1.6x factor has an advantage. Don't you think so?

Jason Hutchinson said:

Because of this, you now need to find a 64lp/mm (40x1.6x) MTF line
to compare to the 40lp/mm you used on the 1Ds.

Click to expand...

This is not correct IMO. 40lp/mm refers to line pairs per mm in lens'es image plane, and does not depend on the media at all. Lens MTF has nothing to do with the media, it's property of the lens only. So, 40lp/mm line on MTF chart is the same for both D60 and 1Ds. Now, there is also resolving power of the sensor, and if not the weaker AA filter on 1Ds, D60's sensor will have more lp/mm resolved than 1Ds' by a factor of 8.8/7.4 (size of pixels in microns).

Mishkin said:

This is not correct IMO. 40lp/mm refers to line pairs per mm in
lens'es image plane
and does not depend on the media at all.
Lens
MTF has nothing to do with the media, it's property of the lens
only.

Click to expand...

So you're saying the lens doesn't communicate to the sensor to find out what type of media it is? Thanks for clearing this up.

Mishkin said:

So, 40lp/mm line on MTF chart is the same for both D60 and
1Ds.

Click to expand...

No kidding. However, MTF is a basically a measure of contrast at differing resolutions. If you want to produce an image at a certain size of a certain subject at a given resolution, you will have to blow up the image 1.6x more with my D60 than with a 1Ds. Therefore, to find out what MTF you'll be able to achieve in the final output, you'll need to use the MTF line corresponding to 1.6x higher resolution. Obviously this assumes you're using a different lens, and framing the same, which is assumed given the posters question.

Jason

Jason Hutchinson said:

Mishkin said:

This is not correct IMO. 40lp/mm refers to line pairs per mm in
lens'es image plane
and does not depend on the media at all.
Lens
MTF has nothing to do with the media, it's property of the lens
only.

Click to expand...

So you're saying the lens doesn't communicate to the sensor to find
out what type of media it is? Thanks for clearing this up.

Click to expand...

LOL

Jason Hutchinson said:

Jason Hutchinson said:

So, 40lp/mm line on MTF chart is the same for both D60 and
1Ds.

Click to expand...

No kidding. However, MTF is a basically a measure of contrast at
differing resolutions. If you want to produce an image at a
certain size of a certain subject at a given resolution, you will
have to blow up the image 1.6x more with my D60 than with a 1Ds.
Therefore, to find out what MTF you'll be able to achieve in the
final output, you'll need to use the MTF line corresponding to 1.6x
higher resolution. Obviously this assumes you're using a different
lens, and framing the same, which is assumed given the posters
question.

Click to expand...

LOL -- no, the lens does not communicate to the paper to find out the output size. You're mixing MTF of the lens, which does not depend on ANYTHING except the lens, with your newly invented MTFs of 1Ds/D60/paper/printer/whatever.

Resolving power in lp/mm has nothing to do to magnification factor. If you cannot resolve two lines printed at 4x6" size, you will not resolve it if you print it at 40x60" size.

Mishkin said:

Resolving power in lp/mm has nothing to do to magnification factor.
If you cannot resolve two lines printed at 4x6" size, you will not
resolve it if you print it at 40x60" size.

Click to expand...

No one said that it did.

What has been said is that, given you want to produce a reproduction of an image file at a given size with a given "sharpness" then you need a lens able to resolve 1.6 times more resolution if you reproduce from a image file that has to be enlarged 1.6 times more (relative to a image captured with a fullframe)

In other words:

Say we have perfect imagers with "very" small pixels that capture anything that is resolved by the lens.

Now say that we have a lens that can resolve 100 lines per mm and a 22.5 mm wide imager. We capture an image that resolves 22.5 x 100 = 2250 lines.

Now say that we have a lens that can resolve only 80 lines per mm but an imager 36 mm wide. We capture an image that resolves 36 x 80 = 2880 lines.

So, even with the lens resolving less lines per mm we gat more information resolved due to the larger imager. Obviously, this matters when reproducing the image file.

