Nikon FM3a with Mecablitz 48-af and Tamron 28-300mm lens incompatible ttl flash.

Hi everyone,

Today I just purchased a Mecablitz 48-af.

When I use it with my Nikon F100, everything is OK (with Tamron AF XR Di cpu lens).
But, when I switch to Nikon FM3a, the TTL flash just don't work (with the same Tamron lens). The manual mode is OK for both camera.

The display lcd on the flash is cannot provide the same information as when I used my Nikon F100 (with the same basic TTL flash "only" mode, not the matrix mode of F100).
On Nikon F100 basic TTL mode, the flash lcd provide aperture info, distance, and zoom position.
But on Nikon FM3a basic TTL mode, only display the zoom position (28mm, 35mm), the aperture and distance range is not displayed.
And no error message on the lcd display of the flash gun.

Can it be because my Nikon FM3a is not compatible with the Tamron cpu lens?
Or both of the lens and flash is not compatible? or all of the three it is not compatible?

I'll try to purchase the nikon lens with cpu for the test.

Have anybody experience this kind of things?
Can the cpu lens uncompatible with the flash gun?

Thank you.

The FM3a is not compatible with any CPU lens in term of providing focal length, distance, maximum aperture. The FM3a should work just fine with the Metz 48AF but will not auto zoom the flash, will not set ISO on the flash and will not display the aperture set on the flash nor the maximum distance for direct flash.
You should not feel bad about it because that is why people are paying a lot more for the FM3a than the F100 mainly because of what it doesn't do.

Well, after reading the manual, I become more confused.
First, the manual book got the TTL flash tutorial, and list of Nikon flash which can be used to do TTL flash.
But at the end of the manual, in lens compatibility chart, it mention that CPU lens will not support TTL flash.
So, my question is does FM3a support TTL flash? or FM3a only support TTL flash with non CPU lens? or FM3a support TTL flash with only Nikon flash?

It is not about which is better, manual or ttl flash. Only that as user, which guided by the manual book at first, become so much confused.

The FM3a does support TTL flash and is compatible with the Metz 48AF.
CPU lens or not is not relevant.
It only supports TTL not other TTL modes like TTLbl etc......
Simply set the lens aperture on the camera. There won't be any display like aperture, max range etc... on the flash. The autozoom feature won't work either.

to mr. chan,
if you sure about it, then I suspect there is a foul in my purchase.
I tried TTL and TTL balance mode in F100 is OK.
But when I switch to FM3a, only manual mode is working.
Sometime in TTL mode, the flash do fire, but only occasionally.
Not everytime, like a lottery. I always wait 3 more second, afraid if the battery is not recharge the flash yet. But it is still like that.

Anton, I think there might be a dirty flash contact in your FM3a, if it works erratically. As suggested in another thread, a good cleaning with alcohol and some "brushing" should clean the oxide layer that maybe has formed.

I think the "TTL metering" expression has been abused by flashes which use autofocus information for exposure.

With your FM3a you have proper TTL metering. A sensor inside the camera cuts the emission of flash light when the exposure is "just fine". So the TTL exposure automatically takes into account the fall of light caused by extension tubes, bellows, filters etc. and also compensates for imprecision in diaphragm closing (f/8 being f/8.5 or f/7.5 so to speak).

This method of measuring works well if your subject is in the region of the frame which weights more for light metering, typically the center of the frame. Now imagine you take a picture, in an ample room, of a dancing couple. You press the shutter when the couple is apart, each dancer being at one extreme of the frame. Between them there is nothing, and the wall is 4 meters behind. The TTL meter will cut the flash only when the exposure is satisfying for the centre area of the frame, the wall, and both dancers will end up overexposed.

Autofocus opened new and different possibilities. The camera can inform the flash about the aperture used, the film speed, and the distance of the subject. This is all the flash needs (in theory) to calculate exposure, just like photographers would do manually knowing the guide number for the film speed, the aperture and the subject distance.

In the example of the dancers above, if the autofocus locks on the dancers, the dancers will be lit correctly, the exposure will be based on the autofocus distance and not on the exposure of the wall.

On the other hand, this is not TTL. This technique would not work with extension tubes, bellows, filters (because it would not know how much is the light fall) and will not compensate for imprecision of diaphragm (because the light is calculated based on an ideal diaphragm efficiency).

Besides, flash guide numbers are calculated considering that flashes are typically used indoor and benefit from a partial reflection of light from a white ceiling.

TTL flash measures light correctly both if you are indoors or outdoors.
"Autofocus" measuring cannot know if you are indoors or outdoors and so cannot figure out a really precise exposure.

I would not exclude, in general, that some producer maybe uses the autofocus information as part of the mix, together with other forms of automatism, to overcome the limits of the autofocus-driven method.

Also, the TTL measuring, like every light meter measuring, is bound to fail the more the subject is dark or bright, i.e. the further is it distant from the 18% middle grey light meters are calibrated upon.

The "autofocus" system is not influenced by the brightness or darkness of the subjects. This makes it an interesting technique for wedding photographers, I presume.

So to answer your post, the working with the FM3a is in TTL mode and the flash doesn't really need to know the aperture, it needs to know the film speed which the camera must communicate (or that you set manually on the flash).

With the autofocus camera, the flash adopts a totally different "strategy" to automate light emission, and it needs to know the diaphragm, and the focus distance, and this is not TTL metering but some producer might call it this way for pure marketing reasons.

Fabrizio

To : Fabrizio Ruggeri,

Thanks for the advice to clean the hot shoe, but it didn't help.
My FM3a is a new old stock, so I don't noticed any grease or dirt, but I already clean it with alcohol and do some rubbing with tiny screw.
So any suggestion for these weird symptom?

And thanks for the information regarding the TTL system on FM3a,
Probably I should try the nikon cpu lens with nikon speedlight.
I'm planning to do the test with the permission of the shop owner in which i bought the metz.

Thank you

Anton, my long explanation could be resumed in a few words: it is entirely likely that there is no malfunction with your FM3a. You should sacrifice a roll to see how the flash automatism work. It is normal that the flash is not aware of the focused distance on the FM3a.

Fabrizio