Lens Test Nikon AF 75-240mm f/4.5~5.6D

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Item
Data
Lens brand & description Nikon AF 75-240mm f/4.5~5.6D
Serial number 219507
Lens purpose Low price zoom tele lens
Date tested Oct/1999 on loan from Maxwells
Lens hood arrangement Bayonet style HB-21 supplied with lens, stores reversed over lens body.
Focal lengths marked 75, 85, 105, 135, 200, 240mm
Lens construction 12 elements in 9 groups
Apertures marked f/4.5 to f/32, camera LCD displays 4.5~32 @ 75mm, 5.6~45 @ 240mm
Aperture blades 7 with rounded aperture shape
Front rotate for focus/zoom Front rotates with focus but not with zoom. Front extends for focus and for zoom.
Filter size 52mm
Weight 415g bare, 485g with hood and caps.
Length Flange to front Min/Max & max diameter No hood - min length 127mm, max length 173mm , diameter 72mm.
With hood - min length 190mm, max length 240mm , diameter 80mm
Colouration check Neutral
Build quality comment Has "Made in China" label. Plastic mount. Build quality looks good. Printing on lens may be easily subject to wear.
Closest focus from film plane & reproduction ratio 1.5m (4.9ft)   RR about 1:4.8 at 240mm
Note: add closeup lens 6T on a 52-62mm stepup ring and nearly 1:1 can be achieved.
Controls on lens Aperture ring with min aperture lock, zoom ring, focus ring.  No focus scales on lens.
Lens contact count 5
First Impressions Nice and light, good feel, auto-focusses well, short throw for manual focus but works well, viewfinder brightness OK on F70 and N8008s but quite a bit dimmer on FE-10. Probably not a lens to use for night shots particularly on the FE-10 as it would be hard to see composition and check focus.Would make a nice cheap light travel lens. The hood supplied is very large and should provide good flare protection.


The lens in question with the hood on and set to minimum length.


Field tests
A series of shots were taken with the camera on a sturdy tripod and using remote release cable in aperture priority mode. To save film, only the maximum aperture, the minimum aperture and the expected best operating aperture were chosen, f/11 was decided as the most likely best aperture.
The results are very close indeed for this lens, you cannot casually browse through the prints and immediately tell which apertures were used. All decisions had to be made with a magnifier on the 4"x6" prints, and some decisions were very difficult. I then used a laboratory microscope at about 40x magnification on the negatives to make final decisions when things were close. I would be happy to use this lens at any aperture, the only really noticeable thing that suffers at maximum aperture is the usual shrinking of depth of field and a minor falloff in quality that is hard to detect. Also there is the usual light fall-off to the corners that is noticeable but not objectionable and is completely gone by f/8. This lens seems to get better as it gets longer at the maximum aperture, the choice between maximum aperture and minimum aperture at 200mm was very hard to make and in the case of 240mm the maximum aperture was only very slightly worse than the f/11 effort.
I tried scanning the prints but I cannot get the same detail that I can see with the magnifier or microscope no matter what dpi I chose. Probably need about 8,000 dpi scan of the film to see what is actually recorded on the film.
 
Image Quality vs Aperture Chart Max Aperture Mid Aperture Min Aperture
at 75mm f/4.5 worst f/11 best f/32 middle
at 85mm f/4.5 worst f/11 best f/32 middle
at 105mm f/4.8 worst f/11 best f/32 middle
at 135mm f/4.8 worst f/11 best f/32 middle
at 200mm f/5.3 worst* f/11 best f/45 middle*
at 240mm f/5.6 middle f/11 best f/45 worst

* means extremely close decision. With all the rest the "worst" really means very close to the "best". The f/number is what I saw in the camera LCD panel. I would happily use this lens at any aperture but would choose f/8 to f/11 if wanting eventual enlargements.

Another test was to manually focus on some horizon scenery about a mile away and shoot at every aperture for one set focal length on three lenses all set to 180mm. The chart shows the order in which the quality was rated, 1 is best, 2 next and 3 worst image of the aperture comparison set.
 

