28mm f/2.8 AI-S
Having spent a lot of time in the normal to short telephoto focal range I wasn't particularly sure about how I'd approach a wide angle lens for 'every day' or environmental photos. Sure, a 50mm is a reasonable choice but I wanted to frame things with a different perspective at the wider end - having scanned my catelogue of photos made with a 24-70mm it was clear I had a preference for the FF 28mm FoV when shooting people: the 24mm always felt too wide with difficult in composing effectively with people and 35mm didn't feel wide enough away from a 50mm.
So the search was on. Having recently picked up a 20mm for dual use as a wide for FF or as a walk-about ~28mm equivalent FoV on DX I started to look for a suitable 28mm prime that could be ultimately used on FF: sometimes you just want something lighter than a 900g zoom lens.
The Nikkor options (new and legacy) for the 28mm focal length is reasonable wide:
- 28mm f/2 AI/AI-S
- 28mm f/2.8 AI, AI-S (0.2m min focus distance)
- 28mm Series E f/2.8 AI-S, f/3.5 AI-S
- 28mm f/1.4G, 28mm f/1.8G, f/1.4D, f/2.8D
And the choices were quickly narrowed to the Nikkor 28mm f/2 AI or the Nikkor 28mm f/2.8 AI-S.
NB: we have discontinued the f/2.8 AI version of this lens as unlike many other AI to AI-S upgrades, the 28mm f/2.8 AI and AI-S do not share the same optical formula: the reason for the optical upgrade is eluded to in the Nikkor 1000 Nights tale with the desire to improve the optics from the Series E which again was already supposed to have bettered the AI design.
The f/2 AI/AI-S vs f/2.8 AI-S: our purpose
The Bjorn Rorslett summary of both lenses are positive with other online commentary drawing the conclusion that whilst both are sharp and have CRC elements to allow for extended close focusing, the f/2 variant has better mid-far performance with better flare/ghost resilience whilst the f/2.8 is better in the close-near performance.Given that I intend to use the lens mostly with people as the main focus the f/2.8 AI-S was the one - classic landscape properties (good infinity and corner sharpness at f/5.6 and smaller) for lenses don't matter so much as I'm typically using the lens wide open to f/4 perhaps f/5.6.
Cleaning the 28mm f/2.8 AI-S
The 28mm is available new (in limited quantities) it's retailing for ~610GBP (Nikon UK online store is asking for another 130GBP!), European eBay prices for these (2nd hand) lenses tend to be in the 130 - 185GBP range with absolute mint items touching 200GBP. I found a near mint item that was mechanically sound, smooth focus and elements clean of nasties (shining LED light through the front and rear elements and observing from the opposite end) but was a little dirty with rear and front elements needing a good optical clean.There is a great resource from Japan based Richard Haw detailing the procedure to tear down and how to access the lens elements. For most folks, if we're cleaning we're hoping to simply cleaning small dust from the lens elements which are arranged as 8 elements/groups but in 3 different optical blocks within the lens barrel: front/CRC block, (4 elements) middle block (1 element) which is buried behind the first block and in front of the aperture mechanism and finally the rear block (3 elements).
28mm f/2.8 AI-S lens cross section, via Nikon
exploded view, via photo.net user MFreeman
Because of the location and arrangement of the middle block (it's screwed in and buried in the lens) you'd hope to not need to access this but the rear block may need a little attention. The tools to give yourself successful and easier access are a lens spanner with flat blades and a JIS cross head screwdriver, like a Vessel 9900 P00-75 (its the P00 size that seems to be best fit, the P0 seems a little big).
To clean the rear three elements for the rear block you would need to set aperture to f/22 and then remove the bayonet lens mount (3x '+' head JIS screws) and lifting up/out which will leave you access to the protruding rear element assembly. At this point a lens spanner can remove the first retaining collar - note this ring screws directly onto the edge of the rear element so be careful not to over tighten when putting back together! With the first retaining ring removed you can lift the element out; next is spacing ring followed by two further elements that be displaced by gravity. Underneath the third and thickest element of this block (it's the one with the black inking on the edge) you will have (some) access to the aperture blades but not able to clean the middle optical group through them.
With the bayonet mount removed, you can also remove the aperture ring to clean the chrome barrel assembly.
Re-assembling the items are reasonably easy (clean the elements whilst wearing latex gloves and lens tissues is recommended!) but ensure the aperture ring and its associated black ring with the silver tab a fitted correctly before trying to fit to rear mount, aligning the underside latch with the silver aperture mechanism.
Another resource suggests that access to the front/middle optical blocks can be achieved without separating the focusing helicoids by removing the front grub screws (when focused at inf) and then unscrewing the front barrel to give access to the optical block which can then be also unscrewed.
