External Flash

Using the Nikon 950/990 with an external flash. 

(Last update October 19, 2000)

I recently bought a (non-Nikon) external flash to use with my CP950 and CP990. A lot of this information applies to using the internal flash too. Although the flash study shown here was done with the CP950, I have now added annotations and notes where the CP990 differs.

NEW! Thinking about getting a flash? I've written down everything I know about it in a Q&A section right here. Also see Tips on using a flash, applies to all flashes.  An excellent place to start on external flashes in general for the 950/990 is the super external flash FAQ by Don Wiss at... External flash FAQ

Warning! Be sure to get the Nikon hot shoe pinout if you order one of these flashes, they make several different versions with the same "266D" model number.


Flash Setup

Here is my external flash setup sitting on a tripod. Sorry about the harsh flash shadow.

THE FLASH: The flash is a Sunpak 266D. I ordered it with the Nikon hot shoe mount. This flash has four modes,

1) Manual, just fires the flash at maximum.

2) A program mode for f2.8

3) Another program mode for f5.6

4) TTL mode.

The TTL mode is the most useful with the 950, although you can use the program modes if you want to.

Note about using a non-Nikon flash: Nikon recommends using a Nikon flash. You could damage the camera if you use a flash that has too high a trigger voltage.  (New! Nikontech has now said on the Nikon BBS that the maximum voltage is actually 250V, previously they had said 15V). Nikon Flashes are 5V. This Sunpak flash measured 7V (measure DC voltage between the center pin on the hot shoe and the outside contacts). You take your own chances using a Non-Nikon flash. Watch out, some older flashes are 200V or more on the flash shoe contacts, I just recently bought a Vivitar 2000 flash at Wal-Mart that was this hot. This would almost certainly damage the camera.

I chose this flash for several reasons... it was cheap!... it is a smaller flash, more suited to the closer pictures that I take... Sunpaks were reported to work with the 950... it has Nikon TTL... it uses regular AA batteries ... It has a "zoom" flash; you can set the flash head lens to cover several different focal lengths.


The cable is the Nikon AS-E900 cable. I bought it from bugeye digital (www.bugeyedigital.com). (I am not affiliated with them) The cable is about a foot long and has the three pin connector for the camera on one end, and a hot shoe on the other end. The bottom of the hot shoe has a regular tripod mount screw hole (1/4 20 thread) so you can attach it.


The Bracket is a random camera bracket that I got at a local camera store. It was necessary to modify two things on the bracket to get it to work. 1) I bent the bracket so that the cable that exits the bottom of the 950 woudl clear. 2) I took off the flash shoe that came with the bracket and drilled a hole for a 1/4 20 screw to hold the AS-E900 hot shoe in place. On second thought, it might be better to cut out a notch for the cable rather than bending the bracket as I did. Oh, well, too late!

Flash Tests

I made a series of test shots with the flash under controlled conditions trying to pin down each point. I will probably be doing more as more questions come up. For all of these shots, I used the 950 at ISO 100 because that matched one of the ISO settings on the flash exactly. These shots were all at 1/30 second at f3.1 using M-Rec mode on the 950, except as noted. I tried to use approximately 50mm zom on all the shots. Matrix metering was used. I reduced the shots to 400x300 for the web, you can still judge the illumination level. The Table was about 8 feet away. I have noted where the 990 performs differently in the same test.


Same shot but with the internal flash on. Note that this filled in the shadows a bit but did not really change the exposure.


Starting here, Auto flash. Auto white balance, internal flash off. f2.8 program Note the green cast.

Conclusion: Turning on the internal flash does not change the overall exposure.


Same shot, with the internal flash off, with white balance set to Flash. Note that the white balance is a lot better.

Conclusion: The 950 does not automatically set the white balance to FLASH when firing the flash! You have to do this manually if you want it! There are some advantages to doing it this way, see below.. Note, the 990 DOES seem to set flash white balance when the flash is used.


