Joining the full frame club

[Dogfish_magnet]

Back on the off-topic then.

How you can possibly suggest that magnification is a meaningless concept is beyond me. The sensor is bigger, the magnification is changed, and that is what is driving the whole debate and underpins everything.

That is what subsequently dictates field of view and focal length, the size and number of pixels, and everything else that goes with it.

So you are still wrong

I always thought a lens provided magnification not a sensor....

1:1 on FF sensor is the same as 1:1 on a crop sensor

 

[amtaylor]

Ok so speaking about the discussion that's been going between magnification and whatever, if it is so important to know this and this will effect you on levels beyond the comprehension of us mere mortals how come at least one is inaccurate, and thus will spend money incorrectly on equipment that you won't be able to use properly. And I must say that according to the poll there are more people that find it to be superfluous information than otherwise. Speaking of the polariser there was a contradiction, the angles that affect it are to do with HOW it works not why, so this is useful information that will help you produce better shots as opposed to why which is interesting but will probably not make any difference. And the same with full frame. How it is better or not is important and will make a difference to what you choose to purchase, how it handles noise, how the focal ranges appear different, how lens resolution is affected, all useful. Why this happens? Again, potentially interesting but not really going to help much. And on that point I will leave my argument.
Thank you and good night, well afternoon.

 

[HoppyUK]

I always thought a lens provided magnification not a sensor....

1:1 on FF sensor is the same as 1:1 on a crop sensor

Yes, and that's the whole point.

The reason you need a certain lens is to provide a certain field of view, which is another way of saying a certain level of magnification. That is dictated by the size of the sensor. Everything follows from that fundamental starting point.

BTW, the 1:1 thing isn't relevant to this as it is independent of sensor size, and is a function of both focal length and focusing distance.

I really don't think I've got anything more to say on this, or that anyone else wants to hear it. It's been done to death, but fun along the way

 

[trencheel303]

That is what subsequently dictates field of view and focal length, the size and number of pixels, and everything else that goes with it.

Focal length is dictated by the lens, aye?

In actual terms the magnification only changes because in order to frame the subject the photographer had to move closer for further back it doesn't just change by itself because the sensor size changes?

 

[Richard King]

Focal length is dictated by the lens, aye?

In actual terms the magnification only changes because in order to frame the subject the photographer had to move closer for further back it doesn't just change by itself because the sensor size changes?

This is correct. However it is comon (and misplaced) terminology to say that a cropped sensor magnifies. It stems from the fact that the image you see on a cropped sensor is "as if" you digitally zoomed a full framed image

This made things easier to understand way back when.. as it explined why images looked zoomed in compared to when they were being used on film cameras

 

[amtaylor]

only in terms of composition equipment and depth of field etc - i.e. the parts of photography that does make this knowledge relevant.

Knowing what a photon is is completely irrelevant to this skill - you don't even need to know that a photon is a word!

Is it anything to do with photon torpedoes? I think quantum torpedoes are superior but I don't know why......
Couldn't resist.

 

[Dogfish_magnet]

Yes, and that's the whole point.

The reason you need a certain lens is to provide a certain field of view, which is another way of saying a certain level of magnification. That is dictated by the size of the sensor. Everything follows from that fundamental starting point.

BTW, the 1:1 thing isn't relevant to this as it is independent of sensor size, and is a function of both focal length and focusing distance.

I really don't think I've got anything more to say on this, or that anyone else wants to hear it. It's been done to death, but fun along the way

I disagree

- i put a lens on FF camera and take a image of a object 1cm in size at 1 x magnification - that object is still 1cm when projected onto the sensor

i put the same lens on crop camera and take a image of a object 1cm in size and take a image at 1 x magnification - that object is still 1cm when projected onto the sensor.

- i put a lens on FF camera and take a image of a object 1cm in size at 2 x magnification - that object is now projected onto the sensor at 2cm

i put the same lens on crop camera and take a image of a object 1cm in size at 2 x magnification - that object is still 2 cm when projected onto the sensor.

there is No change to the size of the object on each sensor

 

[Richard King]

I disagree

- i put a lens on FF camera and take a image of a object 1cm in size at 1 x magnification - that object is still 1cm when projected onto the sensor

i put the same lens on crop camera and take a image of a object 1cm in size and take a image at 1 x magnification - that object is still 1cm when projected onto the sensor.

- i put a lens on FF camera and take a image of a object 1cm in size at 2 x magnification - that object is now projected onto the sensor at 0.5cm

i put the same lens on crop camera and take a image of a object 1cm in size at 2 x magnification - that object is still 0.5 cm when projected onto the sensor.

there is No change to the size of the object

yep - untill you dispay them all on the same sized screen / print - Which was the oversimplification i mentioned earlier - at which point, one lot of images "appear" magnified

 

[arad85]

OK, so if magnification is the right term, what's the magnification of a 100mm lens? (hint - it doesn't have one ).

The reason I'm having such trouble with this is that magnification IS a measurable and quantifiable thing.

