Must watch video on full frame vs crop cameras. "Full frame look" covered.

[fuzzynormal]

What the hell is going on here? I've totally lost track. Bring back film!

35mm or 16mm?

[Nikkor]

70mm, but horizontally :p

[jgharding]

4 * 5 inch motion picture film at 100fps

[Andrew Reid]

With respect to the simple math and examples, where are the errors? If it's not possible to point out an error with this math or images, what he says in the video is essentially correct:

1. Multiply focal length by crop factor: well known and the point of the crop factor for full frame reference.
2. Multiply aperture by crop factor: this matches his examples for apparent brightness and bokeh.
3. Multiply ISO by (crop factor)^2: this matches his example for apparent brightness and makes sense based on what ISO really is: gain; the square term makes sense for sensor area, and works for the examples shown.

Samuel (flaat profile creator) did tests and includes an FOV/DOF calculator which exactly matches what is in the video. He made this post in 2011: http://www.similaar.com/foto/doftest/doftest.html

 

Multiplying aperture by crop factor does not change the brightness of the image or the bokeh at all!

 

What changes with the crop factor is the framing of the shot and the need to move the camera back from the subject to get the same field of view as a larger sensor and THAT is what changes the depth of field, bokeh, nothing to do with the aperture at all.

 

His maths is bollocks.

 

Multiplying ISO by crop factor... same bollocks! If a larger sensor is less noisy and more sensitive than a smaller one (and this is not always the case, like I keep telling people only for them to ignore my argument... BMPCC anyone!?? Old 5D Mk1 vs D5200!?) it has to do with the pixel size and architectural design, plus many other factors of the electronics, not the sensor size.

 

So the maths of multiplying sensitivity by crop factor is just total fantasy.

 

And Karim your top diagram of the full frame sensor capturing more rays... are you talking about intensity here? Because the intensity with 4 rays on the large sensor and 2 rays on the small sensor is the same. It isn't right to imply that the Speed Booster with 4 rays delivers the same light intensity as the full frame sensor is able to capture with 4 rays over a larger area. The full frame exposure with 4 rays is darker than the Speed Booster exposure with the 4 rays concentrated on the smaller area. The image with the Speed Booster is more intense and this is a BENEFIT of a small sensor.

 

I suggest the thread dies a death because it is confusion central, total bollocks, and really just not necessary.

 

Use crop factor to figure out your angle of view and disregard it for everything else. It just doesn't fly, either technically or as a conceptual prop and way of figuring stuff out.

 

The least confusing way to continue is to take each spec of the camera in isolation regardless of sensor size. We don't let something unrelated to sensor size like aperture dictate the whole camera spec do we? So why do we let sensor size dictate completely unrelated specs like ISO and aperture!? Madness!

 

I really question the intention behind the video in the first place... It just looks like a Canon & Nikon FUD piece.

 

Dishe, Andrew, again appreciate the discussion thank you.

I am not arguing for the sake of arguing but so far I do not understand how what I am stating is wrong.

But I will gladly learn something and stand corrected.

 

I do understand that sensor pixel size is to be taken into consideration when talking about exposure of the sensor, larger sensors generally having larger pixels than crop ones for instance. And architecture as far as gaps between pixels and the amount of pixels. 

 

In order for me to understand your arguments, can we proceed step by step?

 

Can we begin solely with light intensity? Regardless of sensor specs.

 

What I don't understand in your arguments is regarding the intensity of the light, focused by speedbooster or not.

 

For the sake of understanding here is a lens that has an aperture that lets through 4 rays of light:

Is this correct or is this wrong?

 

[jasondhsd]

I watched the video but didn't have the time to go through the discussion here. But as far as I am seeing, all he's saying is that marketing teams always apply the crop factor to the focal length and not the aperture, or ISO. 

A 12-35mm lens is in fact a 24-70mm f/5.6, not an 24-70mm F/2.8. 

We all know that in terms of depth of field, that's correct. But his theory is that it also applies to the exposure value. 

That a 12-35mm F/2.8 is not the same brightness as a 24-70mm f/2.8, but it's the same as 24-70mm f/5.6, and smaller sensors have to apply more gain to compensate for that exposure difference, thus have more noise. 

Example:

Two pictures. 

