Telephoto Reach and Digital Cameras - lens comparison

On 12/16/2010 10:17 PM, Paul Furman wrote:
peter wrote:
Roger N. Clark wrote:

Compare that to a mere 1400 mm (real) focal length:
http://www.clarkvision.com/galleries...0mm.d-923.html


I noticed on your site that you take images with stacked teleconverters.
It is my understanding that in addition to loss of light a teleconverter
also exaggerates any flaws in the prime lens. I could not see any such
exaggeration of aberrations.

The stacked teleconverters will also crop off the edges where
aberrations are most troublesome like CA, coma and astigmatism. What
I've found is that teleconverters will give a softer image at the pixel
level but they do generally increase actual subject detail, so not great
for large prints but still useful.

Also, I would think that stacking would work for your astro shots, when
mounted on a proper tracking mount, but would not be very practical for
wildlife photography.

A loose fitting gimbal head is ideal for wildlife:
http://www.google.com/images?q=gimbal+head

Absolutely, a gimbal mount works well.
I was actually referring to stacked teleconverters not being practical
due to the loss of light. In my own experience the only combination I
have liked is the Nikkor 1.7 attached to my 70-200. I have tried the
Kenko 1.4 and the Nikkor 2x on the 80-400, but have not been even close
to happy with the results.

peter wrote:
Paul Furman wrote:
peter wrote:
Roger N. Clark wrote:

Compare that to a mere 1400 mm (real) focal length:
http://www.clarkvision.com/galleries...0mm.d-923.html

I noticed on your site that you take images with stacked teleconverters.
It is my understanding that in addition to loss of light a teleconverter
also exaggerates any flaws in the prime lens. I could not see any such
exaggeration of aberrations.

The stacked teleconverters will also crop off the edges where
aberrations are most troublesome like CA, coma and astigmatism. What
I've found is that teleconverters will give a softer image at the pixel
level but they do generally increase actual subject detail, so not great
for large prints but still useful.

Also, I would think that stacking would work for your astro shots, when
mounted on a proper tracking mount, but would not be very practical for
wildlife photography.

A loose fitting gimbal head is ideal for wildlife:
http://www.google.com/images?q=gimbal+head

Absolutely, a gimbal mount works well.

drool

I was actually referring to stacked teleconverters not being practical
due to the loss of light. In my own experience the only combination I
have liked is the Nikkor 1.7 attached to my 70-200. I have tried the
Kenko 1.4 and the Nikkor 2x on the 80-400, but have not been even close
to happy with the results.

The Nikon 1.4 is good, and small. It basically turns an FX camera into a
DX, I never tried to figure out if that ever makes sense though, I guess
I've assumed not. You'd have to factor in the ISO to really evaluate it;
I think it'd be a wash for shutter speed and the optical compromises of
a teleconverter on FX would let the DX body win. Perhaps FX would win
for astro with a guided head more drool.

On 12/17/2010 01:15 AM, Superzooms Still Win wrote:
As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality.

Yes, they are polished to diffraction-limited quality at the top of a
high moutain by virgin girls under the full moon. They are then laid on
silk cushions and brought back in the valley using buffalo carts, and
the tiny moves of the lenses on the cushions caused by the gentle
rocking of the cart finishes the polishing to perfection.

--
Bertrand

David J Taylor wrote:
"bobwilliams" wrote in message
...
[]
But just to level the playing field a bit, estimate the COST and
WEIGHT of the system you used to get this moon image vs the COST and
WEIGHT of the Superzoom camera to which you made the image comparison.
Bob Williams

That's a fair comment, Bob. One uses the tools most appropriate to the
task in hand, and I know that I won't carry such big lenses as Roger
uses, and I accept the performance will be somewhat worse. I do now use
a DSLR as it has many advantages for me over the cameras I used before,
but I still have a pocket camera for those occasions which require it.
What Roger's page clearly shows is that very small sensors and lenses
cannot overcome the limitations of physics.