The CRC mechanism causes the front element both rotate and to shift in/out of the lens barrel leaving a gap between the front nameplate/ring (that has the serial number) and the front element that may induce some suction of particles into the unit but this, based on Haw's tear down, looks like a difficult task.
Lens Performance and characteristics
Now that the lens is clean and usable, how does it stack up against our original objectives, performing at/near wide apertures for environment portraits/walk-about. Obviously these are my observations and there may be user error or lens sample variations at play affecting my conclusions.Sharpness at different focus distances
The lens has a good reputation for sharpness in the close-mid range but what does that really mean. At minimum focus distance (0.2m) its very good wide open, although this is just an additional benefit to me given I'm not composing with people at this distance.
f/2.8 min focus distance 0.2m
Going to more comfortable distances for environment portraits, we're probably looking at 0.7m - 1.7m distances. Remember this is a wide angle lens so it's not going to be used for head/shoulders.
left: f/2.8 focus distance ~0.8m, liveview focused remote tripped| center crop | right: f/2.8 | f/4 focus distance ~0.7m, liveview focused remote tripped
When compared to the image at MFD, it seems that whilst sharpness is reasonable wide open, it doesn't seem as sharp but it's not bad.
FX | f/2.8 focus distance ~1.2m
FX | f/2.8 focus distance ~1.6m
Going further out with a subject at 1.5m and beyond, I'm finding it difficult to obtain the same level of sharpness compared to the 0.7-0.8m distances. There could be a differing reasons for this, including the inability to focus (although my test images were tripod/liveview) or the contrast at those distances for smaller objects prevents showing absolute sharpness. I'm still to decide.
100% crops of areas of focus (click for full size)
Finally going towards infinity (again wide open) I'm finding details a little mushy, not kit-lens mushy, but its very clear its not as good as in the 'close-mid' distances. Details get better as we stop down but at infinity it never gets to the same performance as close-mid.
This lens sample therefore seems to live up to its reputation of being very good at close-to-mid distances (which I'm defining as 0.2m-1.3m) for sharpness, colour rendition and contrast but further out than these distances the lens is merely ok. These observations don't really affect me as for my intended usage I would prefer near-mid performance gains.
Flaring and Ghosts
Flaring and ghosts are present wide open and provide some interesting patterns but not a big issue with veiling flare although there's a little loss of contrast and doesn't compare to the performance of the 20mm f/3.5 AI in this regard.
20mm f/3.5 AI: left, wide open | right, f/5.6
28mm f/2.8 AI-S contrast and flare/ghosts: left, wide open | right, f/5.6
Out of focus rendition
Whilst bokeh isn't a massive consideration for this lens (it's a wide angle lens!) its rendition of out of focus areas are nice and unobjectionable - close up, bokeh it's very good.
out of focus renditions at MFD
Lens Hood
The official lens hood for the 28mm f/2.8 is the metal screw-in HN-2 which, based on Rich Housh's data, stands at 15.3mm high and 71.5mm wide. Using circular polarisers (with their own filter threads) is generally not a problem except for potential vignetting caused by the profile of the filter itself.
With the hood installed the original clip on 52mm lens cap can still used although it can be frustrating given the tight fit - a modern centre pinch lens cap is easier to fit.
General Use
The 28mm on FF is my preferred wide and performs as expected. On DX, its FoV is 42mm equivalent which is a neither here nor there for me: as noted earlier, it falls in that zone between 50mm and 28mm and it's arguably even worse then a 35mm given it's not even that wide - but this is all irrelevant if you're used to seeing in the classic focal lengths.Compared to a modern 24-70mm at 28mm and wide open
Now various forums posts will make statements along the lines of: the 28mm f/2.8 AI-S is super sharp/sharpest lens ever. Whilst I've seen in my sample to be reasonably sharp at/near wide open, when I compare this to a Nikkor 24-70mm f/2.8G at 28mm and the same apertures, I'm easily convinced the modern day zoom performs better. Both lenses produce nice and sharp images but they are different with the modern day zoom having a little more contrast and a little more saturated colours - skin tones in particular are better on the zoom.But, the old timer with optics designed for 1981 is not embarrassed and we need to recognise this is a comparison against a pro-level modern day optic (who's performance, IME, is optimised in the wider end of the zoom - at the long end of 70mm, the sharpness of the 28mm f/2.8 AI-S is better)
Is it worth it? From my lens sample, there is some overstated online exaggerations about the qualities of this lens but it's still a very reasonable performer. For the price paid (compared to the ~615GBP for new) it's provides an good optical alternative to the (better but heavier) 24-70mm zoom for the 28mm environment portrait use case.
No comments:
Post a Comment