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Want to see an odd DOF effect?

 
 
RichA
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Posts: n/a
 
      04-26-2011
On Apr 25, 7:55*pm, Eric Stevens <(E-Mail Removed)> wrote:
> On Mon, 25 Apr 2011 05:35:08 -0700 (PDT), RichA <(E-Mail Removed)>
> wrote:
>
>
>
>
>
>
>
>
>
> >On Apr 25, 3:31*am, Bruce <(E-Mail Removed)> wrote:
> >> RichA <(E-Mail Removed)> wrote:
> >> >On Apr 24, 12:41*pm, Paul Furman <(E-Mail Removed)> wrote:
> >> >> Eric Stevens wrote:
> >> >> > On Sun, 24 Apr 2011 10:43:14 +0100, Bruce<(E-Mail Removed)>
> >> >> > wrote:

>
> >> >> >> RichA<(E-Mail Removed)> *wrote:
> >> >> >>> Two shots. *One with an Olympus OM Zuiko 50mm f1.8 at f1.8. *Same
> >> >> >>> again, with a Nikon 50mm Series E. *Check out the (impossible?) extra
> >> >> >>> shallow DOF with the OM lens.

>
> >> >> >>>http://www.pbase.com/andersonrm/image/134159846
> >> >> >>>http://www.pbase.com/andersonrm/image/134159847

>
> >> >> >> The Zuiko lens was quite obviously focused at a distance shorterthan
> >> >> >> the distance to the first battery. *So, just as with most of your
> >> >> >> so-called "comparison tests", no conclusions of any kind can be drawn.

>
> >> >> > I agree.

>
> >> >> Try focusing in the middle so you get some foreground and background OOF
> >> >> and can see from the wood table where the focus is. As shot, the focus
> >> >> is probably in the air in front of the table edge so you can't confirm
> >> >> it. An angled tape measure works very well for this kind of test; you
> >> >> can see where the numbers become illegible:http://www.flickr.com/photos/edgehil...-7215760323110......

>
> >> >To *satisfy the doubters, I'll shoot a ruler on the incline, they way
> >> >the you when calibrating focus. *But I've seen this with Olympus
> >> >lenses before.

>
> >> You've seen it before? *You mean, like we've all seen your inability
> >> to carry out a properly controlled test before?

>
> >> Perhaps you wanted *so much* to see a difference between the two
> >> lenses that you deliberately focused the Olympus lens short of the
> >> first battery?

>
> >So you are saying that my conclusions are wrong? *Will you admit YOU
> >were wrong when I post the next test?

>
> He is saying you fudged the first exposure to make it demonstrate the
> aspect in which you so desperately believed.
>
> Regards,
>
> Eric Stevens


Well, here is another one. Check out the ruler shots.

http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

 
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Me
Guest
Posts: n/a
 
      04-26-2011
On 26/04/2011 12:36 p.m., RichA wrote:
> On Apr 25, 7:55 pm, Eric Stevens<(E-Mail Removed)> wrote:
>> On Mon, 25 Apr 2011 05:35:08 -0700 (PDT), RichA<(E-Mail Removed)>
>> wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>> On Apr 25, 3:31 am, Bruce<(E-Mail Removed)> wrote:
>>>> RichA<(E-Mail Removed)> wrote:
>>>>> On Apr 24, 12:41 pm, Paul Furman<(E-Mail Removed)> wrote:
>>>>>> Eric Stevens wrote:
>>>>>>> On Sun, 24 Apr 2011 10:43:14 +0100, Bruce<(E-Mail Removed)>
>>>>>>> wrote:

>>
>>>>>>>> RichA<(E-Mail Removed)> wrote:
>>>>>>>>> Two shots. One with an Olympus OM Zuiko 50mm f1.8 at f1.8. Same
>>>>>>>>> again, with a Nikon 50mm Series E. Check out the (impossible?) extra
>>>>>>>>> shallow DOF with the OM lens.

