Help me understand Matrix Balanced Fill-Flash in the Nikon F-801

[NowhereMan]

I recently got myself a Nikon F-801s and I've only just finished the first test roll. One of the few complicated things about this camera is flash photography. Especially what Nikon calls the Matrix Balanced Fill-Flash I find difficult to understand. Maybe someone who knows the camera can shed some light on this?

Here's a table of the various TTL flash modes available with the F-801 (the left SB-24 column represents fill-flash mode, the right SB-24 column represents standard TTL mode.)

As I understand it, Matrix Balanced Fill-Flash basically adjusts flash output so that the main subject is well balanced with the background - and for doing that it relies on brightness and contrast information from the Matrix Metering system and distance information from the lens. Does that sound about right?

Well here are some of the things I don't understand / would like to know:

1. When the camera is in Matrix Metering and one of the automatic exposure modes it shifts exposure as soon as a flash unit is connected – sometimes quite dramatically. So for example on a sunny day it will underexpose the scene by around 1.3 to 1.7 stops. In manual exposure mode the light meter reading will change by the same amount as soon as a flash is detected. This results in shots with a correctly exposed subject and an underexposed background. This doesn't happen in Center-weighted Metering. What's the rationale behind this? It seems to be the exact opposite of what the Matrix Balanced Fill-Flash is supposed to do. Of course I can override the cameras settings in manual exposure mode but it's annoying having to switch off the flash every time I want to meter the light. Here's an example of what I mean (picture taken in A prio mode):

2. According to the table, Matrix fill-flash is possible in manual exposure mode with an SB-24 flash unit but not with the older flashes. Why would this be the case? All the flash unit needs is a start and a stop signal, this should be possible with any of these flashes.

3. I mostly use manual exposure mode for flash photography. So what is in this case, technically speaking, the difference between using Matrix fill-flash and standard TTL flash? Doesn't standard TTL also use exposure and distance information?

4. Which TTL modes are you using most with the F-801? I also have a Nikon FE2 that only has center-weighted TTL and I am actually quite happy with the way it works. With some experience you can tell in which situations you need to adjust the flash by how much. So I am wondering whether I should bother with Matrix flash at all.

 

[Christiaan Phleger]

Mm, a couple of things about this particular Nikon and Matrix-level flash work, you'll need to have an AF lens with a CPU on it and it may possibly require a "D' level CPU for most accurate results.
"Matrix Fill-Flash" is a different concept than 'Matrix Metering" even tho it uses MM for M-FF, and M-FF is designed to only add 'fill', the SB-24 on-wards has a compensation to add or subtract exposure for the subject.

How I would do outdoor flash for wedding group portraits is to take a overall exposure reading, (likely 1/250 at f/5.6-8, ISO 160 -1/3 stop) and then dial in some exposure compensation on the flash depending on the 'look' of the grouping, all the fellows in black I'd dial back the compensation to -.7 and the ladies in lighter tones -.3 to zero. This is only for a light fill on the face, with a slightly warmed gel on the flash head.

My favorite flash units for that work was a Metz with the proper module, Metz had a physical switch for the flash compensation and I could flip it to More Or Less by feel without fiddling with a screen or sub-menus, this made working quickly with rowdy groups easier and kept my exposures in spec. I found the F4 to be the best for this work, the N8008/801 would give inconsistent fill without warning. I needed accurate, consistent results and it seemed the f4 was more consistent.

 

[NowhereMan]

How I would do outdoor flash for wedding group portraits is to take a overall exposure reading, (likely 1/250 at f/5.6-8, ISO 160 -1/3 stop) and then dial in some exposure compensation on the flash depending on the 'look' of the grouping, all the fellows in black I'd dial back the compensation to -.7 and the ladies in lighter tones -.3 to zero. This is only for a light fill on the face, with a slightly warmed gel on the flash head.

This is basically my approach too, with the FE2. With the F-801, would you rather use matrix or center-weighted metering in this case? It seems to me that matrix metering is obviously better for people who just want a point-and-shoot experience. But if you know how to meter light properly then center-weighted or even spot metering might be the better option because it allows you to more precisely meter for a particular area that you want to have properly exposed.

When I do fill-flash in daylight in manual exposure mode I always underexpose the background a little bit. But I can't see why the F-801s Matrix-FF algorithm underexposes by more than 1 stop.