Cheers,
David


Everything in life (and photography) is a compromise.
There is no question that Roger's Super System will outperform ANY
Superzoom.....But at what cost,in Price, Portability and Convenience?
All of us have to settle for "good enough"...... even Roger.
He is heavy into astro-photography and I suspect that he has even better
moonshots than the ones he posted here, taken with astronomical
telescopes. But these systems used are so specialized that comparing
them to a consumer Superzoom or even to an unaided Canon 5D MkII with a
Canon 300 mm f4 L IS lens is of little practical significance.
BTW, I admire Roger's contributions to this newsgroup and take all his
data, images and conclusions very seriously.
Bob

On 16/12/2010 15:59, peter wrote:
On 12/15/2010 1:56 AM, Roger N. Clark (change username to rnclark) wrote:

Compare to:
http://www.clarkvision.com/articles/...st2/index.html
Starting at Figure 3, at only 300 mm, image quality shows far more detail
than any of the superzoom images, and as you go further down the page,
the
images with the DSLR just keep showing more and more detail, and these
are an in-camera produced jpegs. Figures 4 and 5 are
far past any superzoom P&S camera image possible. Again, simple
physics proves the point. By the time you get to Figure 7 with
the DSLR raw image, it is so far beyond the P&S image, it is amazing.

But wait, we not done yet. DSLRs keep getting better and better.

And more to the point you can hang one on a real telescope at prime
focus. The only worry is getting dust on the sensor and that some DSLRs
burn through batteries when used in B mode for long exposures.

Some of the picassaweb images are claiming 2016 mm equivalent focal
length, e.g.
http://picasaweb.google.com/aniramca...54027503541298
(probably the best P&S image on the page).
Compare that to a mere 1400 mm (real) focal length:
http://www.clarkvision.com/galleries...0mm.d-923.html

The full resolution image is here (781 kbytes):
http://www.clarkvision.com/galleries...d-2385srgb.jpg

No contest, the DSLR blows away any P&S superzoom moon image, as
simple physics proved it would.


I noticed on your site that you take images with stacked teleconverters.
It is my understanding that in addition to loss of light a teleconverter
also exaggerates any flaws in the prime lens. I could not see any such
exaggeration of aberrations.

If anything the aberrations are less with a teleconverter as the longer
effective focal length means the rays going through the lens to the film
plane are closer to the lens axis and at a shallower angle where all the
optics approximations hold more accurately. It is the edge of field
corners where a prime lens has its worst aberrations.

However, you do need a prime lens that is tack sharp since when you
multiply the lens focal length by 2x there needs to be something useful
to go into the additional pixels. Otherwise you could just take the full
frame picture and interpolate the missing pixels in software.

Also, I would think that stacking would work for your astro shots, when
mounted on a proper tracking mount, but would not be very practical for
wildlife photography.

When using teleconverters with a telescope which is already a long focal
length and by comparison with a normal lens many have long back focus
you can alter the magnification a fair bit by adding extension tubes
between the teleconverter/compressor and the camera. This does slightly
affect aberrations but is usually OK.

http://www.nezumi.demon.co.uk/astro/zoom/zoom.htm

Regards,
Martin Brown

peter wrote:

I noticed on your site that you take images with stacked teleconverters.
It is my understanding that in addition to loss of light a teleconverter
also exaggerates any flaws in the prime lens. I could not see any such
exaggeration of aberrations.

Also, I would think that stacking would work for your astro shots, when
mounted on a proper tracking mount, but would not be very practical for
wildlife photography.


Paul,

Stacked TCs work well with wildlife photography too. The Moon is a very
difficult target with very high contrast. Any aberrations will show around
the edges of the Moon and in shadow boundaries in craters. So if your lens
can image the Moon well, it will do very well on wildlife.

Some examples with stacked 1.4x and 2x TCs:
http://www.clarkvision.com/galleries...979.b-700.html

http://www.clarkvision.com/galleries...awk.b-600.html

The biggest problem with stacked TCs is the very long focal lengths mean
one needs to be very steady when taking the picture.

I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Roger

peter wrote:

I noticed on your site that you take images with stacked teleconverters.
It is my understanding that in addition to loss of light a teleconverter
also exaggerates any flaws in the prime lens. I could not see any such
exaggeration of aberrations.

Also, I would think that stacking would work for your astro shots, when
mounted on a proper tracking mount, but would not be very practical for
wildlife photography.


Paul,

Stacked TCs work well with wildlife photography too. The Moon is a very
difficult target with very high contrast. Any aberrations will show around
the edges of the Moon and in shadow boundaries in craters. So if your lens
can image the Moon well, it will do very well on wildlife.

Some examples with stacked 1.4x and 2x TCs:
http://www.clarkvision.com/galleries...979.b-700.html

http://www.clarkvision.com/galleries...awk.b-600.html

The biggest problem with stacked TCs is the very long focal lengths mean
one needs to be very steady when taking the picture.