--
Kjeld Olesen
http://www.acapixus.dk

Mishkin said:

LOL -- no, the lens does not communicate to the paper to find out
the output size. You're mixing MTF of the lens, which does not
depend on ANYTHING except the lens, with your newly invented MTFs
of 1Ds/D60/paper/printer/whatever.

Click to expand...

Actually I'm not mixing anything. MTF of a lens is basically the contrast at a given lp/mm. We wouldn't care what MTF a lens had if it were not that we look at this transfer function in our output, so it is ultimately applicable to this.

Let's say our subject is a bunch of vertical line pairs on a sheet of paper. We want our image to be 1800 of these line pairs, with an MTF of 50%.

To achieve this with the 1Ds, we need an MTF of 50% at 50lp/mm (1800/36). Easy enough.

To achieve this coverage with the D60 using the same lens, we now have to step backwards. We've only got a We now need to resolve 80lp/mm (1800/22) at 50% MTF to get our image.

Please point out where my math is wrong.

Mishkin said:

Resolving power in lp/mm has nothing to do to magnification factor.

Click to expand...

Yes, everyone knows this. I never said that. You'll keep hearing what you want to hear though.

Mishkin said:

If you cannot resolve two lines printed at 4x6" size, you will not
resolve it if you print it at 40x60" size.

Click to expand...

If you're using this off-topic info as an argument, I suspect you really do miss the point that other this thread, as well as many other have tried to make.

Jason

If you're into long focal lengths, then 1.6x is good. If you are into short focal lengths, then it's a pain.

Oscar Latorre said:

Well,

I love to have a 1.6x factor on the D60 instead of a 1x of the 1Ds.
There is one big reason, besides my 300mm lenses are 480mm
automatically (that saves me money, weight, size...).

Did you ever have a look at the MTF charts of your lenses?. In the
corners, you will see that the resolution/definition drops
dramatically even to the 50% of the definition compared with the
center of the lenses.

Since the crop factor of the D60 is 1.6x and the MTF charts behave
very well at these new corners (they only drop 80-90% compared with
the center) I cannot see significant loss of quality in the edges
of my photographies. Besides, no vignetting can be seen, even with
wide-angle lenses (no need for slim filters).

So, not only the 1.6x is a drawback. I know some of you will
complain you cannot go below 24mm but... for my photography I think
it is quite useful to have a 1.6x.

What is your opinion?

--
"Say what you want! but my pictures will tell the truth!"
O.L.

Click to expand...

To get the same shot in camera with a full frame sensor, I'd need a 1.6x larger lens.

OR IF was using the same lens with a full frame sensor on camera A and a 1.6x crop sensor on Camera B, I'd have to crop 1.6x out of the shot from camera A to get the same framed shot.

It's a crop...that's all it is. Apples to Apples please.

I can prove this with a simple drawing. Please don't make me open Paint...it isn't pretty ;^)

Jason Hutchinson said:

Jason

JGM said:

Jason Hutchinson said:

Because of this, you now need to find a 64lp/mm (40x1.6x) MTF line
to compare to the 40lp/mm you used on the 1Ds. With the average
lens, I'd say the 1x crop of the 1Ds is sharper than the 1.6x crop
of the D60. There might be an exception here or there with a few
wide angles, but for every one of those, there are lenses like the
135f/2 which are sharp right the corners.

Jason

JGM said:

From what I understand of MTF is that they measure resolving power
of a lens.

Since it is just a crop we are talking about...what does that have
to do with the resolution of a lens at a given point?

The MTF on a lens should be the same whether it's a D60, 1Ds, 35mm
film, or a piece of blank paper in back of it....

How the sensor interprets that is entirely different
subject...which has nothing to do with MTF from the way I
understand it.

Click to expand...

Click to expand...

--
John
http://www.pbase.com/mankman
Canon EOS D60

Click to expand...

Click to expand...

--
John
http://www.pbase.com/mankman
Canon EOS D60

dimage said:

Or are you saying that there is no disadvantage to cropping?

Click to expand...

No, I'm not saying that.

I'm saying that....

If I am standing in the SAME spot. I take a shot of subject A with a 1ds. I take the same shot of the same subject from the same spot with the same lens on a D60.

