Lens Quality (Fixed vs. Zoom)

[Octoshark]

What is the difference between the following example:

Say you have a 50-200mm lens (I don't know if thats a real lens, just pretend), and you also have a 100mm macro.

What is the difference between taking a picture with the 100mm macro and taking a picture with the 50-200 set at 100mm? In both cases you are shooting at 100mm so how come the quality is better when using the fixed macro?

Can someone explain? Thanks

 

[iceemn360]

I dont really have a technical explanation for this. but typically Fixed focal length lenses or prime lenses just tend to be sharper/faster in general. I guess its because the optics can be fine tuned where as Zooms struggle to main good optics throughout a range that requires moving parts/elements.

There are some zooms that rival the IQ of prime lenses though

the 50 -200 sounds like a kit. Its also probably not that fast (in termps of max aperture) and just doesnt have the quite the IQ of a fixed focal length lens. The 100mm Macro is also probably a faster lens in terms of aperture.

Both are designed for different use.

 

[Octoshark]

I guess its because the optics can be fine tuned where as Zooms struggle to main good optics throughout a range that requires moving parts/elements.

Sounds like it makes sense, thanks.

 

[BlueCorn]

What is the difference between taking a picture with the 100mm macro and taking a picture with the 50-200 set at 100mm? In both cases you are shooting at 100mm so how come the quality is better when using the fixed macro?

This really has nothing to do with fixed vs zoom. It has to do with minimum focusing distance; i.e. how close can you be and still be in focus. With a 100 macro, that distance is about 1'. With a 100mm non macro, zoom or otherwise, it's about 5-6'.

The general consensus is that non-zoom lenses (primes) are sharper than zoom lenses but quality modern zooms are very good. Most folks couldn't tell one from another.

I shoot zooms, except for macro, because there's just no way that I'm going to carry 6 or 8 lenses with me when I'm out shooting.

 

[TitusvileSurfer]

To make a zoom work you need a lot more glass. Say made up Prime lens has 6 elements. The light must pass through 6 "windows" to work through the lens. Say madeup Zoom lens has 23 elements. The light must pass though 23 "windows" to work through the lens. Less individual pieces of glass to pass through = less chance for distortion.

Now this is a VERY basic and unscientific example given I don't have time to research and present a compelling argument. Some of the elements may be "special" and placed to reduce flare or some other extra perk. So more elements does not necessarily = less quality. The "keep it simple stupid" explanation holds the theory of less elements = less chance to distorted light = better quality. The zoom lens needs more elements to create a zoom capability, so that is the general gist of why prime lens will often deliver better quality than a comparably well made zoom lens. That said while an image quality difference between zoom and prime may exist on paper, a good zoom will be hard pressed to be considered "lesser quality" than a good prime in the real world.

 

[Octoshark]

To make a zoom work you need a lot more glass. Say made up Prime lens has 6 elements. The light must pass through 6 "windows" to work through the lens. Say madeup Zoom lens has 23 elements. The light must pass though 23 "windows" to work through the lens. Less individual pieces of glass to pass through = less chance for distortion.

Now this is a VERY basic and unscientific example given I don't have time to research and present a compelling argument. Some of the elements may be "special" and placed to reduce flare or some other extra perk. So more elements does not necessarily = less quality. The "keep it simple stupid" explanation holds the theory of less elements = less chance to distorted light = better quality. The zoom lens needs more elements to create a zoom capability, so that is the general gist of why prime lens will often deliver better quality than a comparably well made zoom lens. That said while an image quality difference between zoom and prime may exist on paper, a good zoom will be hard pressed to be considered "lesser quality" than a good prime in the real world.

That makes sense too, thanks

 

[Jacob D]

It sounds like the 'real question' is: why do I need a macro lens? Beerguy pretty much summed it up. Macro photography is all about magnification and 'normal' lenses just don't magnify well.

I do love primes though. I can't imagine owning 6 or 8 of them (well, ok I can probably if I had money to burn). I own only 3 lenses and they're all primes; often I have only a single lens with me. I shoot people though, sports and landscape are different worlds. I have owned a couple zooms and wouldn't mind owning another for the occasional landscape work... but I'm sure I could make do with a 17mm prime in the kit instead

 

[TitusvileSurfer]

Oh I didn't even realize it was a macro question. I thought he was referring not necessarily to macro primes but primes vs. zooms in general.

 

[boodlefish]

i have noticed that the more i shoot with prime lenses the more i want to shoot with them, it just makes the whole experience more fun for some odd reason. i'm moving from place to place to get the framing i imagine and every time i move i seem to discover a new perspective that is better or different then i expected... it is so fun and IMO encourages the photographer to move around and get more involved with their subject.

with macro photography the photographer is already very involved with their subject, but IMO the fact that most if not all dedicated macro lenses are prime keeps it that way. JMO.

 

[TWallace]

Prime lenses often have wider apertures than zooms, too, making them better for use in dim lighting. For example, Nikon's 50mm 1.8 lens is small, light, cheap ($115 I think) and fantastic in dim lighting. It's near impossible to find a comparably priced zoom lens with an aperture that wide.

 

[TitusvileSurfer]

Good point. The zoom does obviously have the zooming capability, but 80% of the time I use a zoom at one of the extreme ends anyway. My 70-200 f/2.8 IS is admittingly pegged at 200mm more than 80% but the 24-70 f/2.8 (RIP) saw a lot of 35mm and 50mm.