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05-22-2009, 01:39 AM   #91
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QuoteOriginally posted by lithos Quote
Shit, really?

(NOTE: If someone can find me a smilie that's as subtly sarcastic and dry as I intended to deliver that above comment, please post it.)
Of course, unless you have invented a new type of mechanical shutter for use in DSLRs!

05-22-2009, 01:59 AM   #92
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for professional use i'm sure pentax will make leaf shutter lenses for their 645 system. I own a few of them from the 645 NII
05-22-2009, 02:22 AM   #93
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QuoteOriginally posted by RiceHigh Quote
I have seen a lot gripes and complaints about the 1/180s "flash" x-sync speed of the K-7 these two days.

As a professional electronics engineer who has been working in the industry and relevant fields for decades myself, I have something to say for the Pentax's engineers.

The possible major constraint of the K-7 is the miniature size.

X-sync actually represents the highest speed which the shutter blades, i.e., front or rear curtain, is capable of moving.

The 1/8000th is not the true speed of shutter blade movement, it is just a narrowed gap as "line scanned" when the maximum x-sync is exceeded. So, its easy to achieve even with the "existing" shutter.

To make faster shutter blade movement, more instantaneous *power* (energy over time) is required to actuate the shutter and/or lighter shutter blades are required. I believe the materials for shutter blades have been already well established years ago. There is minimum thickness and hence mass of the shutter blades as they have to be strong enough.

So, to make more power to the shutter movement, more powerful magnetic force is desired. So, the magnetic coil need to make larger, with more turns of coil as well as thicker wire for more/larger current - so as to provide the very high energy within a very short period of time. As a result, such the shutter will be (much) larger, as it is required (and consume more battery power as well).

Afterall, I think technology is not a barrier for Pentax to include a faster shutter. As they purchase from Copal anyway. But, the size is, which I believe is the major constraint.

As long as Pentax have to choose between smaller miniature sized DSLR or a higher X-sync, they have NO CHOICE!
Interesting, thanks.
Maybe next time instead, as technology progresses.





QuoteOriginally posted by Venturi Quote
Actually, it's 1/3 stop. And 1/180s to 1/250s is 1/2 stop. But, for the most part yes it's not worth complaining about. The effective duration of most flashes/strobes is in the range of 1/1000s to 1/4000s meaning that except for some fill flash situations the sync speed could be 1/90s and most photographs wouldn't suffer at all.
Yeah that's how I understood it as well


QuoteOriginally posted by CreV Quote
If you're trying to do skiphotog, then you really need faster x-sync/sync faster than x-sync if you're shooting in bright day.
A lot of ski photography, will be at 1/2000 – 1/8000 of a sec. for competition runs. Like can be seen on Rob Galbraith’s site :
Rob Galbraith DPI: A first look at the Canon EOS-1D Mark III

Rob Galbraith DPI: December 10, 2007 update

And I take it, he is using HSS, freezing the ball and player at bottom image here at 1/320 sec. (Canon EOS-1D Mark III + EF 300mm f/2.8L IS, ISO 200, 1/320, f/7.1, Zeus strobes.) :
Rob Galbraith DPI: October 18, 2007 update

And the same here (Canon EOS-1D Mark + EF 300mm f/2.8L IS, ISO 200, 1/320, f/3.5, Elinchrom Style 600 S strobes) :
Rob Galbraith DPI: August 29, 2007 update
(Or I guess he could just be pushing it)

If you want to stop hummingbirds in mid air, you’re gonna need high-speed synch as well.



QuoteOriginally posted by khardur Quote
RH: I really don't think it's the shutter power itself that you need to increase.

Like was said previously about electronic shutter compared to the mechanical shutter - the mechanical shutter could be open for any length of time, the trick is to have the sensor record data for only the specified shutter length. 1/500 let's say.

So the mechanical shutter still could fire at 1/180s, thus ensuring the curtain is fully open when the light is recorded. But also then you must have the sync circuitry within such tight tolerances as to be able to actually fire the flashes accordingly at the proper time, not only for the onboard or hot-shoe mounted flash, but also for corded or wireless flashes as well.

I honestly don't know why Pentax can't (or won't) improve this, 1/250 is so much nicer when using flash in daylight, you have more control over the ambient light vs. flash this way.
well stated


QuoteOriginally posted by jeffkrol Quote
A few other things.. CMOS is more difficult to do electronic shutter. Nikon CCD DSLR (and others) do do electronic shuttering.
Yes the shutter needs to be faster w/ great breaking power to get faster mechanical sych higher than 1/250th.
There are shutters that fast but it seems we hit a cost/performance wall here.
Due noted




QuoteOriginally posted by khardur Quote
I understand your point entirely. But I honestly respect this particular thread that RH has started here. He was actually simply speculating on the reason why the x-sync speed has remained at 1/180s, not saying Pentax is doomed or any of that.