To get an equal image...I mean the framing what I see in the viewfinder with a D60...I'd have to crop the 1ds by 1.6.

See this all depends on your point of view. I like the effect of getting more perceived telephoto by cropping in the camera, so I can shoot what I see and not have to mess around trying to crop in software. It cuts down on my workflow. So I say I'd have to cut down the 1Ds size to get the same effect.

If you want full frame...you say you have to blow up the D60's to match the 1Ds....which if you need/desire full frame this is a totally valid way of looking at it.

--
John
http://www.pbase.com/mankman
Canon EOS D60

Jason Hutchinson said:

To achieve this with the 1Ds, we need an MTF of 50% at 50lp/mm
(1800/36). Easy enough.

To achieve this coverage with the D60 using the same lens, we now
have to step backwards. We've only got a We now need to resolve
80lp/mm (1800/22) at 50% MTF to get our image.

Click to expand...

...that if you resolve 50lp/mm at 50% MTF with 1Ds, and then duct tape the sensor from 36mm to 22mm, it magically kicks the resolution to 80lp/mm at 50% MTF?!

Jason Hutchinson said:

Please point out where my math is wrong.

Jason Hutchinson said:

Resolving power in lp/mm has nothing to do to magnification factor.

Click to expand...

Yes, everyone knows this. I never said that. You'll keep hearing
what you want to hear though.

Jason Hutchinson said:

If you cannot resolve two lines printed at 4x6" size, you will not
resolve it if you print it at 40x60" size.

Click to expand...

If you're using this off-topic info as an argument, I suspect you
really do miss the point that other this thread, as well as many
other have tried to make.

Jason

Click to expand...

Mishkin said:

...that if you resolve 50lp/mm at 50% MTF with 1Ds, and then duct
tape the sensor from 36mm to 22mm, it magically kicks the
resolution to 80lp/mm at 50% MTF?!

Click to expand...

Wow, you're so close to getting it...

No, my point is that would NEED to happen (obviously it doesn't) for a D60 to create an image comparable to the 1Ds with the same lens (and different subject distance obviously).

The above assumes a flat MTF as a function of distance from the center of the lens. Of course you know (I can't assume anything at this point) that since MTFs usually degrade with distance from the center of the lens, this number is theoretical.

The real answer involves using calculus to integrate the MTF curve over the portion of the lens used. A straight integration of course would only give an overall resolution (at a given MTF) and not take into account the subjective weighting a person might have making the center slightly more important than the edges.

In the end, even if you were to ignore the good performing lenses that have near uniform MTF from center to corner, the fact remains that in the center of the image, the larger sensor (all things being equal) will have the output with the better resolution. The distance from the center across which you can make this generalization varies from lens to lens. With the 135f/2 it would be the whole frame, while with the 14f/2.8 it might be the center 5%.

If you're having a hard time understanding all of this, I suggest you read the post just above these by Kjeld Olesen, as he is explaining the same thing.

Jason

Oscar Latorre said:

The 1D so far didn't have a full-frame sensor (1.3x) but still
everybody agreed was a hell of a good camera.

Click to expand...

Yes, because it is moving towards full frame. Don't get me wrong, I wouldn't like a 0.8x crop either. I just like my lens to work as they were intended. If people want to fool themselves they are getting more advantage from 1.6x (or 0.8x) then so be it.

Zero my hero

Exactly, but I prefer to put a longer lens on my camera to get the same FOV as you would from the same spot. That lens on my camera would be at a FOV which I am most familiar with since I started with film cameras and it is easily transferable to a full frame DSLR. Whereas you would have to do the calculation in your head. Now if you never started with film then this is all mute.

JGM said:

See this all depends on your point of view. I like the effect of
getting more perceived telephoto by cropping in the camera, so I
can shoot what I see and not have to mess around trying to crop in
software. It cuts down on my workflow. So I say I'd have to cut
down the 1Ds size to get the same effect.

Click to expand...

--
Zero my hero

John Mason said:

but Kjeld is exactly right

the center area of your D60 has 1.6 less resolution then the center
of a 1Ds.

Click to expand...

