Fixed MM lenses of Zoom Ranged Lenses?

[dan1home]

Are fixed MM lenses better quality then zoom ranged ones?

Example: 70-200mm f4 L versus 200mm f2.8 L

[Ronald S. Jr.]

For the most part, yes. In some cases, very noticeably so.

[cjm]

Um why compar e a 70-200 F4 to a 200mm f2.8?

How about the 200mm f2.8 Vs the 70-200mm f2.8? I would say maybe a wee bit sharper if you pixel peep. Other wise about the same.

But of course a Prime lens that is fixed at a certain length like 200mm and calibrated correctly will be sharper then a zoom lens that has its elements move. But if you buy good zoom lenses, you usually get very sharp results that are worth using a zoom for.

[dan1home]

Um why compar e a 70-200 F4 to a 200mm f2.8?

How about the 200mm f2.8 Vs the 70-200mm f2.8? I would say maybe a wee bit sharper if you pixel peep. Other wise about the same.

But of course a Prime lens that is fixed at a certain length like 200mm and calibrated correctly will be sharper then a zoom lens that has its elements move. But if you buy good zoom lenses, you usually get very sharp results that are worth using a zoom for.

Price wise the 200mm f2.8 and the 70-200mm f2.8 are not in the same category... that's why I wasn't comparing them.

[Ronald S. Jr.]

If you don't need the 2.8 of the 200 prime, I'd get the 70-200 for versatility. It's very very sharp, and quite light for a "big white", too.

[dan1home]

If you don't need the 2.8 of the 200 prime, I'd get the 70-200 for versatility. It's very very sharp, and quite light for a "big white", too.

Im a little concerned that the f4 rating wont give me enough Bokeh on close up shots...

[Ronald S. Jr.]

If you're close up, it'll give you plenty. Just move the background away, and the subject closer. The formula for bokeh. ;-)

[dan1home]

If you're close up, it'll give you plenty. Just move the background away, and the subject closer. The formula for bokeh. ;-)

Hmm... I thought Bokeh had a lot to do with the minimum apeture setting (As in: f2.8 compared to f4; f2.8 being the one giving the better Bokeh)

[Ronald S. Jr.]

better is a subjective term. Just take your 50 1.8 and see the difference between 2.8 and 4. More often than not, the only noticeable difference is the doubled/halved shutter speed.

[lostdoggy]

This might help w/ bokeh
http://www.dofmaster.com/dofjs.html

[dan1home]

better is a subjective term. Just take your 50 1.8 and see the difference between 2.8 and 4. More often than not, the only noticeable difference is the doubled/halved shutter speed.

So definitely helps more with regards to low level light shooting than bokeh effect is what your saying?

[Ronald S. Jr.]

Yup, I'd say so. See, with a zoom lens, your distance to the subject varies so, that 2.8 bokeh at a further distance can look choppier than f/4. However, 5.6 at a good distance can look like 2.8 bokeh. Distance to subject plays a huge part in bokeh.

A 2.8 lens will double your attainable shutter speed with an f/4 lens. For me, that's a biggie.

[dan1home]

The speed at which a lens focuses has nothing to do with it's minimum aperture rating correct?

[Ronald S. Jr.]

right.

[liza]

Are fixed MM lenses better quality then zoom ranged ones?

Example: 70-200mm f4 L versus 200mm f2.8 L

I think they are. Check my sig. ;)

[20droger]

Dan1home, just for your information, a "fixed mm" lens is called a prime lens.

As a rule of thumb, prime lenses tend to have better glass and fewer elements than zoom lenses with an equivalent maximum focal length. Note that I said as a rule of thumb. Obviously, there are crappy prime lenses and excellent zoom lenses.

The following discussion assumes equal buid quality.

Optically speaking, prime lenses have less glass, and that means less distortion. After all, the prime lenses have no need for the zoom elements.

However, the difference is sometimes so small that it is far overridden by the flexibility of the zoom.

A case in point. The Sigma APO 300mm F2.8 EX DG HSM prime lens has 11 elements in 9 groups, whereas the Sigma APO 120-300mm F2.8 EX DG HSM zoom lens has 18 elements in 16 groups. That means, in the zoom lens the light must pass through 7 more pieces of glass.

The MFT chart for the prime lens is:
http://www.sigma-photo.com/images/LensesMtf/113_big.jpg
Notice the nice flat red and green lines (the flatter the better).

The MFT chart for the zoom lens at 300mm is:
http://www.sigma-photo.com/images/LensesMtf/70_big.gif
Notice that the red and green lines droop. This droop indicates that the optics in the zoom lens are not as good as those in the prime lens. The zoom lens is still darn good, however, and when I considers the flexibility of the zoom lens, I would choose the zoom as the best overall.

A purist would disagree. The prime lens IS better than the zoom lens.

Another factor... The MSRPs of the two lenses (for comparison only--NEVER pay the MSRP) are $3600 US for the prime lens and $3210 US for the zoom lens. With the prime lens being so very little better than the zoom lens, with the zoom lens having much more flexibility, and with the zoom lens costing almost $400 less, I would definitely go with the zoom lens.

Again, price is not a consideration to the true purist. He would choose the prime lens.

In other cases, the differences are obvious. Almost any good zoom is better than a mediocre prime. And vice-versa. Only when the quality is the same is there a tough decision to be made.

Zooms have come a long way in the last few years. Not long ago, if you wanted to be able to cover a wide range of situations, you would have to have a bag full of primes. Nowdays, a couple of zooms will do the same thing.

Choose the lenses, either prime or zoom, that will do the jobs you have in mind.

If you wish to shoot small birds at a distance, you need a long telephoto. A zoom is almost required, because birds change position so much that no single prime telephoto will usually do (unless you specialize in blind shots).

On the other hand, if you wish to shoot landscapes, a wide angle prime may serve you very well. There are also some excellent wide angle zooms out there that will increase flexibility, but they are not nearly as required as is a long telephoto zoom for birding.

Above all, whatever you choose, have fun.