The 1.5x crop discussion continued

Started Feb 24, 2008 | Discussions
jp Senior Member • Posts: 1,151
The 1.5x crop discussion continued

Those who are not interested in that thread should ignore it instead of trying to push it to its maximum number of messages.
I find this rather jevenile
Here is my response to beowulf
http://forums.dpreview.com/forums/read.asp?forum=1039&message=26921570

-- hide signature --

cameras don't shoot people
People shoot people.

Kim Letkeman
Kim Letkeman Forum Pro • Posts: 33,424
ok ... I'll play ... here's a reply to Austin Li ...

You (Austin) wrote to me in the other thread just before it died:

Please read the OP's title again here: "Explain how 1.5 crop brings things
closer please".

Exactly. It brings the subject effectively closer by effectively magnifying the image 1.5x ... all else being equal.

As far as the easy calculation about pixel density, cropping between D300
and D3, I am sure everyone can do that and draw their conclusion. But you
guys just mis-understood the OP's question.

Everyone else seems to get it. You are banging your drum incessantly without making any inroads. Try asking yourself why.

I was confused for a short time also asking myself that: the lens is the same
lens, how can a DX sensor bring things closer?

You remain confused ... the OP was wondering why people say things like that. And it is because a 300mm lense on the D300 acts just like a 450mm lense on a D3 where magnification is concerned. And that's really all that matters if the rest is basically the same (it's not ... but it is close enough.)

Now I urge you read the title again, do you still think your 1.5 crop can
bring things CLOSER,

I urge you to leave the drum alone ... banging it hurts everyone's ears by now.

or realize you mis-understood the original question?! Bottom line is: without
a longer lens or you have to move closer, how can you bring the subject
closer?!!!

Sheesh ... how about this: shoot a target from 100 feet with a 300mm lense on the D3, then again on the D300. Which one looks closer? And why does it matter what the OP calls this effect?

You guys just kept calculating the density and crop thing over and over again.
Everyone knows that easy calculation, we don't you to teach that BS.

Your confusion apparently arises from a pedantic need to be right about what he thought he might have meant when he said this one little thing ... even though everyone else knows what he really means when the crop factor gets discussed yet again and ad nauseam.

Who mentioned that I am an idiot? Read the title again and think again and
better re-title it, please!!!

Not me, but I have no reason to disagree ...

Such a simple question from the OP has just brought up so much irrelevant
pixel-counting. You guys are just so stubborn to claim your DX brings things
closer??!!

And yet many excellent wildlife photographers claim that it gives them more effective reach. "Bringing things closer" is a good euphemism for that, no?

 Kim Letkeman's gear list:Kim Letkeman's gear list
Nikon Coolpix 990 Fujifilm FinePix F770EXR Nikon D90 Nikon D600 Panasonic Lumix DMC-GX85 +15 more
Daniel Har Contributing Member • Posts: 637
I fail where the 'discussion' is getting

It's pretty simple. It's a 1.5x crop factor. Meaning that the sensor will only take part of the image that would be generated by the lens in the 35mm equivalent. Remember it's a CROP, not a ZOOM, not a MAGNIFICATION, nothing to do physically with the way the light comes in through the len, only how it's captured.

By the way, although it let's you get your subject bigger (same result than a crop in photoshop), that 300mm is the same 300mm lens in a FX or DX camera. Don't forget that the focal length doesn't vary, as the properties associated to them (like perspective...etc.).

Also, don't compare a FX sensor to a DX sensor, because a FX sensor is not just a bigger DX sensor, it has design differences and properties, you can't just strictly compare one to other.

Finally, a DX lens is just a lens that will not cover the full 35mm 'film' (in this case the FX sensor). So a 200mm lens still has a 200mm focal length, unless some marketing expert starts to say that a 135mm lens is a 200mm lens equiv on a DX, when the focal lengh is still 135mm.

Daniel
Daniel Senior Member • Posts: 1,034
Kim...

