difference in fixed or zoom at same distance

[pixmedic]

I have a bit of a noob question, but i am still a bit of a photography noob so here it goes. Can someone please explain the difference, if any, between taking a picture with a 50mm fixed focal lens and a zoom lens set at 50mm? Thanks.

 

[fjrabon]

There's no theoretical/technical difference. It's just that a prime (fixed) can gear all the lens at being its absolute best at that focal length. Usually this equates to being sharper throughout the entirety of the available apertures. Whereas with zoom lenses, you usually have to find the sweet spot for the focal length to get max sharpness, saturation and contrast.

For instance, I have the nikon f/1.8 35mm prime and the Nikon Kit lens (18-55mm f/4-5.6). at 35 mm and f/8 through f/11 both of them are practically indistinguishable, sharp, contrasty, lots of color. However, at any other aperture the 35mm is vastly superior (on top of the fact that the kit lens won't even get close to the most wide open apertures that the prime will).

Essentially zooms have to make a lot of compromises to be marginally good at a wide range of focal lengths, whereas primes can gear their entire design to nailing just that one focal length.

 

[Trever1t]

if the glass is of the same quality and the f-stop the same, then no difference. In the old days Prime lenses were more precise, offered a higher IQ but that's an almost mute point now. Most primes are faster though

 

[fjrabon]

if the glass is of the same quality and the f-stop the same, then no difference. In the old days Prime lenses were more precise, offered a higher IQ but that's an almost mute point now. Most primes are faster though

if the glass is of the same quality and the f-stop the same, then no difference. In the old days Prime lenses were more precise, offered a higher IQ but that's an almost mute point now. Most primes are faster though

I agree, though I'd add the caveat of "same f-stop in the zoom's sweet spot range"

I can absolutely tell you that a zoom wide open isn't as good as a prime of the same focal length at the same f-stop, since for the prime that's usually stopped down several stops well into the prime's sweet spot.

Basically I find that the sweetspot on the well known mid range 35mm Nikkor DX AF-S f/1.8G prime is everything from about f/3.2 to f/13, whereas similar quality glass in nikon zooms in that range need to be between around f/8 and f/11 at 35mm to have the same sharpness and IQ.

Though things may be radically different as you get into the higher quality zooms and primes.

 

[OrionsByte]

To "noob it down" for the OP - no, aside from image quality (which as someone whose photographic eye is still developing, you may not even notice anyways), there is no distinguishable difference. A photo shot with a fixed lens compared to one shot with a zoom lens will look the same.

 

[pixmedic]

I appreciate the input. me and the wife have quite a few lenses, and i am always hearing about "must have" lenses so i tend to get caught up buying lenses for every occasion.
I dont mind having multiple lenses to cover different situations, since its just a matter of putting away a few hundred dollars for a lens here and there. we have been able to get some good deals on used lenses in excellent shape. I have noticed though, that different people with different shooting styles can have very different opinions on what lenses are best for the same situation. Our prime lenses are all nikkor, and we have two Tamron zooms in f/2.8, mostly because we got a good deal on them and the nikkor versions were very expensive. i have heard varying reports as to how tamron and sigma compare to nikkor or canon, but i have had nothing but good experiences with Tamron lenses so i have no regrets there. =) I think what I have learned here is that I need to get out and really learn the lenses I have before I will really know what other lenses I actually need, if any. thanks again everyone.

 

[480sparky]

One difference might be the aperture the image is taken with. Primes tend to be 'faster', so if you're shooting with low light, you will have more shutter speeds available to you than a zoom.

For instance, if you're using an 18-70 zoom set to 50mm, your maximum aperture may be f/4 or f/4.5. With a prime, it's hard to find a 50mm with a maximum aperture smaller than f/2.

But if both lenses are set to an aperture that's available to both lenses, there's won't be any difference other than a slight IQ difference.

 

[Robin Usagani]

IQ will be different and also vignetting will be different. More than likely the zoom wont be as sharp in the corners. But it really depends on what 2 lenses you are comparing.

 

[fjrabon]

I appreciate the input. me and the wife have quite a few lenses, and i am always hearing about "must have" lenses so i tend to get caught up buying lenses for every occasion.
I dont mind having multiple lenses to cover different situations, since its just a matter of putting away a few hundred dollars for a lens here and there. we have been able to get some good deals on used lenses in excellent shape. I have noticed though, that different people with different shooting styles can have very different opinions on what lenses are best for the same situation. Our prime lenses are all nikkor, and we have two Tamron zooms in f/2.8, mostly because we got a good deal on them and the nikkor versions were very expensive. i have heard varying reports as to how tamron and sigma compare to nikkor or canon, but i have had nothing but good experiences with Tamron lenses so i have no regrets there. =) I think what I have learned here is that I need to get out and really learn the lenses I have before I will really know what other lenses I actually need, if any. thanks again everyone.

Yeah, I really got to knwo the ins and outs of the 35mm prime first. I think it really helped me develop a lot, as it allowed to me to really see what different f/stops did to the DOF. Whereas with a zoom, I was usually limited by what was available, and with a zoom it's like trying to learn several lenses all at once, since each focal length will have slightly different ins and outs, if that makes sense.

After getting a pretty good feel for the 35mm prime (and I still use it as my general go to lens), I then started trying to learn my Sigma 10-20mm wide angle. Which is a beast to learn, but has been very rewarding.

As a beginner, or even intermediate, I think constantly switching lenses keeps you from really picking up on the finer points of any one lens. Once you've really learned that lens, then rotate in another, and then you can start to get a feel for exactly what lens you want for what situations, and exactly what f/stop you want to shoot at with that lens.