Comparing Olympus 4/3lenses to FX "Full Frame" offerings

Started Jan 25, 2014 | Discussions thread
Great Bustard
Forum ProPosts: 24,681
Re: Oh dear.
In reply to Tiger1, Jan 29, 2014

Tiger1 wrote:

Great Bustard wrote:

Tiger1 wrote:

Great Bustard wrote:

Tiger1 wrote:

Ian Stuart Forsyth wrote:

Nikon 300 F4 to Zuiko ed 150 F2 to canon 300 F4

No this is where we disagree. Olympus 150mm F2 is the same as a 300mm F2 FF lens.

It is not. It has neither the same focal length nor aperture diameter.

Of course it's not literally! Are you that daft?

You're asking if I'm daft because I said that a 150 / 2 is not the same as a 300 / 2 when you said, "Olympus 150mm F2 is the same as a 300mm F2 FF lens"? Huh.

Mate, put it easy to take cheap shots when taking things out of context. You have conveniently left out that ISF wrote that a Nikon or canon 300mm F4 was the same as a Olympus 150mm F2! The only way they they are similar is in the diameter of their aperture - who cares about that?

Let's put it this way: in terms of the visual properties of the recorded photo, 300mm f/4 on FF is a lot more "equal" to 150mm f/2 on 4/3 than 300mm f/2 on FF is "equal" to 150mm on 4/3.

Now why do you think that anyone would care about the aperture diameter?

You honestly ask that? Wow.

The aperture diameter is only relevant when it is coupled to the focal length because as a photographer I actually measure light intensity (or luminosity) when I use a light meter. It actually gives me an F stop and a shutter speed. It does not give me an aperture diameter and then asks me for a focal length or vice versa. So f/2 IS f/2 when it comes to taking photos! Isn't that what this whole website is about? It is not about people like you getting so pedantic as to confuse everybody about what really is important.

Wow, just wow. You really don't get it, do you? For a given perspective and framing (may I assume that perspective and framing are important photographic elements?), the same aperture diameter results in the same DOF and diffraction. When coupled with the same shutter speed, it also results in the same amount of light being projected on the sensor. If the sensors are equally efficient, this results in the same noise.

"Why do you think that anyone would care about the aperture diameter?" indeed.

The only reasonable argument is that a FF photographer could buy a 300mm F4 lens and shoot at a higher ISO to compensate for the loss of lens speed because as a general rule the latest FF sensors are less noisy than their FT counterparts.

FF sensors are not "less noisy". Instead, what happens is that the larger aperture diameter of FF lenses projects more light onto the sensor for a given shutter speed, and it is this greater amount of light falling on the sensor, not the sensor itself, that makes FF less noisy.

Gee whiz. Give up! FF sensors using a certain design/technology are less noisy than smaller format sensors with equivalent photosite count and design/technology BECAUSE their photosites are larger and therefore collect more photons and so need less amplification of signal (which introduces noise).

You are, of course, completely and totally wrong. Take a pic of a scene with the same camera and lens at 50mm f/2.8 1/200 ISO 3200 and 100mm f/2.8 1/200 ISO 3200. Crop the 50mm photo to the same framing as the 100mm photo and display them both at the same size.

So, we're using the same f-ratio, the same shutter speed, the same ISO, the same pixel size, and the same sensor tech. Which photo is more noisy and why?

They have the same per pixel noise.

Are we talking about photos, or pixels? When you look at a photo, do you see individual pixels? Maybe you need more pixels, then.

The photo that is enlarged will magnify the noise. So what?

So what? The "so what" is that less light making up the photo means more noise.

That just supports my argument. Why can't you see that?

It does the exact opposite. It tells us that it is the total amount of light that makes up the photo that matters, not the amount of light per area falling on the sensor.

Now, if we put that 300 / 4 in front of a FF sensor, the image it will record will be all but identical to the image recorded by the bare lens in front of a 4/3 sensor. Of course, I'm assuming you know how a TC works, so...

No it won't mate. The TC optically magnifies the image leading to a four fold loss of light.

The light is lost? Where did it go? Remember, we are mounting the 150 / 2 + 2x TC (which is the same as a 300 / 4 -- rather different than your use of the word "same" from the top) in front of a FF sensor.

The light is "lost" is a way of saying that you have effectively doubled the focal length so that at the same aperture diameter the f/2 value has doubled. So what?

Again with the "so what?" The "so what" is that the light isn't lost. That is, all the light that falls on a 4/3 sensor from a 150 / 2 will fall on a FF sensor with a 150 / 2 + 2x TC, but a 150 / 2 + 2x TC really does *equal* a 300 / 4.

This still means that you have effectively lessened light intensity by 4x. That is why the light is "lost".

Again, the intensity of the light means nothing. It is the total amount of light falling on the sensor that matters. I mean, it isn't magic or that larger sensors have better designs than smaller sensors that larger sensor systems have less noise than smaller sensor systems for a given exposure. It's all about the total amount of light falling on the sensor (and the sensor efficiency).

Here's another question for you. Let's say we have a FF DSLR with a 2x crop mode. We take a photo at 50mm f/2 1/200 ISO 3200 in the crop mode and another photo at 100mm f/2 1/200 ISO 3200 not in the crop mode. We display both photos at the same size. Which photo is more noisy and why?

Again. They will have the same per pixel noise of course.

Again? Can't see the forest for the trees, eh? Noise per pixel is a meaningless measure.

Noise per pixel is a relationship to the number photons being captured by photosites. The will be the same per photosite in the centre crop as in the FF shot. The crop will "appear" noisier because you have magnified the image and thus magnified any noise present.

And, again, the reason the crop is more noisy is because it is made from less light -- exactly the same reason 4/3 is more noisy than FF for a given exposure.

Now answer these questions.


Identical cameras with identical FF sensor technology except for the fact one has 36 MP and the other has 24 MP. Both shoot at ISO 12800. Same shutter speed and aperture and lens.

Which one will exhibit more noise per pixel?

The 36 MP photo will have more noise per pixel, but the photos will be equally noisy, assuming equally efficient sensors.

Why is there a difference as they both have the same amount of light hitting their sensors (remember its also 4 times what a FT sensor would receive!!!)?

As I said, in terms of the photos, there is no difference in noise, assuming equally efficient sensors. We are talking about photos, are we not?

Over to you...

OK, so we have a FF DSLR with a 2x crop mode, and it can accept 4/3 lenses.  We put an Olympus 150 / 2 on it and shoot a scene at f/2.8 1/400 ISO 1600 in crop mode.  We put a 300 / 2.8 on it and shoot a scene at f/2.8 1/400 ISO 1600 and f/5.6 1/400 ISO 6400.  We display the two photos at the same size.  Which photos look most similar and why?  How are they alike and how are they different?

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