>>
>>>>>>>>> http://www.pbase.com/andersonrm/image/134159846
>>>>>>>>> http://www.pbase.com/andersonrm/image/134159847

>>
>>>>>>>> The Zuiko lens was quite obviously focused at a distance shorter than
>>>>>>>> the distance to the first battery. So, just as with most of your
>>>>>>>> so-called "comparison tests", no conclusions of any kind can be drawn.

>>
>>>>>>> I agree.

>>
>>>>>> Try focusing in the middle so you get some foreground and background OOF
>>>>>> and can see from the wood table where the focus is. As shot, the focus
>>>>>> is probably in the air in front of the table edge so you can't confirm
>>>>>> it. An angled tape measure works very well for this kind of test; you
>>>>>> can see where the numbers become illegible:http://www.flickr.com/photos/edgehil...-7215760323110......

>>
>>>>> To satisfy the doubters, I'll shoot a ruler on the incline, they way
>>>>> the you when calibrating focus. But I've seen this with Olympus
>>>>> lenses before.

>>
>>>> You've seen it before? You mean, like we've all seen your inability
>>>> to carry out a properly controlled test before?

>>
>>>> Perhaps you wanted *so much* to see a difference between the two
>>>> lenses that you deliberately focused the Olympus lens short of the
>>>> first battery?

>>
>>> So you are saying that my conclusions are wrong? Will you admit YOU
>>> were wrong when I post the next test?

>>
>> He is saying you fudged the first exposure to make it demonstrate the
>> aspect in which you so desperately believed.
>>
>> Regards,
>>
>> Eric Stevens

>
> Well, here is another one. Check out the ruler shots.
>
> http://www.pbase.com/andersonrm/unus...mpus_50mm_lens
>

Wow, that Olympus lens is very soft and has butt-ugly bokeh.
The Nikkor 50mm f1.8D isn't regarded as being flash for bokeh (but no
worse than most of these "standard" f1.4 - f2 ~50mm lenses from any
maker), perhaps the E is much nicer.

 
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RichA
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Posts: n/a
 
      04-26-2011
On Apr 25, 9:23*pm, Me <(E-Mail Removed)> wrote:
> On 26/04/2011 12:36 p.m., RichA wrote:
>
>
>
>
>
>
>
> > On Apr 25, 7:55 pm, Eric Stevens<(E-Mail Removed)> *wrote:
> >> On Mon, 25 Apr 2011 05:35:08 -0700 (PDT), RichA<(E-Mail Removed)>
> >> wrote:

>
> >>> On Apr 25, 3:31 am, Bruce<(E-Mail Removed)> *wrote:
> >>>> RichA<(E-Mail Removed)> *wrote:
> >>>>> On Apr 24, 12:41 pm, Paul Furman<(E-Mail Removed)> *wrote:
> >>>>>> Eric Stevens wrote:
> >>>>>>> On Sun, 24 Apr 2011 10:43:14 +0100, Bruce<(E-Mail Removed)>
> >>>>>>> wrote:

>
> >>>>>>>> RichA<(E-Mail Removed)> * *wrote:
> >>>>>>>>> Two shots. *One with an Olympus OM Zuiko 50mm f1.8 at f1.8. *Same
> >>>>>>>>> again, with a Nikon 50mm Series E. *Check out the (impossible?) extra
> >>>>>>>>> shallow DOF with the OM lens.

>
> >>>>>>>>>http://www.pbase.com/andersonrm/image/134159846
> >>>>>>>>>http://www.pbase.com/andersonrm/image/134159847

>
> >>>>>>>> The Zuiko lens was quite obviously focused at a distance shorterthan
> >>>>>>>> the distance to the first battery. *So, just as with most of your
> >>>>>>>> so-called "comparison tests", no conclusions of any kind can be drawn.

>
> >>>>>>> I agree.

