Part of the difference is certainly in the quality and build of the lens. A cheap lens that breaks after a year may not really be very cheap. Of course, any lens can break no matter what it's cost..
There are a number of things you can rate a lens on, for example:.
Sharpness: How sharp is it, and is it uniformly sharp (or is the center sharper then the edges).
Chromatic Abberation (CA): Some lenses, when you take a picture that has a bright area right next to a dark area will show a purplish have on the edge. Better glass doesn't, or minimizes it. Usually, specially coated glass ($$$) is used to reduce this..
Aperture: Expensive glass tends to offer wider apertures, like 1.4, 1.8, 2.0, or 2.8. This allows you to shoot in lower light. Sometimes upping your ISO can help level the playing field. But most lenses aren't there sharpest at their widest aperture, so a 2.8 lens might look good at F4, where a 5.6 lens might look good at 9. This also typically makes the more expensive glass larger (or, larger glass is more expensive)..
Vignetting: This is where you may notice dark areas around the corners or edges of a shot. More expensive glass typically has little to no vignetting..
Bokah: This is the 'pleasing factor' of out-of-focus areas, such as you would see in the background of a portrait, and is subjective. I would say that more than not, more expensive glass has nicer bokah, which I believe is tied to the diaphram design..
Color and Contrast: Not always noticable, cheaper glass can introduce some color shift, and may have poor contrast..
There are several important factors to consider outside the lens:.
Software makes it possible to correct or at least improve the items above..
If you are shooting for small web images, or only print 4x6, you may never notice some of the issues. If you ever want to make large prints, or perhaps crop and print for 8x10, you may start to notice them. I don't count pixel-peeping here, because this is what we do to analyze an image, not appreciate it..
You may never notice some of the short commings of a cheaper lens until you compare it head-to-head with a 'better' lens. I'm a strong believer of 'every little bit helps', but sometimes if that 'little bit' costs $1,000 I'll just have to forego it..
Everything I write is a personal opinion. Even when I quote facts, they are the facts I personally choose to accept.http://www.pbase.com/mariog..
When you have very little experience of (say) wine, all wines taste great: it takes lots of experience to be able to see/tell the difference -see the finer points- that discriminate between an "OK" wine and a "Great" wine (diamond, painting, tyre, cheese, you name it)..
For many of us, the difference is purely "academic": we can put up with the cask/flagon wine and don't need to pay hundreds of dollars per bottle..
The aficionado can detect at a glance the differences the tyro is unable to notice, because the tyro doesn't know what to look for..
Of course, the tyro may be able to live with the difference and consider the difference in quality not worth the difference in price..
All the same, even expensive lenses can sometimes be faulty or have design flaws...
A couple of points....
1. For Pentax (Samsung) users in particular there are lots of legacy Pentax-fit lenses that work fine; just because they are cheap does not mean that they are optically poor. You can pick up a Pentax 50mm f/1.7 manual focus lens (the old standard lens) on ebay for typically 30; you have to focus manually but the optical quality is great. Of course there are also no-name oddities but they tend to be even cheaper so there's not much risk atatched to having a go..
2. For 4 x 6 prints that go in an album you won't see the difference, especially as deficiences in colour balance, contrast etc. can be fixed easily in photoshop. The bigger you enlarge the more obvious the flaws will be: I have a supposedly 'good' telezoom (Pentax 50-200) but I can see how the corner performance suffers at wide-open apertures on reasonably-sized enlargements. So I crop them, or stop down the lens a bit. If you know what a lens's weak points are you can avoid them..
3. The link between build quality and optical quality is not clear! For example the humble Tamron and Sigma 55-200 zooms - the cheapest, plasticky telephoto zooms for DSLRs around at the moment - have sharpness which puts many more expensive lenses to shame. of course they may fall to bits in a few months..
4. Have a look at the reviews onhttp://www.photozone.de - very informative, with sample images so you can see what the reviewer is talking about..
