# Is a 300mm @21mp same as a 600mm@10mp?

Started Nov 14, 2008 | Discussions thread
So you don't know what zoom is...

LeonXTR wrote:

saynomore wrote:

On the whole, your implying that longer lenses are the best-quality
solution is right, but there's almost always money considerations.
focal-length limited. Anyway, we don't know about the OP. If he can
afford longer lenses, we'll agree that that's what he should get
(until he's focal-length limited, then higher density cameras would
be more relevant).

Pixel density does matter. Your calculations are not right because
they don't take density into account. I'm too lazy to confirm
Andrew's numbers above right now, but for example this you said:

Actually i am very much right
Leave the math to people who are not too "lazy",don't draw
conclusions without having basic knowledge of math or digital
technology.

I said I was too lazy to confirm Andrew's numbers, which take pixel density into account, not to confirm that your numbers are wrong, because you can tell that from a glance and that does not require to look up the pixel size/density of the sensors mentioned.

300mm on your 1DIII is equal to 300mmX1.3(cameras crop factor) this
means its like using a 390mm on a 1DsIII.

is wrong. Andrew's number is more like it. You should take pixel
density into account as well.

I did took pixel density into consideration,read my post,don't be
"lazy"(or not-smart)

You're just multiplying 300mm x 1.3 to get your 390mm number, where did you consider pixel density there? That combination you cited would not give you an equivalent image. The 390mm on a 1DsIII will give you one with more pixels on it.

It's also true that the 50D or 1DsIII
might give you "softer" pixels,

It will DEFINITELY give you a softer image

but that's due to the AA filter (the
L lenses in question are very much up to par with that kind of
density), and unless you got detailed empirical tests of that,

What of what I said is wrong there? If it does, it's because of the AA filter, not because of pixel density per se. Also, softer pixels does not mean a softer image always. And then there's also how you converted to jpeg or which RAW tool you used.

I
don't think it's right just dismissing density out of hand.
Higher-density cameras have been used by birders for years, some
preferring the 1.6 crops over even the 1D cameras.

Find me one,ONE professional (and by that i mean someone who makes
his living out of the pictures he shoots),that will prefer a 50d over
a 1DIII for ANY KIND OF PHOTOGRAPHY

Ask away in the 40D and 50D forums, where most birders hang out. Daniella is one that comes to mind, but there are others. Some even use the XXXD series.

i am assuming you mean if you crop the image from the 20mp cam will
it be the same as an image from 10mp with a higher zoom

[...]

Now if you put your lens on a 1DsIII and crop each side by 50%,thus
making a 10mp image it would give you 50% more zoom

[...]

So switching to a 1DsIII will give you 450mm(on 10mp crop) versus the
390mm you are getting now,plain speaking 60mm more,or 15.384% more
zoom.

You didn't really mean "zoom" did you?

What else would i meant?

Longer focal length. And also missed the words "equivalent to" (which is not the same as "would give you" or "be the same"). None of the lenses mentioned have anything to do with the word "zoom".

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Andy

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