1- 35mm - 2.8 - 800 ISO on M43s
2- 35mm - 2.8 - 800 ISO on fullframe 

1 & 2 don't look similar in terms of field of view, depth of field, or ISO

so to match field of view:

1- 35mm - 2.8 - 800 ISO
2- 70mm - 2.8 - 800 ISO 

Now 1 & 2 look similar in terms of field of view, but they don't look similar in terms of -ISO -Depth of field. 

so to match depth of field 

1- 35mm - 1.4 - 800 ISO on m43s
2- 70mm - 2.8 - 800 ISO in fullframe

1 & 2 now look similar in terms of both angle of view and depth of field, but they don't look similar in terms of - ISO (1 is two stops brighter than 2)
 
so to match ISO 

1- 35mm - 1.4 - 200 ISO
2- 70mm - 2.8 - 800 ISO

now 1 & 2 are exactly identical in terms of field of view, ISO noise, and depth of field. 

_______________________

So as far as I understand his theory is that we should also apply the crop factor to the ISO value. That a smaller sensor at 200 ISO = 800 ISO on full frame, and he takes noise levels as his proof. Thus says that smaller sensors don't have noisier ISOs. 

_______________________

Not suggesting he's right or wrong, I have no idea. 

but it's interesting. 

 

Everyone knows how to calculate dof and angle of view when comparing crop to full frame sensors and sometimes the marketing people will do that for you.  The problem with the whole noise and iso calculation is it's trying to mush together different measurements.  ISO at 200 is going to give you the same exposure across all different cameras, same with 400, 800, 6400, etc.  So not worrying about dof or angle of view, 50mm f2.8 800 ISO will be the same exposure for all cameras.    As far as noise is concerned there's no way of comparing that because it changes constantly and varies camera to camera.  Right now the real world differences in noise from 200-800 is pretty negligible. And what basis do you calculate the noise from....a full frame sensor? Well a MD MkII at 20mp is a lot noisier then any of the current mft sensors at the same ISO, and the Nikon D4 looks like it has about 2x less noise when compared to the MD MkIII even at lower ISO. So what do you use as the base to determine these calculations? The video appears to be using the MD MkIII but what about 3 years from now? If this guy it trying to get manufactures to more accurately advertise their lenses and sensors as compared to a full-frame the advertisers will be constantly having to update their materials as new sensor technology hits the market.  If I'm looking to buy a new lens four years from now and the numbers are based off the noise from a MD MKIII I'm not going to get an accurate assessment because by then technology would have advanced to where the MD MKIII at say 800 is equaled to my GH6 at say 1600 or 3200. Like I said, the manufactures job is to report the physical properties of their camera and lenses. It's up the buyer to determine whether or not they want to compare it to full frame equivalent and whether or not they find the noise acceptable or not in terms of ISO performance.   If someone doesn't know the differences before plunking down $1000+ then they're an idiot. 

[themartist]

Way too much aggression in this thread.

[dishe]

I think I understand what you mean, I was focusing on light transmission only, without acknowledging final light density on the surface of the sensor.

 

So my graphics are correct as:

 

- A crop sensor without speedbooster receives less total light as the full frame sensor

- A crop sensor with speedbooster receives the same amount of light as the full frame sensor

 

But:

 

- Since the crop sensor is smaller, the same amount of light on a smaller surface = higher density

 

correct?

 

You're definitely on the right track, now. When you say the "crop sensor without speedbooster receives less total light as the full frame sensor", you are correct in that the area of light that falls outside the sensor is cut off. Technically, that is light that wasn't received. But the confusion here comes from the idea that this somehow effects the part of the image that IS being exposed in the middle. 
In the original diagram, those two beams of light that hit the full frame and crop are the same intensity. Those pixels will be exposed the same amount, assuming the sensor tech are similar enough. It just won't see what is beyond the borders of the frame, as it is cropped out. 

 

The ISO and Aperture did not change. The entire image got cropped instead. 

 

But, the focal reducer condenses the light into a smaller point, thus making it more dense and intensifying it. Here's a diagram I threw together:


Note that as the beams spread out away from the lens, they get larger and less intense because the photons scatter. And in the second example, the resulting image is just a cut out of the full frame one above it. The intensity of light that is hitting the sensor in the middle is the same intensity of light that is hitting the middle of the full frame one. The exposure is the same, the FOV is same, but now we are only seeing part of the image as the rest was discarded outside the viewable area.