 

[Ardpatrick]

Here is an amazing resource I rely on for all things Nikon SLR & Flash:

Nikon Autofocus Flash Model: SB-24 TTL Speedlight

At the very least, it will give you a clear idea of how the F801 & SB24 are supposed to work together in Matrix balanced fill mode.

And to add regarding your question 3 in the first post - TTL and Matrix Metering are not interchangeable concepts. TTL only refers to flash measured 'through the lens' which can be centre or spot metered too. Matrix Metering is measured through the lens, but includes lots of other calculations incl. AF focus distance, focal length etc.

 

[NowhereMan]

@Ardpatrick Thanks, I know that website, I think I first consulted it back in 2001 when I was given a Canon A-1 Can't believe it's still online and as confusing as ever. Pure Web 1.0.

Regarding my question 3, I guess you misunderstood. I meant: what is the difference between a) Matrix Metering + Matrix Fill-Flash and b) Matrix Metering + Standard TTL Flash? I am asking because I would guess that the standard TTL flash in this case also uses brightness and contrast information from Matrix Metering to determine the appropriate flash output.

 

[Ardpatrick]

That site is an old one, but it's a good one. I've relied upon it myself for guidance on my SB800 which I use very occasionally on everything from an F80 to an F5 to a D800 to a Mamiya 7!

Elsewhere I found a manual for the SB-24

https://cdn-10.nikon-cdn.com/pdf/manuals/archive/SB-24.pdf

It seems clear enough to follow, and I think the question you raise is directly addressed on pages 27-28. Beyond that it's hard to say because I can't verify the manual against either an SB 24 nor an F801s (I had one 1992-2001 and loved it). Sorry I can't be more helpful.

 

[Robert Ley]

Five months ago I picked up a F-801s like yours because I wanted a backup for my F4. Turns out I like the 801 more than my F4. I use an SB-600 on all my Nikon cameras and this flash works very well with my DSLR's and I also use mostly AF-D lenses. I haven't really used it much with the film cameras. Spring has finally come to my neck of the woods and I expect to start shooting more film and want to see how the SB-600 works for fill flash.

 

[reddesert]

I am very much not an expert on this subject, but two thoughts, which seem to agree with the SB-24 manual discussion:

- I think the designers of matrix balanced fill flash saw it as a way to automatically activate the flash to avoid an underexposed subject due to light background. They may have settled on a flash exposure that produces more of a light subject / dark background than a perfectly balanced subject and ground. However, since light subject and dark background is usually much more aesthetically effective than dark subject / light background, they may have decided to err on the side of underexposing the background. It also depends on their limit of slowest shutter speed; bringing up the background requires shorter flash and longer shutter, and they may have imposed some limit (for camera shake reasons).

- If you use standard TTL rather than matrix-balanced, I think you can dial in flash exposure compensation to lower the fill flash amplitude and bring down the subject relative to the background (or more generally, the flash relative to the ambient). Back when all this was pretty new, IIRC people would discuss extensively where they wanted to put that flash exp comp value, like somewhere between -1/3 to -1 stop. I believe Christiaan was mentioning that.

 

[NowhereMan]

Elsewhere I found a manual for the SB-24

It seems clear enough to follow, and I think the question you raise is directly addressed on pages 27-28. Beyond that it's hard to say because I can't verify the manual against either an SB 24 nor an F801s (I had one 1992-2001 and loved it). Sorry I can't be more helpful.

I think I now understand at least the technical difference between Matrix Fill-Flash and standard TTL. With standard TTL, flash duration is determined exclusively by the amount of light reflection from the film – which is detected by a dedicated sensor. With mTTL that "baseline" flash duration is corrected based on the data from Matrix Metering. So mTTL is actually an automatic flash exposure compensation.

The problem I have with the example images in this and other manuals is that they very clearly don't reflect my own experience. Take the outdoor shot of the backlit girl. Background exposure stays the same with or without fill-flash. This is the way it should be. As Nikon write: "A better result can be achieved by leaving the exposure set to the brighter background and then using the flash to illuminate the darker foreground subject."

So why the heck does my camera in the same outdoor situation lower background exposure by more than 1 stop when it detects a flash?

- I think the designers of matrix balanced fill flash (...) may have settled on a flash exposure that produces more of a light subject / dark background than a perfectly balanced subject and ground. However, since light subject and dark background is usually much more aesthetically effective than dark subject / light background, they may have decided to err on the side of underexposing the background.

