My f stop is automatically changing in manual mode

Wendibond007

New member
Question!!!! I need help!!! Why does my f stop automatically change when I manually zoom now? I used to have to manually do it myself with the +/- dial, it's now killing the quality of the photo. It didn't start doing this until tonight.
 

Marcel

Happily retired
Staff member
Super Mod
Have a look at your zoom. What does it say on the lens? You should find the range in mm (18-105, 55-200) AND the aperture values 2.8, 2.8-4, 3,5-5.6. Some zooms have constant aperture while some don't. I strongly suspect that your zoom is not constant. This means that when you zoom in, your aperture changes because of the way the zoom is built. Pro zooms usually have a constant aperture which doesn't change while zooming. This is one reason they are usually more expensive.

Hope this helps.
 

480sparky

Senior Member
Yep. Variable aperture when shooting wide open.

Now, if it's doing that when you're stopping down to 5.6 or 6.3 or smaller, there's another issue.
 

hark

Administrator
Staff member
Super Mod
Contributor
Question!!!! I need help!!! Why does my f stop automatically change when I manually zoom now? I used to have to manually do it myself with the +/- dial, it's now killing the quality of the photo. It didn't start doing this until tonight.

The +/- button is for exposure compensation. Do you mean the front dial? As Marcel and Sparky said, a variable aperture zoom will change the aperture ONLY when the you are shooting wide open or near wide open and begin to zoom. For example, a zoom lens such as the 18-55mm f/3.5-5.6G will shoot at f/3.5 when set at 18mm. However, as you start to zoom out, you will see the aperture begin to stop down on its own. By the time you reach the end of the zoom range (55mm) the aperture will show f/5.6.

Even if you shooting at 18mm f/4.5, as you zoom out, the aperture will stop down to f/5.6 at 55mm. If you are shooting at 18mm with f/5.6 or stopped down further, the aperture will then remain constant when zooming.

You say this just started. What lens is being used, and what apertures change? Please be sure to indicate the focal length (such as 28mm) when it happens.
 

Bikerbrent

Senior Member
Welcome aboard. Enjoy the ride.
We look forward to seeing more posts and samples of your work.

Echoing the above posters, we need to know what lens or lenses you are using and also some pictures with EXIF data would be very helpful to allow us to help you.
 
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