speedlite question

Started 4 months ago | Discussions
Doug Haag Senior Member • Posts: 2,512
speedlite question

I have happily used a totally manual speedlite for literally decades (i.e no TTL, no fine tuning of power output in manual mode, etc).  I recently upgraded to a modern speedlite with these features.  But I have a question about one new feature to which I cannot find an answer in the user manual.

The device has the ability to change the flash coverage through a Zoom setting measured in millimeters of focal length (e.g. 20mm, 24mm etc,)  But it doesn't indicate whether this relates to the field of view for that focal length on a full frame or other sensor size.

Since the TTL mode reads the camera's aperture and iso setting perhaps it is smart enough to know the sensor size of the camera to which it is attached and the flash coverage is adjusted accordingly.

So does the 24mm Zoom setting, for example, match the field of view of a 24mm lens on a full frame camera, but when attached to a crop sensor camera its coverage is equivalent to the field of view of a 16mm lens?  Or is that setting equivalent to the field of view for whatever camera and lens combination it is matched with?  If the latter applies, when it is attached to a crop sensor camera, the coverage at the 24mm Zoom setting would be the same as a 36mm FOV on a FF camera.

If, as I suspect, the Zoom setting is based on full frame equivalence regardless of the camera to which it is attached, I need not set the Zoom below 24mm when it is used with my 17-50mm lens on a crop sensor Nikon,  At that setting, the FOV of the flash would be equivalent to 16mm on my camera.

Richard Hopkins
Richard Hopkins Regular Member • Posts: 476
Re: speedlite question
2

Doug Haag wrote:

I have happily used a totally manual speedlite for literally decades (i.e no TTL, no fine tuning of power output in manual mode, etc). I recently upgraded to a modern speedlite with these features. But I have a question about one new feature to which I cannot find an answer in the user manual.

The device has the ability to change the flash coverage through a Zoom setting measured in millimeters of focal length (e.g. 20mm, 24mm etc,) But it doesn't indicate whether this relates to the field of view for that focal length on a full frame or other sensor size.

Since the TTL mode reads the camera's aperture and iso setting perhaps it is smart enough to know the sensor size of the camera to which it is attached and the flash coverage is adjusted accordingly.

So does the 24mm Zoom setting, for example, match the field of view of a 24mm lens on a full frame camera, but when attached to a crop sensor camera its coverage is equivalent to the field of view of a 16mm lens? Or is that setting equivalent to the field of view for whatever camera and lens combination it is matched with? If the latter applies, when it is attached to a crop sensor camera, the coverage at the 24mm Zoom setting would be the same as a 36mm FOV on a FF camera.

If, as I suspect, the Zoom setting is based on full frame equivalence regardless of the camera to which it is attached, I need not set the Zoom below 24mm when it is used with my 17-50mm lens on a crop sensor Nikon, At that setting, the FOV of the flash would be equivalent to 16mm on my camera.

As you suspect, it is based on full-frame focal lengths, and may convert to equivalents automatically, or via a custom functions setting, or not at all depending on the camera and flash. Check the handbook.

OP Doug Haag Senior Member • Posts: 2,512
Re: speedlite question

Richard Hopkins wrote:

Doug Haag wrote:

I have happily used a totally manual speedlite for literally decades (i.e no TTL, no fine tuning of power output in manual mode, etc). I recently upgraded to a modern speedlite with these features. But I have a question about one new feature to which I cannot find an answer in the user manual.

The device has the ability to change the flash coverage through a Zoom setting measured in millimeters of focal length (e.g. 20mm, 24mm etc,) But it doesn't indicate whether this relates to the field of view for that focal length on a full frame or other sensor size.

Since the TTL mode reads the camera's aperture and iso setting perhaps it is smart enough to know the sensor size of the camera to which it is attached and the flash coverage is adjusted accordingly.

So does the 24mm Zoom setting, for example, match the field of view of a 24mm lens on a full frame camera, but when attached to a crop sensor camera its coverage is equivalent to the field of view of a 16mm lens? Or is that setting equivalent to the field of view for whatever camera and lens combination it is matched with? If the latter applies, when it is attached to a crop sensor camera, the coverage at the 24mm Zoom setting would be the same as a 36mm FOV on a FF camera.

If, as I suspect, the Zoom setting is based on full frame equivalence regardless of the camera to which it is attached, I need not set the Zoom below 24mm when it is used with my 17-50mm lens on a crop sensor Nikon, At that setting, the FOV of the flash would be equivalent to 16mm on my camera.

