Now for lenses

  • Doug
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10 years 6 months ago #4434 by Doug
Doug created the topic: Now for lenses
HI all.

A little advice on lenses? Would you recommend fixed focal length or zoom? Also if the glass is the same all round, F2.8 vs F 4.0? 300mm F4.0 Fixed are a hell of a lot cheaper than F2.8 300mm Fixed? For that extra f-stop, how much better are the pics?
(The pentax 300mm ED F2.8 autofocus = about 40K and the 600mm ED F4.0 Autofocus is about 70K)
In comparison, Sigma make a 50-500 F4.0 - F6.3 that is apparently a truley awesome lens (the 175-500 I have been told to avoid). Does the extra functionality of being able to change focal length in a lens result in reduced image quality over say a fixed 400mm F4?

Cheers.
Doug

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  • mossie
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10 years 6 months ago #4443 by mossie
mossie replied the topic:
Assuming that the glass elements are of similar quality, if you put the lenses through rigorous tests, the fixed focal length will always be better, have less blurring, chromatic aberation and vignetting, this will be more obvious at the extremes, such as low light, high F-stops. This is essentialy due to the fact that zoom lenses have more optical elements inside, which essentially means more diffraction of light within the lens, and therefore less quality.

With that said, under normal conditions, you will probably not notice any difference in the quality of the prints. And you will enjoy the versatility of a zoom lens a lot more, than a fixed focal length.

Mossie

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  • Doug
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10 years 6 months ago #4444 by Doug
Doug replied the topic:
Thanks Mossie.

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2 years 11 months ago #87125 by Maithai
Maithai replied the topic: Re: Now for lenses
My Pentax EF-65ED is a great piece of equipment although the zoom EP is a bit of a let down. I am looking at purchasing a fixed focal EP and have narrowed it down to the XW 10 (39x zoom) and the XW 14 (28x zoom).

Any advice which would be the better option zoom wise.

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  • gordon
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2 years 10 months ago #87128 by gordon
gordon replied the topic: Re: Now for lenses
I would start with the XW14 and get the stronger eyepiece later.

Cheers,
Gordon

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