Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg On Jul 3, 2010, at 11:08 AM, Godfrey DiGiorgi wrote: On Sat, Jul 3, 2010 at 1:56 AM, Bob W p...@web-options.com wrote: All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. I've found it most effective for my taste at 1/15th second, generally when there's already quite a lot of ambient light in the scene. These pictures from midsummer a few years ago are my most successful and (I think) effective efforts, shot at 1/15th. All shot with an Oly E-1 and Oly flash of some sort. Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html Thanks for the photos ... good stuff! The trigger lead time is shorter than I wrote. A 125 second flash burn is 8 ms and that's a long burn; they probably do trigger with 30 ms lead, not 300. :-) -- Godfrey godfreydigiorgi.posterous.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. -- 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: Thoughts on Trailing Curtain Sync
Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg that's a great shot! I watched American Graffiti again on Thursday evening, on French TV. I'd forgotten how good it is, and what a lot of great actors are in it (and I had no idea they all speak such good French!). Thought about you and your cruise shots while I was watching. Bob -- 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: Thoughts on Trailing Curtain Sync
Here's my K10D/540 combo work with trailing curtain: http://www.primelensphoto.com/trailing_curtain/index.html -Brendan - Original Message From: P N Stenquist pnstenqu...@comcast.net To: Pentax-Discuss Mail List pdml@pdml.net Sent: Sat, July 3, 2010 8:20:21 AM Subject: Re: Thoughts on Trailing Curtain Sync Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg On Jul 3, 2010, at 11:08 AM, Godfrey DiGiorgi wrote: On Sat, Jul 3, 2010 at 1:56 AM, Bob W href=mailto:p...@web-options.com;p...@web-options.com wrote: All my FourThirds and Micro-FourThirds bodies allow me to enable second curtain sync any time I want, with any flash. IIRC, both my Sony R1 and my Canon 10D allowed the same. The algorithm is very simple: the flash is triggered about 300ms before the second curtain is released. So it obviously works best with exposure times of a half second or longer, but then that's when I'd use second curtain sync anyway. I've found it most effective for my taste at 1/15th second, generally when there's already quite a lot of ambient light in the scene. These pictures from midsummer a few years ago are my most successful and (I think) effective efforts, shot at 1/15th. All shot with an Oly E-1 and Oly flash of some sort. Start here, and click through about 8 snaps: http://www.web-options.com/Pick2008/content/_6207819_large.html Thanks for the photos ... good stuff! The trigger lead time is shorter than I wrote. A 125 second flash burn is 8 ms and that's a long burn; they probably do trigger with 30 ms lead, not 300. :-) --Godfrey href=http://godfreydigiorgi.posterous.com;godfreydigiorgi.posterous.com --PDML Pentax-Discuss Mail List ymailto=mailto:PDML@pdml.net; href=mailto:PDML@pdml.net;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 ymailto=mailto:PDML@pdml.net; href=mailto:PDML@pdml.net;PDML@pdml.net href=http://pdml.net/mailman/listinfo/pdml_pdml.net; target=_blank 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: Thoughts on Trailing Curtain Sync
John, maybe it tells the flash digitally through the communication line that it has to use the trailling edge of the triggerpuls of the camera for triggering the flash (that would be the same principle as on the Z-1) If it works like that, your adapter board will be very simple :-) Greetz, Jos John Sessoms wrote: It would be useful to have the camera trigger the hot-shoe/PC on the rear curtain so I could use trailing curtain sync with pocket wizard type radio slaves. Obviously, if the AF-540FGZ can do trailing curtain sync when mounted on the shoe, some information is being communicated through one of the contacts that tells the flash when the trailing curtain begins to close. How is the information formatted and what connector does it come through? If I knew that, I might be able to bread-board my own adapter. -- 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: Thoughts on Trailing Curtain Sync
Thanks Bob. On Jul 3, 2010, at 11:42 AM, Bob W wrote: Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg that's a great shot! I watched American Graffiti again on Thursday evening, on French TV. I'd forgotten how good it is, and what a lot of great actors are in it (and I had no idea they all speak such good French!). Thought about you and your cruise shots while I was watching. Bob -- 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: Thoughts on Trailing Curtain Sync
On Sat, Jul 3, 2010 at 8:20 AM, P N Stenquist pnstenqu...@comcast.net wrote: Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg Nice. :-) -- Godfrey godfreydigiorgi.posterous.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.