You remain confused ... the OP was wondering why people say things like that.
And it is because a 300mm lense on the D300 acts just like a 450mm lense on
a D3 where magnification is concerned. And that's really all that matters if the
rest is basically the same (it's not ... but it is close enough.)

Before you accuse others of being confused ad "beating the wrong drum" you should get your facts straight. When you write that "a 300mm lense on the D300 acts just like a 450mm lense on a D3 where magnification is concerned" you are just plain wrong. This is not a matter of opinion, and it is not something that is decided by majority rule. Magnification is a result of lens design; at a given focal length, a lens produces a given magnification, period. Again, this is not an opinion, but a fact. Brush up on your physics (and more particularly optics) and you will see that the confused party is you, not Austin.

Daniel

 Daniel's gear list:Daniel's gear list
Fujifilm X100S Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 28-300mm f/3.5-5.6G ED VR +1 more
Austin Li Contributing Member • Posts: 672
Re: ok ... I'll play ... here's a reply to Austin Li ...

Kim,

First of all, let's cool down a bit, and forget about D3. The OP's original question was to compare a DX image with a full sized one, which is not necessarily from D3. I paste his original text below.

"This is what i need explaining i don't know if I'm just being stupid or what but i thought that the crop just gave a smaller sixed picture or narrower field of view compaired to a full sized image, and that is does not actually bring the subject any closer."

My point is that a 200 mm lens can not resolve the same detail as a 300 mm lens does (we all know that provided the two lenses have the same build quality). So a 200 mm lens on a DX can not give you the same detail as what the 300 mm lens gives on a full frame camera (again, not necessarily D3, let's say a 35 mm film). Then I went on to say that even though the DX image from the 200 mm lens looks "like" as if from 300 mm lens, it actually does not have the same detail resolved compared with the image taken by a full frame camera with the 300 mm lens. Then I went on to conclude that yes, the image looks bigger, but it is an illusion.

The OP mentioned D300 and D3 as examples, but what I understand is that he was confused why the crop gives more reach than a full sized camera. Maybe my English is not good enough, but the term "reach" means how well the detail of the subject is resolved. If the DX detail from 200 mm is not as good as the FX one from 300 mm, even though the image is larger and has enough pixels, it is still meaningless. So again, the appeared reach is not real reach.

Now let's come back to digital, If the full frame camera has the same pixel density of a DX, do you still claim that DX gives more reach?

I don't think I have any more to say. Maybe I AM an idiot, but I hold my believe. I have to stop the discussion from my part and focus on my daily life.

Thanks for your reply, though. Happy shooting,

Austin

kevm14 Senior Member • Posts: 2,253
Not Kim, but...

Daniel wrote:

Before you accuse others of being confused ad "beating the wrong
drum" you should get your facts straight. When you write that "a
300mm lense on the D300 acts just like a 450mm lense on a D3 where
magnification is concerned" you are just plain wrong. This is not a
matter of opinion, and it is not something that is decided by
majority rule. Magnification is a result of lens design; at a given
focal length, a lens produces a given magnification, period. Again,
this is not an opinion, but a fact. Brush up on your physics (and
more particularly optics) and you will see that the confused party is
you, not Austin.

You're doing exactly what Kim accused Austin of doing. And that is pedantically getting hung up on terminology and not making any attempt to figure out what is really meant.

If you want to stand by the fact that "magnification" in its true sense can be changed only by the optics, then fine. What should we call it then? We could call it "subject being rendered by a greater number of pixels given the same exact lens" but that's sort of a mouthful, isn't it? When I say "subject" I mean the projected optical image, which is the same size if it came through the same lens, regardless of the sensor size. I'm sure we agree on that at least.