Trying the f5.6 program mode. Not particularly informative, and I had the camera set to f3.1 I guess you would not really expect this to work.


Manual flash program mode. This just fires the flash at it's maximum, with no squelch of the flash. This could be used in a very big room I guess, but again, not very informative. It does show how the camera does squelch the flash, I suppose.



TTL program mode on the flash. Ah. That looks good. Not much different than the f2.8 program, which is to be expected because the camera was set to f3.1; very close to f2.8. This is the mode where you would expect the best performance. Manual flash white balance.

Conclusion: TTL program mode on the flash works well.


Ceiling bounce with the flash at the same settings as above. If the internal flash had been on also, this would have looked nicer. Bounce always gives me warmer colors, due to multiple reflections off objects in the room.


Same shot as the TTL shot two above, but with auto white balance, again showing that the camera does not set flash white balance by itself.


How about the white balance in A-Rec mode? As you can see, it is the same green cast; the wrong white balance.

Conclusion: The white balance is not set to Flash in A-Rec either, and you can't do anything about it! No wonder so many people complain about green looking flash shots. This means that you should never take a flash shot in A-Rec! (Unless you are using the flash for just fill, in which case the auto white balance setting might be correct) You need to be aware of this when shooting.


The same shot as The "TTL PROGRAM SHOT" above, but with the internal flash on. Still auto white balance.

Conclusion: Using the internal flash does not help the auto white balance flash problem.

The next 3 shots test the EV setting effect.


The auto TTL shot with flash white balance set No EV correction.


Same, EV+2


Same, EV -2

Conclusion: The EV setting does not change the exposure "set point" for the TTL flash operation. This is unfortunate, because this means that you can not use the EV setting to make your pictures lighter or darker if the flash is not exposing properly.  I am not entirely sure how this should work, but it does seem that the EV setting should have an effect since it changes the "target point" for the exposure. The CP990 is the same.

The next shots test aperture priority effect


Switching the camera to aperture priority. f5.2. This did come out less exposed.


Aperture priority f8.7. Even less exposure.

Conclusion: Setting smaller apertures than the standard wide open for flash on the 950 results in less exposure.  This is not what I would expect, you would think that the camera would compensate with the flash duration for the larger aperture. Apparently it does not, but that is good!  This means that you can pick a smaller aperture to control the flash exposure a little.

On the 990, the camera appears to compensate correctly for the smaller apertures and exposes the shot correctly. This is a major difference between the 990 and the 950.

Test of ISO settings effect.


TTL Program shot, ISO 80


ISO 100


ISO 160


ISO 320

Conclusion: On the 950, with the flash set to ISO 100 in TTL mode, the ISO on the camera does effect the results, with higher ISO being brighter.

Again, I would have expected the camera to take the boosted ISO into account when calculating the exposure for the TTL flash. It does not appear to do so. This is also good, you can use this to brighten the exposure.

The CP990 also shows this effect.

Daylight fill flash


Daylight shot with heavy backlighting. No flash. ISO 80


Same shot with TTL flash fill. Auto white balance. Flash forced on. External flash only.


Manual flash mode showing lack of squelch. This demonstrates the ability of the TTL mode to squelch the flash even when forced on.

Conclusion: TTL flash force on can be used for "fill in" with daylight shots.


I've moved the table to achieve a situation with even heavier backlighting. No flash shot.


TTL flash fill in. A lot better, except that there is a slight green cast because I used auto white balance (this might not have happened with the 990 that uses flash white balance for flash). I should have looked at the scene and decided that the flash light would be most of the light and set flash white balance manually.

Flash burn out at close range test.


I took a series of shots. This was from about 2 feet away. Having trouble getting the flash pointed at the subject!


A foot away. The flash is still squelching nicely but the coverage is off.

Shutter priority mode.

