What are main advantages of lenses with constant aperture?

[artphoto]

<p>Would really like to hear why it is better to use such lenses when photographing landscapes?</p>

 

[john_a5]

<p>Generally, they, constant aperture lenses, are just better built to be quite honest. If other things were equal, like IQ and the ability to see through the lens (brightness), most wouldn't care as landscape is generally done with smaller apertures rather than wide open. The rub comes if you meter externally, as you might with film where you can't see an LCD. Then a variable aperture would be more difficult to meter for as you wouldn't really know what aperture you would be shooting at--these types of lenses were never used by pros on assignment, commercial, as you shot a polaroid to test your exposure and shot based on that.</p>

<p>But again, the constant aperture lenses are generally just a superior lens in most lineups.</p>

[Michael R Freeman]

<p>There really is very little advantage to using constant aperture zooms for static landscape photos, as in almost all cases you are going to be stopped down from maximum aperture by several stops anyway. So lens speed, vignetting or autofocus speed is usually not a considering factor, and such a lens may not necessarily be "better" for that application.</p>

<p>Having said that, constant aperture zooms are usually high end professional lenses within the manufacturers product line, and as such they usually have highly corrected optics that may perform better than a variable aperture consumer zoom used at the same mid-range aperture.</p>

[Matt Laur]

<p>Quality issues aside ... in practical terms, it's very nice to be able to set up lighting equipment and an exposure based on a particular aperture, and not have that change when you alter focal length.</p>

[jean_yves_mead]

They allow thick people like me to use the lens on a meterless camera without having to guess at focal-

length-related exposure compensation.

 

More importantly, variable-aperture lenses get slower as the focal length increases, which is usually the

exact opposite of what one needs when trying to hold things steady.

[Michael R Freeman]

<p>While that is true Matt, when used on many modern cameras (Artjom appears to be using a D5000) in effect variable aperture zooms can be set to maintain a constant aperture as the focal length is altered. Provided the aperture in use is equal to or smaller than the maximum at the long end of the zoom, the lens will maintain a constant aperture as you zoom the lens. So even that advantage is gone.</p>

<p>Ain't modern technology grand. ;-)</p>

[mendel_leisk]

<p>I don't see that there's a significant advantage. The Canon 10-22 is a very nice lens, suitable for wide landscape, no real downside to it's variable max aperture.</p>

[Matt Laur]

<p>Maybe I'm funny, Michael - I shoot at f/2.8 all the time. So, it's genuinely help to me to have the lens stay that way, regardless of the focal length I happen to be using. On slower variable-aperture zooms, I work directly in one of their big weak spots.</p>

[jason_hall5]

<p>to add to Matt's point, I would really not like to have to shoot a wedding reception (often poorly lit) at f5.6 (often the max aperture when zoom out on consumer zooms) and not a constant f2.8. As is with the Canon 17-55 and 70-200.</p>

<p>So the advantage is very much still there.</p>

<p>However, the OP asked for landscape, so widest aperture is of no concern. quality of the glass is. In general (with exceptions to every rule), the better lens are constant aperture lens. But I am very sure that there are many variable aperture (consumer level) lens that are very much up to the task. Even more so when they are stopped down to thier "sweet spot". Also, not every high end pro zoom lens is a constant aperture. The canon 100-400 comes to mind. I forget the aperture range...</p>

<p>Jason</p>

[jim_j2]

<p>Jason,<br>

EF 100-400 f/4.5-5.6L IS USM </p>

[kevin_delson]

<blockquote>

<p>Even more so when they are stopped down to thier "sweet spot"</p>

 

</blockquote>

<p>Ahhhh, now we begin to see. :)</p>

<p>For sake of argument, lets pick a slow zoom f/4.5 @ 200 mm and a faster constant zoom, f/2.8 @ 200mm.</p>

<p>More often than not f/4 on the (faster) lens will look a lot better than the slow zoom at f/4.5 @ 200mm since we are quite a bit closer to the "sweet spot" with the constant 2.8</p>

<p>Going a step further, even at 5.6 with the slow zoom, it is not even a full stop closed down yet.<br>

With the f/2.8; f/5.6 is (2) full stops closer and probably right at the "sweet spot."</p>

[markci]

<p>Probably not much of an advantage, except as compared to the very inexpensive variable-aperture zooms, which are crap.</p>

[pbarnes]