The problem is, if I want to see the entire subject (a camera in this case), I need to back up now. And by backing up, I am changing the distance between me and the subject, which changes the DOF calculation as well. But it has not changed the aperture of the lens, it has only changed how I might intend to use it. The DOF caculation is the same math as it always was (aperture size and distance to subject = DOF), saying that the aperture has now changed will really mess with the calculation of DOF as well as exposure. It is wrong IMO to say that. If someone bought a crop sensor and wondered why their DOF appears to be different, they never really understood DOF in the first place.

 

But note the bottom example, the focal reducer aims the beams of light together towards a smaller point of light. As they do that, they are less scattered and more dense, and thereby more intense. The resulting image that hits those photosites is therefore brighter as a result. The resulting image is therefore the same framing and DOF as the original on a full frame, however now it has the added side effect of being at least a stop brighter as well!

 

To all those saying the math in the video appears to be correct:

It may appear to have worked in his example, but its like saying that 2 * 2 = 4, therefore * means addition. Yes, in that case, the answer is correct (2+2=4), but not for the correct reasons. When you try to apply the same math to 3 * 3, your answer won't be what you expected it to be (according to the incorrect assumption, you might say 3 * 3 = 6, however those that understand that * really means multiplication will be expecting the correct answer of 9). His math may appear to work, but his explanation is patently wrong for it!

[dishe]

No need to apologize but I don't think you have the technical understanding to know what you're talking about.  Please stop making yourself look foolish.  

 

Your argument is that (quoting you verbatim) "it it were an F/5.6, images would be extremely dark indoors."  And you're here calling people *asinine*?  Your understanding of how light passes through the lens and how the data is written to your memory card, and everything in between is probably beginner level at best.

 

Just because you are being loud, obnoxious and trying to demonstrate the little knowledge that you have about technology doesn't make you correct.

 

If you had watched the video and read what people are actually saying in the comments, (which you obviously didn't do) is that these small lenses and sensors are delivering *the equivalent of* lenses of higher F-stop numbers when it comes to DOF and noise, and by not making it obvious to everyday consumers, they are getting away with charging premium prices.  But you probably just glanced over it and didn't even catch the *when it comes to DOF and noise* part, and you're just trying to prove everyone wrong without listening to what was said first.

 

Ok, I'll give you one thing- perhaps I was a bit more rude than necessary. I did watch the video, and I even participated in some of the comments there. I don't usually get riled up over petty things on the internet, but this is a subject that is very dear to me. I have engineering in my blood, my father holds some patents involving polarized glass, and I used to teach production mechanics to a high school extra-curricular program. I spent a lot of time as a kid learning about optics with my dad, so when someone starts spreading misinformation on the internet that is accepted like gospel, it stirs something up inside of me. 

 

I apologize if I came off as stand-offish, and if I insulted anyone personally, I truly did not mean it. At worst, I tried to insult ideas which I know to be wrong, but never insult the people saying them (however, your words above are a bit more personal- just saying).
Since I'm clearly stepping on some people's toes, I'll politely back into my corner. Right or wrong, I'm not in this to prove anything about myself. It may be telling, however, that Andrew's opinion (who's technical prowess is why this site exists in the first place) agrees with me. And anyone who seems to know a thing or two about this stuff appears to be arguing with that video. You want to call me a liar? Good luck with that. I'm done.

 

Andrew- I'm sorry I asked you to unlock this thread. I really thought we could help set the record straight, but it appears that we may have just confused a lot more people. :(

[dishe]

Oh, one more thing (since I'm getting it all out of my system).

 

To those who agree with his assertion that camera manufacturers are somehow "ripping you off" because the F/2.8 works more like a 5.6:

 

Understand that wider apertures are more expensive to engineer and produce than smaller ones. The glass is larger and heavier and requires more quality control in the optics. Canon doesn't charge more based on the DOF you get by using it, they charge more because it is technically more complicated to produce a constant aperture zoom with that amount of sharpness and aperture.
Whether you are getting the same DOF as a full frame camera or not, the glass being produced by crop sensor manufacturers like Panasonic has an aperture of F/2.8. The aperture is a measurement of how light passes through that lens, and the lens in this situation IS, in fact, an f/2.8. So why should they not be allowed to charge what an F/2.8 costs? Because YOU don't find it as useful as it is on a full frame? How is that a fault of the lens? It still transmits the same intensity of light, has the same DOF (if you are strictly calculating aperture to distance-to-subject, as it should be), still costs them the same amount of R&D to make because it IS actually a 2.8 aperture. So why are they ripping you off by charging the requisite amount for it? 

 

Don't get me wrong, I wish it were cheaper, but it seems appropriately priced for what it is. 