Photos not shown; uninteresting. I had been thinking that I would be able to control the flash exposure by using shorter shutter speeds. This is totally wrong of course. Why? Because the duration of the flash is so short. For example, the flash unit that I am using shows a flash duration of from 1/1600 to as little as 1/30000 second. That is too short for even the fastest shutter speed on the 950 (1/500 sec) or the 990 (1/1000 sec) to make any difference. All of the test photos looked alike.

Warming filter


External 950 flash shot, internal flash off, auto white balance


Same 950 shot with flash white balance set, the greenish cast is improved. Note, the 990 sets flash balance automatically when the flash is used.


Same shot with a Wratten No. 81EF warming filter over the lens. OK, maybe this is too warm, but I could see using it for portraits


Same shot with the warming filter over the flash. Note how this shot is brighter than the shot with the filter over the lens. This is because with the filter over the lens, the sensor does not know about it and exposes the shot the same.


Just for fun, a neutral density filter over the lens. You can use a neutral filter to reduce the flash exposure as much as you like. Again, because the sensor cannot tell that you have placed a filter over the lens, the shot is darker.

Comments and summary of findings.

The flash program on the Nikon 950 seems to be very primitive. The 990 is only slightly better. You will need to keep certain factors in mind when you use it. Keep in mind that this is not a true TTL flash, the camera simply squelches the external flash when it thinks that enough light has reached the sensor on the front of the camera, it is not based on metering at the "film" plane. In addition, the program used to calculate the proper amount of light is very primitive. 

* On the 950... First, it does not set the proper white balance in either M-Rec or A-Rec modes. This means that the flash is really unusable in A-Rec mode since there is no way to change the white balance there. A -Rec might be used for fill-in during daylight. This is not all bad! The problem is mixed light situations. In that situation (say some light from incandescent lights), the camera has no way of knowing how much light the flash it going to contribute to the final shot. (some cameras use a pre-flash, to measure this, but that has it's own set of problems, I prefer this method). If the camera set flash white balance all the time, it would result in horrible white balance in mixed light situations due to the higher color temperature of the flash. These mixed light situations are very common, and there would be a lot of complaints about the flash white balance, so not setting flash white balance is actually a good choice for those situations. It does seem that there is room for improvement though; the camera could :"know" when it is dark enough that the flash light would be the major component on most shots, and set white balance to flash.

   The way that the camera does work now means that YOU have to decide which light is going to contribute the most to the final shot, and set white balance appropriately.

* The camera does account for the use of the internal flash when it is turned on, and does not overexpose when both the internal and external flashes are used. You can feel free to turn on the internal flash to soften flash shadows without fear of overexposure.

* The camera does not take EV settings into account when calculating the correct amount of light for the flash. In other words, the camera just ignores your EV changes both for setting the exposure and for squelching the flash. I think that it should change the exposure target point when you make EV changes.

* The camera does not take ISO settings into account when calculating the squelch for the flash either. I'm not sure which ISO setting the flash program is correct for, but I suspect 80 (100 for the 990). (I used 100 for most of these shots). If you change the ISO, you get brighter or darker pictures. I think that this is actually a good thing, since it lets you adjust the exposure in a primitive way.

* The 950 does not take aperture changes into account either for the squelch calculation. This is especially problematic, because your aperture varies depending on your zoom level. I think that the camera ignores this.  The 990 appears to compensate correctly, but may not be compensating if you change the aperture with the P* mode, ( I have to experiment more)

* I suspect that the camera flash program calculations are only correct for 1/60 sec, f2.8 at ISO 80 and default EV at one zoom level, and possibly only 50mm zoom.  Note that this makes it very hard to get good flash exposures.  (for the 990, 1/110 second, wide open)

I would like the camera to work the following way:

* When the flash fires in very low light, flash white balance should be used. (this is fixed on the 990.)

* When you make EV changes, it changes the target point for the amount of flash light that is is correct exposure for the TTL system. Users would make adjustments to the flash exposures using the EV setting. This is how other cameras work.

* The ISO and aperture priority behaviours should probably stay the way they are.


