Lens Mathmatics for dummies

Louis_Dobson said:

it can't use the whole "A" (aperture at the front element). It isn't
so much the 200 can't be f3.5, as the 50 can't be f1.8 (or whatever).
But that's still the principle of why the f numner rises with the
focal length, and I still don't understand why constant aperture
zooms aren't wasting light...

In passing, I assume the fact that at the short lengths zooms can't
use the whole front element is why most zooms soften at the long end.

But someone who understands optics properly needs to explain all this
stuff.
--
http://www.flickr.com/photos/acam

Click to expand...

Did a bit of Googling and found this comment at http://photography-on-the.net/forum/archive/index.php/t-236668.html

"I believe that if you examine a constant-aperture zoom lens closely you will find that the iris actually opens up as the lens is zoomed toward a longer focal length. I've examined mine and that's what I found."

The pudding proof, look into the lens and see what happens.

The other comments that surface here and there say that if the full possible aperture was used at the short end of say a 70-200/2.8 then the short end aperture would be maybe f/1.0 and lead to terrible aberrations.

Anyway, not a problem for me as I can't afford constant aperture zooms.

Regards.......... Guy

S N G said:

A lens is a lens - that is an interesting argument.

Click to expand...

Better than interesting. It's a correct argument. An Olympus 35mm lens doesn't become a 70mm lens because it's on an Olympus. In effect, photos taken with it will have an appearance similar to photos taken on a 5D at 35mm that have been cropped. Of course, there DOF increases because of the difference in the Circle of Confusion, but it doesn't magically change the focal length of the lens.

FWIW, the reason Olympus tells people what the field of view would be similar to on a 35mm camera is because a lot of people don't understand the effect of a smaller sensor on lens coverage who do actually understand what lenses are used for what purposes on their old 35mm rigs. And you'll notice that Olympus doesn't have anything in any of their literature telling you that F/2 is really like f/4. My light meter still seems to work properly when metering for f/2 with my 150mm f/2 attached to my E-3. ;-)

Gidday Simon

simpy said:

John King said:

If "equivalence" as espoused by your mate, Joseph James (joe mama)
were correct, no light meter would work, and no exposure could ever
be calculated.

Click to expand...

You are not really getting what equivalence means, do you? It means
that a 50mm f/2 on 4/3 gives similar images to a 100mm f/4 on full
frame assuming that you bump the ISO two stops. Exposure works fine
that way.

Click to expand...

I do "get it", it is just not correct, as espoused. Jens got it exactly right (as did Louis, to a somewhat lesser degree) up-thread. While f4 on "FF" gives the same (similar) DoF as f2 on 4/3rds, and somewhere in between for which ever APS sensor size one chooses, as they are highly variable (Nikon being a "small" APS sensor, and Canon being (mostly, but not always!) a "large" APS sensor, f2 using a 4/3rds lens is still f2. It is therefore two stops faster than said f4 lens on a "FF" sensor, regardless of the DoF.

Since f2 on the 4/3rds sensor has just as shallow a DoF as f4 on "FF" or somewhat less than f2.8 on a Nikon APS sensor, what Sergey keeps shouting to the world at large is just nonsense. Also, since f4/f2.8 respectively on those sensors is practically unusable due to CA, blur and vignetting, whereas all Olympus lenses are usable wide open (maybe not at their best with some lenses, but still usable ... ), the argument is fatuous at best and simply wrong as well.

Simon, I just get heartily sick of this being said over and over again.

It seems to me to be like a "security blanket" that the people who keep stating this cling to like a drowning man (sorry to mix my metaphors ... a lot!).

By stating it they imply (continually) that Olympus' (or anyone else's ... ) f2 lens is "really' only the same speed as an f4 lens, when this is patently not the case. The apparent ( very - apparent) motive for this is to disparage and belittle the very fast, very high quality lenses available for 4/3rds.

The other side of this same coin is that edge-to-edge and corner-to-corner sharpness is unnecessary because (........... {insert any one of half a dozen spurious 'arguments'}). Ditto with the horrible CA and vignetting almost always seen in the "FF" lens offerings, and also quite often in the 3:2 APS sensor lenses.

simpy said:

simpy said:

Get an ultra-basic book on exposure, Sergey - AND read it ...

Click to expand...

And please read the arguments of other posters.

Click to expand...

I do. Tend to read every word. I should just skip over the posts espousing this sort of nonsense; but I realise that others may be deterred from buying an excellent system because of that nonsense. This appears to be the raison de etre of the trolls and bashers here. To investigate their motives further, while interesting psychologically, is fruitless and pointless ... maybe they need to discuss these things with some caring professional.

