A quick opinion of the Nikon 20mm 2.8D

[ravncat]

I've been using the lens quite a bit on digital for a number of years now... So this opinion is based on my usage.

Wide open on full frame (D3/d700). It's very sharp in the center of the frame, and goes to sharp but on the verge of getting soft) through the borders, by the time you get to the edges it's a bit soft, and the corners are quite soft. As you stop down to 4 it's better, and it's very sharp through the plane by 5.6 (except for the extreme corners which stay softer till about f8) It's overall softer on a DX frame, and on cameras without micro lenses the corners tend to stay bad. It's very good on film.

(Note: I have become convinced of this - the borders and corners on dx always end up softer on my d200, I believe that this lens would not be a very good candidate on a high resolution body like the d3x - it might be ok stopped down to f8 - but I haven't had a chance to test it on such a camera. If you are looking for the sharpest wide angle, go get the 14-24, if you aren't interested in "ultimate" sharpness and don't have a d3x - this lens is sharp, and can be very sharp stopped down)

The lens has a level of distortion that's fairly high, enough to notice - if you know what it should look like corrected. The effect is enhanced with field curvature. (Nikon viewfinders also have a small amount of distortion in them too, so it looks worse through the finder than it really is) The distortion is often pleasent in landscape images - but is easily corrected in RAW - Lightroom has an adobe provided profile for this lens. This lens is not the best choice for architecture. With lightroom it's almost a non-issue

Vignetting is strong wide open and drops down by f5.6 I find the vingetting no problem for low light shots and portraiture where the edges are not usually the subject - For landscapes, it's either correctable, adds focus to the central areas or is not a problem when you've stopped the lens down.

Chromatic Abberations - these are strong, but not as strong as you would see on the tokina 11-16. They show up more in contra light - and have a strong effect on the apparent sharpness of the edges of the frame. Newer nikon bodies correct for this automatically in JPG - and CA can be adjusted in raw. CA is a bigger problem at wide apertures.

Flaring will happen when you have a strong light source in the frame (like the sun) but most wide angles do. I've had few flaring issues with this lens from the side- I always use the hood.

I find that it has a slightly cooler color cast than other nikon lenses - especially the cousin 35/50/85 d primes. The 20mm 2.8 is also nice and contrasty. Bokeh ranges from ok to not so great

The lense is also very small and light weight - a tad larger than the 50 1.8 and 35 2 lenses - about the same size as the 851.8d. Makes this a great choice for hiking.The depth of field scale for this lens could benefit from more markings and a longer focus throw - but it is more than we see on alot of modern lenses. The build is about as nice as the other d primes - with smooth mechanics on the inside of a plastic outer shell.

Overall, a competent lens that isn't the sharpest possible choice - but quite good for a lens of it's focal length. There are newer, better and sharper options, as well as from other manufacturers - like the zeiss 21mm. the 20 2.8 is at a lower price point. I wouldn't recommend it for dx shooters - The 20 2.8 a slight upgrade from the 18-55 in image quality and aperture speed - It is on par with other 2.8 options (though retains a very sharp center).


Some images with the 20.2.8 (and d700)

Wide open in the day


Wide open in a cave


f4 indoors



(linked for dps guidelines reasons)
Stopped down in the day (f8)
http://i78.photobucket.com/albums/j1...g?t=1298681139

stopped to (f11)
http://i78.photobucket.com/albums/j1...g?t=1298683225

[zona5101]

I've had one since 1987 or 88. I like that is is the widest nikon rectilinear lens (at the time) but I think you got the one sharp copy.

[OsmosisStudios]

I'd love one for use on my FE with film!

[Almond.Butterscotch]

I'm curious about the OP's conclusion that it's softer on a cropped sensor than on FX/35mm. Anyone else have experience with that happening (with any lens)?

[jdepould]

Originally Posted by Almond.Butterscotch

I'm curious about the OP's conclusion that it's softer on a cropped sensor than on FX/35mm. Anyone else have experience with that happening (with any lens)?

I suspect it may have more to do with the specific body (D200) than DX in general. I shot a D200 for a year or two when it was current, and I prefer the images from my D300.

[zona5101]

Originally Posted by Almond.Butterscotch

I'm curious about the OP's conclusion that it's softer on a cropped sensor than on FX/35mm. Anyone else have experience with that happening (with any lens)?

You know I never noticed how soft it was on my film camera but it certainly is soft on the D90. I just assumed it was me not noticing it when looking at my film shots. But in digital, even after the "major" repair from Nikon it is still soft at every fstop... Also be be clear, it isn't "crap" bad or unusable but it is apparent, especially when zoomed in.

[ravncat]

Originally Posted by Almond.Butterscotch

I'm curious about the OP's conclusion that it's softer on a cropped sensor than on FX/35mm. Anyone else have experience with that happening (with any lens)?

