Is a 300mm really a 300mm or is it something else

Discussion in 'Olympus Cameras' started by fsuscotphoto, Jun 8, 2013.

  1. fsuscotphoto

    fsuscotphoto Mu-43 Top Veteran

    Feb 15, 2013
    St. Cloud, FL
    I know that this has been gone over in every forum forever but maybe I've just not seen a plain English answer.

    If I have a 300mm on my 7D it's "really" a 480mm equivalent. A 300 on my OMD is a 600. Now, is there really a difference in what is being captured or is the field of view just a lot more narrow?

    Obviously, I've got a mental block!

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  2. mikekiwi

    mikekiwi Mu-43 Regular

    Dec 16, 2010
    The Netherlands
    Well, indeed the field of view will be narrower, but also there will be a bit more compression of items in the background (they appear to be closer to each other). But I think the difference between 480mm and 600mm will be very limited in that respect.

  3. kevinparis

    kevinparis Cantankerous Scotsman Subscribing Member

    Feb 12, 2010
    Gent, Belgium
    does it really matter?... what you see in the VF or on the LCD is what you get.

    its not like there is an alternative

  4. fsuscotphoto

    fsuscotphoto Mu-43 Top Veteran

    Feb 15, 2013
    St. Cloud, FL
    No, and that's really my point. If they are all the same, then all of that is just bloviating. But if there really is a difference, then that 300mm on my Oly means not bringing a second camera with me on some days.

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  5. Mikefellh

    Mikefellh Mu-43 Top Veteran

    Jun 7, 2012
    Toronto, Canada
    No, it's REALLY a 300mm lens! It's only equivalent to 480mm on another format, but you're not using that format.

    I don't get this about caring what the lens would look like an another format...but I guess I'm unique in having started photography using 2-1/4" square medium format, used an extreme large 24"x36" (2ft x 3ft) sheet film (tat camera is larger than a person).

    I can understand if you're comparing different formats you want a common format to compare them to, but when you're using the camera why think of another format?

    It's like if I drive in another country that uses different units for speed. I'm used to km, but if I drive in the States where they use miles I don't think, "How many km/h 55mph is?" I just push the gas pedal down until the speedometer says 55mph.
  6. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    I occasionally stun myself about how I am able to take a seemingly simple subject and then run around in circles until I fall over.....

    What you say is kind of correct, sort of, maybe, if you're comparing formats. You should consider thinking of it in terms of either magnification or angle of view. Angle of view is the relationship between the focal length of the lens and the size of the imager (film or sensor). Either increase the focal length or decrease the size of the imager and the field of view narrows. The 4/3 sensor will show half the field of view compared to 35mm, hence the 2x equivalence.

    Another way to think about it is in terms of magnification. Assuming a "normal" lens is 1x and a normal on 35mm is a 50mm (actually a 43mm) and 4/3 is a 25mm. Then a 300mm lens is a 6x lens on 35mm and a 12x lens on m4/3 (ie: the subject will be 12x larger than if shot from the same position with a "normal" lens).

    Now that you're really confused I'll go have dinner..:smile:

  7. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, USA
    A 300mm is still 300mm. The only change is the FOV of your viewfinder due in part to the size of the sensor.
  8. Brucebrad

    Brucebrad Mu-43 Rookie

    Apr 14, 2011
    Sydney, Australia
    Here's my 'plain text' attempt (leaving out other lens and camera quality issues).

    If you have a 600mm lens on a full frame camera and an object fills the screen, then the object will also fill the screen on a 4/3 camera with a 300mm lens. This is because the sensor on the 4/3 camera is only half as wide (and half as tall).

    If the 4/3 camera has as many pixels as the full-frame camera, and each of these is as 'good' as the pixels on the full-frame camera (despite being only half as wide and half as tall), then the 300mm on the 4/3 really is as good as the 600mm on the full frame. Otherwise not.
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  9. FrayAdjacent

    FrayAdjacent Mu-43 Veteran

    The focal length of a 300mm lens on any camera, is 300mm.

    The field of view is different depending on the sensor size. When they say a 300mm lens on an APS-C sensor is "480mm equivalent", they are talking about the field of view.
  10. PaulGiz

    PaulGiz Mu-43 Veteran

    Jan 3, 2013
    Rhode Island, USA
    The lens stays the same, its magnification factor stays the same.
    It is your camera's sensor that crops the field of view.


    If you're the same distance from that thingamajig, nothing is different except the cropping.

    The thing is, if you frame a thingamajig to fill your 4/3, then use the same lens to frame the thingamajig to fill 24mmx36mm, (used to be miniature format, now apparently is HUGE "full frame") you will need to move closer, thus changing the perspective.

    Doesn't really matter, look through the hole or at the screen, click when you like what you see.

  11. carpandean

    carpandean Mu-43 Top Veteran

    Oct 29, 2010
    Western NY
    I've never seen the problem with having a single number that can be compared across all formats, since many photographers and certainly the users of many forums use more than one format. It's true that physically a 300mm is a 300mm is a 300mm, but does that really help anyone? The OP has a Canon APS-C camera and a :43: camera, so it can be useful when looking at his/her lens lineup to have a single number for each lens. Having a 35mm lens for each format (even if it's just the same lens with an adapter) means actually having two different options for framing pictures (for a given distance, which is still important because moving closer to or further away from the subject changes perspective), not just one. Sure, the 35mm/FF choice is rather arbitrary, but that's the one that most of the world has settled on.

    Is fine to say things like "does it matter? Just look through the viewfinder and shoot what you like," but that doesn't help when making purchases or when choosing which lenses to grab or even when talking online.