The resolution of the D60 is higher than the 1Ds.

D60: 2048 vertical pixels / 15.1mm sensor height = 135.6 pixels per mm

1Ds: 2704 vertical pixels / 23.8mm sensor height = 113.6 pixels per mm

However, the images from the 1Ds will require less enlargement and therefore seems to have a higher sensor resolution (not counting differences in the AA and other possible filters).

I suspect that printing an 8x10 from both cameras full frame would be undistinguishable (at least from the resolution point of view)????

tony

Thanks all for replying my original message. I believe the vast part of us have understood the optics mechanism by including a 1.6x factor.

Now, my point was mainly that on the D60, image quality is more homogeneous through the overall image than the 1Ds, 100% power resolutioin at the center of the image and 85-90% on the corners, meanwhile 1Ds users have 100% in the center and 50% on the corners, which is a significant difference. So in their case, cropping the corners may be very often necessarily. Although image resolution will be improved in the center.

This is what I was trying to point out. This is not a war between a 1Ds and a D60. We know the 1Ds will beat the D60 in all the conditions (Canon is not stupid).

Some of you have missed the initial point.

Oscar Latorre said:

Well,

I love to have a 1.6x factor on the D60 instead of a 1x of the 1Ds.
There is one big reason, besides my 300mm lenses are 480mm
automatically (that saves me money, weight, size...).

Did you ever have a look at the MTF charts of your lenses?. In the
corners, you will see that the resolution/definition drops
dramatically even to the 50% of the definition compared with the
center of the lenses.

Since the crop factor of the D60 is 1.6x and the MTF charts behave
very well at these new corners (they only drop 80-90% compared with
the center) I cannot see significant loss of quality in the edges
of my photographies. Besides, no vignetting can be seen, even with
wide-angle lenses (no need for slim filters).

So, not only the 1.6x is a drawback. I know some of you will
complain you cannot go below 24mm but... for my photography I think
it is quite useful to have a 1.6x.

What is your opinion?

--
"Say what you want! but my pictures will tell the truth!"
O.L.

Click to expand...

--
"Say what you want! but my pictures will tell the truth!"
O.L.

Oscar Latorre said:

Now, my point was mainly that on the D60, image quality is more
homogeneous through the overall image than the 1Ds, 100% power
resolutioin at the center of the image and 85-90% on the corners,
meanwhile 1Ds users have 100% in the center and 50% on the corners,
which is a significant difference. So in their case, cropping the
corners may be very often necessarily. Although image resolution
will be improved in the center.

Click to expand...

Hi Oscar

I do not want to reopen the "war" all over again, just reiterate what the anti-crop people has been trying to say:

That due to the 1.6x increased enlargement required of the 1.6x cropped image, it does NOT have 100% resolution in the centre and 85-90 in the corners (relative to the full frame image), but rather 100% / 1.6 = 63 % in the centre and 53-56 in the corners. So, the resolution is worse over most of the image, relative to the full frame sensor. And rarely do we have visually important objects in the corners anyway.

I quite agree that 1.6x crop do have an advantage if you are into small cameras and small lenses, but you started this discussion with a reference to MTF curves, indicating that your concern was about resolution.

--
Kjeld Olesen
http://www.acapixus.dk

Nah, not about resolution.Difference in resolution.

As you said 63%-56% on the D60, 100%-50% on the 1Ds. Isn't that visible on the final shot in big prints?

I mean, if I take a picture of the pattern of a wooden door (the sbuject is overall the picture), I probably will see very evidently the loss of definition at the corners of the picture, right?

Kjeld Olesen said:

Oscar Latorre said:

Now, my point was mainly that on the D60, image quality is more
homogeneous through the overall image than the 1Ds, 100% power
resolutioin at the center of the image and 85-90% on the corners,
meanwhile 1Ds users have 100% in the center and 50% on the corners,
which is a significant difference. So in their case, cropping the
corners may be very often necessarily. Although image resolution
will be improved in the center.

Click to expand...