I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Roger

Superzooms Still Win wrote:
On Wed, 15 Dec 2010 08:39:38 -0700, "Roger N. Clark (change username to
wrote:

Superzooms Still Win wrote:
On Wed, 15 Dec 2010 01:25:07 -0600, Dudley Hanks
wrote:

Now that Roger has debunked your claims about detail, LOL,

perhaps we should run an analysis of the number of colour
shades captured in those DSLR and P&S pics? Or, are you still
smarting from the butterfly drubbing you took ... ?

But but DUDley! Didn't you compare that other image I posted that showed
many many thousands of more color shades in its data so therefore it MUST
be a better image according to your reasoning? What? Didn't you show it to
your sighted friends so they could laugh out loud at your absurdity and
failed reasoning? Didn't you even show them how your "editing skills"
totally trashes every photo you put through your "enhancing" routines?
We've all seen it, that's why they were all remaining so silent, you were
making such a total fool of yourself, AGAIN.

You are not getting it. Simple physics proves you are wrong.
Regarding image detail, the super zoom P&S cameras have clear
apertures on the order of an inch or less. Diffraction from
such a small lens means poor subject resolution. A DSLR with
even a lower end fixed telephoto like 300 f/4 has about a 3-inch
clear aperture, thus on the order of 3x higher resolution
on a subject. The 3x larger diameter lens delivers 9x
more light. More light = finer gradations due to better
signal-to-noise ratio. Again, this is simple physics.
There is no contest between a DSLR versus P&S whether telephoto
resolution on a subject or color tonality, or signal-to-noise
ratio. Simple physics, the DSLR wins. Anyone who can do
simple physics can prove this. Dudley is correct.

Roger

Hey MORON, this has nothing to do with lens physics, DUDley is throwing in
another situation that he created which proved himself too to be a total
moron.

You are wrong. It has to do with both lens physics and sensor
physics. Conisder two cameras, one with double the sensor size,
double the lens focal length, and double the pixel size, and the same
f/ratio lens. The lens has 4 times the area so collects 4 times the
light. The sensors have the same spatial resolution, but the larger
pixels collect 4 times the light from the lens delivering 4 times the
light. The signal-to-noise ratio is double on the large sensor camera.
The higher signal-to-noise ratio delivers finer tonality and greater
dynamic range. This is well proven and simple physics.


As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality. They have to be in
order to allow the photosites resolve individual details. Otherwise nobody
would buy them. Thereby allowing them to have more resolution at larger
apertures. DSLR glass is NEVER ground to diffraction-limited quality,
because the cost to do so puts them outside the reach of every consumer,
therefore they can never attain diffraction-limited resolutions at ANY
useful aperture.

What a laugh! Physics does very well. Again it is simple physics
that shows that the big lenses with DSLRs doesn't even need to be close
to diffraction limited in other to deliver better resolution on a subject
compared to the tiny lenses on P&S super zoom cameras.
Simple physics proves it.

But then you already knew this, or you wouldn't have blatantly biased your
fools' tests again by choosing aperture and exposure settings and
resolutions and JPG compressions which would give an advantage to your
PIECE OF **** DSLR CRAP.

Shove that "physics" up your useless asshole full of relentless BAD-SCIENCE
bull****. Now, go ahead, spend three more years of your useless life trying
to outdo more P&S cameras that have already surpassed anything you have
ever accomplished in your miserable existence.

Simple equation:
Dawes limit = 5.45/D where D=lens clear aperture diameter.
You can try shoving the physics wherever you want to but it won't
change the basic and well understood laws of physics.

Simple physics proves you wrong.
QED

Roger

In article ,
says...

On 12/17/2010 01:15 AM, Superzooms Still Win wrote:
As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality.

Yes, they are polished to diffraction-limited quality at the top of a
high moutain by virgin girls under the full moon. They are then laid on
silk cushions and brought back in the valley using buffalo carts, and
the tiny moves of the lenses on the cushions caused by the gentle
rocking of the cart finishes the polishing to perfection.

If the lenses on superzooms are in fact diffraction-limited then they
would be at their sharpest at full aperture. Are they?

On Fri, 17 Dec 2010 07:43:54 -0700, "Roger N. Clark (change username
to rnclark)" wrote:


I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Only because Canon doesn't make anything in the class of the Nokon
200-400mm f/4 VR Ior II.

:-)