I have these studio flashes by Mettle -

Mettle studio flash

One of the switches on the back lets you dim the modeling light when the flash fires. I typically use this setting (ie. dim when flash fires).

I recently got an iPhone slow-motion video capturing the moment that my flashes fired. You can watch it here:


There are 3 flashes in the video, but only the left two have the modeling light.

What I noticed was that after the flash fires, the modeling lights are still dimming. This says to me it's obvious that the modeling lights are still on at the time of image capture.

That being the case, what is the point of being able to dim the modeling lights at time of flash fire?

I didn't process that jumping shot, but if you're interested, here is an example of how this looks in the final shot.

enter image description here

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    \$\begingroup\$ Is this really a question? It seems more like a complaint.... \$\endgroup\$
    – mattdm
    Nov 6, 2017 at 2:00
  • \$\begingroup\$ Really? It's a fair question. I've always used "dim modeling light" expecting that light to go off and not affect the shot - but the video reveals that it's still on. Surely there are people with experience in strobe design that can comment on this and the impact of this design? And perhaps the answer is that yes - there really is no point, this is just a marketing gimmick for product differentiation to increase sales. Just trying to understand why you would bother with this feature if the modeling light is actually lit for the shot. \$\endgroup\$ Nov 6, 2017 at 2:39
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    \$\begingroup\$ Did you turn the modelling lights totally 'off' and take the same type of super slow motion video? What did you see? What you think is the modeling lights decaying after the flash pulse may, in fact, be the tail of the main strobe's decay. \$\endgroup\$
    – Michael C
    Nov 6, 2017 at 3:33
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    \$\begingroup\$ What is the point? The Modeling light is so dim compared to the output of the strobe it makes no difference Unless you're using a very long shutter speed, and even that might be negligible . If you are indeed using a long shutter speed and worried about it just turn the modeling light off. Agreed, I do not know what the point is. perhaps you should ask the manufacturer of the reason . Maybe it has something to do with their specific circuitry. \$\endgroup\$
    – Alaska Man
    Nov 6, 2017 at 5:53
  • \$\begingroup\$ @MichaelClark - actually this is a good point, but in the linked video, the right-most strobe does not have a modeling light. There is a trailing dim after the flash fires, but not as extensive as the other two, which have modelling lights - so I conclude it's the modelling light. \$\endgroup\$ Nov 7, 2017 at 9:02

1 Answer 1


This feature has nothing to do with adjusting the light output for the exposure. As @AlaskaMan commented, the modeling light is much dimmer than the strobe.

The reason for this feature is to give the studio photographer visual confirmation that the strobe did fire. In a studio with little or no ambient light other than the modeling lights, it’s easy to notice that one or more modeling lights did not dim. (Especially with a multiple light setup, it’s hard to detect a single missing flash without viewing the image.) This advises him/her to look for the problem.

  • \$\begingroup\$ Thanks - I guess that reveals the nature of my assumption - that the dimming is to eliminate the effect of the modeling light on the exposure, but it seems this is in error. Easily testable. And actually, even in the photo in this thread - you can see the left (with modeling light) and right (without modeling light) strobes. If the modeling light had an effect on the left hand side, I cannot see the difference. Thanks. \$\endgroup\$ Nov 7, 2017 at 9:06
  • \$\begingroup\$ Dimming of the modeling light has a secondary purpose: to let you know that the strobe head is still cycling back to the power level you've set. When the modeling light comes back on, it's ready to shoot again at the selected power level. You'll notice that the modeling light comes back on more quickly at lower power settings, and takes longest at full power. Some strobes also beep audibly to serve the same function. \$\endgroup\$ Nov 8, 2017 at 5:24

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