>
> >>>>>> Try focusing in the middle so you get some foreground and background OOF
> >>>>>> and can see from the wood table where the focus is. As shot, the focus
> >>>>>> is probably in the air in front of the table edge so you can't confirm
> >>>>>> it. An angled tape measure works very well for this kind of test; you
> >>>>>> can see where the numbers become illegible:http://www.flickr.com/photos/edgehil...-7215760323110......

>
> >>>>> To *satisfy the doubters, I'll shoot a ruler on the incline, theyway
> >>>>> the you when calibrating focus. *But I've seen this with Olympus
> >>>>> lenses before.

>
> >>>> You've seen it before? *You mean, like we've all seen your inability
> >>>> to carry out a properly controlled test before?

>
> >>>> Perhaps you wanted *so much* to see a difference between the two
> >>>> lenses that you deliberately focused the Olympus lens short of the
> >>>> first battery?

>
> >>> So you are saying that my conclusions are wrong? *Will you admit YOU
> >>> were wrong when I post the next test?

>
> >> He is saying you fudged the first exposure to make it demonstrate the
> >> aspect in which you so desperately believed.

>
> >> Regards,

>
> >> Eric Stevens

>
> > Well, here is another one. *Check out the ruler shots.

>
> >http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>
> Wow, that Olympus lens is very soft and has butt-ugly bokeh.
> The Nikkor 50mm f1.8D isn't regarded as being flash for bokeh (but no
> worse than most of these "standard" f1.4 - f2 ~50mm lenses from any
> maker), perhaps the E is much nicer.


For an economy lens, the E 50's are pretty nice I think.
 
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Me
Guest
Posts: n/a
 
      04-26-2011
On 26/04/2011 1:39 p.m., Better Info wrote:
> On Tue, 26 Apr 2011 13:23:00 +1200, Me<(E-Mail Removed)> wrote:
>
>> On 26/04/2011 12:36 p.m., RichA wrote:
>>> On Apr 25, 7:55 pm, Eric Stevens<(E-Mail Removed)> wrote:
>>>> On Mon, 25 Apr 2011 05:35:08 -0700 (PDT), RichA<(E-Mail Removed)>
>>>> wrote:
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>> On Apr 25, 3:31 am, Bruce<(E-Mail Removed)> wrote:
>>>>>> RichA<(E-Mail Removed)> wrote:
>>>>>>> On Apr 24, 12:41 pm, Paul Furman<(E-Mail Removed)> wrote:
>>>>>>>> Eric Stevens wrote:
>>>>>>>>> On Sun, 24 Apr 2011 10:43:14 +0100, Bruce<(E-Mail Removed)>
>>>>>>>>> wrote:
>>>>
>>>>>>>>>> RichA<(E-Mail Removed)> wrote:
>>>>>>>>>>> Two shots. One with an Olympus OM Zuiko 50mm f1.8 at f1.8. Same
>>>>>>>>>>> again, with a Nikon 50mm Series E. Check out the (impossible?) extra
>>>>>>>>>>> shallow DOF with the OM lens.
>>>>
>>>>>>>>>>> http://www.pbase.com/andersonrm/image/134159846
>>>>>>>>>>> http://www.pbase.com/andersonrm/image/134159847
>>>>
>>>>>>>>>> The Zuiko lens was quite obviously focused at a distance shorter than
>>>>>>>>>> the distance to the first battery. So, just as with most of your
>>>>>>>>>> so-called "comparison tests", no conclusions of any kind can be drawn.
>>>>
>>>>>>>>> I agree.
>>>>
>>>>>>>> Try focusing in the middle so you get some foreground and background OOF
>>>>>>>> and can see from the wood table where the focus is. As shot, the focus
>>>>>>>> is probably in the air in front of the table edge so you can't confirm
>>>>>>>> it. An angled tape measure works very well for this kind of test; you
>>>>>>>> can see where the numbers become illegible:http://www.flickr.com/photos/edgehil...-7215760323110......
>>>>
>>>>>>> To satisfy the doubters, I'll shoot a ruler on the incline, they way
>>>>>>> the you when calibrating focus. But I've seen this with Olympus
>>>>>>> lenses before.
>>>>
>>>>>> You've seen it before? You mean, like we've all seen your inability
>>>>>> to carry out a properly controlled test before?
>>>>
>>>>>> Perhaps you wanted *so much* to see a difference between the two
>>>>>> lenses that you deliberately focused the Olympus lens short of the
>>>>>> first battery?
>>>>
>>>>> So you are saying that my conclusions are wrong? Will you admit YOU
>>>>> were wrong when I post the next test?
>>>>
>>>> He is saying you fudged the first exposure to make it demonstrate the
>>>> aspect in which you so desperately believed.
>>>>
>>>> Regards,
>>>>
>>>> Eric Stevens
>>>
>>> Well, here is another one. Check out the ruler shots.
>>>
>>> http://www.pbase.com/andersonrm/unus...mpus_50mm_lens
>>>