Aperture
Nikon AF 75-240/4.5~5.6D
Nikon AF 180/2.8D ED-IF
Sigma AF 75-300/4~5.6 APO
f/5 2 Slight light falloff to corners 1 No light falloff 3 Light falloff to corners
f/5.6 2 Very slight light falloff to corners 1   3 Slight light falloff to corners
f/8 2 Best aperture probably is at f/9.5 1 Probably best aperture 3 Very slight light falloff to corners
f/11 2 Very close decision 1   3 Probably best aperture
f/16 3 Extremely close decision 1   2  
f/22 3 Extremely close decision 1   2  
f/32 1   - No equivalent aperture - No equivalent aperture

The surprise seemed to be the performance on another test comparing the 75-240 with the Nikon AF 85/1.8D and the Nikon AF 180/2.8D ED-IF at 85mm and 180mm but focussed on detail at maybe 200 yards distance. It gave a slightly different result to the above set (at maybe a mile, careful manual focus). I didn't test all apertures on the next test, just at the widest aperture of the 75-240 and at f/11. The 85mm and 180mm lenses were also set to match the widest aperture of the 75-240 as well as f/11.

In that closer distance test it appears that the prime lenses are just better than the zoom at f/11, it's very close and needs a magnifier on the 6"x4" prints. But at the matching maximum aperture which was f/5 for the 180mm test and f/4.5 for the 85mm, it works out that the 75-240 zoom is just slightly better than the primes. Puzzling, but I've been over the results many times, shuffling the prints and then inspecting and re-sorting them into quality order then turning them over to see what was what. It is very close but it always comes up the same.
I'm not so much learning how good this 75-240 lens is, as finding the weird things that happen at different focus distances. Something similar happened when testing the Nikon 80-200/2.8 (non-S version), it was second to the Sigma zoom on the one mile test but at portrait distances was better than the Sigma.
When you want to buy a lens you need to evaluate it at the distances you intend to use it at. OK, the differences were very slight but may make a difference if needing huge enlargements.



General shooting
One of  my "tourist" shots was a grab of a ferry going by, the lens was at 240mm and the program mode chose maximum aperture. The ferry is OK but the interesting part is the chain wire fence running across the whole picture in the middle distance behind it.

ferry and fence 240mm
Nikon 75-240 lens at 240mm f/5.6 1/400 ISO 100 hand held.

I tried scanning at the maximum optical resolution of 600dpi on my flatbed but the detail cannot be captured successfully. Anyway what I was trying to talk about is the detail in the fence. Maybe it's about 6 or 7 feet high to stop people getting on the rail tracks. With a magnifier on the print it is easy to see the chain wire links in the fence and comparing the edges with the centre there is only a small amount of falloff in quality. In good daylight with the naked eye you can just detect there is a wire pattern at about 8 inches viewing distance on the 4"x6" print. I call this a good optical performance, that is, a lot more detail on the print than the eye can see normally.


Nikon 75-240 at 240mm at f/8 1/400.

I took two shots, one at maximum aperture and this one at f/8 when I shifted the program. That's why I like to use aperture priority normally, I get to chose a more sensible aperture than the camera chooses. The program seems to go to maximum apertures, I know I can hold a camera steady so I go for middle apertures and better quality and depth of field. As usual the scan looks drab beside the sharp and bright print.


Nikon 75-240 at 75mm at f/8 1/320

The shot above was another grab to see whether all the detail looks good all over the frame and sure enough the actual print looks nice and sharp all over. No light falloff to the corners like some lesser zooms I've seen. I really don't know why I bother to scan and display these, they don't do the situation justice at all.



Comparison between appropriate primes and this zoom
Next a film was burnt up comparing the 75-240 to the following lenses at the listed focal lengths. I took four shots in each focal length set, 75-240 at max aperture and f/11 then the rival lens at exact same apertures as the 75-240 indicated on the camera LCD display. The prints were shuffled and examined and the following 1, 2, 3, 4 quality selection was found. The results were very close in a lot of cases and if I did it a few more times another day then the 1234 order may vary a little. Mostly so close it doesn't matter, frightening when a $150 lens is very nearly as good as something many times the price. The target was about 200 yards away.

