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Schneider Apo-Componon
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augusthouse



Joined: 16 Sep 2006
Posts: 1195
Location: New South Wales Australia

PostPosted: Wed Feb 25, 2009 3:01 pm    Post subject: Reply with quote

NU,

A "beat up" lens is not necessarily better. An older, 'well used' lens, in reasonable condition, is (maybe) an indication that it has seen considerable usage because it is a fine piece of glass. I wouldn't dismiss either - all depends on their individual performance.

The Micro Nikkor 3.5/55mm that I currently own would not win a beauty contest, but is takes a beautiful photograph.

Here is an article that examines a 'mint' lens and a 'well used' example: http://www.16-9.net/lens_tests/28mm_2.html

Thanks for the info regarding the large ring on the front of the 2.8/40mm APO and Optical Spanner details.

Craig
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kds315*



Joined: 02 Feb 2009
Posts: 205

PostPosted: Mon Aug 23, 2010 7:08 am    Post subject: Reply with quote

I just bought a few like new (maybe new) Schneider Apo Componon 5.6/50mm HM fixed aperture lenses (f5.6 inset) and will have professional mounts made for them (like the JML mount I showed).

Actually that was triggered by your excellent results shown here! I hope they perform as well as yours!


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Klaus

http://www.macrolenses.de for macro and special lens info
http://www.pbase.com/kds315/uv_photos for UV Images and lens/filter info
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mgoodm3



Joined: 08 Sep 2008
Posts: 273
Location: Southern OR

PostPosted: Mon Aug 23, 2010 1:44 pm    Post subject: Reply with quote

I have one of these 40/2.8's. It isn't my favorite lens. Decent resolution but not particularly sharp. The field isn't particularly flat either. It would benefit from an adjustable aperture.

I have a 45/4 APO-componon that is much better and has an adjustable aperture.
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kds315*



Joined: 02 Feb 2009
Posts: 205

PostPosted: Tue Aug 31, 2010 4:44 pm    Post subject: Reply with quote

Adapter for these are currently being made, allowing also to use these Apo Componons 50mm reversed. More about it later...
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Klaus

http://www.macrolenses.de for macro and special lens info
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http://photographyoftheinvisibleworld.blogspot.com/ my UV diary
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kds315*



Joined: 02 Feb 2009
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PostPosted: Wed Sep 29, 2010 12:38 pm    Post subject: Reply with quote

Here as promised pictures of that Apo Componon HM 5.6/50mm lens (normal on the right, reversed on the left)







(yeah, I should have dusted them off first...)
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Klaus

http://www.macrolenses.de for macro and special lens info
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ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Sat Nov 13, 2010 12:39 pm    Post subject: Reply with quote

mgoodm3 wrote:
I have one of these 40/2.8's. It isn't my favorite lens. Decent resolution but not particularly sharp. The field isn't particularly flat either. It would benefit from an adjustable aperture.

I have a 45/4 APO-componon that is much better and has an adjustable aperture.


I found the MTF results for the apo-componon 40/2.8 (pdf), which seem to indicate that the optimal magnification is around 10x (the results for 3x and 25x are worse) and also, surprisingly, that the lens performs better at f/8 than at f/5.6 (odd for a fairly fast and well corrected lens). The falloff, distortion and transmittance results are also available.

Compare with the MTF of the apo-componon 45/4 which shows the results at f/5.6 and at f/8 to be very close, and overall better than the 40/2.8. Optimum magnification (of the three values tested: 3x, 6x, 25x) is 6x. The spec sheet shows that the actual focal length is 46.5mm.

Unfortunately Schneider do not publish axial focus shift vs. wavelength data.
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20169
Location: Richland, Washington State, USA

PostPosted: Sat Nov 13, 2010 1:31 pm    Post subject: Reply with quote

ChrisLilley wrote:
also, surprisingly, that the lens performs better at f/8 than at f/5.6 (odd for a fairly fast and well corrected lens)

One caution -- it's unclear how these charts correspond to what you'll see in the configuration you care about.

If I'm reading the charts correctly, the three lines are for 10, 20, and 40 cycles per mm, measured at the image plane when the lens is set up to give magnifications of 1/3X, 1/10X, and 1/25X.

But for macro work, the lens will be reversed and used at magnifications greater than one.

So for our purposes, those MTF lines correspond to 10, 20, and 40 cycles per mm on the subject, far below the couple of hundred cycles per mm that we would normally look at to evaluate sharpness at say 5X. The measured frequencies are more in the area that we would call "overall contrast".