I personally do not care what camera someone chooses to buy, as long as it suits their** needs pretty well. When friends ask me for advice, that is the first question I ask them - what do they want to use it for? My recommendation is then based solely on that; not on which camera of a particular brand they should buy, but which camera of any brand actually suits their requirements. Having done this sort of specification of equipment (generally) since around 1975, I have a fairly good grasp of how their need can be filled, to what extent, within the price they are prepared to pay ...

simpy said:

simpy said:

Ray, f2 is always f2. "Equivalence" is just b/s spruiked by the c/n
trolls to try to suggest that somehow an Olympus f2 lens is slow,
just like a c/n f4 lens is ...

Click to expand...

It's a bit cheap to play the troll card, don't you think? I'm an
Olympus user myself, and know a fair bit about physics and
mathematics and it's all pretty obvious if you juggle the equations -
and keep an open mind.

Click to expand...

Not really. Sergey is an outrageous troll, and has been banned for that reason a number of times, under a number of pseudonyms. So have a number of others, who appear "by magic" on this kind of thread. It is always the same dreary argument, based on the same misconceptions that they raise every single time.

I addressed exactly the same issue with Sergey here:

http://forums.dpreview.com/forums/read.asp?forum=1022&message=28423082

And yet here he is, back again with the same rubbish ... ad infinitum, ad nauseam ...

That is why I "come on strong", Simon. Sergey is wrong, and knows it, but keeps on espousing this nonsense for the abovementioned reasons, or to bolster his own fragile self-esteem, and self-assurance because he has "jumped ship" from Olympus to Nikon (that's fine by me, BTW; even if it were anything whatsoever to do with me, which it is not ... ).

Regards, john from Melbourne, Australia.
-----

The Camera doth not make the Man (or Woman) ...
Perhaps being kind to cats, dogs & children does ...

http://canopuscomputing.com.au/gallery2/main.php



Bird Control Officers on active service.

Welcome to DPR, your profile shows you joint the DPR 5 days ago.

Since I have not read all the response / post in this thread, it is possible that someone already suggested using Google - - and search for Lens DOF.

You will, in my opinion find practically all everything you want to learn on lens DOF.

But on the practical side, the view screen of your digital camera can show the DOF. Why not simply use it?
--
ecube

Gidday Sergey

S N G said:

No, this the only advantage for you . I could bring you few more
points for both sides, but then it would be for me , and pretty much
outside the scope of this discussion.

• sergey

Click to expand...

Just BTW, Sergey, you shoot a Nikon D300 with a sensor size that is on the small side of APS sensor sizes at 23.6x15.8. Of course, this is not the actual imaging area, which all manufacturers tend to be a bit coy about; but since the camera gives a 1.6x crop factor, one can work out that the imaging area is actually 22.5 x 15. This is a lot smaller than the biggest Canon APS-C sized sensors, which go up to 28.7 x 19.1 mm, or physically 47% bigger area than your D300 ... Or about the same amount bigger than the D300 sensor as the D300 sensor is bigger than the 4/3rds sensor ... . How come no one here ever seems to "notice" that interesting fact?

The so-called "APS" sensors are very variable in size from 28.7 x 19.1 mm down to the Foveon. One of Sony's APS sensors measures just 21.5 x 14.4 mm, or an area just 27% larger in area than the 4/3rds sensor. I would suggest that for the classification to have any meaning at all, it really needs to include all the mid-sized sensors, including 4/3rds. This would also have the very nice side-effect of disposing of these silly arguments ...

According to Nikon, Nikon APS sensors have a 1.6 crop factor (BUT, the same physical dimensions as the D300 sensor, apparently).

This means that to get the same DoF on a 1.6x crop factor sensor to that obtainable with an f2 lens on a 4/3rds sensor, one needs to have the lens open to f2.5, not f2.8 or f4. At these latter f-stops, the 1.6x crop factor sensor camera will give a greater DoF than the 4/3rds camera at f2. More or less ... as said before, manufacturers tend to be "coy" about the actual imaging area size, and Olympus is not the exception to the rule ...

However, so much for that bit of your 'argument', as well ...

Regards, john from Melbourne, Australia.
-----

The Camera doth not make the Man (or Woman) ...
Perhaps being kind to cats, dogs & children does ...

http://canopuscomputing.com.au/gallery2/main.php



Bird Control Officers on active service.

f/2 means that ration between FL and effective diameter is 2. f/2, for any lens or sensor format, means that exposure is the same for same shutter speed.

If sensor is large, total light reaching is of course more, but average lumens per area is same, so exposure will be exactly same.

That's the whole story, simple and clear.