This is why I responded to this thread in the first place, because he wasn't going out of his way to bash Pentax as has been the case in the past, or to unabashedly plug his blog. I give him kudos for starting a thread with a tone that encourages a civilized discussion, whether or not he's griping about something.

That 1/2 stop of shutter speed is exactly 1/2 stop less power I need from my off-camera flashes when I'm trying to overpower ambient daylight. No it's not a dealbreaker by any means, but it is extra convenience.

(btw, a year or so from now when the price drops some I'll definitely be getting one of these K7's - for now I'm very happy with my K200D)
I follow your point, and agree




QuoteOriginally posted by Digitalis Quote
you're dead wrong mate, landscape photography often involves often running across hells half acre at freezing temperatures at the crack of dawn and getting your "shot" you scouted out the morning before,get your 8X10 set up on the tripod, focus on the dim ground glass, stop the lens down to f/22, use whatever amount of tilt/shift necessary to get the things you want in focus, slide the film holder on,hope the film hasn't buckled in the holder due to temperature changes, use an incident light meter to set your exposure, get everything in the right "zone", set the shutter to 1/4th and hope to hell you cocked the shutter before you miss the golden opportunity...

It takes me about 10~15 minutes to get everything set up properly when I'm using 8X10 view camera....but the results of a properly executed image on 8X10 especially with a high resolution film like Kodak Tech pan (theoretical maximum resolution is in excess of 600LP/mm)
That is one awesome picture !


QuoteOriginally posted by jeffkrol Quote
Understood, but not complete agreement. Your right though Pentax, w/ the blessing of the beancounters, did basically say.. "1/160th good enough"

You could just overexpose a RAW and post process it yourself. That's all these cameras are doing at 50 anyways.... losing DR in the process..
I'm sure I could find a few hundred of these as well as charts and graphs.
the Jeff is not me, and the thread is old:
Jeff:

"If the shot is correctly exposed, highlight issues will be the same regardless of the ISO."

That's not my experience with the 5D.

If you use equivalent exposures, you have a greater chance of blowing the highlights on ISO 50 than on any other ISO setting on my version of the 5D. When I first starting using it, I assumed that lower ISO = better. Just like film. That's an incorrect assumption.

Eric

ISO 50 - when to use it? - Photo.net Canon EOS Forum
This still applies though things are better...a bit simplistic of course.
To do 50 on the bodies that support it, the shot is exposed with the sensor at 100 but the metering system at 50, and then it's adjusted digitally. That's why you get less dynamic range at 50 than at 100.

Canon ISO 50 - Photo.net Canon EOS Forum
Newer:
ISO 50 is actually ISO 100 overexposed one stop. The in-camera RAW converter takes this into account and compresses highlight for ISO 50 only to 0.2 EV.
Chasing a Gray Cat In a Gray Room: the level of middle gray and the headroom in the highlights for Canon 5D Mark II | LibRaw


Yes but it cuts down on the flash power. Flash is pulsed rapidly to follow the shutter curtain slit. You really never get full power (or range)

As always, you have a ton of valuable links. You must be saving a lot of url discussions


QuoteOriginally posted by jbinpg Quote
@GoldenWrecked Angle: Re. lower ISO settings - If you do Multiple Exposures with Auto EV setting, then the *effective* ISO will be the ISO you shot at divided by the number of exposures. So you can get down to 11.1 ISO with the max 9 shots at ISO 100. Granted, ME will not be an option for many shots.
I remember hearing something like this before



QuoteOriginally posted by GoldenWreckedAngle Quote
Ditto that! The way David Ziser uses Canon's ability to cheat the synch speed is pretty cool. Because the curtain is moving faster than the T.1 flash duration it doesn't actually leave a hard black line; it's more like the effect of a strong gradient filter.
This is brilliant, thanks. I hadn’t thought of that.
As I understand it, he is using a Dumb flash.
(Does show the usefulness for many, of high Synch-speed; and how the higher shutterspeed will darken the sky down as well).

He talks about a second tutorial, is there a continuation of it ?


QuoteOriginally posted by GoldenWreckedAngle Quote
Yes, I know it's exactly the opposite of the way flashes currently work. In fact, extending the flash duration pretty much goes against everything flash engineers are trying to achieve right now. I'm trying to inspire some out-of-the box thinking on the part of the people who are actually intelligent enough to solve this problem rather than just speculate about it like me.

That Metz 1/125 limitation was one of the main reasons I didn't buy a Metz when I picked up my latest flash. The problem with small flash technology is that they don't really get more powerful as you up the juice, they just stay on longer to appear to get brighter.

