Nikon 105mm f/1.8 ai-s and 105mm f/2.5 ai comparison

[Bjørn Rørslett]

Thomas made a joke about my 'lens matrix storage' Peugeot ... The fact is of course most lenses stay most of the time in the 'lens house' which is totally smoke free (anyone foolish to try to light up there would be evicted by the back of their pants before they understood what happened to them) and reasonably free of dust.

[Akira]

Obviously a lens isn't hermetically sealed (unless made for submerged use). I had a nice demonstration of this fact  when I recently operated one of my 50 mm f/0.75 lenses to remove a hatched small bug on its inside. The speck of the dead bug was big enough to be visible in the photos. I just considered it being some ordinary dust until looking closer and found it was indeed a bug with feet and antennae and all ... including dried excrements around it.... No idea how it got there or what it fed off inside the lens must have been there for years though.

That's rather surprising.  Rayxar should not have any movable part like aperture ring, aperture lever or focusing ring which all has some slits or holes.  So, the inside of the optics should be pretty much tightly sealed...

[David H. Hartman]

Years ago I tested five 105mm lenses: 105/2.5 Nikkor-PC, 105/2.5 AI, 105/2.5 AIS, 105/2.8 AIS Micro and a 105/1.8 AIS Nikkor. I used a trusted Nikon F2 with a 6x, DW-2 finder. For focusing I used a 1000 watt quarts flood. I turned off the floodlight after focusing, opened the shutter on B with a locking cable, let the vibrations settle for one minute and exposed my film in total darkness with a flash from a Vivitar 285. The film was Kodak Tech Pan developed as a continuous tone film in Kodak Technidol LC. I viewed with a enlarger at 8x, Fujinon-EP 50mm f3.5 enlarging lens and a heavy 10x Omega critical grain focuser. This was the best I could figure out at the time. My test distance was 2 meters a common distance for portraits.

What I found was the best lens was the 105/2.5 AIS and almost tied was the 105/2.8 AIS Micro, then very close the 105/2.5 AI, then 105/2.5 Nikkor PC quite close. I figured the difference in the f/2.5 lenses was sample variation. I today doubt that the difference in the f/2.5~f/2.8 lenses would be seen in common sized prints. Bringing up the tail was the 105/1.8 AIS. All the others beat it from f/2.5~f/2.8 through f/5.6. All were equal by f/8.0. I had special ordered the 105/1.8 AIS so I sold it after a week at a loss as I could not return it. I also tested an 85/1.4 AIS and an 85/2.0 AIS. The f/1.4 was best with the f/2.0 lagging. The 85/1.4 was soft at f/1.4 but beat 85/2.0 from f/2.0 to f/5.6 and then they were equal by f/8.0. I didn't find the 105/1.8 useful anyway as it was quite soft unless stopped down to f/2.8. The 85/1.4 on the other hand was quite sharp by f/2.0.

I tested more lenses and would have liked a 105/2.5 to be the sharpest but it wasn't to be. A 50/1.8 AI and 55/2.8 AIS were tied for sharpest. I never did lens testing like this again.

---

At Gayson's Camera, Glendale California where I had an open account I saw a friend cleaning the window of a film refrigerator. The cleaning cloth had a dark brown residue on it when finished. I told my friend who smoked, “That's Tar.”

Dave

[Jacques]

Purely out of interest where in the quality stakes does the 105/2.8 AF ( 1st generation AF ) sit ?, it was bought to go with the F4 and now sits fitted to my old F4 as a reminder of days past alongside my desk.

[David H. Hartman]

The early 105/2.8 Micro-Nikkor in AF and AF-D had a reputation for poor bokeh as I recall. I remember samples photos posted and the lens didn't interest me. For Portraits and close-up where a tripod can't be use I'd like an AF-S VR Micro-NIKKOR 105mm f/2.8G IF-ED but for macro and close-up from a tripod I'd use my 105/4.0 AI or 105/2.8 AIS Micro-Nikkors. I understand that the AF-S G breaths rather heavily and requires a lot of tripod re-positioning for close-up and macro. It doesn't sound fun.