Regarding DoF, yes, it's different, same f/number will give different DoF once you enlarge images from each sensor to same size (which is the only way to compare DoF, the standard is 8x10" seen at 2 ft distance), if lenses give same FoV. In case of 4:3, one need a lens half the FL of a lens used with 135 film format for simiilar FoV.

That's also the whole story.

Regards.

Juergen Hahn said:

Juergen Hahn said:

You talk about 'the two stop advantage' as if it is some
experimentally determined number. However, the number comes from the
fact that the amount of light that is available to the sensor scales
with the sensor area. A full frame sensor collects four times as much
light for any given f-stop and exposure time.

Click to expand...

Do you have a source to back this up? I highly doubt that this is
correct. Just because the sensor is 4 times as big does not mean that
it receives 4 times the amount of light, as the amount of light that
reaches the sensor is restricted prior to reaching the sensor.

Also, how do you explain this statement:
"Another important result is that if depth of field is the limiting
factor, the required exposure time increases with sensor size for the
same sensitivity." followed by
"On the other hand, exposure times may not necessarily increase as
much as one might initially assume because larger sensors generally
have lower noise (and can thus afford to use a higher sensitivity ISO
setting while maintaining similar perceived noise)."
from
http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

What this means is that for light gathering capability f2 is f2,
regardless of what system you look at. So you are going to have to
compare f2 at 100 ISO with f4 at 400 ISO when it comes to light
gathering capability.

What it comes down to is that
f2, 35-100mm, ISO 100 on 4/3 is equivalent to
f4, 70-200mm, ISO 400 on FF.
Obviously, ISO 400 on FF is better than ISO 400 on 4/3 (for similar
number of MP on the sensor) as the detectors can be a lot bigger.

I am not trying to point out advantages/limitations of different
systems here, however, let's just make a fair comparison.

Click to expand...

--
Regards, Renato.
http://www.flickr.com/photos/11435304@N04
OnExposure member
http://www.onexposure.net/

simpy said:

A full frame sensor collects four times as much
light for any given f-stop and exposure time. If it and a 4/3 sensor
are equally efficient, the larger sensor has a two stop advantage -
or, in other words, you can multiply the f-number by two to get the
same amount of light on the sensor.

Click to expand...

Just for the people who reads here:

In any case and for any sensor for given ISO and aperture the light wich passes through the lens and affects a unit area of sensor is exactly the same. The TOTAL light wich collect the big sensor is 4x (35mm sensor vs 4/3 sensor) and it has the same importance as that the whole earth collects billion of billion times a more light than a single face under the sun wich will be "burned" in the same way as any other.

I mean that for someone with elementary knowledge of physics ( and yes, if you want to discuss about technology of DP you need it) it is obvious that as at any other case we count "amount/unit"

rhlpetrus said:

If sensor is large, total light reaching is of course more, but
average lumens per area is same, so exposure will be exactly same.

That's the whole story, simple and clear.

Click to expand...

Yes, but you are missing the point here. It is the same if you use f2 in both cases. It is not the same if you use f2 on 4/3 and f4 on FF. In that case f2 at ISO 100 on 4/3 will give you the same as f4 at ISO 400 on FF.

That is my point, whereas the poster I was responding to argued that you could get away with ISO 100 on FF at f4 because the sensor is 4 times larger.

rhlpetrus said:

f/2 means that ration between FL and effective diameter is 2. f/2,
for any lens or sensor format, means that exposure is the same for
same shutter speed.

If sensor is large, total light reaching is of course more, but
average lumens per area is same, so exposure will be exactly same.

That's the whole story, simple and clear.

Regarding DoF, yes, it's different, same f/number will give different
DoF once you enlarge images from each sensor to same size (which is
the only way to compare DoF, the standard is 8x10" seen at 2 ft
distance), if lenses give same FoV. In case of 4:3, one need a lens
half the FL of a lens used with 135 film format for simiilar FoV.

That's also the whole story.

Click to expand...

yes i agree
and more on this

meter the scene and an exposure can be calculated making a hypothetical F2 1/60th sec iso100. That is the same on any format .
Exposure of a metered scene doesnt change,
the FOV (field of view) for lenses changes,
and the DoF (depth of field) changes.
But

on Dof, you can and probably would, alter the shooting position relative to the subject. Since the FOV has changed anyway, you would probably need to move in closer to obtain the same portrait. OR change the lens to one half the FL (focal length) of FF (full frame 135) which would return you to the same shooting position.

