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06-16-2013, 12:45 PM   #1
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flash sync / lens mount rants

My K5 has a flash sync of 1/180 sec with a vertical running shutter. It only has to open 15.6 mm but my old Z1P shutter has to travel 24 mm but has a flash sync of 1/250 sec. In theory the Z1P shutter could sync in 1/384 sec in an APS-C format. The Z1P also works perfectly with any K mount lens including DA (if you can live with vignetting at some shorter focal lengths, the kit lens is ok from 24 mm). It will interesting to find out if an FF D-slr would address the present mechanical shortcomings assuming one ever appears.

06-16-2013, 01:05 PM   #2
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Why worry about the exposure duration when the actual flash duration is likely to be much shorter?
06-16-2013, 01:37 PM   #3
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QuoteOriginally posted by Nass Quote
Why worry about the exposure duration when the actual flash duration is likely to be much shorter?
Daylight killing power. Higher sync speeds make your flash effectively stronger when trying to balance with ambient light. Things like ND filters, or stopping down, or lowering your ISO will tame the daylight too, but will adversely affect your flash power in so doing. Shutter speed is a freebie.
06-16-2013, 01:49 PM - 1 Like   #4
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Would you care to comment on the noise your Z1P's shutter makes?

06-16-2013, 02:18 PM   #5
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QuoteOriginally posted by Giklab Quote
Would you care to comment on the noise your Z1P's shutter makes?
I am not sure how noisy the Z1P shutter makes as it is drowned out by the mirror. My K5 is extremely quiet against my K20 or K100 however. The motor advancing the film also makes noise. I could set the camera to 2 sec delay and multiple exposure but it would waste one of my precious frames. What I am trying to explain is that the wonderful digital cameras could be even better if Pentax had not downgraded certain features.
06-16-2013, 02:46 PM   #6
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Don't forget that there is SR on the sensor so it's a bit more then 15,6mm

1/180 is sadly a software fixed limit, i wonder if it can do 1/250 as well but there is no way of trying out...
I wonder if someone can hack the firmware, i already looked for it once without sucess
06-16-2013, 06:47 PM   #7
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QuoteOriginally posted by Anvh Quote
1/180 is sadly a software fixed limit, i wonder if it can do 1/250 as well but there is no way of trying out... I wonder if someone can hack the firmware, i already looked for it once without sucess
It is a limit that is present in both the hardware and in the software, the shutter curtains will be visible at 1/250th and above. At present the only way you can bypass this limit without voiding any warranties is to use a 645 leaf shutter lens, that way you can synch at 1/500th.
06-16-2013, 07:31 PM - 1 Like   #8
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High Speed Flash-sync (HSS) ? Isn't that also an option to get higher sync speeds, if your flash supports it. K-5 supports HSS.

06-16-2013, 10:33 PM   #9
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QuoteOriginally posted by Digitalis Quote
It is a limit that is present in both the hardware and in the software, the shutter curtains will be visible at 1/250th and above.
That is what we are lead to believe, but it difficult to say with certainty that the hardware limit actually occurs at 1/250th because the software won't let us find out. Pentax has chosen to protect us at all costs from those dreaded black bars by disabling the pop-up flash, the hotshoe, and the PC socket at higher-than-sync speeds, so there's no way to send a sync signal. But on Nikon cameras for instance, the PC socket will fire at any speed, and it has been shown that the hardware limit is actually faster than the software limit. The Nikon engineers built a fudge factor into the software, and it may be that Pentax has gone the same route.

But for the sake of argument, lets say that the black bars begin appearing at 1/181st of a second, that still doesn't mean that they will occupy the entire frame at first. David Hobby has some examples of what the bars look like at different speeds in his post about hacking your flash sync speed Strobist: Hacking Your Camera's Sync Speed, Pt. 2 Unfortunately his techniques don't work on Pentax, but it's interesting to see what would be possible if not for the software imposed limitation. With some creative cropping one could get some very dramatic shots at say 1/500th. I for one would like the choice of whether I need to be protected from myself. A simple custom menu option would suffice. We have "permit aperture ring", why not "permit unsynced flash"?

Last edited by maxfield_photo; 06-18-2013 at 07:05 AM.
06-17-2013, 01:56 AM   #10
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Look, no offense, but what's stopping anyone from putting the camera on manual and using a manual flash with speeds faster than 1/180?
06-17-2013, 03:34 AM   #11
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try and find out for yourself
06-17-2013, 03:42 AM   #12
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QuoteOriginally posted by ksm Quote
try and find out for yourself
The only manual flash I have would fry my camera .
06-17-2013, 03:57 AM   #13
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well, in that case.... I have a good news and a bad news... The bad one is, the flash won't fire ...and the good one, your camera won't be fried!
..but I wish it worked that way as you said. sigh...
06-17-2013, 04:01 AM   #14
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QuoteOriginally posted by Giklab Quote
Look, no offense, but what's stopping anyone from putting the camera on manual and using a manual flash with speeds faster than 1/180?
The flash won't fire at speeds higher than 1/180. Hence the X-sync speeds that camera info pages usually list. There is no question that Pentax lags HEAVILY in the flash department compared to Canon and Nikon, and the X-sync speed of 1/180 is no doubt part of that assessment. Canon and Nikon DSLRs start at 1/200 for the entry level.
06-17-2013, 04:06 AM   #15
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QuoteOriginally posted by rawr Quote
High Speed Flash-sync
That's what I was thinking as well. Although pretty sure you need an external flash for that. At least my K-r does - there is no HSS option when using the inbuilt flash. However, if I use my Metz flash and set it to PTTL-HSS then I can get much faster shutter speeds (can't recall exact upper limit).
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