Author Topic: 20/2.8ais  (Read 2985 times)

Zang

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Re: 20/2.8ais
« Reply #15 on: December 18, 2020, 14:38:39 »
Birna, the last picture is awesome :)

And I always thought I'll never get into underwater photography because of 200kg gear, traveling to Mexico, going 200m under the surface... :)

Cheers,
Zang

Gerhard2006

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Re: 20/2.8ais
« Reply #16 on: December 21, 2020, 03:10:28 »
This lens is among the sharpest ever but needs to be adjusted manually. First of all, be sure the lens is not decentered, even to the smallest amount, corner-to-corner. Then, after opening it from the front, adjust its floating compensation optical group. It is a very, very precise job, almost microscopic one, but possible. Will take you about 15-20 hours, LZ
How do you adjust centering and the front group? I thought all the lenses are in groups?

longzoom

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Re: 20/2.8ais
« Reply #17 on: December 21, 2020, 16:04:55 »
If any lens is decentered, forget about it. Nobody can fix or adjust such a lens. About 20/2.8 AIS - remove front group, there is an aluminum waved lever inside. Easy-open 2 micro bolts on it, and by moving this lever left or right, 1/2 of mm, to the left, say, firstly, assembly the lens back and try the lens to infinity. Better - open it and move more. If it isn't as good as before - move to the right. Be ready to spend as much time as needed. This aluminum white lever is connecting to compensate optical group, which is the part of the front optical group, by turning the optics less or more. Be sure you know the very first, manufacturer's adjusted, position of the lever.   Be extremely patient with your microscopic steps, one-by-one! You will be rewarded with sharpness ever possible, after all! Good luck!  LZ   (You MUST have proper tools and skills!).

richardHaw

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Re: 20/2.8ais
« Reply #18 on: December 21, 2020, 16:14:44 »
that sounds like the adjuster for the CRC  :o :o :o

longzoom

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Re: 20/2.8ais
« Reply #19 on: December 21, 2020, 16:27:17 »
Yes, that is what I am telling you about, but through this particular lens only. Any and every other optical system needs its own findings and ways on how to be adjusted correctly. My old MF Noct, from the very first bunch, was precisely adjusted by half-diameter, 10 microns each, bronze-made washers.  LZ

Steven P.

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Re: 20/2.8ais
« Reply #20 on: December 24, 2020, 05:19:49 »
I have owned the Af 2.8 & passed it on. I tried the Ais version and I didn't care for the IQ, & returned it. I quested on the 20's when i was building my Df sack, a small time, back.


I am quite happy with the tiny F4 & would love a pristine 3.5/UD

Roland Vink

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Re: 20/2.8ais
« Reply #21 on: December 24, 2020, 06:04:21 »
I had an AIS 20/2.8 some years ago. When I compared it against my AI 20/3.5 it was sharper by about 2/3 stop (at infinity), which corresponds to the difference in max aperture. However I still prefer the AI 20/3.5 due to its smaller size, it was a better fit with other lenses in my kit due to the standard 52mm filter size. And at the apertures I typically use, it was sharp enough for my needs.

richardHaw

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Re: 20/2.8ais
« Reply #22 on: December 24, 2020, 06:55:47 »
please let me find one for very cheap and glass in good condition...so i can document it :o :o :o

please santa...

David H. Hartman

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Re: 20/2.8ais
« Reply #23 on: December 25, 2020, 02:41:02 »
please let me find one for very cheap and glass in good condition...so i can document it :o :o :o

please santa...

Being realistic I asked Santa for a lump of coal. That would be better than what I got last year.

Dave
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Oh no, must be the season of the witch!

Nasos Kosmas

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Re: 20/2.8ais
« Reply #24 on: December 25, 2020, 11:25:17 »
I had an AIS 20/2.8 some years ago. When I compared it against my AI 20/3.5 it was sharper by about 2/3 stop (at infinity), which corresponds to the difference in max aperture. However I still prefer the AI 20/3.5 due to its smaller size, it was a better fit with other lenses in my kit due to the standard 52mm filter size. And at the apertures I typically use, it was sharp enough for my needs.
I also keep an 20/3.5 for the same reason but it is not standing so good compared to the new lenses in my D750
Light fall of  and resolution is getting worse in the corners

Airy

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Re: 20/2.8ais
« Reply #25 on: December 25, 2020, 12:05:07 »
My 20/3.5 AI performs apparently very well at mid-distance (e.g. interior shots of a celebration). I have not used it so far outside for architecture or landscaping, because infinity is off and I'm struggling to adjust it.
The 20/2.8 AIS is fine, except for
- wavy distortion
- flare sensitivity
Besides, I stop it down to f/5.6 at least for distant subjects in irder to get some +/- uniform quality. With the 20/3.5 UD, the choice is even narrower (f/8 or f/11).
Airy Magnien

Jack Dahlgren

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Re: 20/2.8ais
« Reply #26 on: December 28, 2020, 23:51:40 »
My 20/3.5 AI performs apparently very well at mid-distance (e.g. interior shots of a celebration). I have not used it so far outside for architecture or landscaping, because infinity is off and I'm struggling to adjust it.
The 20/2.8 AIS is fine, except for
- wavy distortion
- flare sensitivity
Besides, I stop it down to f/5.6 at least for distant subjects in irder to get some +/- uniform quality. With the 20/3.5 UD, the choice is even narrower (f/8 or f/11).

I've got a UD, the diminutive f/3.5, and the 1.8G. The first two have been sitting on the shelf since I got the 1.8G. Could the 2.8 be better?

Birna Rørslett

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Re: 20/2.8ais
« Reply #27 on: December 29, 2020, 12:05:42 »
Different, but not "better". The AIS renders the image in a more soft and delicate manner. The 1.8G handles shooting into strong light sources (ie. sun) better and images have delivered with stronger contrast. I use both.

David H. Hartman

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Re: 20/2.8ais
« Reply #28 on: December 29, 2020, 21:34:00 »
I have not used it [20/3.5 AI] so far outside for architecture or landscaping, because infinity is off and I'm struggling to adjust it.

Richard has a couple of articles of interest regarding the 20/3.5 AI, AIS...

Repair: Infinity Focus Calibration

I set the infinity on a 50/1.4 AIS using a Nikon F5 with a DW-31 (6x) waist level finder. Live view at 100% should work as well as the 6x finder. I put the camera on a tripod and used a street light about 3/8 miles (0.6 km) away. The longer the lens the farther the test subject should be. Richard suggests communication towers on the horizon. I would not call setting infinity easy but it's doable. A camera repairman friend cleaned the oil fouled aperture blades of my 50/1,4 AIS and gave the lens back to me to calibrate.

Repair: Nikkor 20mm f/3.5 Ai-S

Hope this helps.

Dave
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Oh no, must be the season of the witch!

Bent Hjarbo

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Re: 20/2.8ais
« Reply #29 on: December 30, 2020, 14:42:25 »
Just got around to take my 20/2.8 for a spin.
Taken f11 with my Df
I have som marks on the rear lens element , that should not be good, but this picture seem ok, both at close and far distance.