Nx 50-150 is it really F4.2

I have just bought the Samsung 50-150 for a great price but my excitement was slightly dampened after finding that F2.8 lens on APS-C is really equivalent to F4.2 full frame lens.  Is this true?

Milondon15 wrote:

I have just bought the Samsung 50-150 for a great price but my excitement was slightly dampened after finding that F2.8 lens on APS-C is really equivalent to F4.2 full frame lens. Is this true?

This great article might help clarity things for you:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

If you read the paragraph under "Aperture" you will find the following answer "f2 is f2 is f2 and f8 is f8...period.

Hope this relieves your anxiety about your lens purchase because this is a GREAT lens.

That's the kind of 'terrorism' spread by the worshippers of FF. The article linked by harley should clarify everything.

btw, aperture is a property of the lens, NOT of the sensor/camera.

Milondon15 wrote:

Krazyheaven wrote:

I'm pretty sure 2.8f is still 2.8f. It's the same speed. The only change being the dof.

Makes me feel much better now.

Great....now get out there and enjoy that awesome lens!  I know you will be impressed.

Some misinformation in this thread.  It is not only the DOF that is different, but also the noise because there is less total light reaching the sensor.  An extensive coverage of the topic is here: josephjamesphotography.com/equivalence

So, yes, in some significant ways it does perform in a way similar to that of an f/4.2 lens on a FF camera, but exactly the same as if you used those FF f/2.8 lenses on an APS-C camera.  But using a Canon 70-200 on their APS-C (1.6x) is like a 112-320mm f/4.2 FF equivalent whereas the Samsung is like a 75-225mm f/4.2 In terms of DOF, but also photon shot noise if the FF and APS-C sensors being used have the same quantum efficiency.

Don't get me wrong, I'm no FF sycophant.  I may have a 5D, but it is a very old camera and my NX1 is far superior.   I am eyeing the 1dxII though, we'll see if it's worth the upgrade to shoot side by with the NX or not.  I prefer the NX system over anything else on the market, but physics is physics and while yes, the lens IS f/2.8, it does not act as an old film FF user would expect an f/2.8 lens to act (and for historical reasons that is some sort of de facto standard, we could just as easily calculate everything in relative terms to any other sensor size, say m4/3) in terms of angle of view, shot noise, and DOF.   Whether you're happy with the physics or not is up to you, I'm quite satisfied with f/2.8 on APS-C for the vast majority of cases.

Harleysoftail wrote:

Milondon15 wrote:

I have just bought the Samsung 50-150 for a great price but my excitement was slightly dampened after finding that F2.8 lens on APS-C is really equivalent to F4.2 full frame lens. Is this true?

This great article might help clarity things for you:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

If you read the paragraph under "Aperture" you will find the following answer "f2 is f2 is f2 and f8 is f8...period.

Hope this relieves your anxiety about your lens purchase because this is a GREAT lens.

Most of this article is very good.  I would quibble about the aperture bit though. He doesn't say anything wrong, but while the f/2.8 on APS-C and on FF have the same brightness, they have different noise levels (for final output images of the same size at the same viewing distance, which is the standard for comparison).  It's true that if your final output is proportionate to the sensor size then this doesn't matter though.   I guess I should also be careful if we are talking about the same framing or the same distance to the subject if we consider DOF.

Harleysoftail wrote:

Milondon15 wrote:

I have just bought the Samsung 50-150 for a great price but my excitement was slightly dampened after finding that F2.8 lens on APS-C is really equivalent to F4.2 full frame lens. Is this true?

This great article might help clarity things for you:

http://www.bobatkins.com/photography/tutorials/crop_sensor_cameras_and_lenses.html

If you read the paragraph under "Aperture" you will find the following answer "f2 is f2 is f2 and f8 is f8...period.

Hope this relieves your anxiety about your lens purchase because this is a GREAT lens.

