what is ED glass

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andyt70

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AndyT
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Yes
and is it worth it?
just eyeing up some zoom lenses - not even sure i want (or need) one, but it got me thinking

why can i buy this
Nikon 70-300mm f4-5.6G Auto Focus for £79
and this
Nikon 55-200mm F4-5.6G DX ED AFS for £129
and this
Nikon 55-200mm DX F4-5.6 Vibration Reduction Zoom Lens For Nikon AF at £175

i understand the premium for VR, but that doesnt state ED but from its spec write up it does have 2 ED elements

so what makes the DX ED worth £50 more for less zoom?

and if money was an issue which would you recommend?
 
Lower light dispersion i.e. more light gets to your film/sensor instead of being reflected/refracted.

It's a mark of higher quality.
 
Ok...
ED glass can focus the three wavelenghts of light so they all errr.. focus at the same point....(more or less) on the film plane. This yields less chromatic abberations, the blue fringing you sometimes see around high contrast edges.

Normal optical glass can usually focus just 2 colours onto the same point.... RED and GREEN....

there are many types of ED glass but the best.. and most expensive type is Fluorite.....(CA2F i think...) its used mainly in the very very best refracting telescopes.


I know of only 1 example where it is used on a camera lens....

and that is the the canon 70-200 f4.. (IS and non IS).

Dave P.
 
ahhh i know all about CA from my astronomy - should have realised - but i am a reflector not a refractor - thats my excuse anyway
i have noticed small amounts of CA on some shots with my kit lens
so ED helps reduce that? - rules out the £79 lens then :D
 
Avoid the Nikon 'G' lenses if possible they are budget end of the range. Ken Rockwell says the following about ED glass:

http://www.kenrockwell.com/nikon/nikortek.htm#ed

ED

"Extra-low Dispersion glass." Nikon started using this only in their super speed super teles in the late 1960s. These lenses say "ED" on and have a gold band around the barrel. All ED lenses say so.

Since only the most expensive lenses used or needed this glass it acquired a cachet. Therefore Nikon started using the moniker on cheaper lenses, and today it seems everything says ED on it. Short and normal lenses have no need of this glass; it's benefit is reducing secondary chromatic aberration, which is green/magenta color fringes that used to plague lenses of 300mm and up.

ED glass is an improvement over the fluorite used by other makers at the time because it is hard enough to use for outside elements, unlike the soft fluorite.

ED glass helps eliminate secondary chromatic aberration (green-magenta color fringes) which is what previously prevented the design of practical super speed, super sharp super teles.

Discount brands now purport to use this glass. Ignore all these claims; they may or may not use this glass, but there are far more important factors in lens design than just what sort of glass was used. See the reviews for specific performance tests.

ED glass is less stable with temperature than conventional glass, and so the focal lengths of these lenses change slightly with temperature. Therefore there is no hard infinity focus stop on ED lenses because the point of infinity focus will change a bit with extremes of temperature.

ED glass also has a lower index of refraction so it requires more deeply curved elements for the same focal length.

The whole point of owning a Nikon is to use these super tele lenses, so don't be a bone head and waste your time with non-Nikon super telephoto lenses. You will find that when you go to sell a Nikon super telephoto that you will sell it for what you paid for it, so it's sort of free. If you have a discount lens (Tokina, Tamron, Spooginar, Sigma, etc.) you will have to sell it for far less than you paid, so the discount lenses actually cost MORE to own.
 
laser_jock99 said:
Avoid the Nikon 'G' lenses if possible they are budget end of the range. Ken Rockwell says the following about ED glass:

http://www.kenrockwell.com/nikon/nikortek.htm#ed

ED

"Extra-low Dispersion glass." Nikon started using this only in their super speed super teles in the late 1960s. These lenses say "ED" on and have a gold band around the barrel. All ED lenses say so.

Since only the most expensive lenses used or needed this glass it acquired a cachet. Therefore Nikon started using the moniker on cheaper lenses, and today it seems everything says ED on it. Short and normal lenses have no need of this glass; it's benefit is reducing secondary chromatic aberration, which is green/magenta color fringes that used to plague lenses of 300mm and up.

ED glass is an improvement over the fluorite used by other makers at the time because it is hard enough to use for outside elements, unlike the soft fluorite.