I think my observations have to do with a combination of things, the oblique angles of the light rays due to the wide angle design, micro lenses, photosite size (pixel density), and in the case of the d200 a higher anti-aliasing filter. (or maybe as implied, i just got a sharper one? It also could be the distance at which the lens is used, focal distance can impact lens performance.)

When the light rays hit the sensor at an angle further and further away from perpendicular, they can get spread over more than one photo-well, and the photowells are not continuous and have alot more depth than film. This means alot of older film lenses - especially wide angle designs - tend to have stronger vignetting and softer edges than they did on film. This is one reason why many lenses have been redesigned for digital. The d200 (and pre-d3 generation cameras) lacks the gapless microlens array which helps route light into the photon wells - I think it makes quite a difference in alot of the older lenses.

Also - the d700 has a larger photosite size than the d200. In fact, the d700 photosite size is very close to the size of the d70 photosites. If you can imagine a pitcher throwing a ball into a box, it's easier to throw the ball into a larger box - that's the kind of thing that is going on here - a larger pixel size allows for a larger circle of confusion and so a lens can be a little softer and have better results with larger photosites. Not just resolution, but also pixel density will start to show flaws in lenses. This is why i conclude that the lens may be a poor performer on the d3x, which has a high pixel density (small photosite sizes) and higher resolution.

The AA filter on the d200 is notoriously strong, which tends to mean softer out of camera images (though this is mostly dealt with by applying capture sharpening). The combination of these three may be the reason that I see softer d200 images with the 20mm. I haven't used a d300, or the lens on a d300 - but I would expect the micro-lenses to offer an improvement - but the d300 has a slightly smaller photosite size than the d200, so I would expect the lens to be stressed more - and overall be simmilar or slightly better to results on the d200. I would bet that the lens would perform poorly (worse than my d200 results) on the d7000.

This isn't to say that i think it's a terrible lens on the d200 - but it certainly isn't the best choice for sharpness. Center sharpness on the d200 is still fairly good - the rays near the center of the lens are closer to perpendicular to the sensor there...

I find similar results with my 35mm f2, but curiously not so much with my 85 1.8 or 180 2.8 (with capture sharpening for the d200 AA filter.) I suspect that the 85 and 180 are sharper than my 35 and 20, but they are telephoto lenses and have off axis light rays that are closer to perpendicular to the sensor as well - maybe reducing the micro lens advantage


also - as an addendum to the above , here's a small 100% crop from that flower image nef above

[vandergus]

I agree with everything ravncat said but have one more possible explanation as to why the lens may appear softer on a cropped sensor than on film or a full frame sensor. It could simply be that an image from a cropped sensor needs to be magnified more than an image from a full frame sensor to achieve the same output size. This would be most notable if, for example, you made two prints of the same size from a DX and an FX camera. Since the DX image would have been enlarged 1.6 times more, it may be easier to see deficiencies in the sharpness. The format size wouldn't have as much to do with pixel sharpness, though, so it depends on how you are judging the images.

[jdepould]

Originally Posted by vandergus

I agree with everything ravncat said but have one more possible explanation as to why the lens may appear softer on a cropped sensor than on film or a full frame sensor. It could simply be that an image from a cropped sensor needs to be magnified more than an image from a full frame sensor to achieve the same output size. This would be most notable if, for example, you made two prints of the same size from a DX and an FX camera. Since the DX image would have been enlarged 1.6 times more, it may be easier to see deficiencies in the sharpness. The format size wouldn't have as much to do with pixel sharpness, though, so it depends on how you are judging the images.

Output size has more to do with resolution (megapixels) than sensor size. A 100 percent/300 dpi print from a 12MP body will be the same dimensions regardless of sensor size. Having said that, the D700 has more pixels than the D200.

[vandergus]

Originally Posted by jdepould

Output size has more to do with resolution (megapixels) than sensor size. A 100 percent/300 dpi print from a 12MP body will be the same dimensions regardless of sensor size. Having said that, the D700 has more pixels than the D200.

Sure, but the concept I getting at doesn't really have to do with the number of pixels. It has more to do with the differences between formats. The reason photographers of old loved the larger formats (4X5, 8X10) was that it allowed for phenomenal detail in greater enlargements. If you tried to take 35mm film and 4X5 film, make a similar photograph, then enlarge them both to 8X10, the image from 4X5 film is probably going to look a lot better. The same principle applies to DX vs FX sensors. The differences won't be as extreme but they will probably be detectable, especially if you are scrutinizing the images for a lens test. And again, this doesn't apply to viewing 100% crops in photoshop. It applies to comparing outputs, on either screen or paper, of identical size. I'm not saying it's the reason, but it could be a factor.