As you suspect, it is based on full-frame focal lengths, and may convert to equivalents automatically, or via a custom functions setting, or not at all depending on the camera and flash. Check the handbook.

I did check the user manual (Godox) and did not locate anything about how to interpret the Zoom focal length settings with respect to different cameras.  And there was nothing about the camera automatically making any equivalency conversions.  But perhaps it is there and I just failed to see it.  Maybe it is like when my wife tells me to get something from the refrigerator and I can't seem to locate it even though it is right there in plain sight when she comes (angrily) to point it out. 

Perhaps someone with a Godox speedlite can refer me to where this information can be found in the manual.

Gato Amarillo Veteran Member • Posts: 7,933
Re: speedlite question

If you are controlling the setting manually I'm confident the number are for full frame, and this would apply to settings made directly on the flash or through a wireless trigger.

I'm thinking if there is any calculation of equivalence it would be made by the camera. If a crop sensor camera is handling the zoom setting automatically the camera may be setting equivalent zoom setting.

Gato

Ellis Vener
MOD Ellis Vener Forum Pro • Posts: 15,739
Re: speedlite question

Your suspicion is correct. The “focal length” settings  are for full-format cameras.

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S Castle
S Castle Senior Member • Posts: 1,263
Re: speedlite question

What everyone has already said is correct. I don't have any speedlites other than Canon, and I can say that they detect connection to a crop sensor and will adjust the zoom accordingly. I don't know about Godox but I suspect similar behavior.

That said, I now usually go full manual on zoom and flash power, using the zoom feature as a sort of built-in snoot, if not in a modifier. The flashes are almost always in a modifier of some kind, when they are usually zoomed to max width.

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Shane

Ex-Leper Forum Member • Posts: 70
Re: speedlite question
1

If you zoom it in from a constant distance, its brighter.  Zoom out from the  same position , it's less bright. Like flood to spot or flood to spot on a fresnel. Which it exactly is.  What matters is how bright it is on subject. The rest is irrelevant.

itsDing
itsDing Senior Member • Posts: 2,517
Re: speedlite question

Zoom settings are a full frame guide if you use a 50mm lens on FF then its 50mm if you use a crop camera then set the zoom to 80mm which is the field of view for crop cameras If you choose to bounce the light of walls and ceilings then you can zoom the flash to a narrower angle, 105mm for example. The bounced light will spread more.

itsDing
itsDing Senior Member • Posts: 2,517
Re: speedlite question

And! If you use the flash off camera with an umbrella or softbox then set the flash zoom to a wide angle 24mm for example so the inside of the modifier is fully lit.

OP Doug Haag Senior Member • Posts: 2,512
Re: speedlite question
2

OP here:

I hate it when people post a question and never return to their own thread.  So here is a thank you to most of you who have responded.  Moderator Ellis Venner seemed particularly confident in his response which I am going to assume is correct in large part  because it seems most logical to me.

I did not return to my thread earlier because none of the responses needed follow-up and no one was able to guide me to definitive language in the Godox user manual.  I apologize for being deficient in failing to mention the brand of my speedlite in the original post.  But I did so in my response to the first person who replied (which was probably missed by the many folks who post on DPR without bothering to read what was posted previously -- another pet peeve of mine.)

One response was accurate with respect to the facts it included, but was curiously non responsive to my specific question and the facts stated, while valid, were irrelevant to the purpose of my question.  I was not surprised that this particular respondent has been a member of DPR for sixty-three fewer years than I have been a photographer.

Klaus dk
Klaus dk Veteran Member • Posts: 7,975
Re: speedlite question

I came late to this party, but would just remind you, that there's an extra wide-angle diffusion lens that can be pulled out and flipped over the fresnel to give extra wide distribution, like 17mm mm FF eq. This can be useful in some modifiers like umbrellas.

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OP Doug Haag Senior Member • Posts: 2,512
Re: speedlite question

Klaus dk wrote:

I came late to this party, but would just remind you, that there's an extra wide-angle diffusion lens that can be pulled out and flipped over the fresnel to give extra wide distribution, like 17mm mm FF eq. This can be useful in some modifiers like umbrellas.

Yes.  On my speedlite it says this diffusion panel expands the coverage to 14mm.

But it doesn't say if this is a coverage width matching a 14mm FOV on a FF camera or 14mm on my crop sensor Nikon.  If it is equivalent to 14mm full frame, that would be equivalent to a spread of light matching a 9.3mm lens on my camera.  It seems logical to me that a fixed diffusion panel would spread the light a fixed amount irrespective of the camera it was associated with.  Consequently, these speedlite statistics must relate to a field of view reference to a single focal length standard.  And that is most likely full frame.