• a lens of the same FL as FF has less DoF than FF
• a lens half the FL of FF has 2 stops deeper DoF

equivalence is theory, and theory doesnt always work out b/se of individual lens charactristics and the provinces of exposure latitude to individual cameras.

hence making a God out of theory that doesnt always work out is nonsense
you would do better to establish the criteria you need with the lenses available
--
Riley

in my home, the smoke alarm is the dinner bell (just)

gianstam said:

exactly the same. The TOTAL light wich collect the big sensor is 4x
(35mm sensor vs 4/3 sensor) and it has the same importance as that
the whole earth collects billion of billion times a more light than a
single face under the sun wich will be "burned" in the same way as
any other.

Click to expand...

Your comparison is flawed as the issue with the earth is that the earth gets billions of times more sunlight than a person as it collects the light with an area that is grater by that amount.

However, that is not what is happening with sensors. The lens collects the light and not the sensor. If a lens collects x amount of light (maybe I should talk about photons here), then it does not matter how big a sensor you project this light to, it is still the same amount of light. This means that the amount of light per area will be less for larger sensors than for smaller ones.

So if your sensor is four times as big then per area you get one quarter of the light. If you want to get the same amount of light per area then you need a bigger lens for the bigger sensor so that you can capture four times as much light. That is the whole point and it is indeed elementary physics.

If you do not believe me then why don't you check Ansel Adams book "The Camera".

gianstam said:

I mean that for someone with elementary knowledge of physics ( and
yes, if you want to discuss about technology of DP you need it) it is
obvious that as at any other case we count "amount/unit"

Click to expand...

John King said:

S N G said:

No, this the only advantage for you . I could bring you few more
points for both sides, but then it would be for me , and pretty much
outside the scope of this discussion.

• sergey

Click to expand...

Just BTW, Sergey, you shoot a Nikon D300 with a sensor size that is
on the small side of APS sensor sizes at 23.6x15.8. Of course, this
is not the actual imaging area, which all manufacturers tend to be a
bit coy about; but since the camera gives a 1.6x crop factor, one can
work out that the imaging area is actually 22.5 x 15. This is a lot
smaller than the biggest Canon APS-C sized sensors, which go up to
28.7 x 19.1 mm, or physically 47% bigger area than your D300 ... Or
about the same amount bigger than the D300 sensor as the D300 sensor
is bigger than the 4/3rds sensor ... . How come no one here ever
seems to "notice" that interesting fact?

Click to expand...

The size differences sure has been noticed John. Your "facts" are wrong though.

Nikon's sensors are the same size as Pentax and they are 60% larger than the 4/3 sensors (area).
The crop factor is not 1.6 but 1.5.

In relation to DOF this is 1.33 f-stops. Then from an 1.5 crop factor sensor to a FF sensor it is another step of 1.5 stops.

The Pentax/Nikon sensors active area are 360mm^2 (23.2x15.5 mm)
The 4/3 sensor is 225mm^2 (17.3x13 mm)

John King said:

The so-called "APS" sensors are very variable in size from 28.7 x
19.1 mm down to the Foveon. One of Sony's APS sensors measures just
21.5 x 14.4 mm, or an area just 27% larger in area than the 4/3rds
sensor. I would suggest that for the classification to have any
meaning at all, it really needs to include all the mid-sized sensors,
including 4/3rds. This would also have the very nice side-effect of
disposing of these silly arguments ...

Click to expand...

I don't see how this could happen. The Oly sensor won't get larger because you call it "APS".

John King said:

According to Nikon, Nikon APS sensors have a 1.6 crop factor (BUT,
the same physical dimensions as the D300 sensor, apparently).

Click to expand...

I have only seen the 1.5 figure. Canon cameras have an 1.6 crop factor sensor. If I have missed something (=Nikon sensors are different size) I would appreciate to learn about it.

John King said:

This means that to get the same DoF on a 1.6x crop factor sensor to
that obtainable with an f2 lens on a 4/3rds sensor, one needs to have
the lens open to f2.5, not f2.8 or f4. At these latter f-stops, the
1.6x crop factor sensor camera will give a greater DoF than the
4/3rds camera at f2. More or less ... as said before, manufacturers
tend to be "coy" about the actual imaging area size, and Olympus is
not the exception to the rule ...

Click to expand...

On a 1.5 crop factor camera you can use f/2.7 to get the same DOF as you get using f/2 with the 4/3 system sensor.

John King said:

However, so much for that bit of your 'argument', as well ...

Click to expand...

Well, I'm not Sergey but I'm tempted to say the same to you anyway.

One can also put it this way: Nothing has changed since the matter was discussed last time. This gives larger sensor an advantage when it comes to DOF control and the smaller sensors an advantage when it comes to reach.

--
Jonas

Kirasir said:

S N G said:

Ray, I do not disagree with you. But ask yourself, why do we need f/2?
1) Shallow DoF - FF can do at f/4 what 4/3rds does at f/2

Click to expand...

