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Changing fstops when zooming

G

Guest

I must be getting dim or something, but I have just noticed that when I am working at focal lengths longer than 24mm, the f-stop shown in the viewfinder display seems to bear little resemblance to what I set on the aperture ring of the lens.
Does this make the slightest difference to anything, or is this just an idiosyncrasy of variable-aperture zooms, and I have just never spotted it before ?
 
G

Guest

Just to finish this thread – it’s a characteristic of variable aperture zooms and varifocal lenses. The aperture ring markings are good for 24mm only – the actual aperture for a given local length is displayed in the viewfinder and top-plate LCD.
 
G

Guest

Question was asked in different thread: "is what is marked on the lens as f8 still an f8 or do I have to compensate and open up a touch when I'm on the long end of my zoom?"

The answer is no, except for the Zeiss 17-35mm zoom. When you turn the zoom range from the wide end to the long end. Somewhere pass the middle of the focal length, the f-stop change. It is visible inside the view finder display. But on the lens, f/8 is now actually f/11. It is critical when you shot flash/strobe or chrome films in manual mode. That's one of the reasons a lot of pros pay big bucks for the fix aperture zoom lenses when available. So, you have to open 1 stop or 1/2 stop depends on where your focal length is. You can also depend on the view finder display. Experience shows that it is accurate enough for exposing chrome films.
 
G

Guest

>Albert,

Would you please elaborate on the 17-35?

thanks,

michael.
 
G

Guest

Micheal, My message was not very clear. What I was trying to say is that the N 17-35mm Zoom Lens is a fix aperture zoom which the aperture does not change on any zoom range. Hence, no compensate for exposure is required.
 
G

Guest

>Albert,

Thank you. I was hoping that is what you meant ... just wasn't sure. Thanks for the clarification.

Michael.
 
G

Guest

I don't have an N1, but I do have an ND which I imagine is similar in most ways, and while the physical marking obviously cannot change, you can set the viewfinder to show the effective f-stop. Also, the metering circuits will compensate so it is only an issue in situations where you are using external metering to set the f-stop manually.

DJ
 
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