<blockquote>

<p>Maybe I'm funny, Michael - I shoot at f/2.8 all the time.</p>

</blockquote>

<p>Matt, I can't get great looking shots <a href="../photo/6692079&size=lg">like this one</a>, sharp from front to back, with a lens at f2.8.</p>

[lex_jenkins]

<p>There's probably no advantage to a faster constant-maximum-aperture zoom if you plan to use a fairly conventional technique for landscapes or scenic photography. If you normally stop down to around f/8 or so and rely on the hyperfocal setting (as with <a href="../photo/11132422&size=lg">this city scene</a>), you won't see much difference in apparent sharpness at f/8 between an affordable variable aperture zoom and a more expensive f/2.8 zoom.</p>

<p>In some cases there's little appreciable optical difference between a good variable aperture zoom and an f/2.8 zoom of a comparable focal range. The main difference besides the faster maximum aperture may be a more rugged build: metal rather than plastic lens mount; screwed-together fasteners rather than snap-together plastic fittings; fewer components held together with adhesive tape (yes, really).</p>

<p>For example, in <a href="../photo/11132422&size=lg">your city scene of the narrow cobblestone paved walkway</a>... it seems reasonably sharp, altho' it might have been a little better at f/11-f/16 (tradeoff between diffraction and greater DOF). You probably wouldn't see much difference between your kit zoom and an f/2.8 Nikkor zoom. But you *might* get better correction for barrel distortion. Note the curved verticals along the left margin: the curved window frame, drain pipe, etc. Now *those* are factors you should consider when purchasing a lens for landscape, scenic or other static-scene photos. But if you're stopping down to f/8 or so, the differences between an f/2.8 zoom and a variable aperture f/3.5-5.6 zoom may not seem cost effective unless the more expensive zoom is better corrected to minimize distortions.</p>

<p>What you might want to look for, rather than worry about the differences in maximum aperture between a non-variable f/2.8 midrange zoom and an f/3.5-f/5.6 is to look for tests that show which is better corrected to minimize barrel distortion, coma, chromatic aberration and flare. Those are factors that will show up, while you may not see much difference in apparent sharpness at f/8 between a $1,500 midrange zoom and a $300 kit zoom.</p>

[matt_needham]

<p>In my opinion they are a disadvantage when shooting landscapes. If I'm only going to be using f/8-f/16 I'd much rather hike around with my small, light f/4-5.6 long zoom than my huge f/2.8 version. It's easy enough to set up the tripod in the backyard and test both to see how the cheaper lens compares at those apertures. </p>

[Matt Laur]

<p>Peter: OK, when I said "all the time" (about using f/2.8) I was being a bit hyperbolic, to be sure. I should have said "a lot." :-)</p>

[William Michael]

<p><strong><em>“What are main advantages of lenses with constant aperture? </em></strong><strong><em>Would really like to hear why it is better to use such lenses when photographing landscapes?”</em></strong><br>

<strong><em> </em></strong><br>

<strong><em> </em></strong><br>

I understand that you are (most likely) asking about constant maximum aperture zoom lenses as opposed to varying maximum aperture zoom lenses.</p>

<p>But there are other constant maximum lenses and they are Prime Lenses.</p>

<p>Some reasons for which these Prime Lenses are better for landscapes are (but not limited to and in no particular order):</p>

 

<ul>

<li>Less expensive</li>

<li>Usually faster</li>

<li>Less prone to Flare</li>

<li>Less prone to Veiling Flare</li>

<li>Have better / more functional Lens Hoods</li>

<li>Brighter viewfinder</li>

<li>Lighter (weight) </li>

<li>Shorter (length)</li>

</ul>

<p>A reason for which they are not as suitable:</p>

<ul>

<li>Not many really wide ones for APS-C format<br /><br /></li>

</ul>

<p>WW<br>

:</p>

 

[plasma181]

<p>I've been looking for the new Toyota that only drives at one speed. </p>

<p>But seriously, the only constant aperture lenses I have ever heard of at the mirror lenses. Their advantage is that you get high magnification in a small package. </p>

[William Michael]

<blockquote>

<p><strong><em>"the only constant aperture lenses I have ever heard of at the mirror lenses"</em></strong></p>

</blockquote>

<p>I agree Robert, that the incorrect use of terminology might cause confusion.<br>