[andy lee]

well said Dische

 

f2.8 is f2.8

 

all this comparison to full frame is cog wash .......lets go filming instead.......far more fun!!

[AndrewM]

Don't want to make it a fight (or any more of a fight than it has been in this thread...) but...

 

It is much harder to make a full-frame f/2.8 than a m43 f/2.8 - that was part of the point of my earlier post. You have to produce a quality image circle that is 4x the area, which takes more glass and a lot more precision.

 

I think a lot of this discussion is being prompted by the competing cameras with different formats, but also by the speedbooster and like products. We know now that you can take a full frame lens and bolt on some more glass and get a great product  for a crop sensor with an amazing aperture that outcompetes the "native" crop lenses in many ways. And people love it. So why are the lens makers for smaller formats producing lenses that just match the aperture of the larger format lenses, when the speedbooster makes it clear that they could do better?

[dishe]

Don't want to make it a fight (or any more of a fight than it has been in this thread...) but...
 
It is much harder to make a full-frame f/2.8 than a m43 f/2.8 - that was part of the point of my earlier post. You have to produce a quality image circle that is 4x the area, which takes more glass and a lot more precision.

This is true. The full frame f/2.8 are bigger and heavier due to the increased coverage. But then there's volume vs supply & demand. Canon's lens will fit on a variety of cameras, with an exponentially larger user base than micro 4/3. That means they can afford to charge less on each one and still make enough money to be worth the effort. Panasonic, meanwhile, needs to charge more because they won't sell anywhere near as many. I'm sure they'd like to charge even more for it than they are now, but it wouldn't seem fair for them to charge significantly more than what other manufacturers charge for a similar spec option. 

 

I know it sounds like a weak excuse, but that's business. I opted for a particular phone handset that wasn't as popular as others and dealt with the same thing - was considering a Samsung Galaxy S3 back in the day, went with a relatively unknown LG model instead. When I wanted to buy accessories, spare batteries, cases, etc. Galaxy S3 options were plentiful and super cheap. Finding an option for my LG was much more expensive for the same thing, simply because it was a less common item to find. 

The compact kit lens that comes with the camera is technically more complicated than that 25mm f/1.4 prime, but they are a dime a dozen and can't hold the same price value as the fast prime.

 

Bottom line here is that creating an F/2.8 constant aperture zoom is a more complicated and expensive endeavor than their previous offerings. They should be allowed to charge more for it, and they do.
 

I think a lot of this discussion is being prompted by the competing cameras with different formats, but also by the speedbooster and like products. We know now that you can take a full frame lens and bolt on some more glass and get a great product  for a crop sensor with an amazing aperture that outcompetes the "native" crop lenses in many ways. And people love it. So why are the lens makers for smaller formats producing lenses that just match the aperture of the larger format lenses, when the speedbooster makes it clear that they could do better?

Actually, I've heard that there are Olympus f/2.0 zooms that are exactly that: Lenses originally designed for larger formats with an optical reduction element in the back. They aren't cheap either.

[jasondhsd]

This is true. The full frame f/2.8 are bigger and heavier due to the increased coverage. But then there's volume vs supply & demand. Canon's lens will fit on a variety of cameras, with an exponentially larger user base than micro 4/3. That means they can afford to charge less on each one and still make enough money to be worth the effort. Panasonic, meanwhile, needs to charge more because they won't sell anywhere near as many. I'm sure they'd like to charge even more for it than they are now, but it wouldn't seem fair for them to charge significantly more than what other manufacturers charge for a similar spec option. 

 

I know it sounds like a weak excuse, but that's business. I opted for a particular phone handset that wasn't as popular as others and dealt with the same thing - was considering a Samsung Galaxy S3 back in the day, went with a relatively unknown LG model instead. When I wanted to buy accessories, spare batteries, cases, etc. Galaxy S3 options were plentiful and super cheap. Finding an option for my LG was much more expensive for the same thing, simply because it was a less common item to find. 

The compact kit lens that comes with the camera is technically more complicated than that 25mm f/1.4 prime, but they are a dime a dozen and can't hold the same price value as the fast prime.

 

Bottom line here is that creating an F/2.8 constant aperture zoom is a more complicated and expensive endeavor than their previous offerings. They should be allowed to charge more for it, and they do.
 

Actually, I've heard that there are Olympus f/2.0 zooms that are exactly that: Lenses originally designed for larger formats with an optical reduction element in the back. They aren't cheap either.

