Steve's Digicams Forums

Steve's Digicams Forums (
-   Flash (External) (
-   -   Flash Unit for Sony A 100 (

sonofgerry Jul 6, 2007 12:49 AM

I can't afford a genuine unit at the moment, can anyone suggest an alternative? By the way, does anyone know the safe trigger voltage for the sony?

Mark1616 Jul 6, 2007 4:30 AM

I would check out the Sigma options if you can't afford the Sony 36, as for the voltage I'm not sure.

JimC Jul 6, 2007 10:28 AM

According to Pete Ganzel (a camera expert that has the KM service manuals and has disassembled KM DSLR models), the hotshoe circuitry is at TTL level with no voltage protection built in. The Alpha is based mostly on the KM 5D, and so it should be the same.

So, it's probably a good idea to stay with a flash with a trigger voltage of around 5 or 6 volts (although I personally wouldn't worry about it if it were under around 10 volts).

What's your budget?

If you don't mind usng Manual Exposure and setting the Aperture and ISO speed on the camera to match the selected Auto Range on a strobe, you can use an old Auto Thryistor type flash via an FS-1100 adapter (which is designed to give you an ISO standard hotshoe). You'd give up HSS and wireless with most of them.

I spent a total of $48 for a flash system to use with my Maxxum 5D (and that included two flashes).

* $16 for an FS-1100 equivalent third party adapter from a Hong Kong based vendor to give me an ISO standard hotshoe. You can get the same adapter here:

* a Sunpak 222 Auto with tilt and two aperture ranges for a smaller flash unit (GN of about 72 feet at ISO 100) for $7.00 from (and they even threw in a nice, coiled PC Sync Cord with it).

* a Sunpak 333 Auto with tilt, swivel and zoom head with multiple auto aperture ranges, as well as better manual settings (full, 1/2, 1/4, 1/8, 1/16).

GN runs from 86 feet to 120 feet at ISO 100, depending on the zoom head setting. I got this one for $25 (like new in box in 10 condition from the used department at B&H).

Total Flash System Investment: $48

These are Auto flashes (in the sense that the flash is capable of throttling it's own ouput, based on how much reflected light it sees for the aperture range selected).

So, it's not as tough as it sounds (more of a set and forget in most indoor environments, letting the strobe control the exposure).

My Sunpak 333 Auto has 3 auto ranges. These ranges have different distances from short to long they can be used at. For example, one of the ranges probably runs around 3 to 22 feet at f/5.6 and ISO 200.

So, I just pick a range and set the camera to the same aperture and ISO speed shown for it on the strobe, and let the flash control it's own output within the range selected.

Shutter speed makes no difference for the amount of light the camera is seeing from the flash. That's because the flash burst is very short (my Sunpak 333 Auto will use a flash length of between 1/1200 second and 1/20000 second).

The only reason to vary shutter speed with a flash exposure is either to allow more or less ambient light in, or to make sure shutter speeds are fast enough to prevent motion blur if there is a lot of ambient light contributing.

That's why many cameras simply set the camera to a fixed shutter speed of around 1/60 second when you use the built in flash. It's a compromise setting. The flash burst length is then varied to control the actual exposure.

If you set it to around 1/100 second, that will be fine for the majority of indoor conditions where you'd need a flash if you are using something like ISO 200 and f/5.6.
If you're like me, you wouldn't be changing apertures a lot indoors anyway.

In a newer non-dedicated Auto Sunpak, the 383 Super has roughly the same specs as my 333 Auto (but, then you'll pay a lot more as they tend to go for around $70 new).

Note that the hotshoe adapter does *not* have voltage protection built in. I'd make sure to measure the trigger voltage for any strobe you want to use via one.

I've got some older Vivitars that I would not try to mount on my KM 5D for fear of frying it without using a Wein Safe Sync to isolate it. See this page for details on trigger voltage. That's why I went with the used Sunpaks (most of these have much lower trigger voltages).