Hi Oscar

I do not want to reopen the "war" all over again, just reiterate
what the anti-crop people has been trying to say:

That due to the 1.6x increased enlargement required of the 1.6x
cropped image, it does NOT have 100% resolution in the centre and
85-90 in the corners (relative to the full frame image), but rather
100% / 1.6 = 63 % in the centre and 53-56 in the corners. So, the
resolution is worse over most of the image, relative to the full
frame sensor. And rarely do we have visually important objects in
the corners anyway.

I quite agree that 1.6x crop do have an advantage if you are into
small cameras and small lenses, but you started this discussion
with a reference to MTF curves, indicating that your concern was
about resolution.

--
Kjeld Olesen
http://www.acapixus.dk

Click to expand...

--
"Say what you want! but my pictures will tell the truth!"
O.L.

Oscar Latorre said:

Nah, not about resolution.Difference in resolution.

As you said 63%-56% on the D60, 100%-50% on the 1Ds. Isn't that
visible on the final shot in big prints?

Click to expand...

Well, even though the full frame in THIS case may be lower in resolution at the corners than the 1.6x cropped image, it will still have more resolution over most of the image area wise.

And I just went along with your figures, but we might well and easilly have chosen another lens that has better MTF's at the corners. In fact, except for the wide angles, virtually all lenses that I recall have MTF curves that do not drop in the corners to less than 63% of what they have at the center. And with such a lens, ideal for shooting patterns on doors, the full frame imager should produce more detail than the 1.6x cropped image - from center to corner.

--
Kjeld Olesen
http://www.acapixus.dk

Oscar Latorre said:

Well,

I love to have a 1.6x factor on the D60 instead of a 1x of the 1Ds.

Click to expand...

Oscar Latorre said:

Did you ever have a look at the MTF charts of your lenses?. In the
corners, you will see that the resolution/definition drops
dramatically even to the 50% of the definition compared with the
center of the lenses.

Since the crop factor of the D60 is 1.6x and the MTF charts behave
very well at these new corners (they only drop 80-90% compared with
the center) I cannot see significant loss of quality in the edges
of my photographies. Besides, no vignetting can be seen, even with
wide-angle lenses (no need for slim filters).

So, not only the 1.6x is a drawback. I know some of you will
complain you cannot go below 24mm but... for my photography I think
it is quite useful to have a 1.6x.

What is your opinion?

Click to expand...

I totally agree with you. Corner performance of short focals is an issue.

Besides, if you buy a Sigma 14/2.8 EX like me, and have it replaced by Sigma with a perfect one due to bad alignment, you also get a useful high quality 21; although, as a 14 it's corner performance is unacceptable.

Check http://www.luminous-landscape.com for a comprehensive comparison with other lenses.

Maurizio.

You can't crop something that isn't there! You pay for 6MP when you buy a D60 and you get the use of them all. If that's enough pixels for the pictures you want then you are getting to use your 300 mm lens like a 480 mm lens at full frame, just like the original poster said. I don't understand the relevence of the fact that you could pay vastly more money for a 15.4MP sensor and crop it to down to the same thing the D60 gives you.

One thing I find interesting is that when a D60 user rails about his 20mm lens becoming a 32mm equivalent lens then no one jumps in and tells him he's talking nonsense but if he's happy about his 300 becoming a 480 he's bound to hear it.

What you're saying is true in regards to the sensor...but in regards to the lens it is indeed a crop. The lens is designed to deliver an image for 35mm film. By putting a smaller sensor back there, you are taking a crop of the image that the lens is designed to produce.

Gordon Berg said:

You can't crop something that isn't there! You pay for 6MP when
you buy a D60 and you get the use of them all. If that's enough
pixels for the pictures you want then you are getting to use your
300 mm lens like a 480 mm lens at full frame, just like the
original poster said. I don't understand the relevence of the fact
that you could pay vastly more money for a 15.4MP sensor and crop
it to down to the same thing the D60 gives you.

One thing I find interesting is that when a D60 user rails about
his 20mm lens becoming a 32mm equivalent lens then no one jumps in
and tells him he's talking nonsense but if he's happy about his 300
becoming a 480 he's bound to hear it.

Click to expand...

--
John
http://www.pbase.com/mankman
Canon EOS D60