You have forgotten to add "if shooting from the same place using the
lens with the same AOV". Because otherwise 4/3 sensor CAN provide the
same or more shallow DOF at f/4, as FF. The demand "same distance,
same AOV" seem to be reasonable... but it only seems to be - it has
nothing common with the real life and real photography.

Kirasir said:

2) Speed and less noise - FF can do at two stops higher than 4/3rd ISO
whenever necessary and deliver the same results

Click to expand...

This statement also seems to be true, but only seems to be. A lot of
times I have asked my colleagues with 1Ds Mk II, working on the same
event, what sensitivity are they using just now. And each time it
turned out, that just the same, as I used. And usually no higher than
400...
You are speaking about "two stops in ISO between 4/3 and FF" as if
it's some law of nature. But difference of E-3 and 5D is less than
one stop, and it can be seen only at iso higher than 1600. Don't
believe me?
This comparison was already posted here:
"



"
There is great difference in noise performance between 5D and D3, and
even greater between different cameras with the same APS sensor size.

Kirasir said:

It can only be an advantage when other system can not do the same.
And as we know it, whatever 4/3rd can do the larger formats do with
ease. "Advantage" therefore is not a correct word for this
relationship, quite opposite applies better.

Click to expand...

Probably You are right. But it also means that You are wrong, and
larger sensors do not have any DOF advantages too. They can obtain
the same result changing two parameters, f-number and sensitivity,
smaller sensors can obtain the goal also by changing two parameters,
focal length and distance.
All theese discussion is just rubbish, but You time by time take out
from the grandpa's barn all that covered by moss ideas.... In Russian
photocommunity it's called photo-automanipulation. Better go and
shoot some good photos, and show them. This will be much more usefull.

Click to expand...

Your addition to the discussion is of quite little value. I see disinformation and then it becomes rubbish just as you say.

Photography is very much of distances and perspectve, which changes when you move. A 25/1.4 can produce shallow DOF. But how good will that portrait be, up and nosy as the photographer will be?

The Dome photo is kinda clever but also hard to read. Anyone having used the 5D knows the noise difference not is less than one stop. Don't believe me? Try it yourself - don't look at a dome with different light and exposures on the different parts.

Discussions aren't rubbish. They can help people understand relations, and they can help anyone with special needs to get the system suiting them the best.

It's another thing that the 4/3 system probably will serve the vast majority of photographers very well.

regards,

--
Jonas

marking
--

There's not 2 but 3 sides to every story. Theirs, yours, and what really happened.

Juergen Hahn said:

Your comparison is flawed as the issue with the earth is that the
earth gets billions of times more sunlight than a person as it
collects the light with an area that is grater by that amount.
However, that is not what is happening with sensors. The lens
collects the light and not the sensor. If a lens collects x amount of
light (maybe I should talk about photons here), then it does not
matter how big a sensor you project this light to, it is still the
same amount of light. This means that the amount of light per area
will be less for larger sensors than for smaller ones.
So if your sensor is four times as big then per area you get one
quarter of the light. If you want to get the same amount of light per
area then you need a bigger lens for the bigger sensor so that you
can capture four times as much light. That is the whole point and it
is indeed elementary physics.

Click to expand...

Wrong. The lens projects an image circle. The sensor intercepts a portion of the projected light. The larger the sensor, the larger portion is intercepted. The portion of the circle projected beyond the sensor dimensions is simply lost (absorbed really by black masks/baffles within the camera body. You're making it sound like somehow the entire image circle (all light collected and projected by the lens) finds its way onto each sensor, regardless of the size of that sensor. That is not the way it works.

Gidday Jonas

Jonas B said:

John King said:

Just BTW, Sergey, you shoot a Nikon D300 with a sensor size that is
on the small side of APS sensor sizes at 23.6x15.8.

Click to expand...

Click to expand...

This statement is absolutely correct, is it not?

Per DP Review of D300 at http://www.dpreview.com/reviews/nikond300/page2.asp:

Sensor * • 23.6 x 15.8 mm CMOS sensor • DX format

Per DPR Sensor Sizes: 4/3" 18.000 13.500 at http://www.dpreview.com/learn/?/Glossary/Camera_System/sensor_sizes_01.htm

NOTE** that neither of these sizes are 'imaging sizes'; you either have to compare sensor size or imaging size, Jonas. It is simply not acceptable to compare other than known dimensions.

Also, funny how CMOS sensors are 'noisy' when used for 4/3rds, but not when used for c/n ...

Jonas B said:

Nikon's sensors are the same size as Pentax and they are 60% larger
than the 4/3 sensors (area).

Click to expand...

Not exactly 60%, nor even approximately correct ...

Jonas B said:

The crop factor is not 1.6 but 1.5.