 

But when you think about it the Panasonic considers the two X zooms equivalent to canon L zooms.  The Canon 70-200 f2.8 sells for $2300 compared to the Panasonic 12-35 f2.8 which sells for $950 so roughly the panasonic is 60% smaller and 60% cheaper. So from that perspective just comparing the physical attributes the lens are prices competitively against one another.   On the other hand if you want to try and directly compare full frame dof, angle of view, etc like the video has then you'd only have to compare it to the 24-70 L f4 which is only $1500 the higher aperture number is compensated by using a higher ISO.   See I do get what the video is TRYING to say but the problem is 1. No one is lying. 2. Doing crop factors for ISO noise is a moving target with no baseline.  3. Not everyone cares about full frame equivalent. 

 

That said, I think if Panasonic revised their zooms to f2 or below constant aperture and could keep the price within $100 or $200 of the current prices I would be an extremely eager buyer and I think they'd boost mft sales significantly. 

[Damphousse]

Is it just me or was the guy's rant totally unnecessary?  I could understand if m4/3 sales were booming and eroding Canon's bottom line but that simply is not the case.  m4/3 sales are anemic.  Panasonic can say whatever they want.  The sell hardly any cameras to the average consumer.

 

And the idea that you would start introducing ISOs and aperture nomenclature that varied from the norms is insane.  The average consumer doesn't understand ISO, aperture and bokeh as it is.

 

The examples he pulled up in his video are just m4/3 fanbois.  I mean comparing a m4/3 camera to a Hasselblad?!  C'mon.  Only an idiot would do that.  The fact of the matter is you don't have to be a genius to go over to DPreview and compare different cameras at different ISOs.  You can see for yourself the noise difference.  The guy is acting like no one every compared noise levels between cameras.

 

I'm sorry it's like I said, for most people m4/3 is a solution looking for a problem.  Just like this guy's video is a solution looking for a problem.  The fact is m4/3 sales are small to tiny.  On top of that many people that go spending a thousand dollars on a lens have the common sense to look at sensor noise comparisons and make an informed decision.

 

If I was lucky enough to be able to afford a GH4 right now I would get it for its wonderful video.  I would not get it to compete with a EOS-1D X stills.  I am sure there are some uninformed consumers that think a sub $1000 m4/3 camera can compete with a full frame camera that costs as much as a small car but most people are smarter than that.

[dishe]

Is it just me or was the guy's rant totally unnecessary?  

 

Everything about this video is totally unnecessary. The internet as a whole is stupider because of it, IMO.

[fuzzynormal]

 If someone doesn't know the differences before plunking down $1000+ then they're an idiot. 

 

That's the bulk of the consumer camera market you know.

[varicam]

That's the bulk of the consumer camera market you know.

 

I think it's more like the prosumer (or enthusiast) market.  Consumers just use iPhones/Android/Lumia.

[dishe]

Lumia's gots the MEGA megapixels!  :lol:

[Axel]

ISO was a reliable factor in analog photography, it had to be. It can still be a reliable factor if you calculate exposure for one and the same camera. I am afraid this is no longer true for digital cameras with different sensor sizes and different ways a full HD video (and in most cases it's not video they are built for!) is derived from a multitude of pixels on that sensor (pixel binning, line skipping, bicubic scaling, and I don't know how debayering fits into this), let alone the question whether cranking up the signal is done by actual electronic gain or just changing the gamma of the raw video before it's baked into a compressed 8-bit file. Because an often ignored fact is, that DoF has another factor: CoC, introducing the pixel size as equally important as the sensor size, or in other words: The sensor size means nothing unless you don't know the pixel size on it. The same lens with the same aperture will have different DoFs at different ISOs. How is that? Because using higher than the sensor's native ISO results in lower resolution. The pixels with actual signals within the noise are being sampled over time (video of cause), but they effectively behave like bigger (and therefore less) pixels, increasing the depth of field.

 

EDIT: On the net, this correlation is frequently denied, stating that higher ISO allowed for smaller apertures and that this alone would then increase the DoF. I admit that CoC combined with ISO is not a very obvious factor. There should be tests executed by maintaining exposure exclusively with ISO and NDs to prove or refute the theory.

 

All this math to reliably compare just too many contributing factors is futile imo. 

 

Try and buy the fastest lenses available for your system, speedboost them if possible, is my advice.

[jgharding]

I feel many beards are being stroked and much confusion is being forged, but I pity those who stray into this uncharted cove without the proper armour...