In astronomy (an ex-hobby, sold everything to fund cameras ), a telescope is effectively a lens with an eyepiece attached (which is a lens in itself). The magnification of a telescope is focal length of telescope/focal length of eyepiece (a 1000mm fl telescope with a 10mm eyepiece gives a 100x view). When you put a camera body in place of the eyepiece (and this is what you have with an SLR and lens - the telescope is just a big lens), magnification is now a meaningless term as the things that dictate what you can see are the sensor area (which gives you the angular field of view) and the pixel size (which gives you the resolution).

 

[woof woof]

It's a times like this I turn to drink.

 

[Cistron]

I disagree

- i put a lens on FF camera and take a image of a object 1cm in size at 1 x magnification - that object is still 1cm when projected onto the sensor

i put the same lens on crop camera and take a image of a object 1cm in size and take a image at 1 x magnification - that object is still 1cm when projected onto the sensor.

- i put a lens on FF camera and take a image of a object 1cm in size at 2 x magnification - that object is now projected onto the sensor at 2cm

i put the same lens on crop camera and take a image of a object 1cm in size at 2 x magnification - that object is still 2 cm when projected onto the sensor.

there is No change to the size of the object on each sensor

Amen.

I bet that a photograph captured with a 7D at a defined distance and an image taken with a 5D from the same spot with the same lens, but cropped by the factor 1.6, will look almost identical.

 

[trencheel303]

it would. Even the perspective wouldn't change because in essence nothing has changed except the crop factor, the amount of the scene being captured behind the lens.

 

[arad85]

it would. Even the perspective wouldn't change because in essence nothing has changed except the crop factor, the amount of the scene being captured behind the lens.

No, the pixel size (and hence noise) would be changed. The 5D2 should look better cropped (assuming the pixel size isn't limiting the image) - at least that's what the physics tells you. Personally, I haven't done the test....

 

[trencheel303]

yes but the picture will look the same. the object would be the same size in relative terms, the perspective would be the same, the DOF would be the same... lets forget about noise and cropping and pixels for just a moment...

 

[arad85]

lets forget about noise and cropping and pixels for just a moment...

And if you put the same lens on a webcam, it would be the same - just a different crop.

But you can't forget about these things. Noise is one of the reasons I chose the 5Dmk2.... and is one of the contributing factors as to why the 5Dm2 is "better" than the 7D.

If we did ignore those things then all cameras would be equal wouldn't they?

 

[Richard King]

Magnification for cameras

Optical magnification = distance from lens to image / distance from lens to object

M=Di/Do

Magnification for telescopes (simple)
Angular magnification = focal length of objective / focal length of eyepiece

AM=f(o)/f(e) - this is a little crude, and knowing the size of the telescopes entrance and exit pupils is the real measure - as this gives true angular magnification

 

[Cistron]

And if you put the same lens on a webcam, it would be the same - just a different crop.

But you can't forget about these things. Noise is one of the reasons I chose the 5Dmk2.... and is one of the contributing factors as to why the 5Dm2 is "better" than the 7D.

If we did ignore those things then all cameras would be equal wouldn't they?

I think we're both actually arguing for a 36x24mm sensor. Going one step further, I'd love to have a medium format camera. Just nobody produces a model I can afford, with a humble 12 million photosites and thus irresistable ISO capabilities.

 

[Richard King]

I think we're both actually arguing for a 36x24mm sensor. Going one step further, I'd love to have a medium format camera. Just nobody produces a model I can afford, with a humble 12 million photosites and thus irresistable ISO capabilities.

i said that a few days ago - lol

 

[arad85]

I think we're both actually arguing for a 36x24mm sensor.

Yup. no question about that... All this is about is just trying to summarise why a 26x24 sensor is better

 

[Richard King]

Yup. no question about that... All this is about is just trying to summarise why a 26x24 sensor is better

I'm seriously considering either saving up for and investing in a d3(whatever) or a MF + back (or hassy)

 

[arad85]

Magnification for cameras

Optical magnification = distance from lens to image / distance from lens to object

Thanks for that. Where is the reference point for the distance from lens to image? (serious question as I'd like to understand more)

 

[Richard King]

Thanks for that. Where is the reference point for the distance from lens to image? (serious question as I'd like to understand more)

It's at the first nodal point of the lens. If the lens is focussed at infinity, it will be the at the focal length of the lens

e.g. 85mm from the sensor for a 85mm lens, if you are focused closer than infinity, it will be slightly further than 85mm away fromn the sensor

(how neat is that)

when you focus the lens, the element moves, so the distance will change slightly

 

[HoppyUK]

OK, so if magnification is the right term, what's the magnification of a 100mm lens? (hint - it doesn't have one ).

The reason I'm having such trouble with this is that magnification IS a measurable and quantifiable thing.

