Sigma DP1M,DP2M,DP3M flash options- the Metz 20 C-2 or the Sigma EF-140 shoe mount flash?

There are currently two flashes that are small and fit on top of the Sigma DP Merrill Series compact cameras, the DP1M, DP2M and DP3M that I would trust. The most advanced flash is the Sigma EF-140 DG flash which features TTL  which prior to the exposure, the camera tells the flash to fire a pre flash, then the camera measures the exposure and  decides what flash level output is needed to provide the right amount of light. This happens at a fraction of a second before photo is shot. This type of flash system really works very well.  Just put the flash on the camera, turn it on and you can set your camera to use the TTL flash as fill flash or as a regular flash---It is simple, not much thinking is involved etc. It can be used manually as well. The Sigma EF-140 sell for around $89.00 ( USD).

I have used Sigma flashes on my Canons and  Sigma DSLRs for years and have never had any issues with Sigma's TTL flash technology. It works. The EF 140 DG has a guide number of 46' (14.02 m) at ISO 100 and 16mm focal length illumination coverage as it was designed for the original DP1 which had a wide angle lens.  Takes two AAA batteries and has a recycle time about 5.5 to 6.5 seconds. The flash lacks a bounce flash feature.There were some complaints that Sigma didn't put a built in flash on the DP Merrill series compact cameras.  I disagree. I really dislike built in camera flashes. I like to have full control over what flash I put on a camera, but I also want a compact flash that also enables me to bounce the flash as well.
I notice that the EF-140 DG flash is no longer mentioned on the Sigma website but can still be purchased from internet retailers so I don't know the status of this product long term--whether is it being refreshed with a new replacement or is being discontinued. But the bottom line is that the EF 140 DG flash was designed for a wide angle camera, so it should work with the DP1M, DP2M and DP3M but lacks a bounce flash feature. No word on this from Sigma yet.  I've put an information request in on the status of the EF 140 DG, so if I get an update from Sigma--I'll share that with you.

So if you are wanting a compact flash with bounce feature, 
would you brave using an old school Automatic flash with Tilt reflector?

Enter the Metz 20 C-2 compact manual flash. At $49.00 (USD) pictured below.

Sigma DP2M with Richard Franiec's add on grip and the Metz 20 C-2 flash

Sigma DP2M with Metz 20 C-2 flash. Notice the locking switch at the foot of the flash.

This flash has a guide number of 20 at iso 100/21 degree coverage ( 35mm focal length)  You have two automatic apertures to choose from if you want to use the flash automatically--F 2.8 (green) and f5.6 (red).  Here is how it works.  Attach it to your camera ( Any camera that can trigger a flash with its mount will work with this flash or any camera that has an X socket can use a cable to attach to the flash's own sync socket

 as well.  The Flash's foot has a locking switch that you lock when you attach the camera to the top of the camera flash shoe. 
Set your camera on manual exposure. Set your camera at the base flash shutter speed at 1/125th of a second or 1/200th --whatever flash setting your camera uses. (Remembering that this flash can be used on any camera) In the case of the DP Merrill series compacts, set your camera ISO at 100. Then put your aperture ( lens opening at either f2.8 or f5.6) Remember if you select F2.8, then you need to put the switch on the back of the camera to F2.8 ( Green). If you use f5.6--then put the switch on the f5.6 setting( Red)  The rest is simple.  Point the camera and shoot. This is an automatic flash but not a TTL (through the lens) flash. It uses a sensor on the front outside of the flash so be careful not to block the sensor with a large lens hood. The flash does not get its information from the camera or communicate with the camera.  It only receives the trigger from the camera's hot shoe, telling it to flash.
The external flash sensor meters the scene and figures out what the flash output should be. The newest firmware update of the DP Merrill compacts allows flash sync speeds at 1/125th sec. I've tested flash sync speeds at 1/125 and 1/200th sec and both work with the DP2M.  Of course you can use the chart on the back of the flash and set the flash manually as well based on how many feet away you and use different Iso other than two auto setting choices. 

 For novices, this may seem daunting with all these new terms--ISO, F-stop, shutter speed etc. 

So here is a quick primer:

ISO--this is the setting that makes the sensor more or less sensitive to light---a carry over from the film days when you would buy a iso 100 film for shooting in the daytime and iso 400 or higher for shooting in lower lighting conditions. 

