50mm 1.8 / F stop query

Robbo

Robbo

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Right this might seem stupidly daft, BUT....

If I had a 50mm 1.8f lens, it would let more light in that a 50mm smallest f.stop of 5f, is that right to start with?

So the question is.....if i set the 50mm 1.8f to 5f would it produce the same image quality as the 50mm standard 5f, or would it be crisper?

does that make sense?:thinking:
 
That was worded better yes!

So it would produce the same quality? I won't even bother why I was askin this hahaha but will try .... My theory was the 1.4 would be a better glass/built to the 1.8 or higher, and would still produce a better image set at the same appature
 
If you set the apertures of different lenses to the same f setting the apertures will be the same diameter so they'll let the same light in but as for quality...that depends upon the lens design but lenses are often better a couple of stops or so down from wide open so if you have a f1.4 and set it at f4 it's probably going to produce a sharper image than a f4-5.6 set at f4. Possibly, probably...:):thumbs::thumbsdown::thumbs::)
 
Some lenses are better wide open than others but...

If you had a 50mm f1.4 and took an image at f1.4 the images will be poorer quality than if taken at f5.6 (generaly)

If you had a 50mm f1.8 and took an image at f1.8 the same will be true (generaly)

If you took images with both (f1.4 & f1.8) lenses at f5.6 then the quality will be better than wide open. Most lenses have an area where they are best. For example my Olympus Zuiko 50mm f1.4 is best at f2.8 through to f5.6. My Olympus Zuiko 35mm & 28mm f2.8's are best at f5.6 through to f8.

When buying lenses it's best to get the fastest you can afford so if you really only use f4 and have a f3.5 -f11 lens the quality is going to be worse than using a f1.8 - f11 at f4.

Hope this makes sense.
 
right thats explained it, i was thinking along these lines just wanted them confirming :-)

thanks
 
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