Does this make sense, or have I misread the charts?

--Rik
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ChrisLilley



Joined: 01 May 2010
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Location: Nice, France (I'm British)

PostPosted: Sat Nov 13, 2010 2:04 pm    Post subject: Reply with quote

rjlittlefield wrote:

Does this make sense, or have I misread the charts?
--Rik


That makes sense.

As the lenses are nearly symmetric, 6-element designs, I had hoped that one might be able to infer something about the performance in the reverse direction too.
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Bob^3



Joined: 17 Jan 2010
Posts: 287
Location: Orange County, California

PostPosted: Sat Nov 13, 2010 2:06 pm    Post subject: Reply with quote

rjlittlefield wrote:
If I'm reading the charts correctly, the three lines are for 10, 20, and 40 cycles per mm, measured at the image plane when the lens is set up to give magnifications of 1/3X, 1/10X, and 1/25X.

Yeah, I saw those MTF charts shortly after buying the newer variable aperture version of the APO Componon 2.8/40, about 6 months ago. It took me awhile to realize the 1/beta callout was indicating the MTF data referred to lower magnifications.
However, I understand one intended application for this lens is as an enlarger lens for small format film. So is it possible that the MTF charts do apply at 3x, 10x and 25x if the lens is reversed with the subject at the normal film plane?
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Sat Nov 13, 2010 2:46 pm    Post subject: Reply with quote

Bob^3 wrote:
However, I understand one intended application for this lens is as an enlarger lens for small format film. So is it possible that the MTF charts do apply at 3x, 10x and 25x if the lens is reversed with the subject at the normal film plane?

Yes, the MTF figures would apply at the film plane if the lens were used for enlarging.

--Rik
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Bob^3



Joined: 17 Jan 2010
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Location: Orange County, California

PostPosted: Sat Nov 13, 2010 3:35 pm    Post subject: Reply with quote

mgoodm3 wrote:
I have one of these 40/2.8's. It isn't my favorite lens. Decent resolution but not particularly sharp. The field isn't particularly flat either. It would benefit from an adjustable aperture.

That is also how I would rate my variable aperture version. In the 3x to 6x range at f/2.8, it is extremely sharp in the center but very soft in the edges and corners on the full frame D700 FX sensor. It's better on the smaller D200 DX sensor---but still not great wide open. It improves stopped down, but needs at least f/5.6 before the corners get usable on DX. On FX the corners are always softer than the center, at any aperture---even at the point where the center become soft due to diffraction at 3x. On DX, I would rate it somewhat better than the El-nikkor 50mm/2.8 (at f/5.6), sharper in the center and about equal in the corners and better color corrected. On the FX sensor, the El-nikkor is better. The JML 21/3.5 out performs both on FX and DX in the same magnification range (albeit at reduced working distance).

I know others get excellent results with the fixed aperture version, at least on smaller sensors. So perhaps I just got a bad copy. Or perhaps Schneider-K tweeked the optical design for the variable aperture version effecting its use for macro? I haven't been able to find good optical diagrams for both lenses that would indicate a difference in design.

I would appreciate any observations from members who have evaluated the variable aperture version.
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Bob^3



Joined: 17 Jan 2010
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PostPosted: Sat Nov 13, 2010 5:06 pm    Post subject: Reply with quote

rjlittlefield wrote:
Yes, the MTF figures would apply at the film plane if the lens were used for enlarging.

Ok, now think I get it. The cycles/mm values are given at the film plane not on the projected image (enlarger use). So they do not scale when the lens is used reversed at higher magnification; it's still max 40 cycles/mm on subject?
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Sat Nov 13, 2010 7:51 pm    Post subject: Reply with quote

Bob^3 wrote:
So they do not scale when the lens is used reversed at higher magnification; it's still max 40 cycles/mm on subject?

Yes, that's basically right.

The APO-Componon certainly has usable MTF for detail much higher than 40 cycles/mm. At f/5.6, it might be delivering something useful clear out to 300 cycles/mm. In fact it may be delivering a lot more at 300 cycles/mm than you would guess from its falloff at 10 to 20 to 40. (See HERE for some explanation of that, albeit with an f/2.8 lens that doubles the frequencies.)

But yes, however much MTF the graph shows at 40 cycles/mm is the value that applies for 40 cycles/mm at the subject when you reverse the lens.

And the frequencies do scale, it's just that they scale in the opposite direction from what one might hope. The line labeled "40 cycles/mm" scales to only 13.3 cycles/mm at the sensor, when you're running at 3X reversed.

--Rik
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