Using old Auto-Flash with K100d

Papersniper · 11-25-2007, 10:45 AM

I have an old Sunpak Auto 144 Thyristor flash. I have a new K100d, and while I plan to get a P-TTL flash eventually, I'd like to try the Sunpak before dropping another $150 plus for camera stuff!

I guess I understand in general how to use the Sunpak, but not sure. Would someone look over my ideas below and tell me if I'm on the right track?

The Sunpak 144 has a slider settings for ISO, which then directs which f stop to use. For instance, if I set ISO 200, the f stop directed is f 2.8, which I cannot set with the 18-55mm kit lens, so I bumped the ISO to 400. Now the Sunpak indicates I need to use f4. Also with the directed f stop the flash gives the effective shooting range, which with ISO 400 is roughly 6 to 33 feet. I use ISO 400 as the flash setting in the example below:

Camera/Lens: K100d/18-55mm f4.5 (I can't set f4 with this lens so I just open it all the way; seems better than bumping the ISO to 800!)

Turn on and charge Sunpak - Set it to ISO 400. Aperture directed is f4.
Turn on the Camera - Set it to ISO 400 (same as flash)
Set Camera to Aperture Priority exposure, set to f 4.5, close to f4 as directed by Sunpak.

But when I try this, the shutter seems to be very, very slow, like maybe .3 second. I can't see the shutter speed, or maybe I don't know how to find that yet. The picture seems to be okay as seen on the LCD, I haven't down loaded to the PC.

It took me a few minutes of screwing around with the Sunpak to discover the ISO slider switch on the Sunpak has two stops. For ISO 400 set at the first stop, it says to use f4 on the camera, but if I slide the switch up to the second stop, it now says to use f11- What in the WORLD is that about? Is the switch busted or something? I don't have directions for the Sunpak 144 and there are no markings on that switch. I'm thinking this might be the "Auto" and "Manual" mode for the flash, but I don't know which is which.

Also, can someone please help me determine the guide number for the Sunpak 144 compared to say, the Pentax 360 P-TTL flash unit. They really confuse me with varying the distance, ISO and other factors - hard to do an apples to apples comparison. If the Sunpak has a very low guide number compared to the Pentax 360 I will probably upgrade sooner than later.

Also, is it possible it use the Sunpak as a slave unit with the addition of some sort of firing unit?

noblepa · 11-26-2007, 01:55 PM

Check the trigger voltage of your flash. I was told in an email response from Pentax, that my K10D can handle a trigger voltage of about 25 volts. I'm pretty sure that the K100D is the same in this regard.

Its easy to check. Just use a simple, cheap, multimeter set on voltage. Charge the flash and then put one lead on the center pin of the hotshoe and the other on the side connection.

Flashes designed for older cameras, which often had purely mechanical flash synch contacts, can have trigger voltages that are high enough to damage the electronic synch circuitry in DSLR's. For example, I have a Vivitar 283 that has a trigger voltage of 115 volts.

Vivitar has re-introduced the 285HV, in a form that has a low trigger voltage, specifically to sell to DSLR (and even the latest film cameras) owners. B & H is selling it for about $90. While the 285HV is not P-TTL compatible, it is a powerful automatic, thyristor controlled flash.

Paul Noble

*Canada_Rockies* · 11-26-2007, 04:45 PM

Your shutter is slow because of the AF system establishing focus. It is nothing to do with using the flash, except that the SunPak doesn't have an AF assist light for you. If you watch the bottom of your viewfinder carefully, you will see that the flash fires virtually simultaneously with the AF OK signal coming on.

*Mapleleaf-Mick* · 11-26-2007, 10:26 PM

Taking the above info into consideration, If I want to use my flash that is off camera (K10D)and attached with a synch cord. Do I set my program to manual; set my shutter speed at say 1/80th and set the aperature according to the guide on the back of the flash ensuring the ISO and distance are set in my camera as listed on the flash ? Does this ensure the flash goes off at the same time as the shutter is released?

Papersniper · 11-27-2007, 07:43 AM

"..trigger voltage of your flash.."

Thanks. I meant to add to my original post that I've done so already.

Papersniper · 11-27-2007, 07:47 AM

Originally Posted by Canada_Rockies

Your shutter is slow because of the AF system establishing focus. It is nothing to do with using the flash, except that the SunPak doesn't have an AF assist light for you. If you watch the bottom of your viewfinder carefully, you will see that the flash fires virtually simultaneously with the AF OK signal coming on.

If the AF signal is that green icon in my view finder, then no, it's indicated within a very short time of pressing the shutter halfway down. I don't actually trip the shutter until I see the the AF icon on and steady.

When I trip the shutter as described in the original post, the mirror drops/raises? so that the viewfinder is black for maybe .3 second, then I heard the "shutter sound".

