Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
11-11-2014, 07:42 AM   #16
Pentaxian
Oldbayrunner's Avatar

Join Date: Mar 2013
Posts: 1,661
QuoteOriginally posted by LensBeginner Quote
A tele will hardly help if your main subject's face is in the shade and you can't/don't want to ask him/her to move (a street performer, for instance).
A reflector would most certainly be more helpful, but the topic is about flash and I took for granted that in this hypothetical situation flash use were necessary.

Huh again, I can use a telephoto lens with the person in the shade, use off camera flash or strobe, drop my ambient light settings and obtain a beautiful defocused background using a telephoto lens all without using and ND filter or using HSS and without asking the person to move, so using those are not the only way as you previously stated.

I can also use a telephoto with on camera flash using a rogue diffuser, lambancy diffuser or something of that nature with the person in the shade and obtain a creamy smooth background. Using a telephoto lens is one of the best lenses for defocusing backgrounds with or without flash lighting. What you are forgetting is the ND filter or HSS use is to control your ambient light and have very little to do with defocussing a background, the lens used and aperture control that.


Last edited by Oldbayrunner; 11-11-2014 at 07:59 AM.
11-11-2014, 07:44 AM   #17
Veteran Member
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 4,696
QuoteOriginally posted by cybertaff Quote
No one shot at a time, the shutter is timed and synched to the release of the water drops, in this case from a solenoid…. The faster I can get that shutter speed the sooner I can catch the collision between them and get more interesting shapes.
But, as I said, the exposure is made only by the flash, unless you also have natural light (which I doubt)!
I mean... what happens is:
1. click!
2. first curtain opens
3. FLASH! (a thousandth of a second or less)
4. exposure lasts 1/180 or 1/250 or 1/10 or whatever (in the dark)
5. second curtain closes

You can try with 1/15s or even 1s and get the exact same result, with a tack-sharp drop since it's only illuminated by flash!
That's why I believe flash sync is a non-issue in your case, flash duration is much less than exposure duration.
11-11-2014, 07:47 AM   #18
Veteran Member




Join Date: Dec 2010
Location: Ontario
Photos: Gallery
Posts: 3,332
QuoteOriginally posted by cybertaff Quote
No one shot at a time, the shutter is timed and synched to the release of the water drops, in this case from a solenoid…. The faster I can get that shutter speed the sooner I can catch the collision between them and get more interesting shapes.
Sorry, I'm also not getting it. Are you saying that when the flash fires during the exposure depends on the cameras shutter speed? AFAIK that's not the case, and if you click the shutter at the same time you'd get the same results using 1/180s, 1/250s, or 1/2s (assuming ambient was low enough to not contribute to the exposure).
11-11-2014, 07:49 AM   #19
Inactive Account




Join Date: Nov 2014
Location: london
Photos: Albums
Posts: 93
no im saying the formation is influenced by how soon i can get the whole thing to happen . but please remeber Im trying to time three diffrent drops colliding please belive speed is an issue, not for the exposure but for the end formation if you will, as i said its a niche thing, i use up to six of those yougnuo yn560 mk2 set at 1/128 , but recently have upgraded my flashes to hss and am happily shooting as fast as i like, (currently trying to capture an air gun pellet through an egg)

11-11-2014, 08:03 AM   #20
Veteran Member




Join Date: Dec 2010
Location: Ontario
Photos: Gallery
Posts: 3,332
QuoteOriginally posted by cybertaff Quote
no im saying the formation is influenced by how soon i can get the whole thing to happen . but please remeber Im trying to time three diffrent drops colliding please belive speed is an issue, not for the exposure but for the end formation if you will, as i said its a niche thing
Are you saying the timing of the flash is changed by the shutter speed? I don't care if it's niche or not, I'd still like to understand what's going on. I've never done anything requiring such precise timing so maybe things happen at different shutter speeds that I'm missing.