Click to expand...

So, I made an error of one decimal point ... I admit it, your Honour, I will never do it again, just don't send me to jail forever ...

Jonas B said:

In relation to DOF this is 1.33 f-stops. Then from an 1.5 crop factor
sensor to a FF sensor it is another step of 1.5 stops.

Click to expand...

This adds up to 2.83 f-stops, Jonas. Since when did 2.83 = 2?

Jonas B said:

The Pentax/Nikon sensors active area are 360mm^2 (23.2x15.5 mm)
The 4/3 sensor is 225mm^2 (17.3x13 mm)

Click to expand...

Please give precise reference for this assertion, since "we" are getting picky, in the extreme.

Funny how in your arithmetic the Nikon loses 0.4mm from the long side of the imaging area, and 0.3mm from the short side. Yet Olympus manage to lose 0.7mm and 0.5mm from a smaller sensor ... You do, of course, have a reference for this interesting "fact".

I was working on the total sensor area (which is a matter of public record). In Olympus' case, they do actually publish and use the imaging area in their specifications - 17.3 x 13.0 (the 4/3rds sensor is total area of 18.0 x 13.5 mm), however this is not a common practice. Hence my working from the known total area of the sensor in each case.

On total sensor area the Nikon is 23.6 x 15.8 = 372.88 mm²; the Olympus is 18.0 x 13.5 = 243 mm². This gives the areal ratio as 1.5345; not 1.60, as you suggest.

Jonas B said:

I don't see how this could happen. The Oly sensor won't get larger
because you call it "APS".

Click to expand...

Funny how the Nikon sensors do ... So do a number of the Canon sensors ... Pentax sensors ... Sony sensors ... all of which are actually smaller than APS-C ...

Again from DPR Sensor Sizes page: "APS-C film measures 25.1 x 16.7 mm" = 419.17 mm². Ummm, this is not the same size as 23.6 x 15.8 = 372.88 mm, Jonas. It would appear that "true" APS-C is 12.41% larger than the Nikon DX sensor (total) size, hmmm.

Assuming (pending references ... ) that the Nikon imaging area size is as you state it to be, i.e. 360mm² (23.2x15.5 mm), then the imaging area is only 85.79% of APS-C size. BUT somehow this becomes (by magic??) an "APS" sensor ... even though it is actually 16.57% smaller than APS-C ...

Jonas B said:

Jonas B said:

According to Nikon, Nikon APS sensors have a 1.6 crop factor (BUT,
the same physical dimensions as the D300 sensor, apparently).

Click to expand...

Click to expand...

So, with all the B/S being spruiked here, I am not the ultimate expert on Nikon sensor sizes (I threw myself on the mercy of the court - see above - rotflmho) ... compared with the absolutely outrageous assertions made here, I am out by a whopping single decimal point and somewhat less than 1/3 of a stop and you are hopping into ME ? What about the "gentlemen" who are out by a factor of two** or more stops in their assertions, Jonas? How about actually correcting some of their arithmetic?

Jonas B said:

I have only seen the 1.5 figure. Canon cameras have an 1.6 crop
factor sensor. If I have missed something (=Nikon sensors are
different size) I would appreciate to learn about it.

Click to expand...

I am not an expert on Nikon sensor sizes. However, I am not out by a factor of two to four in my assertions, Jonas, unlike some here ...

Again per DPR Sensor Sizes page: "Canon has several (smaller and larger) variants, e.g. 22.2 x 14.8 mm and 28.7 x 19.1 mm."

Jonas B said:

On a 1.5 crop factor camera you can use f/2.7 to get the same DOF as
you get using f/2 with the 4/3 system sensor.

Click to expand...

Good grief! So much different from the f2.5 I stated ... I shall have to "resign" immediately ...

What rubbish, Jonas. It gives the larger sensor an ability to have shallower depth of field IF** you can open the lens right up and still have an image worth having ... definitely not the usual case.

Secondly it gives the smaller sensor what is often desperately needed, MORE** DoF at wider apertures. In order to get any decent DoF with the larger sensor, it is necessary to stop the lens down to heck and ramp the ISO as well. Often by at least 4 stops between the two. Diffraction sets in and the ISO performance of the larger sensor is absolutely needed as there is no other choice .

Jonas B said:

and the smaller sensors an advantage when it
comes to reach.

Click to expand...

Yes. Big time. AND decent lens design for UWAs. And transportable** lenses for telephoto work ...

So we reach a point where the "shortcomings" of 4/3rds are actually an advantage, at both ends of the lens range.

AND the lenses are faster, cheaper (relative to grade), smaller (comparing like to like, i.e. an f2 lens with an EFL f2 lens etc - oh, sorry there aren't any ... - well if there were ... , lighter, better optical quality ... DID I mention just better all round?