It was this logic that led me to discount any replies to my question that suggested the field of view coverage for any particular speedlite Zoom setting might be automatically adjusted to be compatible with the camera to which it was mounted.  An interpretation assuming non-adjustability becomes even more logical when you realize that the speedlite might not even be mounted to a camera, but used remotely.

It just seemed strange that the user manual for a product as popular as a Godox would not be more specific about what the published statistics mean if there was a possibility it could be misinterpreted by different users.

This thread has been helpful to my thinking in another respect.  Because I most often use it for bounce flash and not aimed directly at the subject, I now realize it may be less less important that I select a Zoom setting matching the lens I am using,  The bounce surface itself will act as a light spreading component.  In fact, someone pointed out that the narrower the Zoom setting, the more intense will be the light hitting my bounce surface at any particular power output.  So there might be some battery-saving advantage to a Zoom setting slightly narrower than the FOV of my lens.

kli
kli Veteran Member • Posts: 3,986
Re: speedlite question
2

It depends on the speedlight. Most of the time, it will be for full frame.

But, as Richard Hopkins stated, sometimes it will be adjusted for a different sensor format based on a custom function in the flash.

For example, my Godox TT350-O, which is for Olympus/Panasonic four-thirds cameras, which use a 4/3"-format sensor with a 2x crop format, there's a C.Fn 43. If I set it to OF, then the widest angle when I pull out the wide angle diffuser panel, displays as 14mm (full frame equivalent FoV). If I set that function to ON, it then displays as 07mm. This is not in the manual, as the feature was added by a firmware update. [eyeroll].

Similarly, on a Nikon SB-900, there is a custom function (C-23) to switch between FX and DX.

Generally speaking, the cameras don't communicate sensor format size to the speedlight, so this setting has to be done explicitly on the speedlight itself. However. Most of us don't bother to worry about the specific mm being used, since that type of field of view coverage, like guide numbers, is really only accurate for direct on-camera flash. Most of us bounce, or do off-camera flash, at which point, the scene coverage you would have had with the flash on-camera pointed directly forward isn't going to matter that much. And the zoom setting on a flash is simply how focused the beam is.

All the setting really does is position the flash tube forward or back inside the head, with the longest "focal lengths" having the tube all the way in the back, and the widest angle (typically 24mm) with the tube at the front, just behind the fresnel panel.

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Richard Hopkins
Richard Hopkins Regular Member • Posts: 476
Re: speedlite question
1

kli wrote:

It depends on the speedlight. Most of the time, it will be for full frame.

But, as Richard Hopkins stated, sometimes it will be adjusted for a different sensor format based on a custom function in the flash.

For example, my Godox TT350-O, which is for Olympus/Panasonic four-thirds cameras, which use a 4/3"-format sensor with a 2x crop format, there's a C.Fn 43. If I set it to OF, then the widest angle when I pull out the wide angle diffuser panel, displays as 14mm (full frame equivalent FoV). If I set that function to ON, it then displays as 07mm. This is not in the manual, as the feature was added by a firmware update. [eyeroll].

Similarly, on a Nikon SB-900, there is a custom function (C-23) to switch between FX and DX.

Generally speaking, the cameras don't communicate sensor format size to the speedlight, so this setting has to be done explicitly on the speedlight itself. However. Most of us don't bother to worry about the specific mm being used, since that type of field of view coverage, like guide numbers, is really only accurate for direct on-camera flash. Most of us bounce, or do off-camera flash, at which point, the scene coverage you would have had with the flash on-camera pointed directly forward isn't going to matter that much. And the zoom setting on a flash is simply how focused the beam is.

All the setting really does is position the flash tube forward or back inside the head, with the longest "focal lengths" having the tube all the way in the back, and the widest angle (typically 24mm) with the tube at the front, just behind the fresnel panel.

Apologies if this has already been said, but the auto-zoom function only works for direct, on-camera flash.

If you tilt/rotate the head, or remove the flash from the camera, auto-zoom is disabled (as it should be). AFAIK this applies across the board.

OP Doug Haag Senior Member • Posts: 2,512
Re: speedlite question

Richard Hopkins wrote:

kli wrote:

It depends on the speedlight. Most of the time, it will be for full frame.

But, as Richard Hopkins stated, sometimes it will be adjusted for a different sensor format based on a custom function in the flash.