I know of some people that use the newer Vivitar 285HV via an FS-1100. But, some of the older ones had high trigger voltages.

In a dedicated flash, I'd personally avoid the Sigmas. I've seen multiple KM DSLR owners that decided to return them, sometimes even after the flash made more than one trip to Sigma for recalibration (and sometimes coming back with worse exposure accuracy than they had to begin with).

Some of the newer serial number Sigmas are supposedly using more compatible firmware. But, reports I've seen are a "mixed bag" (some owners report exposure problems, some owners report they work OK).

Here is a chart that may help out if you can look at the serial number on a Sigma EF 500 DG Super, if you really want to consider using one:

Serial # 1 or 2xxxxxx are non Dg and are not compatable with KM5D/7D/a100

Serial # 3 to 6xxxxxx DG MA version. Flash needs to be set to FP (high speed sync) using the sel button on the flash, and setting the camera ADI Auto.

Serial # 7xxxxxx DG MA-ADI version. Set flash to FP and the camera to ADI Auto.

Serial # 8xxxxxx Default setting is FP. No sel changing necessary.

Note that even with the newer (supposed dSLR compatible) models , I've seen it reported that some compensation may be needed, depending on whether or not you're bouncing.

Strangely, most people report that exposure is fine when the flash is off camera using wireless, even those with severe exposure problems otherwise.

There are a number of other choices around now, too. But, be very careful. Most dedicated flashes designed for the Minolta Maxxum flash shoe were designed for film cameras. Most of these are not compatible with KM or Sony dSLR models and will only fire at full power if you try to use one.

JimC Jul 6, 2007 10:46 AM

If you really want a dedicated flash, here is a thread concerning a lower cost (compared to Sony/KM models) Sunpak that you may want to look into:;forum_id=84

sonofgerry Jul 7, 2007 8:05 PM

I have a Minolta Auto 200X and a FS1100 clone which together work onthe Sony A100. I think I will stick with them for the time being. Thanks for the advice.


shmeldrick Jun 10, 2008 6:42 AM

Hi, this is my first ever post on this site, I just joined because I wanted to ask if the sunpak 383 flash is fully compatible and safe with the sony a100 using this adapter, please tell me out of experience, not guessing because I don't wanna damage my camera!

JimC Jun 10, 2008 6:49 AM

The 383 Super will work fine via an FS-1100 equivalent adapter. This flash model has a relatively low trigger voltage.

I've seen a number of posters mention using one, and I've got a Sunpak 333 Auto I use myself on both a KM 5D and Sony A700. My 333 Auto is an older model compared to the 383 Super with similar specs + a manual zoom head).

As for compatibility, you'd need to use manual exposure on the camera, setting the camera and flash to match for aperture and ISO speed, keeping your shutter speed set within the camera's x-sync limits (you'd need to keep your shutter speed at 1/125 second or slower with stablization on, or 1/180 second or slower with stabilization off). So, it's not a dedicated solution, you wouldn't have high speed sync support, and their is no communication between the flash and camera (except for triggering the flash).

shmeldrick Jun 10, 2008 6:56 AM

I see, thanks, although I've heard it's a semi-automatic flash and I'm not really sure how it works, if anyone could explain it to me?

JimC Jun 10, 2008 7:01 AM

This flash has a built in sensor designed to measure reflected light, and you have sliders you can vary the settings with (after selecting one of 3 Auto Ranges).

When the flash sees enough reflected light for the aperture and iso speed selected, it automatically terminates the flash output.

One benefit of that approach (letting the flash control it's own output) is that you eliminate the need for a metering preflash.

shmeldrick Jun 10, 2008 7:07 AM

so does that mean I use manual mode, Put in the aperture and iso settings on the camera and then on the flash to match. Then I put the maximum shutter speed (I think it's 1/1000) and the flash stays on for as long as it needs? (sorry for all the questions but I have never used an external flash, never mind one like this!)

All times are GMT -5. The time now is 6:03 PM.