>> Wow, that Olympus lens is very soft and has butt-ugly bokeh.
>> The Nikkor 50mm f1.8D isn't regarded as being flash for bokeh (but no
>> worse than most of these "standard" f1.4 - f2 ~50mm lenses from any
>> maker), perhaps the E is much nicer.

>
> There's very little to no difference in the "quality" of the bokeh between
> the Olympus and the Yashica. In fact, I prefer the bokeh "quality" of the
> Olympus lens, though slight the difference may be.
>
> A brainless Nikon fanboi are ye? If so, then you might want to consider
> switching brands to mindlessly rave about if those exposure and aperture
> settings are true. Nikon only became popular on the sheep-principle,
> nothing more.
>
>

Even though bokeh is subjective "personal preference", that Olympus lens
bokeh is very harsh, so if you prefer that, then you're either blind, or
all your taste is in your mouth.
And BTW, I made no comment about the Yashica, but now I'll comment that
it also has butt-ugly bokeh, the old el-cheapo budget "E" Nikkor looks
much nicer, and I don't care a rat's arse if you think that's a "fanboi"
comment.
 
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RichA
Guest
Posts: n/a
 
      04-26-2011
On Apr 26, 1:14*pm, Better Info <(E-Mail Removed)> wrote:
> On Mon, 25 Apr 2011 22:01:37 -0500, Rich <(E-Mail Removed)> wrote:
> >Better Info <(E-Mail Removed)> wrote in

>
> >>>http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>
> >> The answer is in your shutter speed. The Nikon is lying about its
> >> aperture. Or you are. <-- The more plausible answer.

>
> >The Nikon and the Olympus have the same size front lens aperture and the
> >Nikon's rear aperture is about 1.5mm smaller in diameter than the Olympus.
> >However, only testing would determine if that aperture defines the light
> >cone. *

>
> The sizes of the front and rear elements are no indication of the f/ratio..


The size of the front element "may" not have anything to do with it,
if they are larger than the prescribed diameter for the focal ratio.
If a lens is a 50mm f2.0, it needs at least 25mm of clear aperture in
the front element to reach the f2.0 speed. That's physics that even
you can't ignore.
 
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Rich
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Posts: n/a
 
      04-27-2011
On Apr 26, 2:55*pm, Paul Furman <(E-Mail Removed)> wrote:
> RichA wrote:
> > Eric Stevens wrote:
> >> RichAwrote:
> >>> Bruce wrote:
> >>>> RichA wrote:
> >>>>> Paul Furman wrote:
> >>>>>> Eric Stevens wrote:
> >>>>>>> Brucewrote:
> >>>>>>>> RichA wrote:

>
> >>>>>>>>> Two shots. *One with an Olympus OM Zuiko 50mm f1.8 at f1.8. *Same
> >>>>>>>>> again, with a Nikon 50mm Series E. *Check out the (impossible?) extra
> >>>>>>>>> shallow DOF with the OM lens.

