[Recovered Thread: 85008]

[tmoreau]

Bigger... different effect.... collecting fainter light... yeah, I'm SOLD! Its too bad your giving up, I'm quite perplexed by this, uh, emotional description and I'd like to hear the science behind it.

[JimC]

The bottom line is that you need to take each sensor/lens combination on a case by case basis to see what it's capable of resolving, with the way the image is being processed also coming into the equation.

But, with current technology used in DSLR models, a shorter focal length lens for a given angle of view with an APS-C sensor can resolve just as much detail as a longer focal length lens on a 35mm film size sensor, if the resolution of the sensor (how many photosites it has) is equivalent.

Will we reach a point where the sensors are outresolving the lenses? Sure we will, just like we have larger format film when that happens.

But, for all practical purposes, a DSLR model using an APS-C sensor with a 100mm lens will resolve just as much detail as a DSLR model with a 35mm film size sensor using a 150mm lens, if the resolution of the sensors is the same (number of photostites in the sensor), with equivalent light gathering ability (aperture, as rated in f/stop), for the amount of light the sensor receives, as long as you're using lenses of equivalent quality (good lenses can outresolve the sensors).

[DBB]

BillDrew wrote:

DBB wrote:

I don't understand that at all. Shooting should depend on filling the sensor/film with the subject and desired surrounds. If several cameras, say 8x10" view camera, dSLR with an APS sized sensor, film SLR, ... are set in the same possition and have lenses that cover the same subject, there will be no difference in the photos (resolution, lens quality, ... aside). So it make sense to say that a 12" lens on the view camera is equivalent to a 43mm lens on the SLR and equivalent to a 28mm lens on the dSLR. So it would be very reasonable to say that the 28mm lens is equivalent to a 12 inch lens - except that very few people would have any idea what you are talking about.

That is the whole point of quoting 35mm equiv focal lengths - lots of people have a feel for what that means.

tmoreau gave as good an explanation as I have seen.

Here is an example to prove my point. Let us say we are shooting with a crop factor of 200 and a true magnification of 200, and we look at the planet Mars.

In case a, we will have a very smooth, very clear, orange dot. With the true magnification we will be seeing the planet Mars.

Capiche?

I don't want to put down the cropping factor. It is useful, because with digital it allows more pixels on the target. But more pixels on the target does NOT equal the true resolving power of magnification.

I tell you this with some actual experience, having shot with a 500mm on a 1.5 croping factor and 850mm on a Canon Mark II 1Ds.

Details, details, details... :G

Dave

[JimC]

DBB wrote:

I tell you this with some actual experience, having shot with a 500mm on a 1.5 croping factor and 850mm on a Canon Mark II 1Ds.

That's because the sensor in the Canon 1Ds Mark II has more photosites. It's a 16MP Sensor. ;-)

If you're comparing sensors with the same number of photosites, I doubt you'd see any difference at all, if the camera's image processing was equivalent, and the lenses used were of equivalent quality.

Now, if you tried to stuff 16 Million Photosites into an APS-C size sensor, you may or may not have a problem with lens limitations (not being able to resolve enough detail for the sensor).

But, with current models, that's not the case yet with good quality lenses, if you're comparing models with the same resolution sensor.

[BillDrew]

DBB wrote:

gave as good an explanation as I have seen.


Here is an example to prove my point. Let us say we are shooting with a crop factor of 200 and a true magnification of 200, and we look at the planet Mars.

In case a, we will have a very smooth, very clear, orange dot. With the true magnification we will be seeing the planet Mars. ...

Not true unless you are refering to the limitations of the film/sensor, neither of which is relavant to this discussion.

DBB wrote:

... I don't want to put down the cropping factor. It is useful, because with digital it allows more pixels on the target. But more pixels on the target does NOT equal the true resolving power of magnification.

I tell you this with some actual experience, having shot with a 500mm on a 1.5 croping factor and 850mm on a Canon Mark II 1Ds.

Details, details, details... :G

Dave

I'd make a bet that the lens on the Canon was better quality and/or the basic sensor in the Canon was better and/or various settings (sharpness, contrast, ...) had better values in the Canon. You are right: details do matter.

[YunusEmre]

I've been reading this thread because I am going to buy a 30D. I've a pretty good understanding of physics of light (in fact it is one of my favorite topics, always been fascinated by the properties of light and the fact that we cannot explain how it both behaves like a wave and particle). But I still do not know if my 30D will give me real magnification or it will appear to give magnification.

Most physicists performed simple experiments to prove something. So can somebody here who has both an FF and a 1.6x crop camera (or whatever you want to call it) perform an experiment and tell us (or show) the results?

1) shoot a stationary object from the same tripod with
a) FF camera with a 300mm lens
b) 1.6x crop camera with a 300mm lens

2) compare the results, does the picture from 1b show the object larger than the picture 1a?

Note: let us ignore the resolution, so if the cameras used have different MP ratings that should be OK. I am interested in the 'magnification' factor. Does it, or does it not magnify?

Is this an experiment that would be useful? What do you guys think?

[DBB]

JimC wrote:

DBB wrote:

That's because the sensor in the Canon 1Ds Mark II has more photosites. It's a 16MP Sensor. ;-)

If you're comparing sensors with the same number of photosites, I doubt you'd see any difference at all, if the camera's image processing was equivalent, and the lenses used were of equivalent quality.

Now, if you tried to stuff 16 Million Photosites into an APS-C size sensor, you may or may not have a problem with lens limitations (not being able to resolve enough detail for the sensor).

But, with current models, that's not the case yet with good quality lenses, if you're comparing models with the same resolution sensor.

Actaully the Nikon D2x puts MORE pixels on the target than the Mark II 1Ds...:G

Does it not?

If you can't SEE tjhe details, no sensor will be able to resolve them.

Dave

[YunusEmre]

BTW I have seen a few examples like this one:

http://bobatkins.photo.net/photograp...5d_or_20d.html

and I thought I understood the issue. But having read this thread, it is all very fuzzy.

[YunusEmre]

Here is another one that explains this in good detail:

http://www.the-digital-picture.com/C...op-Factor.aspx

[JimC]

DBB wrote:

Actaully the Nikon D2x puts MORE pixels on the target than the Mark II 1Ds...:G

Does it not?

If you can't SEE tjhe details, no sensor will be able to resolve them.

Dave

Actually, no. The D2x is 12 Megapixels versus the 16MP sensor in the Canon.

But, if you used the same lens on both cameras, you'd get more apparent magnification with the D2x (but the Canon would have a higher resolution sensor to help make up the difference). Can you reach a point where sensor can resolve more than a lens? Sure.

I applaud Canon for keeping the new EOS-30D at 8 Megapixels. That helps to keep noise down, and helps insure that you don't have a problem with the sensor outresolving the lens.

But, if you test a model like the D2x, it still outresolves an 8MP model like the EOS-20D on resolution chart tests (so with better quality lenses, we haven't reached that point yet).