As I said before, this stands in direct opposition to what Nikon claims mTTL is for. Quote: "The result is a well-balanced photo with the correct exposure for both background and foreground subjects."

I have read lots of manuals and even bought a book about the F-801. But I haven't found anywhere a mention of this automatic underexposure in Matrix Metering. I'm starting to think this is a defect in my camera but it would be a very strange defect since it's otherwise working perfectly.

 

[Ardpatrick]

I think I now understand at least the technical difference between Matrix Fill-Flash and standard TTL. With standard TTL, flash duration is determined exclusively by the amount of light reflection from the film – which is detected by a dedicated sensor. With mTTL that "baseline" flash duration is corrected based on the data from Matrix Metering. So mTTL is actually an automatic flash exposure compensation.

The problem I have with the example images in this and other manuals is that they very clearly don't reflect my own experience. Take the outdoor shot of the backlit girl. Background exposure stays the same with or without fill-flash. This is the way it should be. As Nikon write: "A better result can be achieved by leaving the exposure set to the brighter background and then using the flash to illuminate the darker foreground subject."

So why the heck does my camera in the same outdoor situation lower background exposure by more than 1 stop when it detects a flash?


As I said before, this stands in direct opposition to what Nikon claims mTTL is for. Quote: "The result is a well-balanced photo with the correct exposure for both background and foreground subjects."

I have read lots of manuals and even bought a book about the F-801. But I haven't found anywhere a mention of this automatic underexposure in Matrix Metering. I'm starting to think this is a defect in my camera but it would be a very strange defect since it's otherwise working perfectly.

For what it’s worth - I would think about this exactly as you are. The behavior you expect is what I think I would likewise expect with that combination of gear + settings.

You said in the 1st post that you had shot one roll of film with the camera. What are the results like in practice?

 

[NowhereMan]

Yes, I've only shot one roll to test camera functionality. You mean the results of flash photography or in general? I general I think I like the camera. I am very satisfied with the autofocus, it is spot on in every frame. The light metering is very accurate, too. I like that everything is very intuitive, except flash photography. The Matrix flash with auto exposure is a mixed bag. It seems it generates excellent results with well-balanced subject and background indoors, but as soon as I go outside and there is a very bright area in the frame (e.g. an overcast sky) it does the underexposure thing.

 

[Alan Edward Klein]

Yes, I've only shot one roll to test camera functionality. You mean the results of flash photography or in general? I general I think I like the camera. I am very satisfied with the autofocus, it is spot on in every frame. The light metering is very accurate, too. I like that everything is very intuitive, except flash photography. The Matrix flash with auto exposure is a mixed bag. It seems it generates excellent results with well-balanced subject and background indoors, but as soon as I go outside and there is a very bright area in the frame (e.g. an overcast sky) it does the underexposure thing.

I tend to like Center-weighted rather than matrix. I move the camera around to select an average of sections, such as a little sky, and more ground with some brighter and some shadow areas. Once I get the exposure that I think is right, I press the exposure hold select button that keeps that exposure setting. Then I move the camera to compose the framing I want.

 

[MattKing]

I tend to like Center-weighted rather than matrix. I move the camera around to select an average of sections, such as a little sky, and more ground with some brighter and some shadow areas. Once I get the exposure that I think is right, I press the exposure hold select button that keeps that exposure setting. Then I move the camera to compose the framing I want.

A bit tough to do though if you are metering for flash!

 

[NowhereMan]

I tend to like Center-weighted rather than matrix. I move the camera around to select an average of sections, such as a little sky, and more ground with some brighter and some shadow areas. Once I get the exposure that I think is right, I press the exposure hold select button that keeps that exposure setting. Then I move the camera to compose the framing I want.

This is basically my approach with the FE2 - only that I use manual exposure mode instead of the exposure lock button. I think I'll probably be doing flash photography the same way with the F-801. For non-flash photography Matrix Metering certainly has its advantages, particulary in situations where speed is important and you don't have time to meter the light properly.

I've still no clue why Matrix and Center-weighted fill-flash are apparently possible in manual exposure mode with the SB-24 and newer flashes but not with older ones. But maybe it doesn't matter much because I think it's probably best to use an SB-24 or a newer flash with this camera anyway.