What we need is a flash that actually gets brighter as synch speed increases. Come to think of it, there's not really a good way to do that with a Thyristor system... or is there? I'm starting to see some potential benifits in continuous lighting that I haven't considered before. Maybe using bright continuous light sources in conjunction with pulsing high speed synch flashes would get me in the neighborhood of what I need?

There's always the Joe Mcnally in the desert with a tree full of high-speed synch flashes option, for a price.
Pretty cool work. I like how he states : "I never met a subject I couldn’t overlight", and this is going into the desert of Dubai

Last edited by Jonson PL; 05-22-2009 at 05:10 AM. Reason: A lot of great info in the thread
05-22-2009, 03:24 AM   #94
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[ "Wake up buddy, it's not 1937 any more.

If you really want to go back to the dinosaur days of flash bulbs and unreliable shutters, that's certainly your perogative. Some of us look forwards to what we can do today, not backwards to some happier, simpler time when the sun was dimmer and fill flash was easier
." ]


I was looking through this thread to see if there was any info on whether the K7 has rear-curtain sync? Haven't seen it listed anywhere. Does it?

As for the comment above and the mood of this thread, I can only suggest that you guys actually go back to the 1930s and look at the photography of Harold Edgerton. He's the dinosaur who invented flash and with his crappy old cameras he could photograph bullets speeding through an apple at 1,000,000th of a sec. (and measure it). He also invented radar.

In fact, what you may not know is that you can take a photo with the K7, or indeed almost any camera, even a pinhole camera, at speeds of 10,000th-25,000th of a second etc by turning the flash power down to its lowest setting and firing in bulb. The flash acts as a shutter in effect by freezing the action at the flash speed, not the shutter speed. And flash speeds are very fast. By shortening the power output you are actually just shortening the flash speed. A vivitar 283 flash (a 1970s antique) works nicely...

You ought to check out some history before you go knocking it. Most of the masters have done it already and what you want to do with your camera can be done already. But I wonder if you understand things as much as you think you do.

Harold Edgerton - the master of flash. check him out then tell me what you think of dinosaur photographers and equipment. Then see how the K7 might do something that ain't in the manual or this forum...

Amen.

PS I admit I'm biased. I like the quality of pictures from the 1850s.

05-22-2009, 03:33 AM   #95
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I would say it most likely has rear curtain sync. my pentax K10 certainly does.

and that trick involving bulb mode does not really work during daylight hours.
05-22-2009, 04:04 AM   #96
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iso 50 or perhaps 25 in a new firmware update can solve the problem
05-22-2009, 04:38 AM   #97
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QuoteOriginally posted by RiceHigh Quote
Of course, unless you have invented a new type of mechanical shutter for use in DSLRs!
So how can the Canon 50D aps-c camera have a 1/250th sync speed?
Canon EOS 50D Review: 2. Specifications: Digital Photography Review
Shutter • Focal-plane shutter
• 100,000 exposure durability
• 30 - 1/8000 sec
• 0.3 or 0.5 EV increments
• Flash X-Sync: 1/250 sec
• Bulb

The 1/160 vs 1/250 was probably a purely economic decision... balance multiple factors (speed, endurance, x-sync) and come up w/ the most effective price/performence ratio. As an "engineer" you would come across this constantly.....

Last edited by jeffkrol; 05-22-2009 at 05:01 AM.
05-22-2009, 05:39 AM   #98
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In my opionion too ISO 50 would be the easiest solution for pentax. Even if it would be lower quality than ISO 100. It could be same kind of expansion as 6400 is on custom menu.
I'm sure that at least some of the flash shooters would be satisfied, even some others too.

.muus

05-22-2009, 07:06 AM   #99
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QuoteOriginally posted by mr.voigtlander Quote
[I]
... I can only suggest that you guys actually go back to the 1930s and look at the photography of Harold Edgerton. He's the dinosaur who invented flash and with his crappy old cameras he could photograph bullets speeding through an apple at 1,000,000th of a sec. (and measure it). He also invented radar.

In fact, what you may not know is...

You ought to check out some history before you go knocking it...

... I wonder if you understand things as much as you think you do.

... the K7 might do something that ain't in the manual or this forum...
Gee, I guess I ought to read some stuff er sumpthin...

Mr. Voigtlander, much as I appreciate the condescen... er, condensed history lesson on the good professor, and the concise explanation of high speed flash photography, I'm just not quite smart enough to figure out how either applies to this thread. Sorry, would you mind writing that a little more slowly for me? Thanks.
05-22-2009, 07:27 AM   #100
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QuoteOriginally posted by mr.voigtlander Quote
[ "Wake up buddy, it's not 1937 any more.