For example, my Godox TT350-O, which is for Olympus/Panasonic four-thirds cameras, which use a 4/3"-format sensor with a 2x crop format, there's a C.Fn 43. If I set it to OF, then the widest angle when I pull out the wide angle diffuser panel, displays as 14mm (full frame equivalent FoV). If I set that function to ON, it then displays as 07mm. This is not in the manual, as the feature was added by a firmware update. [eyeroll].

Similarly, on a Nikon SB-900, there is a custom function (C-23) to switch between FX and DX.

Generally speaking, the cameras don't communicate sensor format size to the speedlight, so this setting has to be done explicitly on the speedlight itself. However. Most of us don't bother to worry about the specific mm being used, since that type of field of view coverage, like guide numbers, is really only accurate for direct on-camera flash. Most of us bounce, or do off-camera flash, at which point, the scene coverage you would have had with the flash on-camera pointed directly forward isn't going to matter that much. And the zoom setting on a flash is simply how focused the beam is.

All the setting really does is position the flash tube forward or back inside the head, with the longest "focal lengths" having the tube all the way in the back, and the widest angle (typically 24mm) with the tube at the front, just behind the fresnel panel.

Apologies if this has already been said, but the auto-zoom function only works for direct, on-camera flash.

If you tilt/rotate the head, or remove the flash from the camera, auto-zoom is disabled (as it should be). AFAIK this applies across the board.

Thanks for the clarification even though it doesn't apply for someone like me who almost always uses bounce flash.

But the main reason for this reply is to tell you how much I liked your "Practical Photography" magazine.  I have owned a camera for 63 years and been a serious hobbiest for approximately 50 of those.  Back in the day before the internet, photo mags were my main source of knowledge about techniques, etc.  And Practical Photography was one of my favorites.

Richard Hopkins
Richard Hopkins Regular Member • Posts: 476
Re: speedlite question
1

Doug Haag wrote:

Richard Hopkins wrote:

kli wrote:

It depends on the speedlight. Most of the time, it will be for full frame.

But, as Richard Hopkins stated, sometimes it will be adjusted for a different sensor format based on a custom function in the flash.

For example, my Godox TT350-O, which is for Olympus/Panasonic four-thirds cameras, which use a 4/3"-format sensor with a 2x crop format, there's a C.Fn 43. If I set it to OF, then the widest angle when I pull out the wide angle diffuser panel, displays as 14mm (full frame equivalent FoV). If I set that function to ON, it then displays as 07mm. This is not in the manual, as the feature was added by a firmware update. [eyeroll].

Similarly, on a Nikon SB-900, there is a custom function (C-23) to switch between FX and DX.

Generally speaking, the cameras don't communicate sensor format size to the speedlight, so this setting has to be done explicitly on the speedlight itself. However. Most of us don't bother to worry about the specific mm being used, since that type of field of view coverage, like guide numbers, is really only accurate for direct on-camera flash. Most of us bounce, or do off-camera flash, at which point, the scene coverage you would have had with the flash on-camera pointed directly forward isn't going to matter that much. And the zoom setting on a flash is simply how focused the beam is.

All the setting really does is position the flash tube forward or back inside the head, with the longest "focal lengths" having the tube all the way in the back, and the widest angle (typically 24mm) with the tube at the front, just behind the fresnel panel.

Apologies if this has already been said, but the auto-zoom function only works for direct, on-camera flash.

If you tilt/rotate the head, or remove the flash from the camera, auto-zoom is disabled (as it should be). AFAIK this applies across the board.

Thanks for the clarification even though it doesn't apply for someone like me who almost always uses bounce flash.

But the main reason for this reply is to tell you how much I liked your "Practical Photography" magazine. I have owned a camera for 63 years and been a serious hobbiest for approximately 50 of those. Back in the day before the internet, photo mags were my main source of knowledge about techniques, etc. And Practical Photography was one of my favorites.

Hi Doug, that's very kind, thank you.

Yes, those were the days! Serious photography was never quite popular enough to get much coverage in the mainstream media, but plenty big enough for specialist magazines to thrive. Our parent company, Emap plc, built a massively successful portfolio mainly on the back of specialist interests like photography, motorcycling, angling, cars, golf, music, gardening, you name it. We ruled the roost.

Then the internet came along and changed the game. No problem we thought, just put all our magazines on-line and switch to a subscription model, or micro-payments or whatever. Well, that didn't work and it's interesting how few major publishers from the old guard have truly made the transition from print (if any, TBH). Coincidentally, on the same day that Olympus announced their exit, Practical Photography magazine also closed its doors. But we had a damn good run

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