D7000 Aperture changes on zoom while on liveview mode

H

hectordsilva

Member
Hi folks, I have an serious issue on nikon D7000 yet not discussed much on forums, i wonder if this is only with my camera or with all user.
The issue is"why the fstop changes while you zoom in or out, i am using an nikon kit lens of 18-108mm 3.5/5.6. Its known if its variable it will change from 3.5 to 5.6, but why it has to change from, lets say f/5.6 or f/8. It changes in increment of about 2 stops from where ever you start. eg. if i keep 18mm f/8 then zoom in to 105mm, it will change to f/13. this is disgusting. well this donot happen in photo mode but only in liveview mode. I have kept the setting in manual movie mode ON, on this fstop changes on zoom. while if you keep manual movie setting OFF, this will not change the fstop Nos, but it will do auto gain, or shutter/apperture compensate or what not that also without informing you on LCD, even on this if you have AE lock hold ON and them zoom, this will chage the ftop but not show on LCD. Please give me some tip how to get away with this issue.
Thanks
 
That's normal in LiveView since the D7000 can't change aperture in this mode (which is pretty stupid).

When you're out of LiveView mode, it compensate automatically the "ramping" (phenomenon which results in a loss of light because the aperture's diameter doesn't mechanically follow the zoom according to this formula: Aperture F = (Focal length)/(Aperture Diameter). Contrary to a constant aperture zoom lens which mechanically widen the aperture during the zoom, the f/ number doesn't change), but in LiveView, the D7000 is incapable of changing the aperture to compensate the ramping (same problem as changing the aperture in LiveView mode without an aperture ring).

Hope it helps.
 
Thanks for ur help blackP.., i am very surprise with D7000, where the aperture should change in manual liveview mode, it is not changing, while in zoom mode where it should not change, it is changing. very very stupid.
Yes you are right, in fix aperture lens with variable zoom it does not change. I hope nikon fix this in coming firmware.
Thanks
 
The issue is with the lens as far as changing aperture while zooming in LV, not the camera. The 18-105 has a minimum aperture based on the focal length, so it will lighten the image at the wide F/3.5 end, and darken it at the zoomed F/5.6 end. You can't go lower than F/5.6 at 105mm, it's a limitation of the lens. No firmware will fix this.
 
yes BB, i understand the limitation of f/3.5 to f5.6. what i am saying is, if i keep f/8 from the start @18mm then zoom in @105mm this will change to f/13. This is very strange. well this donot happen, if i come out of LV mode. by the way this happen in any of the variable apperture lens. Can you explain.
thanks
 
The lens is causing the darkening due to the smaller effective aperture when zooming. On constant aperture lenses (70-200mm F/2.8 VR for example), the aperture opens as the lens zooms in, maintaining the aperture to focal length ratio. This does not happen on the 18-105 and similar lenses. The aperture stays set, so as you zoom in, the effective aperture becomes smaller, and the image dims. The lens transmits this to the camera as a narrower aperture in order for the camera to expose correctly. The camera has no control over this, it only displays the info the lens is giving it.

As far as no dimming while you look through the viewfinder, the camera always keeps the aperture wide open to meter and AF properly, and so you can see. It instantly stops the aperture down when you hit the shutter release. If you have the opportunity to use a manual lens like an AI-S, you'll see the aperture change in real time through the viewfinder when you stop it down. You'll see how dark the viewfinder gets. At around F/8, Nikon states the camera will have problems with AF.
 
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