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Exposure changes by itself while zooming in or out


Gaurav

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I am using my Fuji X-T4 with Fujinon 16-55 f2.8. The problem is when I am zooming in or out while shooting videos, exposure changes automatically. I have tried all the possible options including full manual mode but camera still auto compensates the exposure while zooming in/out. This issue basically renders the video useless and hence the camera for video users. I watched and read almost all available reviews on X-T4 but none of them mentioned this issue. Please Fuji tell me that this issue will be fixed in firmware update.

Edited by Gaurav
Made a typo in lens's specs
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Thanks for the reply, first of all really sorry that misquoted the lens. My lens is 16-35 f2.8 and I have tried all combinations poosible and still the problem persists. I found a video on exactly the same issue, I hope this clarify things further:

 

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On 8/6/2020 at 5:10 PM, andrei89 said:

the 18-55 is not a constant aperture lens. when zooming in the aperture will close to f4.

have you tried setting the aperture to f4 and experienced the same issue?

He said not about 18-55 but 16-55 f2.8 constant.

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When you set the camera on automatic exposure and zoom in or out, the view angle changes and with that the balance of lighter and darker elements in your view. That changes the exposure esp. when it is all on Auto and metering is set to multi-segment or average. When you don't want that to happen, you should switch to manual exposure (aperture, shutter speed and ISO). Zoom lenses with variable aperture emphasize the issue. When you zoom in, the aperture becomes smaller and the two effects impact exposure simultaneously. 

Edited by Herco
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This works on my X-T3, haven't tried it on other X cameras:
1) Zoom lens set to auto aperture "A"
2) Set shutter manually
3) Set an ISO value manually so the aperture result is above 5.6 or more (aperture number is white, not orange).
4) Then hit AE-L (auto exposure lock) button next to viewfinder. Do a zoom!

On my Fuji 10-24 f4 on X-T3, this eliminates the exposure stepping flicker during zooms,
but you will see a slight darkening at the telephoto end.
This is the natural behavior of most zoom lenses. The lens is not really constant aperture.
Normally the camera compensates for the brightness change from wide to telephoto by opening the aperture through a series of 1/3rd stop steps to keep the exposure constant. (When zooming the other way it is closing the aperture. Note that in the Youtube video above the first zoom out shows a darkening for each flicker.)

Put your ear to the lens and you might hear a faint clicking with the camera on and turning the zoom.
The lens in your case is probably f2.8 at the telephoto end but may actually be a stop faster at the wide end.
The Fuji 18-55 does three exposure steps (one stop) over its zoom range (unless wide open),
but at least here the lens is labeled f2.8-4 which is more accurate.
In other cameras the apertures may be changing more gradually without stepping, which would make the aperture changes invisible.
If need be, I take out the natural darkening of the "locked" zoom shots in my NLE software with keyframed exposure adjustments to gradually bring the brightness back up across a zoom. 
You can also do this with vintage manual SLR zoom lenses. 

 

 

Edited by pixilated
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  • 6 months later...

I have this same issue with my X-T4, and I just verified it's occurring with my PRIME, so we're not talking about a simple zoom aperture change.  I am at loss to figure it out.  Nothing is set to "auto"... everything manual (except auto focus) and I have specified my ISO, SS, Aperture and exposure compensation.  Seems to me the lighting should not be shifting around just because I re-frame or move my focus from a lighter to a darker area. This isn't just in movie mode either... it's straight photo mode.

Edited by Enli
(added camera model); (verified happening with Prime lens)
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  • 2 weeks later...
On 3/2/2021 at 5:02 AM, Enli said:

I have this same issue with my X-T4, and I just verified it's occurring with my PRIME, so we're not talking about a simple zoom aperture change.  I am at loss to figure it out.  Nothing is set to "auto"... everything manual (except auto focus) and I have specified my ISO, SS, Aperture and exposure compensation.  Seems to me the lighting should not be shifting around just because I re-frame or move my focus from a lighter to a darker area. This isn't just in movie mode either... it's straight photo mode.

as per my guess you have put photometry to "spot" ,so it changes whenever you move the focus point also when camera is moved (since the focus point is moved with it and it changes according to the lighting where the focus point is present). also in lenses with variable aperture , the light changes when zooming in and out .but if it happens with prime etc.. then you should reset your camera settings , to factory default and then check again without tweaking any settings  ,at fixed iso, shutter speed, andaperture . only these 3 make it fixed using the dials , don't change anything else . and if you are still getting the same issue even then. then i advise you to take your lens and camera to a fujifilm service center and have them checked , soon (some products may have manufacturing defects, happens with all companies and brands , but if it's the cause , they will replace or repair it for free) .i hope this helps , have a nice day ahead !

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  • 6 months later...

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