>
> >>>>>>>>>http://www.pbase.com/andersonrm/image/134159846
> >>>>>>>>>http://www.pbase.com/andersonrm/image/134159847

>
> >>>>>>>> The Zuiko lens was quite obviously focused at a distance shorterthan
> >>>>>>>> the distance to the first battery. *So, just as with most of your
> >>>>>>>> so-called "comparison tests", no conclusions of any kind can be drawn.

>
> >>>>>>> I agree.

>
> >>>>>> Try focusing in the middle so you get some foreground and background OOF
> >>>>>> and can see from the wood table where the focus is. As shot, the focus
> >>>>>> is probably in the air in front of the table edge so you can't confirm
> >>>>>> it. An angled tape measure works very well for this kind of test; you
> >>>>>> can see where the numbers become illegible:
> >>http://www.flickr.com/photos/edgehil...-7215760323110....

>
> >>>>> To *satisfy the doubters, I'll shoot a ruler on the incline, theyway
> >>>>> the you when calibrating focus. *But I've seen this with Olympus
> >>>>> lenses before.

>
> >>>> You've seen it before? *You mean, like we've all seen your inability
> >>>> to carry out a properly controlled test before?

>
> >>>> Perhaps you wanted *so much* to see a difference between the two
> >>>> lenses that you deliberately focused the Olympus lens short of the
> >>>> first battery?

>
> >>> So you are saying that my conclusions are wrong? *Will you admit YOU
> >>> were wrong when I post the next test?

>
> >> He is saying you fudged the first exposure to make it demonstrate the
> >> aspect in which you so desperately believed.

>
> > Well, here is another one. *Check out the ruler shots.

>
> >http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>
> Thanks, that's an interesting comparison. The Nikkor appears to be
> slower than the others. It shows 1/13th second vs 1/40th and the OOF
> blur circles are a lot smaller. The Yashica appears to show astigmatism,
> where the edges wig out asymmetrically.
>
> More interesting is the non-Nikkors appear to have better foreground
> bokeh than background, perhaps due to over-corrected spherical aberration?


I have a Voigtlander 58mm f1.4 lens that has decent optical
quality, but ugly bokeh wide open. Seems to support your observation
about the Olympus and Yashica linking SA with good bokeh.
 
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Rich
Guest
Posts: n/a
 
      04-28-2011
On Apr 27, 8:19*pm, Paul Furman <(E-Mail Removed)> wrote:
> Rich wrote:
> > Paul Furman wrote:
> >> RichA wrote:
> >>> Eric Stevens wrote:
> >>>> RichAwrote:
> >>>>> Bruce wrote:
> >>>>>> RichA wrote:
> >>>>>>> Paul Furman wrote:
> >>>>>>>> Eric Stevens wrote:
> >>>>>>>>> Brucewrote:
> >>>>>>>>>> RichA wrote:

>
> >>>>>>>>>>> Two shots. *One with an Olympus OM Zuiko 50mm f1.8 at f1.8.*Same
> >>>>>>>>>>> again, with a Nikon 50mm Series E. *Check out the (impossible?) extra
> >>>>>>>>>>> shallow DOF with the OM lens.

>
> >>>>>>>>>>>http://www.pbase.com/andersonrm/image/134159846
> >>>>>>>>>>>http://www.pbase.com/andersonrm/image/134159847

>
> >>>>>>>>>> The Zuiko lens was quite obviously focused at a distance shorter than
> >>>>>>>>>> the distance to the first battery. *So, just as with most ofyour
> >>>>>>>>>> so-called "comparison tests", no conclusions of any kind can be drawn.

>
> >>>>>>>>> I agree.