I find VR very helpful for hand held close-ups near or just after sunset when using a friend's AF-S 16-85/3.5-5.6G ED VR DX Nikkor.

Dave

My 105s are a 105/2.8 AIS, 105/2.8 AIS and 105/4.0 AI.

[Bjørn Rørslett]

Purely out of interest where in the quality stakes does the 105/2.8 AF ( 1st generation AF ) sit ?, it was bought to go with the F4 and now sits fitted to my old F4 as a reminder of days past alongside my desk.

It is not a bad performer. Not at all. In  terms of sharpness not far from the renowned 105/2.8 AIS Micro-Nikkor. However, it could render the background a tad harshly if you were careless with background detail.

Its AF was glacial and more a joke than offering any practical value.

Do note it had the same tendency to break-up of the A/M switch ring as several other Nikkors of the same era.

[Roland Vink]

My experience with the AF-D 105/2.8 micro echos other here. It is respectably sharp at medium-far distances, but bokeh is poor. Bokeh is fine at close range. I mostly used it mounted on a PN-11 for macro shots beyond 1:1 up to about 1.6x life size. Working distance was about right for this magnification and performance was very good (can't comment about wide open performance as I always used it stopped down for more DOF). The bokeh was pleasing, only the straight-edge 7-blade aperture can sometimes show up in out of focus blurs.

Manual focus feel was good for an AF lens, it lacks the buttery smooth feel of manual lenses, and has a plastic friction feel, but is otherwise reasonably smooth. Focus throw is very short (just 180° from infinity to 1:1) which makes accurate focusing tricky at far distances, but fine at close range.

[Tristin]

Still doing some testing out of curiosity when time permits.  This time around, a test of their close range performance with a poster at a bit over a meter away.  All shot in raw, focused with live view, mirror lockup and converted with no sharpening or correction.  Both lenses are clean as a whistle.  Only thing modified was the WB to more accurately judge their color, the f/2.5 consistently AWB'd a hair more magenta than the f/1.8, +2-3  in ACR 9, which I matched to the f/1.8.

Full shot of the poster for reference







At near range, the f/1.8 is superior at all aperatures and at all parts of the image.  Most notable is the lack of CA in the f/1.8 while the same cannot be said for the f/2.5.

I am going to redo my distant performance tests as well.  Looking through the first shots again there is quite a bit of variance, so I am going to do it again more strictly.

[Daniel Bliss]

I have a late pre-AI 105/2.5, from sometime in 1976 judging by the serial number.  I like the rounded aperture blades.  Sharpness is simply phenomenal even wide open on the D800 but the lens has a tendency in combination with the camera's ground glass and electronic rangefinder to entice you into slight front focus at times.   Bought this well-loved sample over a used but mint 105 2.5 AIS while in grad school to save 30 bucks and get a metal aperture ring, as I was feeling sour about plastic in any shape or form at the time.  Finding out later about the deal with the bokeh and the aperture blades was a bonus.

[Roland Vink]

At near range, the f/1.8 is superior at all aperatures and at all parts of the image.  Most notable is the lack of CA in the f/1.8 while the same cannot be said for the f/2.5.

I wonder if that is because the 1.8 has a flatter field than the 2.5? A lot of lenses test poorly on flat subjects in the corners, but are fine in 3D.

[Tristin]

Daniel, this f/2.5 is also a pre-Ai that was converted with the factory kit.   

Roland, that was exactly my thoughts.  I need to find a more suitable scene to test their distant rendition, I am guessing the f/2.5 will fare much better there.  I've also noticed that the f/1.8 seems to see plenty of use in reproduction, which I'm sure stems from it's fantastically flat curvature (or practical lack of?) and negligible distortion.