If I have made any other 0.1 errors, Jonas, please forgive me ...

Regards, john from Melbourne, Australia.
-----

The Camera doth not make the Man (or Woman) ...
Perhaps being kind to cats, dogs & children does ...

John King said:

By stating it they imply (continually) that Olympus' (or anyone
else's ... ) f2 lens is "really' only the same speed as an f4 lens,
when this is patently not the case. The apparent ( very - apparent)
motive for this is to disparage and belittle the very fast, very high
quality lenses available for 4/3rds.

Click to expand...

Well, and the thing is that there are chinks in the Olympus armor, but the people who seem most desperate to disparage the 4/3 system always seem to go after nonsensical "flaws" in the Olympus system instead.

If they really wanted to slag Olympus the most factual and direct way to do it would be to point out that a Zuiko lens has to resolve twice as much detail as a 135 lens to have the same overall resolution. The pro lenses are still out-resolving the sensors, but at some point they're going to run into a brick wall. Presumably at 20 megapixels, if their original 4/3 system plan took took the limits of lens design into account (which it probably did).

So there's your slag point. And since Canon has already crossed the 20-megapixel line and both Nikon and Sony are poised to get there by fall (one assumes) then the logical gloating point would be that those systems have already surpassed the point where Olympus will find the end of the development road in another five years or so.

Horses for courses, though. If small "sensors" were the highest state of the art then Ansel Adams would have been shooting the Sierras with a half-frame 35mm camera, but instead he used 8" x 10" view cameras and shot such long exposures that he had jackstands on the four corners of his truck to raise it up off its shock absorbers when he set up to shoot. And yet while Ansel was out there working in his later career Olympus was selling nearly 17 million of their Pen series half-frame cameras. The Graflex Speed Graphic was probably the best-selling large format camera of all time, built for well over 30 years, and there were still far fewer than 100,000 units produced. Yet a Speed Graphic photo taken with a 50's vintage lens on modern film can be scanned at 8000 dpi on an Aztek to yield a 1280 megapixel image. If you have the time, patience and training to go that route. And an application that calls for it.

You can always find something to criticize about a camera. I used to whine all the time about being "limited" to shooting 16mm until I got a proper 35mm cinema camera, shot in the field with it for six months and herniated a disc in my back. When they tell you in film school that it takes a minimum two-man crew to shoot 35mm they aren't just pontificating for no reason.

There are drawbacks to the E system. Even the fastest E can only shoot at 5 fps, so it's not really an ideal camera for people who cover sports. Even with the fast glass an E-3 isn't going to be shooting in light as low as a Nikon D3, either. And you aren't going to see Olympus introduce a 20+ megapixel model next year to compete with the Canon, Sony and Nikon offerings that will undoubtedly be selling like mad in 2009.

However, the Olympus dust-buster works like a charm, so dealing with dust is a non-issue. The 4/3 lens mount works as advertised, so Olympus lenses almost never have issues with vignetting or corner softness. The pro Zuiko glass is magnificent, too. When I was shooting for newspapers in decades gone by the standard-issue lens was always a 300mm f/2.8 (unless you used Olympus and then it was a 350mm f/2.8). We could push HP5 or Tri-X to 800, but it was grainy. Some editors thought it was too grainy. So effectively a lot of times the upper limit was 400. Neopan woulda been nice, but I digress. Anyway, a ZD 150mm f/2 is a stop faster and about a third the weight of the 350mm f/2.8 and the E-3 shoots at 800 with no problem at all. It's also about half the weight and still a stop faster than the modern 300mm f/2.8 lenses offered by Canon and Nikon. About half as big, too. There's a range of applications there that the Olympus is perfectly suited to perform.

I wouldn't buy one to shoot landscapes or sports, but for the overwhelming majority of things that people use DSLR cameras to shoot, it's a very user-friendly high-quality system. And that apparently irritates some people a lot. ;-)

Sorry for going on and on. I get started sometimes and can't shut up.

Gidday RRJ

RRJackson said:

John King said:

By stating it they imply (continually) that Olympus' (or anyone
else's ... ) f2 lens is "really' only the same speed as an f4 lens,
when this is patently not the case. The apparent ( very - apparent)
motive for this is to disparage and belittle the very fast, very high
quality lenses available for 4/3rds.

Click to expand...

...

... for the
overwhelming majority of things that people use DSLR cameras to
shoot, it's a very user-friendly high-quality system. And that
apparently irritates some people a lot. ;-)

Sorry for going on and on. I get started sometimes and can't shut up.

Click to expand...