Tips on how to use an external (or internal) flash.

* Set the flash white balance yourself when you need to on the 950.. If the light from the flash will be the primary souce, use flash white balance. If Sunlight will be the primary source, use sunny or auto white balance. Always keep the light source in mind and set the flash accordingly. If the scene is almost totally dark, manually set flash white balance. On the 990, if sunlight will be the primary source, set sunny white balance because it picks flash white balance automatically.

* Keep in mind the published "minimum working distance" for your flash. If it says 4 feet, then don't complain if your shot at 3 feet is overexposed.

* If the flash is overexposing your shots, a common problem, try these things.

1) On the 950, set aperture priority and go up to the next allowed size. (smaller opening). The camera does not pay attention to this when calculating the exposure, and you get darker shots. You can stop down all the way if you have to. On the 990, just reduce the flash power in the flash menu.

2) On the 950, set ISO 80. (default) This makes the camera expose less. The higher the ISO, the brighter your shots.

3) Turn off the internal flash if using external.

4) Use bounce flash if using external especially if you are closer than 4-5 feet.

5) You can try a thin piece of tissue paper over the internal flash to diffuse it. The thinner the better. Don't cover the flash with tape or it might burn up.

*  Keep your fingers away from the sensor in the front. It needs to see the light from the flash. A common problem is to get your finger or camera strap near the sensor, which reflects light into the sensor and results in a mysterious super dark flash shot. I've had this problem when shooting flash through a fence.

* Changing the shutter speed will not help you because even the longest flash duration is shorter than the fastest speed you can set on the 950 or 990, sorry!

* You can use a warming filter or neutral density filter. If you put the filter over the lens only, it will reduce the overall exposure since the sensor does not know that you are doing this! If you put the filter over the flash, it can change the color of the light. A Wratten 81EF filter works for me.

External Flash Q&A (This is everything I know about the subject, not in any particular order though!)

* If you order a Sunpak flash, or bid on one at auction, be very sure to order/get the Nikon style hot shoe. TTL squelch will not work on the Nikon 950 or 990 if you don't get the Nikon hot shoe. I can't emphasize this enough, people have gotten the wrong versions of this flash. Mine has a little sticker on the side that says "Sunpak, dedicated for Nikon Cameras".

* A good page about flashes in general is here. A good starting point, better read that first if you don't know what a zoom flash or what a program mode or a guide number is.

* There are several mounting options. You can either get the AS-E900 cable and bend up or make your own bracket, or buy the official Nikon bracket SK-E900, which comes with the AS-E900 cable. The AS-E900 cable is only one foot long! There are some other cables that might work, but they start at 5 feet!

* The AS-E900 shoe has daisychain ports.

* Hint, you can take the AS-E900 apart, and make the wires come out the other side.

* The TTL flash feature (where the camera adjusts the flash during the exposure) does work if you get a flash with the TTL setting, but it is not "real" TTL. The camera will squelch the flash based on light received at the flash sensor on the front of the camera; it usually works pretty well. Where it starts to mess up is when the geometry isn't right, such as a very close shot where the sensor can't "see" the spot that the flash is illuminating.

*  Nikon SB-28 and other flashes:  NONE of the other fancy flash features that your flash might have will work, such as multiple flash,  red-eye reduction, auto focus light, zoom setting etc, even on the official Nikon flashes. None. Absolutely zero. The type of flash does not matter. This especially applies to the Nikon SB-28, which is loaded with features that the camera can't use. You need a flash with a manual "zoom" head for the flash if you want that feature, for example. There are only three conductors in the official cable, just enough to trigger the flash and for a squelch line. No other features are supported on ANY flash. In my opinion, it is not worth paying extra for those features unless you think that the flash might be used on some other camera some day. Don't waste your money on flash features that the camera will not be able to use.

