EL-5 zoom with RF 100mm F/2.8 focal length mismatch

[mysql]

Hello,

I have R6 MarkII (lastest firmware), paired with RF 100mm F/2.8 and when I use my EL-5 (also lastest firmware) I noticed, it automatically zooms to 80mm and to 100mm (when used with autozoom), yes I can fix it by manual zoom and setting it to 100mm but that is not my point. 

I am here more for technical reason, why 80mm on Speedlite and not 100mm, when lens clearly is 100mm.

Is there a technical limitations or did Canon found it behaves better on 80mm zoom on Speedlite, when it is 100mm lens?

Just curious and also it may become handy for others if they found this thread.

Thank you.

[mysql]

Hello rory586,

• I don't think it is technical limitation, it can zoom to 100mm totally fine when using for example 24-105 F/4 L
• Calibration can be a thing but does it really make 20mm? It is not small amount 
• I am probably most for this option - intentionally made for as you wrote "better coverage"

Manual can totally "fix" this problem but again as you wrote "not ideal"

Firmware is up to date on everything (camera, lens flash).

Thank you

[mysql · Accepted solution]

So I did little research or better to say test and probably reason why EL-5 Speedlite goes to 80mm and not 100mm is because it actually can´t do 100mm zoom, it is only capable of 105mm and more (up to 200mm).

And this same behavior happens with regular zoom lens like for example 24-105mm F/4L it goes in steps:

• 24mm
• 28mm
• 35mm
• 50mm
• 70mm
• 80mm
• 105mm
• 135mm
• 200 mm

Those are also in manual selection of zoom range, this probably solves this "issue/strangenes".

Now I am wondering what happens with 85mm for example? Does it go to 105mm or goes back to 80? When it has fixed predefined steps? I don´t own it but just curios.

Thank you

[p4pictures]

As the Speedlite head moves to the defined positions the area illuminated changes in size. The area illuminated gets smaller as the zoom setting goes from wide to telephoto. This has a benefit that more power is available as the light doesn’t need to spread out so wide. 

Using this information the auto zoom setting will always be less than or equal to the focal length, so that the illumination covers the field of view of the lens being used. 

I did some tests in the past where I manually changed the zoom setting on the Speedlite 600EX II-RT from 24mm to 200mm with a 24mm lens fitted to the camera.

Speedlite at 24mmSpeedlite at 200mm

When the Speedlite is on camera it makes sense for it to zoom with the lens. However when a Speedlite is configured as a receiver unit it will automatically zoom to the 24mm position to give a wide spread of light. I often override this 24mm setting to constrain the beam of light for creative reasons, making it more of a spotlight effect, but also it increases the amount of light available. 

[mysql]

That is true, Speedlite heads moves (if it has this functionality) to make ilumination area smaller as it gets smaller more you zoom lens. 🙂

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This probably is what we are looking for:

• Using this information the auto zoom setting will always be less than or equal to the focal length, so that the illumination covers the field of view of the lens being used. 

I used it on camera, not as receiver (on camera of course zoom it with lens) of camera as big coverage as possible, or also creative reason as you say.

Thank you