Paul C. Buff, Inc. Technical Forum

Greetings,

Equipment Used:
- 3 AB 800
- HSA
- standard sync cord
- Pentax K10D small format camera

I'm having little luck with using the PC sync cord with the HSA to fire the first of 3 flashes in my setup. If I press the HSA's test fire button it'll fire every time, but when shooting it fires maybe a quarter of the time and cannot be counted on. The camera is set to fully manual, and I've tried various flash settings other than red eye (hehe).

Would it be crazy to just use my camera's wireless mode to set off the onboard flash which in turn triggers all flashes since my onboard flash will not contribute to the exposure?

Any help with this would be much appreciated :shock:

first, i will guess the thumb knob is tightened quite snugly on the HSA. If so, loosen it a bit. As it tightens, it actually draws up the contact ball off the shoe, losing contact. If this does not work, take a paperclip or balde of a knife and jump the metal square foot to the center contact ball on the bottom. Do the lights fire?

Using the on board flash is not reccommended as all digital cameras emit a preflash that will fire the lights too early and result in underexposure. (there may be a threshold on the AB settings that make the flash to appear to work properly in this configuration, but do not be fooled). That said, if your flash has a manual mode, you can set it to that mode and dial it down as low as possible. Since this mode eliminates preflash, it will trigger your lights rather reliably. Do not use any built in remote function, as even in manual mode, there are typically communication preflashes.

Thanks so much for your reply.

I've tried loosening the HSA a bit, and I do see now how I can press down on the ball spring.

Needless to say I'm very new to using strobes, and playing with the shutter speed has proven interesting. Is it normal for the strobes not to fire when the shutter speed is set to 200 or higher? I'm getting consistent pops with f11 and shutter speeds of anything less than 200, the ISO is 100. As soon as I make the shutter speed 200 or higher the strobes no longer fire.

This is probably operator error on my part, not understanding a key concept. Any clarification would be very helpful :D

That is abnormal, however not impossible. It has been a few years since i played with the K10D, so i am working on hypothesis here. Every camera has a sync speed, typically between 1/125 and 1/250 (exceptions always apply). This is the fastest shutter speed that will expose the entire frame at once as the flash fires. With faster shutter speeds, the second curtain of the shutter starts to close before the first curain finishes its journey. If you exceed this speed, you will get black bands (from the second curtain) encroaching on your image. The faster the shutter speed, the bigger the band. At some point, the entire frame will be black, both from timing and shutter curtains.

If you are not getting any firing of the strobes (that is not just an absence of light in the image, but the lights actually do not fire), it is possible Pentax has designed the camera so that the hotshoe is disabled at faster shutter speeds (unless a dedicated Pentax speedlite is used). If so, this could be a custom function you can over ride. Again, this is hypothetical.

Otherwise, i do not know why it will not fire at higher speeds if it fires at lower speeds. Even if it is the case, you are probably better served leaving it there anyway, as shutterspeed typically has no bearing on a flash image (again, exceptions apply).

No pentax/samsung cameras can trigger at speeds higher than x-sync. Firmware shuts off the middle pin if you exceed 1/180

I really appreciate the replies.

My camera does have a X-sync mode I can play with, I don't fully understand what it does quite yet, reading the manual now.

Do I need to be concerned about not having a shutter speed more than 180 in manual mode in my home studio setup with 3 AB 800's?

I apologize about my inexperience, though I've read quite a bit it does take some practical and per-case knowledge to get things humming!

Thanks again and I'm looking forward to your response(s). :mrgreen:

quick answer: if you take a photo without the flashes firing (but all other settings the same), and the image is complely black, then a faster shutter speed will not be helpful.

Long answer: First, let's remove the all syncing limitations, and pretend a camera can sync at any shutter speed and get the full amount of flash in doing so (this statement would be impossible, but that is another discussion all together). In a completely black room (no lights at all, except for the actual burst of light from the flash), if you maintain the same ISO, aperture, and flash output, you can take a portrait of 10 minutes, 1 minute, 1 second, 1/100, & 1/1000 of a second, and get exactly the same exposure, with no motion blur. This is because the shutter speed only cuts the amount of ambient light (zero divided by zero is still zero). We don't live in such a vacuum, and ambient light will exist. Usually this is in the form of interior incadescent or flourescent lighting, which is still usually very low. Typically 1/125 of a second is enough cut the ambient light to nothing. If you wish to include some of the environmental lighting, you can lower the shutter speed to let it soak in. Outdoors, the more you raise the shutter speed, the darker you can make a sunny day, letting the flash expose the subject properly, adding contrast and drama.

Adding our limitations back in, you cannot go over 1/200 outside, so you need to reduce your aperture to cut the sun, necessitating more flash power (or more efficient flash power). This is about the only time a faster sync speed is useful.

Flash durations will vary from model to model, but the flash duration (t.1, the action stopping ability measurement) on an AB800 is 1/1100 of a second (at full power). This means if the flash is the sole (or overwhelmingly dominant) source of light, you will freeze action the same as you would if your camera was set to 1/1000 shutterspeed, thus negating the need for an actual higher setting on your shutter speeed. If ambient light is fairly high versus flash power, some blurring can occur, so be careful lighting basketball games, for example.

a few things to remember:
shutter speed only affects ambient exposure
flash output settings only affects flash exposure
ISO will equally effect ambient and flash exposure
Aperture will equally effect ambient and flash exposure

I can't thank you enough for your time and expertise.

For me this is the 'ah ha!' :idea: moment that helps solidify what I've read and what I think I know. I hope others find this information helpful in the future.

I'm printing this to have at my side while I learn to use your equipment and this type of photography, thanks again!

:!: