How Camera Manufacturers and Reviewers Mislead or Lie.

[Renato1 (Renato)]

This might be old news to many here.

I've been reading lots of camera reviews the last week trying to find a suitable super-zoom camera for photographing birds when we go on vacation. Then while looking at video reviews, I came across the chap in the video below, who states the bleeding obvious.

In a nutshell, he says camera manufacturers apply the crop factor to lenses to get the 35mm/full frame equivalent, but then mislead the customers by not applying the crop factor to the F-number.

To illustrate, one example he gives is a Panasonic 12-35mm f/2.8 lens for a Micro 4/3s camera which has a 2X crop factor. Advertisers then say it's a 24-70mm f/2.8 full frame equivalent lens, when in physical fact it is a 24-70 f/5.6 full frame equivalent lens.

Then I thought back to how many supposedly "Tech Head" type reviewers I'd been reading, who went along with that type deception in their reviews of super zooms.

It also occurred to me that my actual camera has been misleading me. When I put a full frame lens on an APS DSLR, and set the lens to say F/4 and take a picture, the data in the photo says F/4 - what the lens was set to - when in fact the actual value was f/6 due to the crop factor.
Regards,
Renato

https://www.youtube.com/watch?v=DtDotqLx6nA

[Atmos (Colin)]

The "crop factor" is a bit of a misnomer as it doesn't really do anything other than describe field of view differences.

Take a telescope for instance. I have a 130mm F/5.2 refractor which I have used with multiple cameras; ASI1600/QHY163M, Nikon D7200 and Nikon D810/ASI094. The first is a M4/3, the second APS-C and finally the last is FF.

Using the crop factor logic I have a 2x (1350mm), 1.6x (1080mm) and 1x (675mm). In all of this the aperture, focal length and focal ratio have not changed and it doesn't matter what camera you have, it has no affect on the focal ratio because neither the physical focal length or aperture have changed.

Now you are correct in that TECHNICALLY using the crop factor would make it a 130mm F/10.4 IF you were to use absolute comparisons between a M4/3 and a FF. This is only applicable if you're saying one lens is like another (your first comparison).

You're camera isn't misleading you though because you're not talking back technicalities about actually taking photos. Using an APS-C doesn't magically change a 50mm F/4 to a 80mm F/6, only that you would get the same amount of light output and FOV as a 50mm F/4.
In real life you are still shooting with a 50mm F/4 because your lens has a 12.5mm aperture and a 50mm focal length regardless of whether you're using a M4/3. an APS-C or FF.

[Wavytone]

Focal ratio is F/D... f/4 is f/4 and always will be.

“crop factor” is an ugly fiction that should be ignored - stick to the actual measurements in mm, always.

The sensor dimensions and focal length of the lens determine the field of view. Simple geometry.

[leon]

Hey Renato, this bloke will set you right, any camera any lens, he is very through and tells it the way it is

https://www.the-digital-picture.com/Reviews/

Leon

[JA]

Originally Posted by Renato1

This might be old news to many here.

I've been reading lots of camera reviews the last week trying to find a suitable super-zoom camera for photographing birds when we go on vacation.

Ciao Renato,

In the "Superzoom" / Bridge camera segment a Sony Cyber-shot DSC-RX10 III (24-600mm FFequiv field of view) or if you want to spend much less a Panasonic Fz1000 (24-400mm FFequiv field of view, or upto 480mm in the MkII version) would be excellent for that use and they have very good 4K video. They both have 1 inch sensors. Of course you can go for longer focal lengths, at the expense of sensor size. You don't need 1000+mm equivalent FF focal length field of view at the expense of increased noise from the smaller sensors.

Go luck in your selection.

Best
JA

PS: the is also a new model, a Sony Cyber-shot DSC-RX10 IV. Whatever you choose go to the dpreview website and compare the same image across your potential selection of cameras

[Renato1 (Renato)]

Originally Posted by Atmos

The "crop factor" is a bit of a misnomer as it doesn't really do anything other than describe field of view differences.

Take a telescope for instance. I have a 130mm F/5.2 refractor which I have used with multiple cameras; ASI1600/QHY163M, Nikon D7200 and Nikon D810/ASI094. The first is a M4/3, the second APS-C and finally the last is FF.

Using the crop factor logic I have a 2x (1350mm), 1.6x (1080mm) and 1x (675mm). In all of this the aperture, focal length and focal ratio have not changed and it doesn't matter what camera you have, it has no affect on the focal ratio because neither the physical focal length or aperture have changed.

Now you are correct in that TECHNICALLY using the crop factor would make it a 130mm F/10.4 IF you were to use absolute comparisons between a M4/3 and a FF. This is only applicable if you're saying one lens is like another (your first comparison).

You're camera isn't misleading you though because you're not talking back technicalities about actually taking photos. Using an APS-C doesn't magically change a 50mm F/4 to a 80mm F/6, only that you would get the same amount of light output and FOV as a 50mm F/4.
In real life you are still shooting with a 50mm F/4 because your lens has a 12.5mm aperture and a 50mm focal length regardless of whether you're using a M4/3. an APS-C or FF.

Thanks, but the crop factor - applied to focal length and to f number - describes the field of view and depth of field equivalences/characteristics.

At constant ISO, a 50mm F/4 lens in an APS non-Canon camera gives the same image on the sensor as a 75mm f/6 lens on a full frame camera. And a 50mm f/4 lens on a full frame camera gives the same image as a 33.3mm lens f/2.66 lens on a non Canon APS camera.

And putting each of your cameras in your telescope (which I'm very envious of) and taking pictures of the moon, will give images 1.6X and 2X bigger with the smaller sensor cameras than that with the full frame camera.

Plainly effective focal length has changed, while the lens's actual focal length hasn't.

f number is meant to be a dimensionless number that enables one to get equivalencies between lenses. Without taking effective focal length into account, the equivalencies disappear.
Regards,
Renato

[Renato1 (Renato)]

Originally Posted by Wavytone

Focal ratio is F/D... f/4 is f/4 and always will be.

“crop factor” is an ugly fiction that should be ignored - stick to the actual measurements in mm, always.

The sensor dimensions and focal length of the lens determine the field of view. Simple geometry.

Thanks, but I have to disagree.

Most people don't know the size of their sensors, and are unlikely to be able to do the simple geometry you suggest. They may, however, be able to do the simple arithmetic to work out equivalancies using effective focal length and effective f number to match the actula results they see in their camera.
Regards,
Renato

[Renato1 (Renato)]

Originally Posted by leon

Hey Renato, this bloke will set you right, any camera any lens, he is very through and tells it the way it is

https://www.the-digital-picture.com/Reviews/

Leon

Thanks Leon,
I've bookmarked the page, but this chap doesn't seem to review the low end, small sensor, vacation cameras I'm looking for. He's mainly looking at the good stuff.
Cheers,
Renato

[Renato1 (Renato)]

Originally Posted by JA

Ciao Renato,

In the "Superzoom" / Bridge camera segment a Sony Cyber-shot DSC-RX10 III (24-600mm FFequiv field of view) or if you want to spend much less a Panasonic Fz1000 (24-400mm FFequiv field of view, or upto 480mm in the MkII version) would be excellent for that use and they have very good 4K video. They both have 1 inch sensors. Of course you can go for longer focal lengths, at the expense of sensor size. You don't need 1000+mm equivalent FF focal length field of view at the expense of increased noise from the smaller sensors.

Go luck in your selection.

Best
JA

PS: the is also a new model, a Sony Cyber-shot DSC-RX10 IV. Whatever you choose go to the dpreview website and compare the same image across your potential selection of cameras

Thanks for your input.

Yes, the Sony DSC-RX10 with "only" 600mm focal length does seem to be the favourite of many of the reviewers because of it's bigger sensor relative to the tiny ones of most of the other super zooms, and they do say that cropping its photos gives a better result than the images from the higher powered super zooms. It does get a mention in the video below, for misleading with respect to f number, but plainly, it is still a class camera.

The FZ1000 looks impressive too, especially the accurate autofocus.

Unfortunately - both are heavy. And it's my wife's hobby, not mine, and I'd wind up having to lug the camera around. Which means I've also ruled out the heavy Nikon P1000 and P900 with their oustanding long zooms.

I was using an old lightweight Nikon P500 with 880mm focal length, but it's had too many trips overseas and is playing up now - image keeps jumping around at the longest zoom, and seems to always back focus.

I nearly bought a Nikon A900 the other day, till I read a user review that one will likely be disappointed with it if one mainly wants it for the high power - unless one is willing to take a tripod around all day. It seems like I need something like what I had, where I stabilize the camera using both hands and the viewfinder in my eye socket (which rules out the Canons).
Cheers,
Renato

[leon]

OK mate, you choose what you are looking for.

Leon

[skysurfer]

The focal length / f ratio / crop factor is a confusing one.

But why don't the camera and lens manufacturers not specify the actual FOV instead of the fake millimeters ? That is correct for every camera from medium format to cellphone.
So no 50mm f/4, but 46 degrees f/4.
And the Nikon P1000 is 84 to 0.7 degrees FOV.
But for exchangable lenses cameras with different sensor sizes (such as Canon EF for FF and APS-C and Nikon legacy mount for both FF and DX) the millimeter measure is better as it are real millimeters and the FOV varies between FF or APS-C.

And these f/ratio is even confusing some astrophotographers. The myth is that a telescope 80mm f/5 is 'faster' than 100mm f/5.6 and shows fainter stars and nebulas than the 100mm f/5.6 'because 5 < 5.6'.
Well, the sky background is brighter and due to the larger FOV. more stars are crammed in the field, but not fainter stars.
Remember that a high magnification eyepiece shows fainter stars than a low mag eyepiece on the same telescope ? Same principle.

[Atmos (Colin)]

Originally Posted by Renato1

Thanks, but the crop factor - applied to focal length and to f number - describes the field of view and depth of field equivalences/characteristics.

At constant ISO, a 50mm F/4 lens in an APS non-Canon camera gives the same image on the sensor as a 75mm f/6 lens on a full frame camera. And a 50mm f/4 lens on a full frame camera gives the same image as a 33.3mm lens f/2.66 lens on a non Canon APS camera.

And putting each of your cameras in your telescope (which I'm very envious of) and taking pictures of the moon, will give images 1.6X and 2X bigger with the smaller sensor cameras than that with the full frame camera.

Plainly effective focal length has changed, while the lens's actual focal length hasn't.

f number is meant to be a dimensionless number that enables one to get equivalencies between lenses. Without taking effective focal length into account, the equivalencies disappear.
Regards,
Renato

The crop factor is a way of comparing the relationship between sensor size and focal length. Depth of field is entirely determined by the relationship between distance and focal ratio.

There is no such thing as effective focal length when you're talking about optics, there is only it's actual focal length. This is why in my first post I said it's all a misnomer and it can be easily proven scientifically.

I have a Nikon D810 which is a 36.3MP FF camera but it is also the equivalent of being a 16MP APS-C camera if I crop or a 9MP M4/3.
If I took an image with my D810 and a 16MP APS-C camera with my telescope and compared the images, they'd be near enough to identical. The APS-C camera would NOT have a different focal length. The APS-C sensor would NOT be imaging through a different focal ratio.

Consider that what you're suggesting is that merely cropping an image down changes the effective focal length and changes the focal ratio because there is no difference between cropping a FF to APS-C or M4/3 than actually using one.

[Renato1 (Renato)]

Originally Posted by Atmos

The crop factor is a way of comparing the relationship between sensor size and focal length. Depth of field is entirely determined by the relationship between distance and focal ratio.

There is no such thing as effective focal length when you're talking about optics, there is only it's actual focal length. This is why in my first post I said it's all a misnomer and it can be easily proven scientifically.

I have a Nikon D810 which is a 36.3MP FF camera but it is also the equivalent of being a 16MP APS-C camera if I crop or a 9MP M4/3.
If I took an image with my D810 and a 16MP APS-C camera with my telescope and compared the images, they'd be near enough to identical. The APS-C camera would NOT have a different focal length. The APS-C sensor would NOT be imaging through a different focal ratio.

Consider that what you're suggesting is that merely cropping an image down changes the effective focal length and changes the focal ratio because there is no difference between cropping a FF to APS-C or M4/3 than actually using one.

I think we're just talking in circles about what winds up being the same thing.

As a mental exercise, suppose that for many years there was only one standard eyepiece on the market of 20mm focal length. Put it into a telescope of 100mm diameter, 500mm focal length (F/5), and the magnification is 25X.

Then after many decades someone markets a new eyepiece and says it has a crop/magnification factor of 2X, which effectively doubles the focal length of the old telescope. Technically, it may be wrong, but in practice it makes zero difference in describing reality of the image that is delivered in the new eyepiece. People would then start talking about equivalent focal lengths of using the old and new eyepiece - which accurately describes what occurs at the eyepiece.

A problem that may occur though is when someone starts selling a telescope with 50mm aperture, 250mm focal length (F/5) and that 2X eyepiece, claiming it is exactly the same as the first telescope since it has a 25X magnification, since it contains a bright f/5 system.

The error plainly is that the small telescope will have an exit pupil half the size of that in the bigger telescope, and the purchaser may wonder why the image he is looking is only as bright as if it's from an f/10 telescope.

That pretty much describes the camera sensor situation. That video uses the crop factor terminology to describe the misleading claims being made by camera manufacturers, as there is no way that tiny lenses can capture the amount of light implied using the f number of the tiny lens and applying it to the crop factored equivalent.
Regards,
Renato

[Geoff45 (Geoff)]

Let’s take crop factor to ridiculous extremes. Just keep making your sensor smaller and smaller, thereby increasing the crop factor. Eventually we get to a 1 pixel sensor with a crop factor of around 3-4000. Great stuff!

[bojan]

"Crop factor" is idiocy that has to be disregarded.
And people should not have excuse for not knowing about their sensor size.
They should learn something about their equipment first before go out and start shooting images.... and start giving reviews in "poetic" languuage, which ci=ontain no useful information.
BTW, I like 1 pixel sensor example

[gts055 (Mark)]

If I take an image with a 50mm f1.4 on a say 2/3 crop sensor and take another image with the same lens on a full sensor, I thought the centre 2/3 of the full size sensor image would be identical to the image on the crop sensor. In other words, the full sensor can be made to look like a crop camera image by simply "cropping" the full sensor image to 2/3 size. Mark

[bojan]

Originally Posted by gts055

If I take an image with a 50mm f1.4 on a say 2/3 crop sensor and take another image with the same lens on a full sensor, I thought the centre 2/3 of the full size sensor image would be identical to the image on the crop sensor. In other words, the full sensor can be made to look like a crop camera image by simply "cropping" the full sensor image to 2/3 size. Mark

Provided the pixel size is the same (because some may argue the images are not the same size.... )

[Renato1 (Renato)]

Originally Posted by bojan

"Crop factor" is idiocy that has to be disregarded.
And people should not have excuse for not knowing about their sensor size.
They should learn something about their equipment first before go out and start shooting images.... and start giving reviews in "poetic" languuage, which ci=ontain no useful information.
BTW, I like 1 pixel sensor example

You say that crop factor is idiocy, but you have not explained what arithmetically is incorrect about using crop factor - what wrong answer it gives in terms of describing image relative to a 35mm full frame sensor.

I don't know what the error is that you are alluding to, all I started off saying is that applied incorrectly it - as some manufacturers do - it can be misleading.
Regards,
Renato

Originally Posted by Geoff45

Let’s take crop factor to ridiculous extremes. Just keep making your sensor smaller and smaller, thereby increasing the crop factor. Eventually we get to a 1 pixel sensor with a crop factor of around 3-4000. Great stuff!

Yes - your point being?
Arithmetically, relative to a 35mm Full frame camera, it works out the same as doing it geometrically.
Regards,
Renato

[Renato1 (Renato)]

Originally Posted by gts055

If I take an image with a 50mm f1.4 on a say 2/3 crop sensor and take another image with the same lens on a full sensor, I thought the centre 2/3 of the full size sensor image would be identical to the image on the crop sensor. In other words, the full sensor can be made to look like a crop camera image by simply "cropping" the full sensor image to 2/3 size. Mark

Hi Mark,
Yes, entirely correct.
Regards,
Renato

[Ukastronomer (Jeremy)]

Originally Posted by Renato1

This might be old news to many here.

I've been reading lots of camera reviews the last week trying to find a suitable super-zoom camera for photographing birds when we go on vacation. Then while looking at video reviews, I came across the chap in the video below, who states the bleeding obvious.

In a nutshell, he says camera manufacturers apply the crop factor to lenses to get the 35mm/full frame equivalent, but then mislead the customers by not applying the crop factor to the F-number.

To illustrate, one example he gives is a Panasonic 12-35mm f/2.8 lens for a Micro 4/3s camera which has a 2X crop factor. Advertisers then say it's a 24-70mm f/2.8 full frame equivalent lens, when in physical fact it is a 24-70 f/5.6 full frame equivalent lens.

Then I thought back to how many supposedly "Tech Head" type reviewers I'd been reading, who went along with that type deception in their reviews of super zooms.

It also occurred to me that my actual camera has been misleading me. When I put a full frame lens on an APS DSLR, and set the lens to say F/4 and take a picture, the data in the photo says F/4 - what the lens was set to - when in fact the actual value was f/6 due to the crop factor.
Regards,
Renato

https://www.youtube.com/watch?v=DtDotqLx6nA

There are too many posts for me to read here but there is a lot more to crop sensors/lenses/cameras than you can even begin to imagine.

As a paid professional photographer shooting for glossy magazines I sometimes use both crop and full frame but I never ever use compact/hybrid/superzoom/bridge cameras.

Just take crop v full frame, first there is not one that is better than the other it is horses for courses, FF has many benefits over crop, crop has a few benefits.

FF has better more easier controllable DOF over crop
FF Has a much wider range of "Pro" lenses available
FF has a greater Pro system available

FF lenses work on Crop sensors crop sensor lenses will NOT work on FF, one of the biggest mistakes people make, they buy a crop camera, later want to shoot FF but have bought a load of crop frame lenses, BUY FF lenses for any camera as they fit both.

Cropped sensors on my Nikons do allow me to extend my 600mm lens considerably where my converter on my FF will not reach, however it will be at the loss of quality magazines want. I would rather shoot at 16-18Mp on my Pro Nikon bodies that 16-36Mp on a crop sensor, and in low light, shooting in doors FF all the way, and I have shot Canon and Nikon and Canon has the edge on low light and colour though my gears is all Nikon

Also as in astro photography a crop sensor will not match a FF for quality, low light etc

The problem today is everyone who buys a camera thinks they are David Bailey, there is no learning a camera now, from my first camera when I was 12 to, today when I get a piece of kit I learn what it does for a week at least shooting in all situations before ever using it for work, people today don't buy a camera they are "sold" it, shame