>
> >>>>>>>> Try focusing in the middle so you get some foreground and background OOF
> >>>>>>>> and can see from the wood table where the focus is. As shot, thefocus
> >>>>>>>> is probably in the air in front of the table edge so you can't confirm
> >>>>>>>> it. An angled tape measure works very well for this kind of test; you
> >>>>>>>> can see where the numbers become illegible:
> >>>>http://www.flickr.com/photos/edgehil...-7215760323110....

>
> >>>>>>> To *satisfy the doubters, I'll shoot a ruler on the incline, they way
> >>>>>>> the you when calibrating focus. *But I've seen this with Olympus
> >>>>>>> lenses before.

>
> >>>>>> You've seen it before? *You mean, like we've all seen your inability
> >>>>>> to carry out a properly controlled test before?

>
> >>>>>> Perhaps you wanted *so much* to see a difference between the two
> >>>>>> lenses that you deliberately focused the Olympus lens short of the
> >>>>>> first battery?

>
> >>>>> So you are saying that my conclusions are wrong? *Will you admit YOU
> >>>>> were wrong when I post the next test?

>
> >>>> He is saying you fudged the first exposure to make it demonstrate the
> >>>> aspect in which you so desperately believed.

>
> >>> Well, here is another one. *Check out the ruler shots.

>
> >>>http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>
> >> Thanks, that's an interesting comparison. The Nikkor appears to be
> >> slower than the others. It shows 1/13th second vs 1/40th and the OOF
> >> blur circles are a lot smaller. The Yashica appears to show astigmatism,
> >> where the edges wig out asymmetrically.

>
> >> More interesting is the non-Nikkors appear to have better foreground
> >> bokeh than background, perhaps due to over-corrected spherical aberration?

>
> > * * I have a Voigtlander 58mm f1.4 lens that has decent optical
> > quality, but ugly bokeh wide open. *Seems to support your observation
> > about the Olympus and Yashica linking SA with good bokeh.

>
> Only good in the foreground though, which seems odd, or at least
> normally less useful. The DC (Defocus Control) Nikkors have SA
> adjustable to make foreground or background softer, whether
> over-corrected or under-corrected.


The next new Nikon you ever see that in will cost $2000.
 
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Bruce
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Posts: n/a
 
      05-09-2011
Paul Furman <(E-Mail Removed)> wrote:
>RichA wrote:>>
>> Well, here is another one. Check out the ruler shots.
>> http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>
>Thanks, that's an interesting comparison. The Nikkor appears to be
>slower than the others. It shows 1/13th second vs 1/40th and the OOF
>blur circles are a lot smaller. The Yashica appears to show astigmatism,
>where the edges wig out asymmetrically.
>
>More interesting is the non-Nikkors appear to have better foreground
>bokeh than background, perhaps due to over-corrected spherical aberration?



I asked my university professor colleague to look at these. He would
obviously like to see a more carefully controlled test, but on the
basis of what is shown, this was his opinion:

"The Yashica and Olympus lenses display near-identical depth of field
with only slight differences in boke.

"The Nikkor [*actually a Nikon Series E] displays a significantly
greater depth of field, suggesting it is stopped down by between one
and two stops from wide open, or somewhere between f/2.4 and f/3.5, so
probably around f/2.8.

"Assuming identical lighting, the difference in shutter speeds between
the Nikon shot (1/13 sec) and the other two (1/40 sec) would appear to
support this. The lens should be examined to ascertain whether the
iris diaphragm blades are capable of opening fully."


So the conclusion of a university professor of optical engineering is
that the test was not properly controlled and the result is therefore
misleading. Specifically, the lens aperture of the Nikon Series E was
probably nearer f/2.8 than f/1.8. This alone would explain the
difference in depth of field.

Must try harder, Rich.


[*For the purpose of this test, there was no significant optical
difference between the Nikon Series E and contemporary AIS Nikkor. The
optical design was the same, the only difference was that the Series E
had cheaper anti-reflection coating. Indeed, the second, later
version of the Series E optic (with the chrome knurled ring replacing
the molded black castellated ring) has both optics *and* coatings that
are in all respects identical with the AIS Nikkor.]