Anyway, if you render a subject with a greater number of pixels, and we aren't maxing out the lens, which we are not for just about any lens with the name Nikon on it, nor maxing out our sensor by making the pixels too small, which we are not, then at 100% view we have a physically larger subject. And given the previous declarations, we would have the ability to print larger at the same DPI. What are we supposed to call it again?

kevm14 Senior Member • Posts: 2,253
Re: I fail where the 'discussion' is getting

Daniel Har wrote:

By the way, although it let's you get your subject bigger (same
result than a crop in photoshop),

What now? Same as a crop? Yeah, in terms of angle of view it is. But cropping a D3 image to DX size is sure as hell not going to still be 12MP when you are done. The angle of view will be identical to DX, but you've now got a 5.2MP image.

Austin Li Contributing Member • Posts: 672
I just remembered an ad

A while back there was an ad saying: To see it is to believe it. Now I really believe this ad is so powerful!

It seems lots of people here believe DX sensor brings subject closer by just seeing the larger picture. They don't use their brain to think one basic fact: the focal length is still the same focal length, how can a camera sensor (just a recorder) bring something closer!

I bet if these people lived in the times of Columbus, when they were told that the earth was round instead of what they saw as flat, they would just laugh to death.

Sorry, but I don't want hurt anyone,

Austin

RAL Veteran Member • Posts: 6,377
Help fill me in, I'm lost in this one.

Are there folks around here that don't think that the DX sensor comparte to the FX sensor has a crop factor? Isn't it pretty well established that it has a 1.5 crop factor? What's to argue about. Doesn't that not say that the full image from a DX sensor with a 300mm lens has the same coverage as the full image from a FX sensor with a 450mm lens? We can certainly crop either image to whatever width we want later, but the original image coverage comparison of the full sensor with all its pixels stands as fact. What's to argue?

Mofongo Forum Pro • Posts: 14,863
Yes, seeing *is* believing...

Austin Li wrote:

It seems lots of people here believe DX sensor brings subject closer
by just seeing the larger picture. They don't use their brain to
think one basic fact: the focal length is still the same focal
length, how can a camera sensor (just a recorder) bring something
closer!

No one here believes that a DX sensor brings a subject closer. Why do you keep saying this over and over?

No lens, not even a 1200mm lens brings a subject closer. Only a rope, bait or sweet talking will do that...

We are now and have all along been talking about "effective" reach or field of view...

Bottom line is the subject "looks" larger and closer in the frame and this is all that matters...

Seeing is believing. Forget all the technical mumbo jumbo and all the semantics with terminology. Keep it simple as in what you see is what you get...

Shoot a lion from the same spot with a 300mm lens on both the D300 and D3...

Make an 8x12 (or any size print) of both...

In which print does the lion look larger and closer...

Yes, the D300 lion "appears" 1.5x closer...

End of discussion...

Bob

-- hide signature --

Photography is more about depth of feeling than depth of field
http://www.pbase.com/mofongo

Daniel
Daniel Senior Member • Posts: 1,034
Re: Not Kim, but...

And you're mixing apples and oranges. The concept "crop factor" has nothing to do at all with pixel count; people here are hung up on the pixel sizes of the D300 and D3 sensors. The 6 megapixel D40 had a crop factor of 1.5 as well, and a 5 megapixel DX sensor camera would have a crop factor of 1.5 also. This latter case is interesting because the pixel density would be the same as the one of the D3 sensor (which is why you get a five megapixel photo when you use the DX option on the D3). Needless to say, you're crop factor is still there, but where is your pixel advantage? Trying to explain the cropping factor and discussing the relative merits of using a particular lens on two very specific cameras is NOT the same thing.

What you're saying is, "don't read what I say, understand what I mean." That's not a rule by which to have a sensible discussion.

Daniel

 Daniel's gear list:Daniel's gear list
Fujifilm X100S Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 28-300mm f/3.5-5.6G ED VR +1 more
Daniel
Daniel Senior Member • Posts: 1,034
RAL...

Are there folks around here that don't think that the DX sensor comparte
to the FX sensor has a crop factor? Isn't it pretty well established that it
has a 1.5 crop factor? What's to argue about.

The argument is not about whether the cropping factor exists but about whether the cropping factor in itself results in greater magnification. Of course, the answer is no.