Papersniper · 11-27-2007, 08:02 AM

Any more ideas why my Sunpak 144 has two "on" settings with vastely different f stops?

On the shutter speed, I think I'll just try setting the camera on Manual exposure and set the shutter to 1/180 second and whatever the flash indicates as the f stop, although I still don't have any idea why it has those two "on" settings. I suppose I can experiment to figure this out, but I was hoping someone could save me the time; I'm impatient sometimes! <G>

*Mapleleaf-Mick* · 11-27-2007, 08:20 AM

Do those two "on" settings represent two levels of power or a primary and secondary flash?

*Mike Cash* · 11-28-2007, 04:09 AM

Originally Posted by Papersniper

Any more ideas why my Sunpak 144 has two "on" settings with vastely different f stops?

On the shutter speed, I think I'll just try setting the camera on Manual exposure and set the shutter to 1/180 second and whatever the flash indicates as the f stop, although I still don't have any idea why it has those two "on" settings. I suppose I can experiment to figure this out, but I was hoping someone could save me the time; I'm impatient sometimes! <G>

It is meant to cover two different distance ranges, which should be indicated in some way on the scale. Beyond the range, the flash isn't strong enough to get you the aperture indicated. Short of the range the auto circuitry can't assure you of shutting down the flash output in time to avoid overexposure.

Papersniper · 11-28-2007, 07:01 AM

".....It is meant to cover two different distance ranges...."

A-HA! That makes sense. Thanks.

Artesian · 12-01-2007, 11:45 AM

I have a Ds and use a Pentax 280T flash on it. I used this set up with the 18 to 55mm kit lens. I found that if I set the apreature I wanted (around F11) in the Av mode and press the AE-L button , then change the setting from AV to Manual, I can then set the shutter speed to what I want, up to 1/180sec. I was always over exposing because it wanted to set the aperature at f4. This seems to work pretty well. I am not sure about the K100 or the K10 though.
SH

keithg · 12-05-2007, 08:53 PM

Paul. Seems to me like Pentax want to get there act together and say what is right and what is wrong as far as voltage is concerned with K10D. I have a 30 year flash that is 190 v. I rang Pentax and spoke to there technical department and was told it was no problem what so ever. I questioned again and same responce. They told me that how it works on the Pentax was no different to what it has been for years. They said it used the same system. So, ive used mine for months including weddings and it does a fantastic job with no problems what so ever. On another site pentax quoted 600v. [Steves] Other well known brands. Different story. Cheers Keith

wombatwal · 12-09-2007, 04:25 AM

I am led to believe that 6V is the maximum recommended for DSLRs.
My sunpak (old one) gives me from my measurements 180V. I would not use it connected directly to a K100D.

Papersniper · 12-09-2007, 07:58 AM

Originally Posted by wombatwal

I am led to believe that 6V is the maximum recommended for DSLRs.
My sunpak (old one) gives me from my measurements 180V. I would not use it connected directly to a K100D.

I can't ague with that. Mine measured a lot less, about 6-8 volts I think. I have not measured it lately, but it's working fine with the K100d, although I still want to get a dedicated P-TTL when I can figure out which will work best for me and not cause me to sell a kidney.

filmamigo · 12-10-2007, 09:08 AM

Originally Posted by Papersniper

If the AF signal is that green icon in my view finder, then no, it's indicated within a very short time of pressing the shutter halfway down. I don't actually trip the shutter until I see the the AF icon on and steady.

When I trip the shutter as described in the original post, the mirror drops/raises? so that the viewfinder is black for maybe .3 second, then I heard the "shutter sound".

That's the correct behaviour. I use a Nikon SB22s flash with my *ist DL and see the same thing.

When you are using an auto-only flash, (or something that's not fully compatible like my Nikon) then the flash won't automatically set the camera shutter speed to the maximum synch speed. The feature of having the flash tell the camera to set the maximum synch-speed (which is 1/125 second for the DL, and is often 1/90 or 1/60 on older cameras) is what you get with a "dedicated" flash, which will communicate with the camera.

Without a dedicated flash, your camera continues to think that it is shooting with no flash. So, after you set an aperture in Av mode, the camera adjusts the shutter speed to get a good exposure *with no flash*. As you experienced, that means a long shutter speed. Same thing happens if you leave it in P mode.

If you want to set a shutter speed that is faster, you need to go fully manual. Use the camera and the flash in exactly the same manner you would use an old manual 35mm SLR. Set the shutter to speed the maximum "X" synch speed (1/125), set the aperture to the number indicated on the back of your flash based on the distance from the camera to subject. Doublecheck the exposure, and if it's a little dark or a little light, tweak the aperture.