Quiz about pixel density and sensor sizes

[liquidstone]

on this, while we're on the subject of system resolution (sensor/AA
filter and lens resolution).

I think I have accidentally shown that the Sigmonster at 800 f/9
outresolves my 350D sensor. If this is correct, then adding a TC
will result into a net gain in system resolution for the 350D +
Sigmonster. Comments?

I'd be completely shocked if the Sigmonster did NOT out-resolve
your sensor at f9.

Nearly every lens can resolve more on our current sensors with a TC
than without. Here's my 70-200 2.8L IS:

Thanks for the comments. That allows more room then for even smaller pixel pitch in future APS sensors without the danger of maxxing out the resolving power of our current sharp lenses (provided noise can be held at bay and DR maintained).

Your test shows a gain in system resolution at least up to 2x TC with the 70-200 L IS. This is a 2x gain linearly, or 4x gain in terms of total pixel area.

Wow... if my math is correct, this is exciting, as we can look forward to up to 32 MP in an APS sensor in the near future without having to discard our current top lenses.

This is like having a built-in 2x relative to our current 8 MP, and my Sigmonster will have a 1600 mm "reach" without the TCs.

--
Liquidstone
http://www.pbase.com/liquidstone/top25

 

[Hamming]

OK, for same f-number, the lens will open up and you will lose depth of field..

Or lens aberrations will increase..

 

[Doug Kerr]

n/t

 

[Lee Jay]

OK, for same f-number, the lens will open up and you will lose
depth of field..

Or lens aberrations will increase..

Nope. DOF stays the same with TCs. The TC makes the lens slower but longer.

--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

You can't go to bed without learning something new. This thread will allow you to go to bed on time!

--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

...the fact that the 20D is using the "sweeter" part of the lens
than the 5D? There will be less astigmatism, etc, at the corners
of the 20D's image vs. the 5D.

Nope. Add the hypothetical 1.28x TC to the 5D and crop to 1.3 crop and you will be using exactly the same part of the lens as the 20D was using.

--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

Wow... if my math is correct, this is exciting, as we can look
forward to up to 32 MP in an APS sensor in the near future without
having to discard our current top lenses.

Indeed. Here's an old thread of mine:

http://forums.dpreview.com/forums/read.asp?forum=1019&message=14158998

This is like having a built-in 2x relative to our current 8 MP, and
my Sigmonster will have a 1600 mm "reach" without the TCs.

Hmmmmmmmm........

--
Lee Jay
(see profile for equipment)

 

[Doug Kerr]

. . . a certain field of view (a certain object field at a certain distance) covered with an image of the same pixel dimensions (cropped if need be, and I use that word with its real meaning), you can do that with a smaller focal length lens on the 20D than on the 5D. That might be advantageous (depending on the lens catalog you are working out of).

Or if you want the camera to be lighter, then the 20D is better than the 5D.

Or if you have to pay for the camera by digging ditches at $7.50/hr, then the 20D is better than the 5D.

Best regards,

Doug

 

[Hamming]

You still need to open the aperture to keep exposure the same, don't you -- that doesn't decrease dof?

OK, for same f-number, the lens will open up and you will lose
depth of field..

Or lens aberrations will increase..

Nope. DOF stays the same with TCs. The TC makes the lens slower
but longer.

--
Lee Jay
(see profile for equipment)

 

[Doug Kerr]

Hi, Lee Jay,

You can't go to bed without learning something new. This thread
will allow you to go to bed on time!

Is that only valid if what I learn is something new?

Best regards,

Doug

 

[Lee Jay]

You can't go to bed without learning something new. This thread
will allow you to go to bed on time!

Is that only valid if what I learn is something new?

Hmmmm...that could be a problem.

Oh well. After you're up about 72 hours in a row or so without learning something, your brain will put you to sleep forcefully. When you wake up, you will know how long you can stay awake (one thing) and how long you will sleep afterward (second thing). So I think the rule holds, right up there with conservation of energy.

--
Lee Jay
(see profile for equipment)

 

[Doug Kerr]

Hi, Lee Jay,

Nope. Add the hypothetical 1.28x TC to the 5D and crop to 1.3 crop
and you will be using exactly the same part of the lens . .

"Same part of the lens"? Really, now. What does that mean?

Maybe you are speaking about the same part of the lens' image circle.

Best regards,

Doug

 

[drip01]

http://forums.dpreview.com/forums/read.asp?forum=1032&message=15680612

--
Brian

 

[Lee Jay]

You still need to open the aperture to keep exposure the same,
don't you -- that doesn't decrease dof?

You don't need to open up. In fact, you need to close down (wierd, huh?).

400mm f5.6 100 feet on the 20D, DOF = 4.04 feet
200mm f2.8 100 feet on the 20D, DOF = 8.15 feet

--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

I already know you know the answer!

--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

Here's the deal. I can add the TC to the 5D to get everything back but then it's like 2/3 of a stop slower and so it won't auto-focus anymore since it's limited to f5.6 just like the 20D. So the 20D has the advantage for that reason.

In fact, if you want the maximum possible reach, you want to be able to autofocus at the diffraction limit of your sensor. It doen't matter much where that is just that you can AF there.

The 5D is about the worst. The 50% MTF diffraction limit is at f12.5 while it can AF at only f5.6. The 20D is better because its diffraction limit is at f9.7 while it can AF at f5.6. The 1DsII is the best of the Canon line because its diffraction limit is at f10.64 while it can AF at f8.

But the king of reach is currently the Nikon D2x. It's diffraction limit is at f8.4 and it can AF at f8.
--
Lee Jay
(see profile for equipment)

 

[Lee Jay]

Maybe you are speaking about the same part of the lens' image circle.

That's what I meant.

--
Lee Jay
(see profile for equipment)

 

[drip]

--
I don't tolerate morons. (not you)

 

[Doug Kerr]

Still, I think the weight is more compelling!

Best regards,

Doug

 

[Lee Jay]

Still, I think the weight is more compelling!

I think I like Romy's first answer best!

--
Lee Jay
(see profile for equipment)