Doesn't that not say that the full image from a DX sensor with a 300mm lens
has the same coverage as the full image from a FX sensor with a 450mm lens?

"Coverage" is not the same as "magnification"! The angle of view certainly does change, but that is a different question altogether. Any lens has a given magnification at a specific focal length. If the image of an object it creates on a DX sensor is 6 mm tall, then it will be 6 mm tall on a FX sensor (but there will be more stuff around it on the FX sensor; that's why we can say that the DX format is a crop of the FX format).

By how many pixels those 6 millimeters are represented on the sensor is another story that has nothing to do with the cropping factor. For example, following your logic, you can argue that a D300 has more "reach" than a D40 because whatever your lens puts on the sensor is represented by a larger number of pixels and will, if rendered at a certain dpi, result in a larger image. It is the pixel density that provides the "reach" people are talking about here, not the cropping factor. There is no cropping factor when going from a D40 to a D300.

Daniel

 Daniel's gear list:Daniel's gear list
Fujifilm X100S Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 28-300mm f/3.5-5.6G ED VR +1 more
kevm14 Senior Member • Posts: 2,253
Re: Not Kim, but...

Daniel wrote:

And you're mixing apples and oranges. The concept "crop factor" has
nothing to do at all with pixel count; people here are hung up on the
pixel sizes of the D300 and D3 sensors.

Yes, and I posted this in the last thread. The discussion is supposed to be about the D300 vs the D3. Both are 12MP. Given the same MP count, the crop factor of 1.5 HAPPENS to also correspond to the additional detail captured with the same lens. It's circumstantial, and that's it. But it's real, and that was my point.

kevm14 Senior Member • Posts: 2,253
Re: RAL...

Daniel wrote:

For
example, following your logic, you can argue that a D300 has more
"reach" than a D40 because whatever your lens puts on the sensor is
represented by a larger number of pixels and will, if rendered at a
certain dpi, result in a larger image. It is the pixel density that
provides the "reach" people are talking about here, not the cropping
factor. There is no cropping factor when going from a D40 to a D300.

Yes, exactly.

Kim Letkeman
Kim Letkeman Forum Pro • Posts: 33,424
Re: Kim...

Daniel wrote:

You remain confused ... the OP was wondering why people say things like that.
And it is because a 300mm lense on the D300 acts just like a 450mm lense on
a D3 where magnification is concerned. And that's really all that matters if the
rest is basically the same (it's not ... but it is close enough.)

Before you accuse others of being confused ad "beating the wrong
drum" you should get your facts straight. When you write that "a
300mm lense on the D300 acts just like a 450mm lense on a D3 where
magnification is concerned" you are just plain wrong.

And again ... take the images on these specific cams with the same lense (all else being equal, remember?) and tell me that the FOV is not different by exactly the crop factor ... 1.5x. Which of course effectively magnifies the image ...

Play all the semantics you want, but this is the whole point of the discussion.

This is not a
matter of opinion, and it is not something that is decided by
majority rule. Magnification is a result of lens design; at a given
focal length, a lens produces a given magnification, period. Again,
this is not an opinion, but a fact. Brush up on your physics (and
more particularly optics) and you will see that the confused party is
you, not Austin.

Right ... like the people on the forum have not figured out that a 450 mm lense magnifies more than a 300mm lense. On the same sensor of course ...

Buthat is the FOV relationship when the two are mounted on the D3 and the D300? Try swapping a 300 and a 450 around between the D3 and the D300 ... this is what happens:

Combo 1: D300+300 & D3+450 ... same FOV ... subject same size in both 12mp images

Combo 2: D3+300 & D300+450 ... FOV is actually 675 equivalent ... D300 subject is 2.25x magnified over the D3 combo ...

See why the wildlife shooters like the cropped sensor?