Maybe something of an aside here, but have you tried bulb mode in a dark room and syncing the flash firing with the water drop release (with appropriate delay) instead of letting the camera trigger the flash? If you decouple the cameras control of the flash and handle it directly, wouldn't you get much finer control of when it captures the splash?
11-11-2014, 08:20 AM   #21
Veteran Member
AquaDome's Avatar

Join Date: Jan 2014
Location: New Carlisle, IN
Photos: Gallery | Albums
Posts: 1,475
QuoteOriginally posted by BrianR Quote
Are you saying the timing of the flash is changed by the shutter speed? I don't care if it's niche or not, I'd still like to understand what's going on. I've never done anything requiring such precise timing so maybe things happen at different shutter speeds that I'm missing.

Maybe something of an aside here, but have you tried bulb mode in a dark room and syncing the flash firing with the water drop release (with appropriate delay) instead of letting the camera trigger the flash? If you decouple the cameras control of the flash and handle it directly, wouldn't you get much finer control of when it captures the splash?
That works great with film. A dSLR should be able to do it also, BUT: in a film camera, the film sits passively awaiting the light. At most, only a tiny electromagnet is powered to hold the shutter open. In a dSLR, holding the shutter open engages everything on the data-bus. It sucks almost as much power as leaving the camera in Live View or shooting video. Expect rapid battery drain.
11-11-2014, 08:20 AM   #22
Veteran Member
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 4,696
QuoteOriginally posted by Oldbayrunner Quote
Huh again, I can use a telephoto lens with the person in the shade, use off camera flash or strobe, drop my ambient light settings and obtain a beautiful defocused background using a telephoto lens all without using and ND filter or using HSS and without asking the person to move, so using those are not the only way as you previously stated.
I don't get it...
Let's say you shoot the person from 10ft with a 50mm at f/2, pretty much ok for a portrait. DoF is 0.96ft on a Pentax APS-C
Let's say you take a 200mm tele and walk away, so the subject stays the same size in the frame.
You get 39.8832ft* 200mm at f/2, and FoV is still 0.95ft, so quite comparable... Even by f/2.2 you still get a much deeper DoF...
How is this minimal difference going to help you in dropping ambient light? Am I missing something?

* 27° vertical AoV (50mm lens), vertical size 4.7879ft at 10ft... same vertical size for a 6.87° vertical AoV (200mm lens) entails a 39.8832ft distance from subject

11-11-2014, 08:22 AM   #23
Pentaxian
Oldbayrunner's Avatar

Join Date: Mar 2013
Posts: 1,661
QuoteOriginally posted by LensBeginner Quote
But, as I said, the exposure is made only by the flash, unless you also have natural light (which I doubt)!
I mean... what happens is:
1. click!
2. first curtain opens
3. FLASH! (a thousandth of a second or less)
4. exposure lasts 1/180 or 1/250 or 1/10 or whatever (in the dark)
5. second curtain closes

You can try with 1/15s or even 1s and get the exact same result, with a tack-sharp drop since it's only illuminated by flash!
That's why I believe flash sync is a non-issue in your case, flash duration is much less than exposure duration.
Huh? No it's not, there are still two exposures, ambient and flash, you create your effect by controlling both exposures.

Not not necessarily, at certain shutter speeds the second curtain is closing slightly behind the first curtain, the flash exposure lasts and occurs during the interval inbetween.
11-11-2014, 08:23 AM   #24
Inactive Account




Join Date: Nov 2014
Location: london
Photos: Albums
Posts: 93
QuoteOriginally posted by BrianR Quote
Are you saying the timing of the flash is changed by the shutter speed? I don't care if it's niche or not, I'd still like to understand what's going on. I've never done anything requiring such precise timing so maybe things happen at different shutter speeds that I'm missing.