The lenses comparison was between the Nikon 74-240 and the Sigma AF 75-300mm APO zoom (the good one, about vintage 1993), the Nikon AF 85/1.8D, the Nikon AF 180/2.8D ED-IF at the appropriate focal lengths, the chart should make sense, if not give me a yell and I'll make it clearer.
 
 

At 200 yards test
Nikon 75-240
Nikon 85/1.8
Nikon 180/2.8
Sigma 75-300
At 75mm f/4.5
3, very close
4
At 75mm f/11
1, very close
2
At 85mm f/4.5
3, extremely close
4
At 85mm f/11
2, very close
1
At 180mm f/5
3, extremely close
4
At 180mm f/11
2, very close
1
At 240mm f/5.6
3, very close
4
At 240mm f/11
1, very close
2


Closeup shots.
I also did a set of shots at the minimum focus distance of 1.5 m (4.9 feet) and the image quality checks out fine, again, if chasing quality it would be best to stick to f/11. The quality doesn't fall off much at maximum aperture but the depth of field shrinks dramatically at close focussing with a tele zoom and may lead to problems.

The 75-240 as a Macro lens.
Then for a macro comparison I put the Nikon 6T closeup lens on the 75-240mm using a 52-62 step-up ring and set it to minimum focus to get very close to 1:1 and compared it to the Nikon AF 105/2.8D macro lens at the same apertures, f/8 and f/22. If buying this lens then the sensible thing to do would be to get the Nikon 4T closeup lens (+2.9 dioptre double element) in 52mm size.
When zoomed to 240mm the image yielded was nearly 1:1 and the working distance from the front of the lens to the subject was about 270mm. This seems like a nice easy way to achieve macro. There was slight pincushion distortion, but not too disturbing and that would not be a problem if shooting a bug or flower. The image looked good from centre to edge. A lesser quality (single element) closeup lens would not yield as good an image. Of course the depth of field is the usual problem, but it's exactly the same shallow depth of field as with any macro lens. More tests on the same bank note and on a 3D object like an old watch innards look very much the same as the 105/2.8 macro except for the pincushion distortion.


Nikon 75-240 at 240mm at f/22 with 6T magnifier

The print image looks better than the scan as usual, note the slight pincushion distortion along the top edge, the note wasn't placed properly so the left side is a little higher in the frame. Not a combination for serious flat work copying but would be great for general macro. There appears to be no quality falloff to the edges. The width shown was the whole 4"x6" print and measures 35mm of the actual bank note. The whole negative has about another couple of millimetres of the subject thus making it very slightly less than 1:1 on the film.



Evaluate Bokeh
So far the Bokeh looks nice both sides of the focus point. Most Nikon lenses tend to have a harsh background Bokeh but this lens looks very smooth. I've taken a few deliberate out of focus foreground and out of focus background shots and the degree of blur looks pretty much the same both back and front. I need to get out and do night shots and see what happens to the out of focus street lights. The rounded shape of the iris diaphragm should help the blur detail have a nicer shape.


Summary
The conclusion from all that is that the Nikon 75-240mm is a surprisingly good lens. A close look at the 4"x6" prints does not give a clue as to which lenses were which. Closer examination with a magnifier shows that the prime lenses are generally just a bit better, but it's very, very close indeed at times. Of course f/11 is better than wide open in all cases, possibly the best aperture being half way between f/8 and f/11, but at the longer zoom end on the 75-240mm the difference is not so much. I suspect the 75-240mm was designed for best performance wide open at the long end. But it still is an exceptionally good lens at the shorter focal lengths. I'm also learning that lenses like the magnificent Nikon 180/2.8 definitely aren't as good as people make out once you get away from f/8 ~ f/11. That was the result from the distance tests, maybe a 2 metre distant test would give a different result.
I like this lens for it yields good quality images and I will probably buy one to use as a cheap, light travel lens.
I want one now!


 
Thanks for looking at this very early effort, there has been enough interest to cause me to put something here now before I have all the films back.  Regards...........  Guy

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