 Kim Letkeman's gear list:Kim Letkeman's gear list
Nikon Coolpix 990 Fujifilm FinePix F770EXR Nikon D90 Nikon D600 Panasonic Lumix DMC-GX85 +15 more
Kerry Pierce
MOD Kerry Pierce Forum Pro • Posts: 19,757
arguing semantics

Daniel wrote:

The argument is not about whether the cropping factor exists but
about whether the cropping factor in itself results in greater
magnification. Of course, the answer is no.

When you have 2 photos and the subject in one is rendered larger than the other to the viewer, is it magnified or not?

If you view 2 photos, a DX 200mm shot and a FF 300mm shot, both shots will appear to be the same magnification. True or not?

If you say that that the DX shot isn't magnified, then what is it and why does one appear larger than or the same as, the FF shot, if it isn't magnified?
http://www.answers.com/magnified&r=67
http://en.wikipedia.org/wiki/Magnify

Doesn't that not say that the full image from a DX sensor with a 300mm lens
has the same coverage as the full image from a FX sensor with a 450mm lens?

"Coverage" is not the same as "magnification"! The angle of view
certainly does change, but that is a different question altogether.

It's not a different question. The end result is what you view.

For a FF camera to present a subject in an image that appears to be the same size as the subject is presented in a DX image, without cropping, the lens on the FF camera needs to be of a focal length 1.5x longer than the DX lens. True or not?

Any lens has a given magnification at a specific focal length.

The lens is not the entire package. The lens + sensor = image.

By how many pixels those 6 millimeters are represented on the sensor
is another story that has nothing to do with the cropping factor.

That is true.

example, following your logic, you can argue that a D300 has more
"reach" than a D40 because whatever your lens puts on the sensor is
represented by a larger number of pixels and will, if rendered at a
certain dpi, result in a larger image. It is the pixel density that
provides the "reach" people are talking about here, not the cropping
factor.

Crop factor becomes important when practical use comes into play, meaning the details that are captured for use in the image (pixel density), along with the cost, size, weight and portability of the entire system.

There is no practical advantage to a DX camera of 5mp compared to a FF 12mp camera, with respect to details captured, so there would be no need to buy longer lenses for FF. But, there is still a practical advantage to that 5mp DX camera, with respect to cost.

There is a significant practical advantage for crop factor, when comparing DX and FF cameras with similar MPs, such as the d300 and d3, because there is a significant difference in pixel density that is in favor of the d300. To make up for that significant difference in pixel density, you must buy lenses 1.5x longer for any given FOV. Of course, then the cost, size, weight, portability advantages also go to the d300.

If one wishes to project a future nikon FF camera with the same pixel density as the d300, it would be 27mp and it would then equal the d300 for details captured, with the same lens.

But, then you have to ask yourself, how would that 27mp body be more practical? You would still have pay a huge price premium. For example, the 21mp canon 1dsmkIII is $8k for the body alone and it gives you a DX crop of 10mp. Is it really more practical to buy an $8k body just to get an image that is almost the same for pixel density as the $2k d300? If you're shooting mainly telephoto, the answer would likely be no.

-- hide signature --

my gallery of so-so photos
http://www.pbase.com/kerrypierce/root

 Kerry Pierce's gear list:Kerry Pierce's gear list
Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF Nikkor 85mm f/1.4D Nikon AF Nikkor 105mm f/2D DC Nikon AF Nikkor 135mm f/2D DC +17 more
Daniel
Daniel Senior Member • Posts: 1,034
Re: Not Kim, but...

The discussion is supposed to be about the D300 vs the D3

Really? The title of the original thread is "Explain how 1.5 crop brings things closer please" and the original poster began by saying. "Hi All, I keep reading on the different forum's about how the crop factor of the DX format camera's gives people more reach with there lenses [...]"

How exactly does this make it a discussion about the D300 vs. the D3?

Daniel

 Daniel's gear list:Daniel's gear list
Fujifilm X100S Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 28-300mm f/3.5-5.6G ED VR +1 more
Kerry Pierce
MOD Kerry Pierce Forum Pro • Posts: 19,757
Re: Not Kim, but...