    For the OP, it may help just to know that the crop factor for :43: vs. Canon APS-C is about 1.23 (or roughly a quarter more.) So, that 300mm on :43: will look roughly like a 375mm on the 7D (though, the native aspect ratio is a little squarer.) It's not much more complicated to say that the 300mm on :43: will look like a 600mm on FF, while the same lens on the 7D will look a 480mm (actually, about 486mm, since Canon's APS-C crop is 1.62x.)
  12. fsuscotphoto

    fsuscotphoto Mu-43 Top Veteran

    Feb 15, 2013
    St. Cloud, FL
    I appreciate all the replies. Let me simplify the question after reading them: Will my APS-C 300 see exactly the same as my MFT 300, except for field of view? Or does the MFT 300 really get me more reach?

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  13. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, USA
    The reach advantage is real. The OM-D's 16mp sensor yields excellent results when shooting telephoto. The only limitation really is the glass at this point. DSLRs have better choices when it comes to solid telephoto primes.

    Though, I've compared Nikon's new 80-400 VR II (cost $2800) on a D800 versus the OM-D and 100-300 OIS ($499), honestly for a telephoto zoom I'd rather use the OM-D/100-300 combo and pocket the money difference. The only noticeable advantage is that the Nikon combo will be superior in continuous focus tracking.
  14. Cruzan80

    Cruzan80 Mu-43 All-Pro

    Aug 23, 2012
    Denver, Co
    Sean Rastsmith
    Yes, and yes (perception wise). The 300mm gives you the same scene, at the same aperture, etc. All that happens is that on the m4/3 arts of it gets cropped off (due to sensor size differences). When making the print the same size, it gives more "apparent" reach, as an object will be larger on the m4/3, due to it being a crop of the image compared to the APS (larger portion of the frame). Alternatively, if you were to take a 300mm shot on APS, and take ~80% of the center, you will see the same thing as a photo taken on m4/3.
  15. LovinTheEP2

    LovinTheEP2 Mu-43 Top Veteran

    Feb 15, 2011
    Crap. Had a long post and darn ipad mini and cookies etc and submitted and lost my iD so lost my post when submitted!!! Argggg


    For bokeh, I feel it's more then 2 and more like 2.5 - 3 depending on focal length.

    Due to 2 actual crops in real world ie sensor size and then image format size between m43 and aps I feel it's not quite 2. You need a bit more length in m43 and then post process crop and lose some pixels so its more like 2.1x to 2.2x

    So if you plan on using 2 formats often, 1st pick a consistent image format 1st accepting you'll be throwing pixels in 1 of the systems, give m43 extra buffer over the stated 2x crop factor if you want real world as close to possible image for both f- number for subject isolation and also in telephoto changes and with understand you need to move your feet as well if you want to get the same image from both systems.
  16. rhoydotp

    rhoydotp Mu-43 Top Veteran

    Aug 5, 2012
    Toronto, Ont
    finally a correct answer to the question! :2thumbs:

    i get what the OP is asking. on my full-frame, I'd be very happy to shoot with my 50mm and still be able to be versatile with the composition. But the same 50mm on my Nikon DX format, it starts to feel like a 70mm. And then, the same 50mm on a m43 feels like a 100mm. Yes, I know it's technically 50mm and that can't be changed no matter what you do. But it definitely change the feel/composition that I use for the same exact lens
  17. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    I think this is the easiest way to visualise it:

    - Forget about cameras first - just imagine a lens projecting its image onto a sheet of paper behind it. Let's say the lens has a 300mm focal length.

    - Now draw a box on the paper to represent the sensor frame. If it's a big sensor (say FF), then the box will be bigger and there will be more in it than if we drew a smaller box (say MFT).

    - So, we see a smaller bit of the image if the sensor is smaller.

    - Now imagine that we want the big box (FF) to have the same size image in it as we got with the smaller box. How do we do that? Well, we can make the lens's focal length longer. By the magic of maths, we find that since the diagonal of FF is twice that of MFT, then we need a lens of twice the focal length to pull the trick off.

    - So, we find that a 300mm lens on MFT has the same field of view as a 600mm lens on FF. so, we have a 'crop factor' of 2 when comparing MFT to FF.

    So far so good. It gets complicated though when you start comparing different focal lengths on different formats and distances from camera to subject. There's talk about DOF, magnification, 'reach' etc. IMHO, it's best just to forget all that and get to know what different focal lengths do on the camera you're using.
  18. Yohan Pamudji

    Yohan Pamudji Mu-43 Veteran

    Jun 21, 2012
    Mississippi, USA
    I don't know if this will help or confuse further, but in terms of reach the commonly used metric is the number of pixels on target, or in some circles "pixels per duck" (assuming you're photographing a duck :smile:). Will you get more pixels per duck with a 300mm on a 16MP m4/3 sensor vs. a 300mm on an 18MP APS-C sensor? Yes, but not a whole lot more. If your goal is to not have to bring along an APS-C camera to get the reach you want then that goal is certainly met by the 300mm + 16MP m4/3 sensor combo.
  19. fsuscotphoto

    fsuscotphoto Mu-43 Top Veteran

    Feb 15, 2013
    St. Cloud, FL
    Does it matter what kind of duck? GRIN!

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  20. fsuscotphoto

    fsuscotphoto Mu-43 Top Veteran

    Feb 15, 2013
    St. Cloud, FL
    Thanks everyone! I found a discussion on this over at DPR and it devolved into a scientific discussion that totally lost me. I majored in history and economics...anything beyond H2O and I'm lost! This was very helpful.

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