 
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John Turco
Guest
Posts: n/a
 
      05-12-2011
Bruce wrote:
>
> > Paul Furman <(E-Mail Removed)> wrote:
> >> RichA wrote:
> >> Well, here is another one. Check out the ruler shots.
> >> http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

> >
> > Thanks, that's an interesting comparison. The Nikkor appears to be
> > slower than the others. It shows 1/13th second vs 1/40th and the OOF
> > blur circles are a lot smaller. The Yashica appears to show astigmatism,
> > where the edges wig out asymmetrically.
> >
> > More interesting is the non-Nikkors appear to have better foreground
> > bokeh than background, perhaps due to over-corrected spherical aberration?

>
> I asked my university professor colleague to look at these. He would
> obviously like to see a more carefully controlled test, but on the
> basis of what is shown, this was his opinion:


<deleted "proffessorial" double-talk>

> So the conclusion of a university professor of optical engineering is
> that the test was not properly controlled and the result is therefore
> misleading.


<edited>

So, in reality, one of "Bruce's" beer buddies (with a "degree" in
sanitation engineering) was in a drunken stupor, once again.

Oh, wait a moment..."Whisky-dave" (his fellow Britisher) works at
a college, does he not? (He's a cafeteria dishwasher, no doubt.)

--
Cordially,
John Turco <(E-Mail Removed)>

Marie's Musings <http://fairiesandtails.blogspot.com>
 
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Bruce
Guest
Posts: n/a
 
      05-13-2011
Bruce <(E-Mail Removed)> wrote:
>Paul Furman <(E-Mail Removed)> wrote:
>>RichA wrote:>>
>>> Well, here is another one. Check out the ruler shots.
>>> http://www.pbase.com/andersonrm/unus...mpus_50mm_lens

>>
>>Thanks, that's an interesting comparison. The Nikkor appears to be
>>slower than the others. It shows 1/13th second vs 1/40th and the OOF
>>blur circles are a lot smaller. The Yashica appears to show astigmatism,
>>where the edges wig out asymmetrically.
>>
>>More interesting is the non-Nikkors appear to have better foreground
>>bokeh than background, perhaps due to over-corrected spherical aberration?

>
>
>I asked my university professor colleague to look at these. He would
>obviously like to see a more carefully controlled test, but on the
>basis of what is shown, this was his opinion:
>
>"The Yashica and Olympus lenses display near-identical depth of field
>with only slight differences in boke.
>
>"The Nikkor [*actually a Nikon Series E] displays a significantly
>greater depth of field, suggesting it is stopped down by between one
>and two stops from wide open, or somewhere between f/2.4 and f/3.5, so
>probably around f/2.8.
>
>"Assuming identical lighting, the difference in shutter speeds between
>the Nikon shot (1/13 sec) and the other two (1/40 sec) would appear to
>support this. The lens should be examined to ascertain whether the
>iris diaphragm blades are capable of opening fully."
>
>
>So the conclusion of a university professor of optical engineering is
>that the test was not properly controlled and the result is therefore
>misleading. Specifically, the lens aperture of the Nikon Series E was
>probably nearer f/2.8 than f/1.8. This alone would explain the
>difference in depth of field.
>
>Must try harder, Rich.
>
>
>[*For the purpose of this test, there was no significant optical
>difference between the Nikon Series E and contemporary AIS Nikkor. The
>optical design was the same, the only difference was that the Series E
>had cheaper anti-reflection coating. Indeed, the second, later
>version of the Series E optic (with the chrome knurled ring replacing
>the molded black castellated ring) has both optics *and* coatings that
>are in all respects identical with the AIS Nikkor.]



Poor Rich.

He's unable to reply because he has his head in the sand.

 
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