Daniel wrote:

The discussion is supposed to be about the D300 vs the D3

Really? The title of the original thread is "Explain how 1.5 crop
brings things closer please" and the original poster began by saying.
"Hi All, I keep reading on the different forum's about how the crop
factor of the DX format camera's gives people more reach with there
lenses [...]"

How exactly does this make it a discussion about the D300 vs. the D3?

You cut off a significant part of your quote of his first paragraph, Daniel, the part that specifically mentioned the d300 and d3.

"Hi All, I keep reading on the different forum's about how the crop factor of the DX format camera's gives people more reach with there lenses, one guy saying he bought the D300 instead of the D3 so he could get more reach for wildlife photography."

http://forums.dpreview.com/forums/read.asp?forum=1039&message=26845285

-- hide signature --

my gallery of so-so photos
http://www.pbase.com/kerrypierce/root

 Kerry Pierce's gear list:Kerry Pierce's gear list
Nikon AF-S Nikkor 70-200mm f/2.8G ED VR Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF Nikkor 85mm f/1.4D Nikon AF Nikkor 105mm f/2D DC Nikon AF Nikkor 135mm f/2D DC +17 more
Daniel
Daniel Senior Member • Posts: 1,034
Kerry...

When you have 2 photos and the subject in one is rendered larger
than the other to the viewer, is it magnified or not?

Magnification is the size of the image on the sensor; enlargement is what you then make of it, and the key difference is that magnification occurs while the photo is being taken while enlargement occurs afterwards. You can see, I'm sure, that I can print a 4.6 or an 8x10 from the same image file, and neither cropping factor nor pixel count is involved in the operation except that the quality goes down as the size increases. However, this discussion is about answering a question regarding the cropping factor.

If you view 2 photos, a DX 200mm shot and a FF 300mm shot, both shots
will appear to be the same magnification. True or not?

Not true. The size of the images ON THE SENSOR will be different because a 200 mm lens will never produce the same size image as a 300 mm lens. The sensor size is simply not an issue when it comes to the size a subject is rendered as by a lens. Now the size of the photo itself depends on many other issues, none of which have the slightest bearing on the cropping factor issue.

If you say that that the DX shot isn't magnified, then what is it and why does
one appear larger than or the same as, the FF shot, if it isn't magnified?

It appears larger because it occupies a larger portion of a smaller frame, and when that smaller frame is reproduced at the same size as the larger frame, there is more enlargement, and that is why the subject is bigger. If you transpose this whole problem to film (to get around the pixel count issue) and make contact prints, you will see that the subjects end up exactly the same size.

In addition, the pixel counts of the D3 and D300 are such that if you print the two images at the same dpi, the D300 photo will indeed be larger. The reason for that is the pixel count, not the cropping factor. The D300 simply has a higher pixel density than the D3, so that a subject of a given size will be represented by more pixels with the D300. As I just wrote in another post: you could argue that the D300 has more reach than the D40; a subject rendered at the same dpi will be larger simply because there are more pixels. Since there is no cropping factor between the D40 and the D300, do you not see that your entire line of argument, while not false, has nothing to do with the OP's original question which was about the cropping factor?

Daniel

 Daniel's gear list:Daniel's gear list
Fujifilm X100S Nikon D750 Nikon AF-S Nikkor 16-35mm F4G ED VR Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 28-300mm f/3.5-5.6G ED VR +1 more
eurycea Contributing Member • Posts: 525
kids fighting over candy

This is just a stupid semantic argument. Why do you people bother?
--
*************************************
insert ego pumping camera porn/gear-list here
*************************************

 eurycea's gear list:eurycea's gear list
Nikon D70 Nikon AF Nikkor 50mm f/1.8D Nikon AF-S Nikkor 70-300mm f/4.5-5.6G VR Nikon AF-S Micro-Nikkor 105mm f/2.8G IF-ED VR Nikon AF-S Teleconverter TC-14E II +4 more
Keyboard shortcuts:
FForum MMy threads