ED glass helps eliminate secondary chromatic aberration (green-magenta color fringes) which is what previously prevented the design of practical super speed, super sharp super teles.

Discount brands now purport to use this glass. Ignore all these claims; they may or may not use this glass, but there are far more important factors in lens design than just what sort of glass was used. See the reviews for specific performance tests.

ED glass is less stable with temperature than conventional glass, and so the focal lengths of these lenses change slightly with temperature. Therefore there is no hard infinity focus stop on ED lenses because the point of infinity focus will change a bit with extremes of temperature.

ED glass also has a lower index of refraction so it requires more deeply curved elements for the same focal length.

The whole point of owning a Nikon is to use these super tele lenses, so don't be a bone head and waste your time with non-Nikon super telephoto lenses. You will find that when you go to sell a Nikon super telephoto that you will sell it for what you paid for it, so it's sort of free. If you have a discount lens (Tokina, Tamron, Spooginar, Sigma, etc.) you will have to sell it for far less than you paid, so the discount lenses actually cost MORE to own.
Click to expand...

G lenses? I thought these marked digital only (i.e camera controls aperture, no aperture ring).

Or am I barking mad? :bonk::bang:
 
From Ken Rockwell ...

G Series: 2000 (won't work on manual focus cameras)

G is not a feature, G is a handicap. G stands for gelded.

G lenses are lenses which have been crippled by removing their aperture rings to save cost. This is a classic example of taking away features while making customers think they are getting something new. G eliminates many features with older cameras.

These newest AF lenses have no aperture ring. This means that they will not work on manual focus cameras since there is no way to set the aperture. You can mount them, however every shot will be made at the smallest aperture and your metering will be way off (probably about SIX stops underexposed) since the camera has no way to know what the aperture will be.

This is silly, but you may get them to work on closed-loop auto exposure cameras like the FA in A mode. Good luck if you want to waste your time on this.

The G series work fine on all current AF Nikon cameras on which the manual aperture rings were a pain. On legacy AF cameras like the 8008 and 6006 you may lose the A and M modes, you'll have to see. I forget if for those modes if one sets the aperture on the camera or on the lens aperture rings.

All the G series are also D. They are not AI-s.

This removal of the aperture ring is typical migration for Nikon: Nikon tends to make new lenses work on all cameras for about 15-20 years after they discontinue the camera. AF cameras have not needed aperture rings for most modes since they were created about 20 years ago! Of course collectors growl about this and the brilliant new G lenses won't work at all on the brilliant FM-3a, but so what; all the other manual and AF lenses made today still work great on every camera they've made since 1977, and with a small modification to add an aperture prong will work great (with all meter coupling) even on the original Nikon F from 1959. This is good, although G lenses are still useless on manual focus cameras.

For an AF camera to control the aperture on any non-G lens with an aperture ring you just turn the aperture ring to the minimum setting in orange (usually f/22) and flick the lock so it stays there, and then everything is done on the camera body. If for some reason the lens is set otherwise the camera will flash something like " F - - " to let you know to set the lens back to the minimum setting.
 
LeeP said:
From Ken Rockwell ...

G Series: 2000 (won't work on manual focus cameras)

G is not a feature, G is a handicap. G stands for gelded.

G lenses are lenses which have been crippled by removing their aperture rings to save cost. This is a classic example of taking away features while making customers think they are getting something new. G eliminates many features with older cameras.

These newest AF lenses have no aperture ring. This means that they will not work on manual focus cameras since there is no way to set the aperture. You can mount them, however every shot will be made at the smallest aperture and your metering will be way off (probably about SIX stops underexposed) since the camera has no way to know what the aperture will be.

This is silly, but you may get them to work on closed-loop auto exposure cameras like the FA in A mode. Good luck if you want to waste your time on this.

The G series work fine on all current AF Nikon cameras on which the manual aperture rings were a pain. On legacy AF cameras like the 8008 and 6006 you may lose the A and M modes, you'll have to see. I forget if for those modes if one sets the aperture on the camera or on the lens aperture rings.

All the G series are also D. They are not AI-s.

This removal of the aperture ring is typical migration for Nikon: Nikon tends to make new lenses work on all cameras for about 15-20 years after they discontinue the camera. AF cameras have not needed aperture rings for most modes since they were created about 20 years ago! Of course collectors growl about this and the brilliant new G lenses won't work at all on the brilliant FM-3a, but so what; all the other manual and AF lenses made today still work great on every camera they've made since 1977, and with a small modification to add an aperture prong will work great (with all meter coupling) even on the original Nikon F from 1959. This is good, although G lenses are still useless on manual focus cameras.

