Possible Major Constraint on the 1/180s X-Sync Limitation

RiceHigh · 05-20-2009, 05:45 AM

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!

cateto · 05-20-2009, 05:55 AM

Wrong thread.

Official BASH the K7 thread

mattdm · 05-20-2009, 06:05 AM

Originally Posted by RiceHigh

As long as Pentax have to choose between smaller miniature sized DSLR or a higher X-sync, they have NO CHOICE!

Sounds plausible — camera design has a lot of compromises to balance. I understand why some people would benefit from higher sync, but for me, the smaller size is way more important.

gazonk · 05-20-2009, 06:11 AM

Originally Posted by cateto

Wrong thread.

Official BASH the K7 thread

He's not bashing - quite the contrary!

ogl · 05-20-2009, 06:22 AM

Originally Posted by Erik

I'm going to put this thread out of its whimpering, pathetic misery right now:

Nikon D40. 1/500.

It's not by shutter.

ogl · 05-20-2009, 06:23 AM

Originally Posted by RiceHigh

I have seen a lot gripes and complaints about the 1/180s "flash" x-sync speed of the K-7 these two days.

higher X-sync, they have NO CHOICE!

There are the same opinions at Russian pentax club

Erik · 05-20-2009, 06:23 AM

Originally Posted by ogl

It's not by shutter.

I just realized that this is an apples/oranges situation and deleted my post, sucks that you would be quick enough to make me look stupid on the Internet forever

flyer · 05-20-2009, 06:24 AM

Originally Posted by Erik

I'm going to put this thread out of its whimpering, pathetic misery right now:

Nikon D40. 1/500.

I think the Nikon D40 uses a kind of electronic shutter WHEN the mechanical shutter is fully opened to obtain that X synch speed.

ogl · 05-20-2009, 06:31 AM

Originally Posted by flyer

I think the Nikon D40 uses a kind of electronic shutter WHEN the mechanical shutter is fully opened to obtain that X synch speed.

Yes. Right

and · 05-20-2009, 06:45 AM

canon 1000d and nikon d40x are both faster with 1/200

RiceHigh · 05-20-2009, 07:34 AM

Originally Posted by and

canon 1000d and nikon d40x are both faster with 1/200

The difference of 1/200 and 1/180 is 1/1800s or 0.55555.. millisecond. In EV terms, it is only 0.15EV. From both prospectives, it is more or less neglectible.

Torphoto · 05-20-2009, 07:46 AM

Originally Posted by RiceHigh

The difference of 1/200 and 1/180 is 1/1800s or 0.55555.. millisecond. In EV terms, it is only 0.15EV. From both prospectives, it is more or less neglectible.

true but we so were hoping for 1/250th!!

not a deal breaker once we understand that it's hard to put a big super fast mirror box in such a small cam.

Still ordering a K7 anyway.

Peter Fang · 05-20-2009, 07:52 AM

Originally Posted by flyer

I think the Nikon D40 uses a kind of electronic shutter WHEN the mechanical shutter is fully opened to obtain that X synch speed.

Yes, if I recall correctly, the D70 was the first one to use this kind of "hybrid shutter" for faster X sync speed.

Peter

Digitalis · 05-20-2009, 07:52 AM

have any of you guys HEARD the sound of a 1 series canon DSLR?...they aren't even remotely comparable to a Leica M3.

yes, the sync speed is a bitch, but it's either a louder shutter or a 1/2 stop slower synch speed...your pick.

if you REALLY need high speed sync, go buy yourself a Leica S system...the Leica 180mm f/4 leaf shutter lens is capable of sync at speeds faster than any current DSLR.

from what I have heard some S system lenses can sync at 1/1000s

CreV · 05-20-2009, 07:52 AM

Just tell me if pentax k-7 allow syncing flashes above x-sync; cheating x-sync

If I can sync above 1/180 I'm happy, I don't care if the shutterblade will cover half of the sensor at 1/400, just so I can place the subject in the "open" area.