Author Topic: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)  (Read 3663 times)

Per Inge Oestmoen

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #15 on: January 31, 2018, 20:46:06 »
I was afraid, that was the problem, may consider the cost vs getting an other sample ???


These lenses - as in this case the Nikkor 28mm 2.8 AIS - do have an optical as well as mechanical quality that justifies the expense of a repair. Even though repair is relatively costly, you get a high-quality lens which is not likely to require more maintenance for a very long time, if at all.
"Noise reduction is just another word for image destruction"

Per Inge Oestmoen

richardHaw

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #16 on: February 01, 2018, 15:36:27 »
the dreaded CRC unit of this lens :o :o :o

Bent Hjarbo

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #17 on: February 01, 2018, 19:17:53 »
And how to get into it?
The iris doesn’t look good  :o

whatdoineed2do

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #18 on: February 08, 2018, 00:07:02 »
Just to bring some closure (for myself) for my original question.  I ended up finding a 28mm f/2.8 AIS, serial 76xxxxx which was in good mechanical order and thanks to Rich Haw's most recent repair guide I managed to clean up the rear 3 elements.  So, to answer my own question - how's this (sample) for sharpness in the f/2.8 - f/4 range for environmental portraits?

My initial experiments (wide open) suggests the 24-70mm beats the 28mm AIS in terms of sharpness but the MF lens is not overly embarrassed.

Close focus at 0.2m is quite sharp and this trend appears true for me all the way up to about 1m-1.5m, where after this distance I'm finding getting eyes in the same level of sharp focus difficult as say, at 0.7m:  tripods / live view + static objects don't seem to help too much but this could be user error.

Going further out towards infinity details seem to get a little mushy wide open but I appreciate this probably isn't a typical use case - going down one stop to f/4 seems to help tremendously.


Some final observations - this copy seems to have an ever so slightly clunk in the front of the barrel when I quickly shift lens pointed down to up  -  I presume it's the CRC.  The other thing I noticed was the front element rotates as I focus but I believe this is normal operation for the CRC.  The filter ring is fixed though so no problems for circular polarisers.


I'd be interested to hear if these experiences are similar to long term users of this lens (ignore the confirmation bias in the loaded question)

Roland Vink

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #19 on: February 08, 2018, 00:41:31 »
The AI-S 28/2.8 (also 28/2 and 20/2.8 ) all have CRC operating on the front group of elements. The way they are built means the front element rotates within a fixed filter ring. As you focus closer you will see a small gap open up between the beauty ring and the front element, this is the CRC in operation. On the 24/2.8 and 35/1.4 the CRC operates on the rear group instead. On the AI-S 55/2.8 micro neither the front or rear groups rotates. These are just differences in mechanical design, the effect is the same - the distance between the front and rear groups changes as you focus to maintain better correction through the focus range. There is some evidence that the front CRC designs are more easily damaged by knocks, and the gap at the front might be an opening for dust?

My AI-S 28/2.8 has no noticeable "clunk" when tipping the lens up or down, apart from some slight rattling of the aperture stop-down mechanism. The front and rear CRC groups should be held reasonably tightly, any looseness would mean some elements may be displaced resulting in incorrect spacing or going out of alignment, which could affect performance.

I'm not sure if I ever shot mine wide open, I usually stop down for DoF. My sample seems reasonably sharp at far distances, but I haven't used it much recently as I have other lenses with better flare resistance.

JKoerner007

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #20 on: February 08, 2018, 02:45:33 »
My initial experiments (wide open) suggests the 24-70mm beats the 28mm AIS in terms of sharpness but the MF lens is not overly embarrassed.

Doubtless because the AF of the former nailed the focus, while your manual effort did not.

Try again with a tripod + Live View and the results will be much different.

99% of the time people who complain about manual lenses do so because they failed to use best practice.

FYI, it is easier to focus with the 28mm on closer objects (because you can see the details in the viewfinder) ... while the opposite is true trying to achieve absolute focus on distant objects.

pluton

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #21 on: February 08, 2018, 23:49:07 »

Going further out towards infinity details seem to get a little mushy wide open but I appreciate this probably isn't a typical use case - going down one stop to f/4 seems to help tremendously.