For an AF camera to control the aperture on any non-G lens with an aperture ring you just turn the aperture ring to the minimum setting in orange (usually f/22) and flick the lock so it stays there, and then everything is done on the camera body. If for some reason the lens is set otherwise the camera will flash something like " F - - " to let you know to set the lens back to the minimum setting.
Click to expand...

In other words....avoid the G lenses! What Ken fails to mention is that optically they're not on the spot either. Any of the buget ED lenses will be better. I just managed to give the last of my G lenses away (the 70-300 zoom) to seal the deal on a camera body sale....
 
laser_jock99 said:
In other words....avoid the G lenses! What Ken fails to mention is that optically they're not on the spot either. Any of the buget ED lenses will be better. I just managed to give the last of my G lenses away (the 70-300 zoom) to seal the deal on a camera body sale....
Click to expand...

So you're saying that the Nikon 70-200G-ED F2.8 VR isn't optically up to much? His review for that lens was out of this world!!
 
LeeP said:
So you're saying that the Nikon 70-200G-ED F2.8 VR isn't optically up to much? His review for that lens was out of this world!!
Click to expand...

leeP , it would seem you have added an extra G to that lens it dont have a g in it and yes it is a corker of a lens
 
daftbugga said:
leeP , it would seem you have added an extra G to that lens it dont have a g in it and yes it is a corker of a lens
Click to expand...

:bonk::bonk::bang::bang: confusion rains/reins/reigns :LOL:
yes youre right in that a g type lens has no aperture ring

copied from plate on lens itself af-s vr-nikkor 70-200mm1.2.8G

as i said it is a corker of a lens , the 70-300 however is at budget end of range and is not too good .
 
daftbugga said:
:bonk::bonk::bang::bang: confusion rains/reins/reigns :LOL:
yes youre right in that a g type lens has no aperture ring

copied from plate on lens itself af-s vr-nikkor 70-200mm1.2.8G

as i said it is a corker of a lens , the 70-300 however is at budget end of range and is not too good .
Click to expand...

LOL.

Aye, it comes from not being IF, poor aperture, though a good budget lens with the new VR technology.

I've used it a few times and have it in my kit bag for emergencies (ie the big 'un dies)!

cheers

Lee
 
Ken Rockwell is an idiot. Don't read his site and take it with any degree of seriousness
 
andyt70 said:
why can i buy this
Nikon 70-300mm f4-5.6G Auto Focus for £79
and this
Nikon 55-200mm F4-5.6G DX ED AFS for £129
and this
Nikon 55-200mm DX F4-5.6 Vibration Reduction Zoom Lens For Nikon AF at £175
Click to expand...

so the first lens should be avoided because it is both G and NON ED
the second although using higher quality glass is still a no no cos its G

what i dont get now is why G is bad - i am only using a digital body, only ever will be using this on a digital body so why does it matter that i can only set aperture on the body?
and if i get a lens with an aperture ring i have to lock it at the smallest aperture and let the body control it anyway??

the VR lens above is VR & ED & G and thats also not good?
 
Ross said:
Ken Rockwell is an idiot. Don't read his site and take it with any degree of seriousness
Click to expand...


Amen to that:


Do not take Ken Rockwell as gospel.

This is the guy who feels o.k. writing lens reviews without having ever touched the lens in question.

He also thinks the SB400 is the best flash Nikon have ever made, the guy's a berk most of the time.
 
andyt70 said:
so the first lens should be avoided because it is both G and NON ED
the second although using higher quality glass is still a no no cos its G
Click to expand...

o.k lets try and solve the confusion


i'd agree totally with your first line ,that lens is pretty much carp and yes i had 1 once ( not for long )

as for your second line i'd disagree , afarik its a good lens.

laserjock 99 's comment re- avoid G lenses would apply to that 70-300 but not other G type lenses ,IMO anyway
 
so... as with pretty much all my hobbies / interests .. there are no shortcuts.. you get what you pats for and you need the good stuff :)

so if i did decide i wanted some kind of decent zoom i am looking best part of £200 at least

i'll stick to wide angle landscapes for now :D
 
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