* You can also use a flash that has a "program" mode, where you fix the aperture on the 950 to match one of the program settings as close as you can.  Program mode means that the flash controls it's own exposure with a sensor on the flash. If you do this, pay attention to the useful range for that mode as shown on the back of the flash usually. Since there are only three apertures available, you might have to zoom in or out a bit to get a better match. A program mode can be very useful if you have a lens such as the TC-E2 or wide angle that blocks the flash sensor on the camera, preventing you from using the pseudo-TTL mode.

* On the 990, the flash program modes is especially easy to use if you set constant aperture mode. That will (try to) hold the aperture constant as you zoom. The fact that you can set any aperture is great.

* The 950 does not really have enough flexiblity to be used with a fully manual flash or with limited program mode flashes  (non-TTL or program, just fires). Such a flash might be useful in a big room though. The problem is that there are not enough aperture settings (only 3) on the 950 to give you enough control. If you have a flash that is fully programmable, you will be able to match the limited aperture settings on the 950 with the flash exactly.

* You might think that you can control the flash exposure with the shutter priority mode, I did! However, this will not work, since the duration of the flash is so short, even shorter than the 1/500 second fastest speed that you can set on the 950 or 1/1000 on the 990.

* Some flashes have a reduced power mode (1/2 1/4, etc). That could be useful for fill flash or for very close shots. Mine does not have that feature so I can't test it, but it is reported to work nicely. This does NOT help for TTL mode though, but it might help you get reduced minimum range from a flash.

* A manual zoom setting on the flash is nice. (usually a movable lens over the flash that controls the "spread" of the flash). That lets you focus the flash for telephoto shots. Remember. motorized zoom heads will not work with these cameras.

* If your typical shooting is at close range (not trying to light up a big hall), you might want to consider a smaller flash with lower guide number. There are some reports of overexposure with larger flashes, but I really don't have any experience with this. I chickened out and bought a smaller flash. This might depend on what the minimum duration that is availible for the flash is. Pay attention to the minimum working distance, they aren't kidding! The minimum distance can be even larger if you have a bright object in the field.

* You can use the internal flash with the external flash for more light or softer shadows if you like. The camera seems to squelch both properly.

* The guide #s for the Sunpak 266D that I have at ISO 100 are 66 for the 35mm setting, 80 at 50mm, 86 at 70mm, 92 at 135mm. The flash measures 7.2 volts at the hot shoe.

* I can't tell you what flash to get. I have heard of people using the Nikon flashes of course, with the 22s and 28 being the most popular. I have heard of the following Sunpaks working, 266D, 355AF, 433D. I am not recommending these flashes, just reporting what I have heard.. If you can afford it, get an official Nikon flash so you don't have to worry.

* Whatever flash you use, be sure to check the voltage on the hot shoe!  Nikon has now said on their BBS that up to 250V is safe, but this is hearsay, check it out for yourself. The Nikon flashes are supposed to be 5V, but often read 6V or more.  Nikon mentions the possiblity that a flash might appear OK, but might spike up higher than 250V when it fires. Do not blame me if you burn up your camera. I have however not heard of a case of any flash damaging a 950 or 990 yet.

* Check out Juri Munkki's external flash setup page, it is very nice.

* Minimum working distances. Pay attention to the minimum working distance published for your flash. They aren't kidding. If the minimum working distance is 5 feet, don't be too surprised if you get blow outs on closer shots. For example, the Sunpak 266D mentioned above, the minimum working distance at F2.8 is 5 feet at ISO 100. Note that the CP990/950 uses full open aperture with the flash if you are using auto, so don't expect the flash to work closer than 5 feet. At F5.6, the minimum distance is 2 feet. Some flashes have better minimum distances, and you can always stop down more if you want to get closer.


Summary of differences between the 950 and the 990 when using external flash.

* The 990 does appear to set flash white balance when using the flash

* The 990 does appear to compensate for aperture changes that you might set.

* The 990 has an EV adjustment for the flash (although why they didn't just make the regular EV adjustment work instead, I don't know). The adjustment works for the external flash as well as the internal.