Best wishesMike..
Thanks for the great info so far guys! Very helpfull. I feel like I at least know what to start keeping an eye out for now..
Nix..
As a newbie myself, I chose to spend my money on good light, a good tripod etc before spending on good glass..
Its like my golf game. Better clubs will only improve my perfect shots. Alas, also they are few and far apart..
Tom..
Mario Giannini wrote:.
Part of the difference is certainly in the quality and build of thelens. A cheap lens that breaks after a year may not really be verycheap. Of course, any lens can break no matter what it's cost..
There are a number of things you can rate a lens on, for example:.
Sharpness: How sharp is it, and is it uniformly sharp (or is thecenter sharper then the edges).
Chromatic Abberation (CA): Some lenses, when you take a picture thathas a bright area right next to a dark area will show a purplish haveon the edge. Better glass doesn't, or minimizes it. Usually,specially coated glass ($$$) is used to reduce this..
Aperture: Expensive glass tends to offer wider apertures, like 1.4,1.8, 2.0, or 2.8. This allows you to shoot in lower light.Sometimes upping your ISO can help level the playing field. But mostlenses aren't there sharpest at their widest aperture, so a 2.8 lensmight look good at F4, where a 5.6 lens might look good at 9. Thisalso typically makes the more expensive glass larger (or, largerglass is more expensive)..
Vignetting: This is where you may notice dark areas around thecorners or edges of a shot. More expensive glass typically haslittle to no vignetting..
Bokah: This is the 'pleasing factor' of out-of-focus areas, such asyou would see in the background of a portrait, and is subjective. Iwould say that more than not, more expensive glass has nicer bokah,which I believe is tied to the diaphram design..
Color and Contrast: Not always noticable, cheaper glass canintroduce some color shift, and may have poor contrast..
There are several important factors to consider outside the lens:.
Software makes it possible to correct or at least improve the itemsabove..
If you are shooting for small web images, or only print 4x6, you maynever notice some of the issues. If you ever want to make largeprints, or perhaps crop and print for 8x10, you may start to noticethem. I don't count pixel-peeping here, because this is what we doto analyze an image, not appreciate it..
You may never notice some of the short commings of a cheaper lensuntil you compare it head-to-head with a 'better' lens. I'm a strongbeliever of 'every little bit helps', but sometimes if that 'littlebit' costs $1,000 I'll just have to forego it..
Excellent post, good summary. Let me just add one additional item. Price isn't always the criteria for a good lens. A rule of thumb would be to say that camera manufacturer "name" brands are on average better than third party lenses, such as those made by Sigma, Tamron and Tokina. But this is not always the case. And sometimes even when there is a slight superiority, the diffference is too small to notice..
So when one decides on a particular lens, it pays BIG TIME to compare the name brand to the third party lens makers - You can save a bundle!.
Dave..
Mikelis wrote:.
When you have very little experience of (say) wine, all wines tastegreat:.
I don't know if that's true. When you don't appreciate it, it all seems ok, but you can't get the same enjoyment out of a nicer one that you would otherwise get..
I don't have a very well developed taste for wine, but I definitely enjoy even not very nice wine more now than I used to..
Hopefully the analogy doesn't get too lost when applied back to lenses...Peter.
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Ptodd wrote:.
Mikelis wrote:.
When you have very little experience of (say) wine, all wines tastegreat:.
I don't know if that's true..
And you'd be right to think that... .
When you don't appreciate it, it allseems ok, but you can't get the same enjoyment out of a nicer onethat you would otherwise get..
He, heh, in my opinion some wines taste like roadkill. This goes for some pretty expensive stuff as well..
Here's a quote from Hugo's, the best wine quide in the business. "The best wine is the wine you like best.".
I don't have a very well developed taste for wine, but I definitelyenjoy even not very nice wine more now than I used to..
My favorite quote from a wine seller is, "The more expensive the wine the better it is.".