In astronomy (an ex-hobby, sold everything to fund cameras ), a telescope is effectively a lens with an eyepiece attached (which is a lens in itself). The magnification of a telescope is focal length of telescope/focal length of eyepiece (a 1000mm fl telescope with a 10mm eyepiece gives a 100x view). When you put a camera body in place of the eyepiece (and this is what you have with an SLR and lens - the telescope is just a big lens), magnification is now a meaningless term as the things that dictate what you can see are the sensor area (which gives you the angular field of view) and the pixel size (which gives you the resolution).

These debates quite often revolve around the lens - and a lens is a lens, focal length is focal length etc. Which of course it is, but the lens is secondary and we change it all the time. You can put a magnification value on it, but only when a subject of a certain size and distance is focused, and that of course varies. 'Magnification' simply means a change of size - you can't put a single number on it here, and there's no reason to.

What we are taking about is the practical aspect of actually taking photographs (nothing to do with telescopes). The starting point for that is always the camera, which for very good reasons has been selected for the purpose and is not a variable part of the process. We then choose a shooting position after moving forward/back up/down (if we can) to optimise the view and perspective. And then we select the focal length to frame the image as we want it.

In other words, we change the magnification of the lens to fit the sensor and deliver the field of view we want. The term 'magnification' can be applied to various things here - focal length, field of view, subject distance, format size, whatever.

But the fact remains that when you take a photograph the size of the sensor is fixed and everything else is changed to suit that change of magnification. It was always thus, and always will be.

 

[arad85]

It's at the first nodal point of the lens. If the lens is focussed at infinity, it will be the at the focal length of the lens

e.g. 85mm from the sensor for a 85mm lens, if you are focused closer than infinity, it will be slightly further than 85mm away fromn the sensor

(how neat is that)

when you focus the lens, the element moves, so the distance will change slightly

Thanks for that (although a quick google reveals it isn't quite as simple - are things ever )

 

[HoppyUK]

It's at the first nodal point of the lens. If the lens is focussed at infinity, it will be the at the focal length of the lens

e.g. 85mm from the sensor for a 85mm lens, if you are focused closer than infinity, it will be slightly further than 85mm away fromn the sensor

(how neat is that)

when you focus the lens, the element moves, so the distance will change slightly

Focal length is measured from the rear nodal point, focused at infinity.

 

[joescrivens]

i think I might cry

 

[Richard King]

Thanks for that (although a quick google reveals it isn't quite as simple - are things ever )

you are right, but it is a good starting point

there is an equation for it, but you need to know focal lenght of lens, distance to subject. in reality the distance to the first nodal point of the lens doesnt move that much as you focus. There is another shcool of thought that says you measure from the last element in the lens (that moves), and yet another form the "middle of the lens" and yet another from the apeture of the lens

Blunt reality - you cant put a real ruler on any of these in practice, although the manufacturer could indicate where the apeture was exactly

 

[Richard King]

i think I might cry

dont - it explains why when you buy a "click in" M42 mount for a Nikon, if it doesnt recess the lens back or have a correction lens, or both, you have bad focussing issues

 

[arad85]

In other words, we change the magnification of the lens to fit the sensor and deliver the field of view we want. The term 'magnification' can be applied to various things here - focal length, field of view, subject distance, format size, whatever.

But the fact remains that when you take a photograph the size of the sensor is fixed and everything else is changed to suit that change of magnification. It was always thus, and always will be.

And this is where I have the problem. Magnification is just multiplying something by a value. Moving the camera, altering the perspective etc.. is NOT magnification, by definition.

 

[arad85]

i think I might cry

It always amazes me there's always someone who claims not to be interested, yet still follows the thread 100 posts in

 

[HoppyUK]

i think I might cry

I'm gonna join you.

 

[joescrivens]

It always amazes me there's always someone who claims not to be interested, yet still follows the thread 100 posts in

you're amazed? you should see how amazed I am , although I am actually just skim reading these posts hoping for a time when we get back to the chat I like

 

[arad85]

you're amazed? you should see how amazed I am , although I am actually just skim reading these posts hoping for a time when we get back to the chat I like

Did I say that I really like the test shots I took on my 5Dmk2 before I broke it? :bonk:

 

[Richard King]

deleted

 

[chris321]

Good Lord guys what happened to this thread


On another note, when I get my 5D, should I put a UV filter on my lens? Please discuss...

*Goes off to PM Arkady*






I'll have another go at reading the 3 pages that appeared since I last checked this thread when my eyes stop bleeding

Chris

 

[AndyWest]

Can someone point me to image examples from the 5D Mk2 with 24-105 f4L lens please

 

[jockwav]

I got my 5D MK1 a few weeks ago,just love it to bits.

 

[joescrivens]

Good Lord guys what happened to this thread


On another note, when I get my 5D, should I put a UV filter on my lens? Please discuss...

*Goes off to PM Arkady*






I'll have another go at reading the 3 pages that appeared since I last checked this thread when my eyes stop bleeding

Chris

my advice is don't, because when your eyes stop bleeding, your brain will start!

 

[dod]

i think I might cry

we agree about something

 

[arad85]

my advice is don't, because when your eyes stop bleeding, your brain will start!

Ahh... if we can kick-start your brain - then we have a result