Well said, I thought. I seriously doubt that Olympus lenses are going to struggle in two years time, not the way that some brands have been struggling for many years - and still are ... rotfl.

The 'wonderful' 21 MP (nameless) that could sometimes focus some of the time in bright sunlight is apparently out resolving its lenses by around 5~8 MP already ...

Nuff said, mate.

Regards, john from Melbourne, Australia.
-----

The Camera doth not make the Man (or Woman) ...
Perhaps being kind to cats, dogs & children does ...

http://canopuscomputing.com.au/gallery2/main.php



Bird Control Officers on active service.

Juergen Hahn said:

Juergen Hahn said:

......

Click to expand...

Click to expand...

You obviously ignore my graph that shows the way that any unit area is affected by the same amount of light (of course the total area does not matter).
You need some "good desire" to accept my example about earth as good.
The lens does not collect light. It directs the light wich pas through the lens.

John King said:

Gidday RRJ

Click to expand...

Hiya. You can call me, 'Rob.' ;-)

John King said:

Well said, I thought. I seriously doubt that Olympus lenses are going
to struggle in two years time, not the way that some brands have been
struggling for many years - and still are ... rotfl.

The 'wonderful' 21 MP (nameless) that could sometimes focus some of
the time in bright sunlight is apparently out resolving its lenses by
around 5~8 MP already ...

Nuff said, mate.

Click to expand...

Well, Olympus designing their digital SLR series from scratch was a really good thing. Obviously I'd have been happier if they'd elected to base it on a slightly larger sensor size, but because they didn't already have a large selection of autofocus lenses that they had to accommodate with a legacy mount, they were able to really concentrate on designing a lens mount and lens design philosophy that worked well with digital sensors. So we've never had any of the issues that have plagued other marquees. We've also never had to deal with screw-driven lenses like everyone but Canon in the DSLR market grandfathered in. The 4/3 system is a really good DSLR design. Sensors four times the size are going to have an edge over it, but if you have an application that it will satisfy, a 4/3 system is WAY more pleasant to live with than any of the other DSLRs I've tried.

Over the last year or so I owned a Nikon D200 and a Canon 5D. I'd been really frustrated waiting for an E-1 replacement and ended up going the Nikon route first, but the autofocus was horrid. It was faster than my E-1 and it didn't hunt, but it also didn't accurately focus. Then the 5D was a dream come true until it started filling with dust. The autofocus and high ISO performance was amazing, but it had to be cleaned constantly. And even paying for professional cleaning didn't clean all the dust out of the lightbox and off the bottom of the prism. I don't know how people deal with cameras that aren't...well, that aren't made by Olympus. ;-)

G'day again Rob

RRJackson said:

John King said:

Gidday RRJ

Click to expand...

Hiya. You can call me, 'Rob.' ;-)

RRJackson said:

Well said, I thought. I seriously doubt that Olympus lenses are going
to struggle in two years time, not the way that some brands have been
struggling for many years - and still are ... rotfl.

Click to expand...

Well, Olympus designing their digital SLR series from scratch was a
really good thing. Obviously I'd have been happier if they'd elected
to base it on a slightly larger sensor size, but because they didn't
already have a large selection of autofocus lenses that they had to
accommodate with a legacy mount, they were able to really concentrate
on designing a lens mount and lens design philosophy that worked well
with digital sensors. So we've never had any of the issues that have
plagued other marquees. We've also never had to deal with
screw-driven lenses like everyone but Canon in the DSLR market
grandfathered in. The 4/3 system is a really good DSLR design.
Sensors four times the size are going to have an edge over it, but if
you have an application that it will satisfy, a 4/3 system is WAY
more pleasant to live with than any of the other DSLRs I've tried.

Over the last year or so I owned a Nikon D200 and a Canon 5D. I'd
been really frustrated waiting for an E-1 replacement and ended up
going the Nikon route first, but the autofocus was horrid. It was
faster than my E-1 and it didn't hunt, but it also didn't accurately
focus. Then the 5D was a dream come true until it started filling
with dust. The autofocus and high ISO performance was amazing, but it
had to be cleaned constantly. And even paying for professional
cleaning didn't clean all the dust out of the lightbox and off the
bottom of the prism. I don't know how people deal with cameras that
aren't...well, that aren't made by Olympus. ;-)

Click to expand...

Dust? Dust! What's that ... ? ;-)))))))))

Always very interesting to hear the comments of someone who has actually owned modern cameras from the competition that Olympus "can't compete with" (just) rotfl ...

Regards, john from Melbourne, Australia.
-----

The Camera doth not make the Man (or Woman) ...
Perhaps being kind to cats, dogs & children does ...

http://canopuscomputing.com.au/gallery2/main.php



Bird Control Officers on active service.