If you really want to go back to the dinosaur days of flash bulbs and unreliable shutters, that's certainly your perogative. Some of us look forwards to what we can do today, not backwards to some happier, simpler time when the sun was dimmer and fill flash was easier
." ]


I was looking through this thread to see if there was any info on whether the K7 has rear-curtain sync? Haven't seen it listed anywhere. Does it?

As for the comment above and the mood of this thread, I can only suggest that you guys actually go back to the 1930s and look at the photography of Harold Edgerton. He's the dinosaur who invented flash and with his crappy old cameras he could photograph bullets speeding through an apple at 1,000,000th of a sec. (and measure it). He also invented radar.

In fact, what you may not know is that you can take a photo with the K7, or indeed almost any camera, even a pinhole camera, at speeds of 10,000th-25,000th of a second etc by turning the flash power down to its lowest setting and firing in bulb. The flash acts as a shutter in effect by freezing the action at the flash speed, not the shutter speed. And flash speeds are very fast. By shortening the power output you are actually just shortening the flash speed. A vivitar 283 flash (a 1970s antique) works nicely...

You ought to check out some history before you go knocking it. Most of the masters have done it already and what you want to do with your camera can be done already. But I wonder if you understand things as much as you think you do.

Harold Edgerton - the master of flash. check him out then tell me what you think of dinosaur photographers and equipment. Then see how the K7 might do something that ain't in the manual or this forum...

Amen.

PS I admit I'm biased. I like the quality of pictures from the 1850s.

I prefer the work of Dr.Erich Salomon, master of available light.his weapon of choice was the Ermanox which he used to devastating effect. The ermanox was essentially an early 645 camera, I'll also point out it used a focal plane shutter with speeds from 1/20th to 1/1000th. The ernostar 85mm f/1.8 lens it was the noctilux of the early 1900s it's optical design pushed the limits of optical technology.

I perfer photographers that pushed the boundaries of what was possible instead of safely working within the limits of what was possible. If it wasn't for these progressive figures in history I doubt photography would be what it is today.

and now i'm going to go out with my classic Leica M3 with the Noctilux 50mm f/1.0 and do some street photgraphy....

Last edited by Digitalis; 05-22-2009 at 07:33 AM.
05-22-2009, 09:23 AM   #101
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Well, while were at it, let's not forget Winogrand, Adams (both Ansel & Robert), Friedlander, Alvarez, Brandt, Hine, Brassai, Evans, Porter... well, pretty much everyone who was well known before digital went mainstream.

Should I list the modern masters currently shooting at 1/250 or just conceed the point that I'm doomed to inferior image making because I feel 1/180 is a gear limitation I shouldn't have to work around with a modern DSLR?
05-22-2009, 09:38 AM   #102
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QuoteOriginally posted by Digitalis Quote
I prefer the work of Dr.Erich Salomon, master of available light... and now i'm going to go out with my classic Leica M3 with the Noctilux 50mm f/1.0 and do some street photgraphy....
Available light... I'll have to try that sometime - Flash synch problem solved. Why didn't I think of that. I'll be glad to return the favor of the old school lesson by showing you how to flip an avatar in Photoshop if your interested.
05-22-2009, 10:30 AM   #103
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What is the major contraint on allowing the camera shutter speed to go higher than sync speed and still take a photo with a darkened area? Some subjects can be great for this. Nikon, and Canon both do not limit shutter speed to sync speed. Why does Pentax do this? AND, this is something that could be easily chanaged in firm ware. Just add an override option in the menu somewhere.
05-22-2009, 10:34 AM   #104
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QuoteOriginally posted by jbinpg Quote
@GoldenWrecked Angle: Re. lower ISO settings - If you do Multiple Exposures with Auto EV setting, then the *effective* ISO will be the ISO you shot at divided by the number of exposures. So you can get down to 11.1 ISO with the max 9 shots at ISO 100. Granted, ME will not be an option for many shots.

Jack
Hang on now... I just re-read that and BLING, the light went on. Great idea! I'm going to do some more reading and experimenting on this one - Thanks.
05-22-2009, 10:36 AM   #105
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QuoteOriginally posted by Photomy Quote
What is the major contraint on allowing the camera shutter speed to go higher than sync speed and still take a photo with a darkened area? Some subjects can be great for this. Nikon, and Canon both do not limit shutter speed to sync speed. Why does Pentax do this? AND, this is something that could be easily chanaged in firm ware. Just add an override option in the menu somewhere.
I don't know if it can be overwritten in firmware or not but man-oh-man would I gladly pay for an upgrade to my K10D firmware to unlock it if it can.
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