F-stop- This is simply the size of the opening of the camera lens aperture. This is controlled by little blades that you will see change the size of the hole into the lens by opening and closing the hole. The smaller the number--the more light that is allowed into the lens to the sensor  Example-f2.8. The larger the number , the less light that is allowed to enter and hit the sensor, Example --F5.6.

Shutter speed--This is how fast the shutter opens and closes letting light in to hit the sensor. Most flash sync settings are 1/125th of a second to 1/200th of a second.  The advantage of TTL flashes that these meter through a camera's lens and the camera and the flash are communicating with each other to provide accurate scene illumination.  The Metz has you do some innitial settings, then the flash meters the scene and gives the amount of light it thinks the scene needs and then the right LED will flash red afterward briefly to confirm that you got the correct exposure.

Using the Metz flash is really very simple. Remember if you use the bounce setting---you will get underexposed photos if you don't have anything overhead to bounce the light off of.  In a house with an 8 foot high white ceiling--there should be no problem shooting with the bounce, but you may have to increase your ISO setting from 100 to 125 or 200 respectively--or change your shutter speed from 1/200th to 1/125th as well. You can always use the chart on the back of the flash and shoot manually.  Just pick the ISO you want to use, how many feet you are away from the subject and the chart will tell you what the F stop should be set at. Expect to fiddle with the controls and experiment if you are going to be bouncing the flash. It can be tilted to 30- 45- 60 or 90 degrees. The flash duration is between 1/1200 to 1/25000 of a second with a color temperature of 5500K.  It is designed for to be shot at iso 25 to iso 400. The written manual has a some nice math formulas that you can use to figure the exact setting to use the flash for more advanced features like fill lighting etc. Note: Read the manual. 

I've really never understood what all the fuss was about it being hard to use manual flashes or the older " Auto" flashes that came before TTL type flashes used proprietarily by each camera manufacturer. Surprisingly, there are quite a few of us from the film days that still know how to manually use flashes but this is a simple skill that might come in handy for novice photographers or newbies to flash photography. The nice thing about the Metz is it's simplicity with its two Auto flash Fstop settings of F2.8 and F5.6.  The addition of having the ability to bounce the light and the low cost for this pocketable flash make it a good option for use with your DP Merrill compact series cameras or any camera for that matter.  If you need a more automated through the lens TTL flash option, then the only flash available right now is the Sigma EF-140 DG flash with a slightly higher price tag and minus the bounce feature, or put a full size Sigma EF 610 Standard or DG super Flash on top of the camera for use with the DP Merrill series compact cameras.  Some of the other manufacturers make smaller TTL flashes for their respective brands, so you might have a compact solution

Do I recommend the Sigma EF-140 DG over the Metz 20 C-2 or vice versa?  No--that depends on your needs. If you don't need to bounce your flash and want a small pocketable TTL flash, then the Sigma EF-140 DG is going to work better for you but at a premium.  Want to bounce flash with a compact flash? The you might consider the Metz 20 C-2. 

I should mention there are more powerful manual flashes with manual mounts for available from Metz and also a full size one from Vivitar, both coming in around the $89 range USD as well if you want to go the auto sensor on the flash route instead of the Sigma TTL options, but these full size flashes will look mammoth on the tiny  DP Merrill series compact cameras (DP1M, DP2M or the newest offering, the DP3M).  For compact pocketable simplicity stick with the Sigma EF-140 DG compact flash or the Metz  20 c-2 compact flash.  Pick what will work best for you. The Sigma EF-140 DG being the simpler more sophisticated solution and the Metz requiring a little more user input for Auto flash mode but has the additional feature of enabling the use of bounce flash in your photography. Of course, you could own both. 

Metz 20 C-2 with bounce flash feature

Finally, how about the obligatory first Pet photos using this very interesting little flash on my DP2M direct without bounce just to give you a taste of the Metz 20 C-2?  Buddy agreed to model for me on short notice---I accidentally knocked the shutter sync speed from 1/200th to 1/160th--whoops--but when shooting raw--the files are so forgiving, so i didn't reshoot as Buddy wanted to renegotiate his modeling contract and get paid with more dog food.

F5.6 (RED) Auto mode, iso 100 at 1/160sec flash

F2.8 ( Green) Auto mode, iso 100 at 1/160th sec 

Happy Shooting!