Maybe something of an aside here, but have you tried bulb mode in a dark room and syncing the flash firing with the water drop release (with appropriate delay) instead of letting the camera trigger the flash? If you decouple the cameras control of the flash and handle it directly, wouldn't you get much finer control of when it captures the splash?
Yeah am trying it with lasers atm... looks hopefull
11-11-2014, 08:24 AM   #25
Veteran Member




Join Date: Dec 2010
Location: Ontario
Photos: Gallery
Posts: 3,332
QuoteOriginally posted by AquaDome Quote
That works great with film. A dSLR should be able to do it also, BUT: in a film camera, the film sits passively awaiting the light. At most, only a tiny electromagnet is powered to hold the shutter open. In a dSLR, holding the shutter open engages everything on the data-bus. It sucks almost as much power as leaving the camera in Live View or shooting video. Expect rapid battery drain.
True, but you're not holding the shutter open for long at all here for it to matter. You're not sitting in the dark with the shutter open waiting for something to happen, you get to control when the water drops (in this case).
11-11-2014, 08:28 AM   #26
Veteran Member
LensBeginner's Avatar

Join Date: Sep 2014
Photos: Albums
Posts: 4,696
QuoteOriginally posted by Oldbayrunner Quote
Huh? No it's not, there are still two exposures, ambient and flash, you create your effect by controlling both exposures.

Not not necessarily, at certain shutter speeds the second curtain is closing slightly behind the first curtain, the flash exposure lasts and occurs during the interval inbetween.
Not if the studio is completely dark, or if you're stopped down, or the exposure is massively low with respect to what it would be needed to get a picture without the flash. Natural light becomes a negligible and two pictures shot at 1/250 and 1/180, even less in some circumstances would not show changes in exposure or movement because the "natural light photo", so to speak would be massively underexposed, while the bulk of the exposure would be made by the flash.
That's what I expect in a strobist-like drop-dropping scenario.

If you're not past sync speed (which is the point in this discussion) then the flash fires in a moment when the sensor is completely exposed, first curtain has completed its travel and second has yet to start moving.
Past sync speed there's only part of the sensor exposed at any given moment, but then you cannot use a non-HSS flash, and it's beyond the scope of this discussion.

---------- Post added 11-11-14 at 04:32 PM ----------

QuoteOriginally posted by BrianR Quote
Sorry, I'm also not getting it. Are you saying that when the flash fires during the exposure depends on the cameras shutter speed? AFAIK that's not the case, and if you click the shutter at the same time you'd get the same results using 1/180s, 1/250s, or 1/2s (assuming ambient was low enough to not contribute to the exposure).
This.
11-11-2014, 08:37 AM   #27
Veteran Member
AquaDome's Avatar

Join Date: Jan 2014
Location: New Carlisle, IN
Photos: Gallery | Albums
Posts: 1,475
QuoteOriginally posted by BrianR Quote
True, but you're not holding the shutter open for long at all here for it to matter. You're not sitting in the dark with the shutter open waiting for something to happen, you get to control when the water drops (in this case).
When I do it, there is always lots of fiddling and fumbling in the dark before anything happens.
11-11-2014, 08:48 AM   #28
Veteran Member




Join Date: Dec 2010
Location: Ontario
Photos: Gallery
Posts: 3,332
QuoteOriginally posted by AquaDome Quote
When I do it, there is always lots of fiddling and fumbling in the dark before anything happens.
Sounds like my first time, but I got better with practice.

Wait...what are we talking about again?
11-11-2014, 08:58 AM - 2 Likes   #29
Site Supporter
Site Supporter
maxfield_photo's Avatar

Join Date: Mar 2011
Location: Cincinnati, OH
Posts: 1,216
QuoteOriginally posted by Culture Quote
Why do people complain about the 180 flash sync speed for Pentax compared to Nikon that has 250. I mean the difference is not even half a stop. Can the difference have that much effect on the ambient light during flash photgraphy?
The easiest way to understand the problem is to get out there and try it yourself. Go out on a bright sunny day with a friend, and bring your camera and a HSS capable flash unit. Now, put the sun behind your subject to give a nice glow to the hair, and to keep him/her from squinting. Put your camera in Shutter priority and set, oh 1/4000th as the shutter speed, and take a shot. That's about the shutter speed you'd like to use to get a nice portrait, but obviously you won't get a flash and your friend will be completely backlit.

