# Does Crop Factor Affect Aperture?



## deveaushawn (Dec 29, 2013)

For example, I have an Olympus OM-D E-M5 and want to shoot with a Nikon 24mm 2.8D lens using an adapter.

I understand that my camera will double the Field of View, making it equivalent to a 48mm lens on a FF camera, but does the 2x crop factor also double the aperture?

I have never shot Full Frame, so I don't even really know what I'm missing in terms of FoV; I just frame the shot as I want it to be. 

Aperture though, if affected, will determine depth of field and it would be nice to know how it is affected.

Thanks,

Shawn


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## amolitor (Dec 29, 2013)

No. Aperture remains the same unless your adapter changes the actual focal length of the lens (e.g. a teleconverter). Note that the ACTUAL focal length is not usually changed, the crop factor makes the lens 'equivalant to' whatever, but does not actually change the optical focal length of the lens.


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## KmH (Dec 29, 2013)

While the lens aperture will be the same, the DoF will not be the same because of the different image sensor size.
Digital Camera Sensor Sizes: How it Influences Your Photography


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## Solarflare (Dec 30, 2013)

Adapters typically dont change the optics at all, they just make a lens fit to another lens mount than the original one for this lens.

Thus all parameters stay the same.

Except if the sensor size is different (i.e. smaller, because if it was larger, the lens wouldnt fill the full sensor with light), then focal length now means something different.


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## lennon33x (Dec 30, 2013)

deveaushawn said:


> I understand that my camera will double the Field of View, making it equivalent to a 48mm lens on a FF camera, but does the 2x crop factor also double the aperture?



This is somewhat of a misconception. A 24mm lens has the same FoV as a 48mm (with a 2x crop factor). There is an increase (significantly) in distortion in a 24mm compared to a 50mm. It doesn't necessarily make the 24mm equal to a 48mm lens. It just retains the same field of view. 

I _personally_ would only shoot a 24mm on a crop factor for _*maybe*_ group pictures (and at a pretty significant distance away from the subject(s)), never for portraits. It distorts the faces of the subjects too much for my taste.


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## deveaushawn (Dec 30, 2013)

reavesce said:


> I _personally_ would only shoot a 24mm on a crop factor for _*maybe*_ group pictures (and at a pretty significant distance away from the subject(s)), never for portraits. It distorts the faces of the subjects too much for my taste.



AH! Distortion.... Hadn't considered that. So my question then is, what does one use on a m43 camera that is _equivalent _in all respects to a given FF lens? Most of the information I find relates to FF. For example, I've read that a 50mm FF lens replicates (approximately) what we see with our eyes. Does a 50mm m43 lens do the same, or do I need a 25mm m43 lens?

I apologize if these are stupid questions; I don't get out much!


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## lennon33x (Dec 30, 2013)

deveaushawn said:


> reavesce said:
> 
> 
> > I _personally_ would only shoot a 24mm on a crop factor for _*maybe*_ group pictures (and at a pretty significant distance away from the subject(s)), never for portraits. It distorts the faces of the subjects too much for my taste.
> ...



I forget when it came about, but it wasn't but too recently that 50mm became the "gold standard" for what we see with our eyes. What I think the real conversion is is somewhere around 42-46mm. But our eyes are drastically more sensitive. 

Unless you move to full frame, you won't truly get every aspect the same. For instance, when I shot with my 50mm on my old T3, it gave me an 85mm perspective. Which was great, except that my distortion was weird. When I moved to a 5D, wow, did that make a difference. Working distance improved, DoF was more dramatic (albeit more difficult) and low light sensitivity was great. If you can do it, move to FF.


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## lennon33x (Dec 30, 2013)

deveaushawn said:


> AH! Distortion.... Hadn't considered that. So my question then is, what does one use on a m43 camera that is equivalent in all respects to a given FF lens? Most of the information I find relates to FF. For example, I've read that a 50mm FF lens replicates (approximately) what we see with our eyes. Does a 50mm m43 lens do the same, or do I need a 25mm m43 lens?  I apologize if these are stupid questions; I don't get out much!




Here's an explanation by Greg Cazillo







The only thing that really changes is FOV. I never quite got it until I made the switch. 

What are you shooting (in regard to subjects)?


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## deveaushawn (Dec 30, 2013)

reavesce said:


> The only thing that really changes is FOV. I never quite got it until I made the switch.
> 
> What are you shooting (in regard to subjects)?



Thanks reavesce. The video helped a lot. 

Unfortunately, the more I learn, the more I'm realizing I likely should have gone FF from the start. I did tell myself that I was purchasing the E-M5 to _introduce_ myself to dSLR photography, so I'll use that excuse for now. If nothing else, I have a teenage daughter that has taken an interest in photography, so I could go FF (when money allows!) and donate my m43 gear to her.

I like to travel, so tend to shoot landscapes and architecture. I bought m43 because of the size; I don't want to carry heavy gear around. I also like the fact that it is a little more discreet when working in public. 

I'm happy to stick with my current gear and get as much as I can out of it. Being a n00b, I'm sure it will take quite a while to outgrow it. 

I really appreciate all the helpful, friendly folks who take the time to share their knowledge and experience with us n00bies!


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## lennon33x (Dec 30, 2013)

deveaushawn said:


> reavesce said:
> 
> 
> > The only thing that really changes is FOV. I never quite got it until I made the switch.
> ...



I'm glad I started the way I did. I learned what and what not to do and what I did and didn't like. Photography is an ever-evolving and learning process, and I'm sure the veterans will say the same thing (granted it is much easier for them to accomplish something that we as "newbies" seem difficult). I don't have a particular familiarity with landscapes and architecture - just my preference. I like taking photographs of people. Someone with more experience in that genre should be able to help. 