BUT, as I mentioned, the Original Post is most certainly referring to <em>Constant <strong>Maximum</strong> Aperture Zoom Lenses</em>, as opposed to <em>Varying <strong>Maximum</strong> Aperture Zoom Lenses</em>.<br>

On the other topic as well as mirror lenses - there are scientific and other special application lenses which have a constant (or fixed) aperture, some could be used on DSLRs or SLRs.<br>

Also, some phone cameras and one use cameras, are other examples of Fixed Aperture Lenses. A Pinhole Camera, is, I suppose, the most basic example.</p>

<p>WW </p>

 

[jpo3136b]

<p>Most telescopes are built to constant aperture because there is no aperture control on a fixed tube with fixed optics; they're wide open all the time, and that's their constant, maximum aperture. Just about every telescope you've ever seen has probably had a solid tube and therefore, a constant maximum aperture.</p>

<p>If you think about telescopes as an example, sometimes it can be a downright disadvantage to have a constant maximum, if that constant maximum is not wide enough. In the case of using telescopes, it often is not wide enough. Many will fall into f/11 or narrower apertures.</p>

<p>I understand this is usually a zoom feature; but, keep in mind, a constant maximum aperture, optically, can be achieved with very simple, almost no, lens assembly mechanics. In this respect, they've been around since 1608!</p>

<p>For the fru-fru zooms with the mechanical adjusters to maintain constant apertures: I don't think it matters much. For example, if you are using TtL metering, with the zoom set wide; and, you receive a good return on CWA exposure from the meter (hypothetical: 1/125 at f/4); then, if you switch to a narrower field of view, like the most telephoto of the zoom options, how likely is it that your exposure will be off? Not by much.</p>

<p>I would say that<strong> excluding an area of the field of view and its contributing illumination would be more influential </strong>than the difference created by the aperture not mechanically re-adjusting itself for a change in focal length. Just as a practical matter, I haven't seen the mechanics of the zoom lens assembly affect things that much. Besides, in landscape, there's always depth of field preview; and, overall exposures made with handheld spot meters are possible and common.</p>

<p>I would imagine that constant aperture lenses in zooms would give their most benefit not to landscape, but to sports or other action photos. That is, the mechanical adjustments that the lens assembly makes in response to change in focal length are a convenience function for the photographer who is not going to take his time and adjust his equipment before making the photo.</p>

<p>So, in the case of landscape, I would say, "Negligible advantage."</p>

[jpo3136b]

<p>To imagine excluding an area of an angle of view being more influential:<br /> Imagine that a really bright corner of sky was in the photo as the zoom was set wide. Then, without changing camera position or angle, you zoomed in tight: tight enough to exclude that bright patch of sky. Now, your frame is filled with mid-tone whatever (no bright sky); in that situation, as a practical matter, taking away the big, bright light source would be more influential on the landscape's exposure than an optical refinement like a constant aperture mechanism built into the zoom lens.</p>

<p>So, I feel the advantage would be negligible because:</p>

<ul>

<li>photo topics like landscape that favor deliberate processes don't need rapid action anything</li>

<li>camera position in 3D space is more likely to adjust for how much light is needed</li>

<li>the loss of aperture by zooming is not a great amount</li>

<li>the person doing the choosing over what's in the frame and what's out will have more influence over light control than a change in aperture as some zooming is done.</li>

</ul>

[kevin_delson]

<blockquote>

<p>Most telescopes are built to constant aperture because there is no aperture control on a fixed tube with fixed optics; they're wide open all the time,</p>

 

</blockquote>

<p>Although this is not a astronomy or telescope forum, a clarification if you don't mind.</p>

<p>Telescopes are quite often stopped down for a number of reasons (solar observation) as one example. A simple (restrictor) mask is placed at the primary objective. Though not a zoom, it is changing the aperture of the instrument.</p>

 

<blockquote>

<p> In the case of using telescopes, it often is not wide enough. Many will fall into f/11 or narrower apertures.</p>

 

</blockquote>

<p>Schmidt Cassegrain's (folded optical path) are available to consumers at f/8<br>

Aplanatic designs like a Ritchey-Chrétien easily attain f/4<br>

Standard Newtonian reflectors easily attain f/4<br>

Schmidt-Newtonians even faster.<br /></p>

<p>Telescopes for astronomical use are not good examples to compare to camera lenses as most camera lenses are simple refractive optical tubes.<br /></p>