So now switch over to manual and start stopping down your lens until the point where you can activate your flash. 1/4000th>1/2000th>1/1000th>1/500th>1/250th>1/180th That's 4 and a half stops (1/180th is half a stop under 1/250th by the way) So if you started at f/1.4, your lovely portrait will now be at an uninspiring f/6.7.

Now that you are at (or below) your max sync speed, you can begin to compress the dynamic range of the scene with a flash and get some blue back into those blown out skies. Unfortunately your lens is at f/6.7 which has reduced your guide number from 50 meters down to 7.5 meters. Now that's at full power, but for reasons that I won't go into (but you can read up on it), you really don't want to shoot at full power if you can help it. You really want to be at quarter power or less. So that brings your working distance down to 3.7 meters. Did you want to add a softbox to make those shadows a little less harsh? That will cost you another stop. Are we done yet? Nope. The light from the flash is cooler than the ambient light, so that will require maybe a 1/2 CTO gel to keep your subject from looking cyanotic, that's another half a stop. So our final working distance is about 2.2 meters, hope you only wanted a headshot.

BUT, you say, there's always High Speed Sync! Well, try it. As soon as you cross the max sync barrier, your guide number drops to about a quarter of the full power of the flash. As you crank your shutter speed higher to cut out more ambient light, more and more light from the flash is wasted bouncing off the ever-widening shutter curtains, and very little actually makes it to the sensor. By the time we get back up to our original 1/4000th, you working distance is about the end of your lens, so hope you brought a macro lens (hey, they're good for portraits... of nose hair)

Ok, so what is the point? Well as you have observed some users complain that Pentax has a slower max sync speed than Canon or Nikon, these folks are also missing the point. The point is that Canon and Nikon's sync speeds are also too slow, but when trying to balance ambient light, every stop counts. Ideally there would be no such thing as max sync speed, you'd be able to sync all the way up to the camera's maximum shutter speed. There are some cameras, like the Nikon D70s, that can do that by using a hybrid electronic/mechanical shutter, but there are some problems getting that trick to work with a CMOS sensor. Leaf shutters in lenses would be a good compromise, but there are far too few of those out there and none for the K-mount. Those who say 1/180th should be good enough are obviously not trying to take the same types of images as those who advocate for higher sync speeds.

[edit: Oh, almost forgot, because of Pentax's implementation of HSS, you need a HSS flash attached to the hotshoe. This means that unless you have multiple flashes, you won't be able to stand back with a telephoto lens, you need to be close to the subject. Don't get me started on the Pentax flash system]

Last edited by maxfield_photo; 11-11-2014 at 09:03 AM.
11-11-2014, 09:05 AM   #30
Veteran Member
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,996
Aside from some special applications such as the one mentioned by cybertaff, I don't think that the max sync speed matters that much in our every day use when compared with slightly higher sync speed offered by Canikon cameras. I find it to be sufficient for my use to freeze subjects at 1/180 shutter speed.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
ambient, aperture, curtain, discussion, exposure, exposures, filter, fires, flash, flash sync, hss, light, lighting, moment, photo studio, sensor, shutter, slit, strobist, sync
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K30 Flash Sync Speed rp_dxn Pentax K-30 & K-50 5 05-22-2014 02:52 PM
Flash Sync speed Wolfeye Pentax K-30 & K-50 3 09-29-2013 10:25 AM
Pentax K5 flash sync speed old4570 Troubleshooting and Beginner Help 26 09-16-2013 05:20 PM
K20D slow speed sync flash mpress Troubleshooting and Beginner Help 3 05-20-2013 08:19 PM
K-01 maximum flash sync speed? truonganh Pentax K-01 6 11-15-2012 11:36 AM



All times are GMT -7. The time now is 04:49 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top