[Roland Vink]

Try shooting the same target with the camera aimed up at a slight angle. You will no longer get a sharp image corner to corner since the top and bottom of the target will be outside the focus plane, but you will get a zone of sharpness across the middle of the picture. If the lens has a flat field, the zone of sharpness will be a straight line across the middle. If the lens has some curvature the zone will curve up or down at the sides, depending on the direction of the curvature.

This is a more useful test than shooting directly onto a flat target. It gives you information about field curvature, how the focus plane rolls off into the near foreground and background, LoCAs will show up, and you can still judge sharpness from side to side by looking along the line where the focus plane intersects the target.

[Tristin]

Will do so and report back 😉

[Tristin]

Conducted a comparison test at infinity focus with a challenging scene.  The sun is ~45° to the left of the framed area and ~45° from the horizon, creating quite the glaring scene.  The f/1.8 was tested with it's built in hood extended and the f/2.5 with the HS-4 hood on.  This may have put the f/1.8 at a disadvantage given how short it's hood is, but I felt it better to test it with the hood I would use with either.

Full shot for reference




At f/2.8, the f/2.5 manages the flare better than the f/1.8.  Both lens sharpness is pretty much the same, though the f/2.5 doesn't hold up on the edges as well as the f/1.8.  I was surprised to see that the f/2.5's field curvature was strong enough to knock the lower right corner oof, which had to be 100-150 meters away.  The f/2.5's field curvature seems to only effect the outer corners, but it plunges pretty strongly.




The f/1.8 displays the same contrast drop at f/4, slightly improves at f/5.6 and levels out with the f/2.5 at f/8.  At f/8, sharpness in the center area remains the same between both lenses, though the f/2.5 still has some CA visible.  On the edges the f/2.5 still doesn't quite catch up to the f/1.8, though it is a pretty small difference.

At f/11 and f/16, both lenses are virtually equal.  At f/22 the f/2.5 pulls ahead slightly in all areas of the image. 

[Tristin]

After getting a f/1.8 in nicer condition I re-did my tests which proved out my earlier findings.  The f/1.8 beats out the f/2.5 in all areas of the frame and all focal distances, though the differences at a distance are small and differences at near focus are quite significant.  The f/1.8 is virtually CA free at near distances and negligible at far distances, while the f/2.5 has quite noticeable CA at near distances and near negligible at far distances.

I decided to compare their bokeh and how they handle flare with a light source in front of the lens and came up with something I am not understanding.  Perhaps someone can inform me how this is panning out.  Here are both lenses at f/2.8.

105mm f/1.8 Ai-s


105mm f/2.5 Ai


The f/1.8 handles the flare much better but exhibits some ghosting, while the f/2.5 fares worse in flaring but has no ghosts.  This is the same thing I noticed with the night shot I did the first time around.  What I'm confused by is I have learned that the f/1.8 handles flare from light sources outside of the FOV worse than the f/2.5.  How does it handle it better when it is in the FOV, yet worse when out of the FOV?  The difference in the handling of flare in the scenario pictured above is quite drastic.  The f/2.5 must be stopped down to f/5.6 to match the contrast of the f/1.8 at f/1.8.

On bokeh, the f/2.5 exhibit smoother bokeh balls at f/2.8.  Stopped down any further and the f/1.8 appeared smooth, due to more blades.  Combined with the fact that the f/1.8 has very smooth bokeh at f/1.8 and f/2, I can't see any advantages here for the f/2.5 unless shooting at f/2.8 specifically.

I am done comparing these two. Below are the optical strengths of either compared to the other, available aperature differences aside as those are obvious.

f/1.8

• Better edge to edge performance up to f/16
• Better handling of CA
• Significantly better performance at close range
• Better handling of flare from light sources in FOV
• *Subjective* More rays from starbursts

f/2.5

• Better edge to edge performance from f/16-f/22
• Better handling of flare from light sources outside of FOV
• Much less ghosting
• Smoother bokeh at f/2.8

On a very minor note, the f/1.8 has a tighter FOV than the f/2.5.  Though to a negligible degree.