I'm sure the linked article is great. But f2 is not f2 is not f2. That's the whole point. In SOME WAYS your f/2.8 is f/2.8 is f/2.8, and in SOME WAYS it is "just like" or "very similar to" f/4.2 on full frame... otherwise people wouldn't have invented the term "equivalent aperture".

Here's the whole story in as short a nutshell as possible. (I didn't read the article)

+ Your 50-150 2.8 will be "the same as" a 75-225 f/4.2 on full frame in the following sense: the field of view and depth of field will be precisely the same. (That's why they are "equivalent").

+ It is "different" in the sense that the PHOTONS PER UNIT AREA PER UNIT TIME is different. (say, 50 f/2.8 on APS-C or 75 f/4.2 on FF). It is the f-number that tells you the photons per unit area per unit time. This is the info you need (photons per unit area per unit time) to compute the exposure properly.

+ So if you compare a 50-150 f/2.8 on APS-C to a 75-225 f/4.2 on FF, the FOV and DOF will be precisely the same, but you will need to expose longer or increase the ISO on FF since you are at f/4.2. For "equivalent sensor technology" for fixed exposure time (say 1/60 second) increasing the ISO on the FF will give essentially the same image with the same noise.

+ (OPTIONAL READING) Of course a 75-225 f/2.8 on full frame will have a narrower DOF and less noise for the same exposure time since you are back down to the same ISO you were using on APS-C but one doesn't always WANT narrower DOF (I can rarely get two human faces in focus on APS-C at anything more open than f/2.8 unless I have people glued into a chair).

DONE.

Please no more discussions of equivalence

anywhere

ever

Go get the Samsung lens if you aren't worried about extinction of the NX line.  Full frame is overrated (Sony wants you to buy buy buy!!!).

http://www.dpreview.com/articles/2666934640/what-is-equivalence-and-why-should-i-care

If only, but unfortunately some people don't accept physics and https://xkcd.com/386   ^_^

Its full frame equivalent lens would be 75-225 f/4.2, yes, but it is still a 50-150mm f/2.8 lens, those physical properties never change.

The equivalent part comes into play if you were to use a 70-200mm f/4 lens on your 6D, shooting at 200mm f/4 ISO250 1/100 sec you would select 135mm f/2.8 and ISO100 1/100 sec to get exactly the same shot: framing, depth of field, image noise, and shutter speed (assuming similar sensor tech).

You will find that full frame offers more flexibility, but is not unilaterally better. There is always a trade off. For full frame you can trade depth of field for faster shutter speed, longer shutter speed for lower image noise, etc.

Of course not. Your lens is equivalent to 550-1650mm f/31 lens in full frame. You do know that 8x10 is full frame? 36x24mm is small format photography...

I'm not old enough to know, so I'm really asking.  I see people say that sometimes, but was the "full frame" moniker actually ever commonly applied to large format?  My impression is that the term started being used with the first digital cameras that were 35mm since it was such a common format in film and the typical user of it was previously being forced to downsize to jump to digital.   I could be totally wrong though.

It's true that the sensors are usually not the same, but quite often in these comparisons the newer better tech sensor is actually in the APS-C body (Sony being the apparent exception since they're iterating their FF so fast).  I think it is important to mention the light though,  because it is why FF appears to be less noisy, not because of bigger pixels and whatnot (actually that matters, but not in the way the average Joe thinks it does).  Maybe we should try to make it more clear that it's not a slower lens per se, but a slower-ish (I don't like the terms fast and slow for lenses... I know why they are used but feel they're a bit misleading) lens/sensor combo and it's not different than their expectations probably were anyway for the combo?  Light per pixel isn't the issue, it's the total amount of light given the same final size comparison, pixels aren't needed to derive this at all.

It was more a joke, not to think about numbers but to shoot and enjoy oneself

I guess it depends on geography (language) as well, in Germany they (35mm - 135) were called kleinbildfilm (small image film). They were a revolution as they allowed compact cameras you could just carry with you (take a look at some of the more compact, for example, Konica models - they are tiny and yet 35mm).