Hopefully the analogy doesn't get too lost when applied back tolenses....
It comes apart at the seams.... Ever buy a lens on the basis of taste? Would you say the best lens is the lens you like best?.
Peter.
Dave..
Nixter wrote:.
Http://forums.philosophyforums.com/.
Nix.
I once speculated on the origin of the word whine, when I had an ephphany and realized it came from the speech that frustrated wine buyers make when they get that first taste of the $249 bottle Chateau de Merde '76... .
Sorry, couldn't find a debate on that link about "wine." For that matter, couldn't find one on "whine," either..
Dave..
Mario Giannini wrote:.
Vignetting: This is where you may notice dark areas around thecorners or edges of a shot. More expensive glass typically haslittle to no vignetting..
I agree with everything Mario has to say. I'd like to add two points though. With regards to vignetting, if you stop down the lens (use a higher number aperture) it will reduce this effect. Obviously this will affect your depth of field and shutter time/ISO needed..
Also consider autofocus speed and ability. Personally I don't have a need for super fast autofocus, but I do have a need for high autofocus ability. My walkaround lens is F/4, so when I'm in a dark situation I'll use my 50mm F/1.4 so I can take advantage of my camera's autofocus better. Even if I use the same aperture, it will focus using the larger aperture which makes it much more reliable..
-Porter..
Chato wrote:.
Ever buy a lens on the basis oftaste? Would you say the best lens is the lens you like best?.
Well, maybe it's not so far from the truth. Some aspects of a lens' rendering that make it appealing are not the things that one can deduce from MTF charts and so on....
For example, take a look at these comments on the Pentax SLR forum, regarding the Sigma 17-70:http://forums.dpreview.com/...forums/read.asp?forum=1036&message=24512050.
John Bean (UK) wrote:.
It's not a lens for pixel-peepers taking pictures of walls - neitheris the new DA*16-50 either - but it's a lens for photographers wholike a certain "look" from a lens..
Shifting the subject again, it's also often true of microphones, for example, that people desire (and pay big money for) a certain 'character' rather than an accurate signal..
Peter..
Ptodd wrote:.
Chato wrote:.
Ever buy a lens on the basis oftaste? Would you say the best lens is the lens you like best?.
Well, maybe it's not so far from the truth. Some aspects of a lens'rendering that make it appealing are not the things that one candeduce from MTF charts and so on....
You got me there. Good point.... .
Dave.
For example, take a look at these comments on the Pentax SLR forum,regarding the Sigma 17-70:http://forums.dpreview.com/...forums/read.asp?forum=1036&message=24512050.
John Bean (UK) wrote:.
It's not a lens for pixel-peepers taking pictures of walls - neitheris the new DA*16-50 either - but it's a lens for photographers wholike a certain "look" from a lens..
Shifting the subject again, it's also often true of microphones, forexample, that people desire (and pay big money for) a certain'character' rather than an accurate signal..
Peter..
Mario Giannini wrote:.
Chromatic Abberation (CA): Some lenses, when you take a picture thathas a bright area right next to a dark area will show a purplish haveon the edge. Better glass doesn't, or minimizes it. Usually,specially coated glass ($$$) is used to reduce this..
No, CA is corrected by the design of the optics and the types of glass. Coatings don't reduce chromatic aberration..
Bokah: This is the 'pleasing factor' of out-of-focus areas, such asyou would see in the background of a portrait, and is subjective. Iwould say that more than not, more expensive glass has nicer bokah,which I believe is tied to the diaphram design..
The diaphragm shape does play a part - more blades is good, circular is best. But the most important factor is how even the defocus is, as evidenced by out-of-focus highlights. If they are very even, like little bright disks, or with slightly soft edges, that will tend to produce attractive bokeh. If they are darker in the centre and brighter round the edge (in the extreme case, making a ring), that will usually make for unattractive out-of-focus blur...