Fixed Aperture Lens vs Variable Aperture Lens?

Mar 18, 2011
I've been looking around for a sharp zoom lens. It doesn't matter whether there is distortion or not, as long as it could be fixed easily during post-processing. Then, i came across 2 type of lenses, fixed aperture lens and variable aperture lens. The fixed aperture lens cost ALOT more than the variable ones. Yes, the build quality is much better and some of them have special coatings.

Take a look at these 2 lenses:
NIKKOR 24-120mm f/4G vs NIKKOR 24-85mm f/3.5-4.5G

Yes, the zoom range might be more but the price is really alot more. at focal length 24mm, the 24-85mm can take in more light than the 24-120mm. It is only at mid-higher focal range where the 24-120 shine. But this doesn't justify the discrepancy in price. So i asked the sales woman, and she told me that the 24-120mm is able to take sharper photos. Then i wondered, how can i tell if she is telling the truth. Are there any specs to look out for? Or i should just read tons of reviews to know more about the lens that i'm interested in? >.>


Senior Member
Nov 28, 2005
This question again???

How can you tell if she's telling the truth? easy! READ REVIEWS. Test the lenses for yourself.


Senior Member
Dec 28, 2010
The Universe
Just for clarification, fixed aperture lens refers to examples such as mirror lenses where the aperture is just that - fixed, i.e. you can't vary. Read link here: Mirror Lenses

You are talking about CONSTANT aperture lens.

In general, constant aperture lenses are more expensive because it costs that much more engineering and design-wise. In general, these tend to be higher-grade lenses which will also be sharper overall. This is not to say that the variable aperture lenses are necessarily not-sharp and the constant aperture lenses are necessarily sharp. It depends on the individual lens in question.

So to answer your question, you should read user reviews. I'm sure there are many of these on the net. Don't take any saleswoman's word for it, in particular since the 24-120mm f/4 costs more (so naturally she gains more if you buy the more expensive lens). You should also calibrate this with your own needs, not everyone needs an extraordinarily sharp lens.

One more point to note is that constant aperture lenses tend to be heavier than their equivalent counterparts, as usually more glass is required.


Staff member
Sep 27, 2004
Punggol, Singapore
the thread has been deleted base on

2. New Posters (newbies) - Use the Search Engine to find out if whatever information you are seeking has been posted before posting a question.

Title Your Threads Properly when asking for help

you spend little efforts on posting a question, only tell us that you have little interest on getting the answer.

Mar 18, 2011
oops. i guessed i was in a middle of a thought on picking a subject, and then i hit the post button. :X

Dec 11, 2008
oops. i guessed i was in a middle of a thought on picking a subject, and then i hit the post button. :X
Haiyo... people like you give newbies a bad reputation. :nono::nono:

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