Re: Thoughts on Trailing Curtain Sync
Thanks Godders. Trailing curtain and cars kind of go together. I don't use it often enough. Paul On Jul 3, 2010, at 7:12 PM, Godfrey DiGiorgi wrote: On Sat, Jul 3, 2010 at 8:20 AM, P N Stenquist pnstenqu...@comcast.net wrote: Trailing curtain synch with K10D and FA 540 flash. http://photo.net/photodb/photo?photo_id=6315560size=lg Nice. :-) -- Godfrey godfreydigiorgi.posterous.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. -- 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: Thoughts on Trailing Curtain Sync
On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms jsessoms...@nc.rr.com wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? Very difficult unless certain assumptions about burn time are made, which won't be accurate. You need to fire the flash at just about exactly the burn time before the shutter closes for trailing curtain to work corectly. Most speedlights have a roughly 1ms full-power burn, but at low power levels it can be an order of magnitude shorter as output is normally controlled by burn duration rather than intensity. Olympus did allow this on some OM models, but it only worked because of the low sync speed of the camera's (1/60) so that even if the flash burn time was much shorter than the assumed ~1ms you don't get much exposure after the burn ends. This doesn't work so well with today's high sync speeds. -Adam -- 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: Thoughts on Trailing Curtain Sync
On Jul 2, 2010, at 7:05 PM, Adam Maas wrote: On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms jsessoms...@nc.rr.com wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? Very difficult unless certain assumptions about burn time are made, which won't be accurate. You need to fire the flash at just about exactly the burn time before the shutter closes for trailing curtain to work corectly. Most speedlights have a roughly 1ms full-power burn, but at low power levels it can be an order of magnitude shorter as output is normally controlled by burn duration rather than intensity. Olympus did allow this on some OM models, but it only worked because of the low sync speed of the camera's (1/60) so that even if the flash burn time was much shorter than the assumed ~1ms you don't get much exposure after the burn ends. This doesn't work so well with today's high sync speeds. Of course you can shoot trailing curtain synch at low shutter speeds on either the K10 or the K20. I get good results shooting trailing synch on the K10, K20 and K7 at 1/8th or 1/15th. Paul -Adam -- 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: Thoughts on Trailing Curtain Sync
On Fri, Jul 2, 2010 at 9:21 PM, paul stenquist pnstenqu...@comcast.net wrote: On Jul 2, 2010, at 7:05 PM, Adam Maas wrote: On Fri, Jul 2, 2010 at 4:53 PM, John Sessoms jsessoms...@nc.rr.com wrote: The K-10D and K-20D both allow you to set the on-board flash to trailing curtain sync. How difficult would it be for them to make the hot-shoe also fire on the trailing curtain when a non-dedicated flash is installed? Very difficult unless certain assumptions about burn time are made, which won't be accurate. You need to fire the flash at just about exactly the burn time before the shutter closes for trailing curtain to work corectly. Most speedlights have a roughly 1ms full-power burn, but at low power levels it can be an order of magnitude shorter as output is normally controlled by burn duration rather than intensity. Olympus did allow this on some OM models, but it only worked because of the low sync speed of the camera's (1/60) so that even if the flash burn time was much shorter than the assumed ~1ms you don't get much exposure after the burn ends. This doesn't work so well with today's high sync speeds. Of course you can shoot trailing curtain synch at low shutter speeds on either the K10 or the K20. I get good results shooting trailing synch on the K10, K20 and K7 at 1/8th or 1/15th. Paul -Adam low shutter speeds work better for non-dedicated flash and rear curtain sync, it's at high sync speeds where the problem occurs becaue the burn time is a much larger portion of the period the shutter is open so a short duration burn triggered early nets you mid-curtain sync rather than rear-curtain sync. With a dedicated flash it's a non-issue because the burn time can be predicted and the flash triggered at the right moment so it cuts off just before the shutter closes. -Adam -- 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.
