Is it better to have more lens elements or fewer?
#1. "RE: Lens Elements" | In response to Reply # 0vfnewman Basic MemberWed 18-Jul-01 10:06 PM
The short answer is "the fewer the better"
Every element introduces an interface, either to air or another element. Every interface causes some amount of light loss and scattering that degrades the final image quality.
In general any prime lens has fairly few elements. Extreme focal lengths tend to deviate from this. The AF 18mm f/2.8 has 13 elements in 10 groups. No lens in my Nikon Product Guide (vol 5, 1999) has fewer than 6 elements. The most is 18 elements in 14 groups for the AF Micro 70-180 f/4.5-5.6
Which leads me to my next point.
If it were not for new and sophisticated designs that utilize quite a few elements, we wouldn't have superb lenses like the AF-S 17-35mm. The AF 35-70mm f/2.8 has 15 elements in 12 groups. Just about everyone will agree that it is a fine lens. The very good 80-200 f/2.8 (non-AF-S version) has 16 elements in 11 groups, so more does not necessarily mean worse, either.
#2. "RE: Lens Elements" | In response to Reply # 1jrp Charter MemberWed 18-Jul-01 11:13 PM
As Vic said, there is no simple rule, prime lenses don't seem to need Internal Focusing, some only CRC; so it depends on the specific formula and both lens and built quality. The famous Carl Zeiss lenses are (were?) hand polished, one at a time.
You keep reminding me of a gorgeous manual Enna Ennalyt f/4 that had a single element. How? Don't ask me, but it produced incredible portraits for about US$50, bought in the then Soviet occupied Germany.
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#3. "RE: Lens Elements" | In response to Reply # 2Thu 19-Jul-01 02:14 AM
So when we read the specs for a lens, do the number of elements and groups tell us anything about the quality? If not, are they there just to help us differentiate one generation from the next?
#4. "RE: Lens Elements" | In response to Reply # 3jnscbl Basic MemberThu 19-Jul-01 02:56 AM
It's as meaningless to the user as the number of cylinders and tracks on a hard disk drive in a computer.---scott
"I am always doing that which I cannot do, in order that I may learn how to do it."
#7. "RE: Lens Elements" | In response to Reply # 4f5fstop Basic MemberFri 20-Jul-01 11:33 PM
However, the number of cylinders that are still operating in an engine can tell you a lot about how the car may run.
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#5. "RE: Lens Elements" | In response to Reply # 1
#6. "RE: Lens Elements" | In response to Reply # 5vfnewman Basic MemberFri 20-Jul-01 11:18 PM
You are correct.
According to the "Nikon Compendium", the old GN 45 f/2.8 not only has 4 elements, but in 3 groups. The Nikon USA website says the new 45 f/2.8 P is 4/3 as well. That would seem to make these lenses the winner in the "least groups/elements" category.
Other lenses that have but 4 elements (in 4 groups) are the 135 f/3.5, Series E 100 f/2.8, and the Series E 135 f/2.8.
#8. "RE: Lens Elements" | In response to Reply # 0
The Contax T2 has fewer elements than the newer and vastly sharper Contax T3. It all depends on the formula. I would say it makes no difference except in the extreme zooms.
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#9. "RE: Lens Elements" | In response to Reply # 0
PROVIDED the designer has been able to correct aberrations to the desired degree, THEN fewer elements will probably lead to higher contrast and better flare and ghost resistance.
Nevertheless, some requirements will be impossible to fulfill without a large number of elements, and element number is a (very) rough indicator of how sophisticated one lens is and how much money the producer is willing to spend to produce it.
An outstanding classic lens such as the Leica Elmarit 90/2.8 has just 4 elements in 4 groups, while Nikon's Nikkor 105/2.5 is a 5/4 lens; but the newer Leica Summilux-R 50/1.4, designed to be the best 50 mm. lens ever even at full aperture, has 8 elements in 7 groups, compared to the classic 7/6 construction of most high quality fast 50 mm. lenses.
So, in the end, I would sum it up this way: look at how many elements a given lens has, and look at how many elements similar lenses tend to have. If the given lens shows a MUCH simpler construction, then it probably is just that. If it shows an higher degree of coplication, it could mean that the producer is trying to make a great lens in its category and probably this will be indicated by an higher price. But, since we usually have lens tests, why to worry?
#10. "RE: Lens Elements" | In response to Reply # 9Tue 24-Jul-01 06:25 AM
Speaking of lens tests, why isn't there an online clearinghouse of sorts for scientific lens tests? Photodo has done many tests but that site hasn't been updated in over a year. Popular Photography doesn't put its vast collection of lens tests online. Even if they do, there's no easy way to use their tests to compare lenses.
You would think someone would try to test, review and rank lenses coming to market... as a resource for consumers.
#11. "RE: Lens Elements" | In response to Reply # 10geo Basic MemberTue 24-Jul-01 11:50 AM
you are right, in my opinion. Photodo tests provide useful and probably reliable information, too bad here are no new tests coming out. Even more than tests, or together with them, I would like to see lens reviews, since MTF does not say all. Popular Photography tests were all right in my opinion, very practical and easier to understand than MTF charts, but they are not available online.Surfing the web I found interesting resources, like David Ruether's rankings and Bjorn Rorslett's reviews. The big question mark that remains unsolved with tests is that about sample variation, and some reviewers try to help with this.