Your observation comports with most users' reported experience of the performance of the 28/2/8 AiS at infinity.  This isn't the only wide angle lens that seems to lose contrast on small objects at longer distances. The Zeiss ZF 25/2 lens I've used does something similar. 
Keith B., Santa Monica, CA, USA

Wally

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #22 on: February 10, 2018, 07:07:17 »
Just found a mint- 28mm/2 AI for an amazing price at the Salvation Army  ::)
This lens is incredibly sharp and surprisingly flare resistant. Highly recommended.
I get the feeling my AFD 28mm/1.4 will stay home for now  :-[

Řivind Třien

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #23 on: February 10, 2018, 09:31:55 »
Your observation comports with most users' reported experience of the performance of the 28/2/8 AiS at infinity.  This isn't the only wide angle lens that seems to lose contrast on small objects at longer distances. The Zeiss ZF 25/2 lens I've used does something similar.

I am not sure I agree with this description regarding my copy of the 28mm f/2.8 AIS. It shows very little difference in resolution and contrast from just stopped down by 1/3 stop to the performance at f/8 (thus only showing f/3.2 below). I have only used it on a DX sensor so I do not have any data with respect to what happens outside that frame. The light was problematic in these quick captures yesterday on the way to work, sun just outside the frame, which might have reduced the overall contrast. (Shooting against the sun is not its strength, and in particular not in IR. Edit: Also an NC filter was attached during these captures.)


NIKON D7100, 28 mm f/2.8 AIS (P)@ f/3.2, 1/1600s, ISO 100


100% crop (open large in new tab) at left side of frame, the lens does not seem to have much problem with the high pixel density of the 24 Mpix DX sensor.


Crop  NIKON D7100, 28 mm f/2.8 AIS (P) @ f/3.2, 1/1600s, ISO 100


Of course performance close up is nothing to complain about:


 NIKON D7100 28 mm f/2.8 AIS (P) @ f/8, 1/200s, ISO 100

As noted in another thread, this lens has been through some really bad accidents without taking noticeable harm (rolling down a 4m drop-off with rocky outcrops, dropped from 1.5m onto epoxy coated concrete floor).  It does not appear to be any looseness in the CRC mechanism (no clunking sound).
Řivind Třien

whatdoineed2do

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #24 on: February 11, 2018, 18:23:37 »
Wide open the 28mm f/2.8 AIS certainly doesn't like the sun in frame (unlike the 20mm f/3.5 AI) - but contrast isn't too badly affected in my eyes.  Interesting to get sun stars from point light sources wide open!

although a bit better at f/5.6 but there's still ghosting


no filter on the front of the lens for these images

JKoerner007

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Re: Opinion: 28mm f/2 AI or f/2.8 AIS (0.2mfd)
« Reply #25 on: March 20, 2018, 17:32:05 »
I am not sure I agree with this description regarding my copy of the 28mm f/2.8 AIS. It shows very little difference in resolution and contrast from just stopped down by 1/3 stop to the performance at f/8 (thus only showing f/3.2 below). I have only used it on a DX sensor so I do not have any data with respect to what happens outside that frame. The light was problematic in these quick captures yesterday on the way to work, sun just outside the frame, which might have reduced the overall contrast. (Shooting against the sun is not its strength, and in particular not in IR. Edit: Also an NC filter was attached during these captures.)

The images you chose are challenging, to say the least.

In decent lighting, I've found the 28mm AI-S works just fine ... not like my Zeisses ... but the results are pretty decent.



San Dimas Canyon Reservoir by John A. Koerner II, on Flickr



Rainbow Falls by John A. Koerner II, on Flickr


The 28mm AI-S also does exceptionally-well as a reverse-macro:



Green Bottle Fly by John A. Koerner II, on Flickr



Western (aka: Brown) Lynx ♀ by John A. Koerner II, on Flickr


The great thing about this lens is it does 1:4 reproduction ratio @ 8" MFD, properly-oriented, and 2.4:1 reversed.

I am replacing this lens with a Zeiss 25mm f/2.8 Distagon T*, which offers a 1:2 ratio @ 6cm MFD, and gives me 3:1 reversed, but the 28mm offers the advantage of being lighter and more portable, so I will miss it in a way.