Understanding the basics is key to extrapolating more info. I recommend checking out "Understanding Exposure" by Bryan Peterson; it can give you more insight than you thought. 

Also, don't discount the gear you already have - I've seen some phenomenal work from crop factor cameras.


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## astroNikon (Dec 30, 2013)

I asked this question in the past (such as the title).

What I read in one of the Sigma 1.4 lens descriptions which I was trying to get answered (I cannot find the specific lens information anymore, I forgot which one), was that the description stated something like ... with the 1.4 aperture it gathers light similar to a Full Frames 2.8 aperture.   I cannot recall the wording exactly but that is what I thought it meant.

So I came to understand that a crop sensor affects the "real" aperture from what is stated versus a full frame.  
But I never got an answer to my question.


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## lennon33x (Dec 30, 2013)

astroNikon said:


> I asked this question in the past (such as the title).  What I read in one of the Sigma 1.4 lens descriptions which I was trying to get answered (I cannot find the specific lens information anymore, I forgot which one), was that the description stated something like ... with the 1.4 aperture it gathers light similar to a Full Frames 2.8 aperture.   I cannot recall the wording exactly but that is what I thought it meant.  So I came to understand that a crop sensor affects the "real" aperture from what is stated versus a full frame. But I never got an answer to my question.



I saw on a different thread that DoF changes in FF because of a decreased working distance (i.e. subject is closer to camera). That's what "improves" DoF


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## astroNikon (Dec 30, 2013)

reavesce said:


> astroNikon said:
> 
> 
> > I asked this question in the past (such as the title).  What I read in one of the Sigma 1.4 lens descriptions which I was trying to get answered (I cannot find the specific lens information anymore, I forgot which one), was that the description stated something like ... with the 1.4 aperture it gathers light similar to a Full Frames 2.8 aperture.   I cannot recall the wording exactly but that is what I thought it meant.  So I came to understand that a crop sensor affects the "real" aperture from what is stated versus a full frame. But I never got an answer to my question.
> ...



but this was not DOF that I am refering to.
This was specifically speaking about the light gathering ability of FF vs crop, and how a larger aperture such as 1.4 on crop is similar to a 2.8 on FF.


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## astroNikon (Dec 30, 2013)

here it is

So I was reading this lens review 
Sigma 18-35mm F1.8 DC HSM Review: Digital Photography Review

and came across this
_
Sigma's choice of F1.8 as maximum aperture isn't a coincidence; it means that the lens will offer the same control over depth of field as an F2.8 zoom does on full frame. What's more,* it will also offer effectively the same light-gathering capability as an F2.8 lens on full frame*. By this we mean that it will be able to project an image that's just over twice as bright onto a sensor that's slightly less than half the area, meaning the same total amount of light is used to capture the image. This is important as it's a major determinant of image quality. Essentially it means that APS-C shooters will be able to use lower ISOs when shooting wide open in low light and get similar levels of image noise, substantially negating one of the key advantages of switching to full frame.


_

But now that I have a DX and a FX camera, I can actually test it if I really wanted to.


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## deveaushawn (Dec 30, 2013)

astroNikon said:


> here it is
> 
> So I was reading this lens review
> Sigma 18-35mm F1.8 DC HSM Review: Digital Photography Review



I read the same review astroNikon, which is what prompted my question in the first place.


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## lennon33x (Dec 30, 2013)

I'm not really sure about this. If this is true, then wouldn't it apply to all lenses when it comes to crop factor vs ff? 

It would be interesting to see if someone tested this out & posted it here


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## lennon33x (Dec 30, 2013)

After re-reading it, I think it is essentially comparing the difference between 1.8 and 2.8 on aps-c to full frame. The FF offers greater light sensitivity, and at the two comparative apertures, are probably equal. 

What I mean is this:
The histogram of the same image/setup on a FF camera at 2.8 should be equal to 1.8 on a CF camera. The reason it's probably occurring is bc of the greater light sensitivity of FF. 

I can test this theory out tomorrow. My coworker has the old T3 I sold her and I'll shoot the same setup (ISO/shutter speed) with the same lens and I'll let you know what happens


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## astroNikon (Dec 30, 2013)

per your other question ... crop vs FF for working distance can be seen here
http://www.thephotoforum.com/forum/...rence-between-full-frame-cropped-sensors.html


With the aperture, The theory, as I'm assuming is this:
a crop camera uses a smaller area than a FF while using a FF lens
Thus, it's not taking in all the light that a 1.8 or 2.8 lens takes in on a FF camera .. it's using less of the projected image area. So if you cut out the extra light that isn't being used (as in the above link) then a 1.8 aperture is really the same amount of light gathering as a 2.8 lens.

That is what I assume the above review meant.
I can actually test that theory .... we'll see if I have time later on.

a crop specific lens, if I understand it correctly, can use less glass etc as it only has to project an image large enough for a crop sensor.  If you use a crop lens on a FF camera then you get black/vingetting heavily around the edges as the image is not large enough to cover the entire FF sensor.


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## timor (Dec 30, 2013)

Aperture is about intensity of the light on every square millimeter of sensor or film and size of the medium have no influence on that. It is not about "gathering" the light, it is about transmission. If the light meter is showing f8 at 1/100 of a second with ISO 100, it applies to any size of the camera and sensor and lens in any combination.


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## lennon33x (Dec 31, 2013)

So I tested this out with a 1.8 lens on both my 5D and my old T3. Same distance, ISO, shutter speed. I looked at this histograms, and it appears that at 2.8, the 5D FF captures less highlights and more shadows, and at 1.8 on the T3, more highlights. I'm not sure that Sigma is really boasting anything about a lens, but more about theory of wider apertures.


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