How are reach and sensor size related and what are the merits of different options?

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  • snakebunksnakebunk Posts: 976Member
    edited January 2014
    Ok, here is a summary of my point of view.

    When I hear "reach" I think of how far away you can be to your target and still get a decent picture. To me the term is only relevant in situations where it's hard to get close enough. Two things are important:
    1. The focal length. Determines the magnification.
    2. The pixel density. Determines how much you can crop before the pixels of the image gets larger than the pixels of your target display (and you want to add a little bit of a margin to that).

    At some point you start to get other issues though, for example too much hot air between the target and the lense, the camera is not steady enough or the quality of the lense is not good enough.

    There is one thing that has absolutely nothing to do with reach and that is the sensor size. It just happens that small sensors often have high pixel density.

    So, the short answer to your question is: No, they are not related.
    Post edited by snakebunk on
  • donaldejosedonaldejose Posts: 3,393Member
    Of course sensor size and reach are related. That is the whole 1.5 times multiplier thing. You see your image in the viewfinder using the entire viewfinder, not just a part of it. You want to compose your photo using all of the viewfinder (i.e. all of your pixels) not just a part of it. Consider the issue of photographing a bird across a stream. You have a 300mm and two bodies: a 24mp D610 and a 24mp D7100. You have good enough light to shoot either body at 200 ISO. When you put the lens on the D610 you see the bird occupies about one half of the frame and you effectively have about 12 megapixels covering that bird. When you put the same 300 mm lens on a D7100 the bird occupies almost the entire frame and you have about 24 megapixels covering that bird. The difference in whether or not you are using all your camera body has to offer in this situation is due entirely to the additional "reach" a 24 mp DX sensor gives you over a 24 mp FX sensor. In situations where you want to get closer but cannot for whatever reason (danger, subject will fly away, impassable obstruction, etc) the same lens on a DX sensor will allow you to optically "reach out more" and get closer to your subject. Thus, DX sensors give you more "reach" than FX sensors using the same lens.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    . Thus, DX sensors give you more "reach" than FX sensors using the same lens.
    Yes but the Fx photographer is using the "wrong" lens, if he know in advance he going to have to crop he should use the "right lens " eg 450mm and he will have exactly the same reach as the Dx man

    Yes a 400m or 500mm lens is going to cost more than the 300mm and there is absolutely no denying, a very big advantage the DX, is that it cheaper

    It can reasonably be argued that the additional cost of FX is difficult, to justify, as most people may not notice the improvement in image quality, but provided you use the "right lens" there will be an improvement

    There little or nothing that can be on Dx that cannot ( at a price) be done with FX




    Post edited by sevencrossing on
  • donaldejosedonaldejose Posts: 3,393Member
    edited January 2014
    Sure, but as I pointed out earlier with the current 34 mp DX sensor compared to the current 24 mp FX sensors you are paying more than 4 times more money for about one stop more IQ. If you had the D610 and the 300mm lens you could spend $!,200 for the D7100 to get the shot or you could spend $8,000 for a 500mm f4 lens to get the same shot and have about one stop better IQ. If you are not forced to work at high ISO and can shoot at ISO 200 and will not be printing larger than about 16 x 24 that extra image quality should not be evident in your image.

    Given the same lens reach varies between FX and DX. Or you can have the same final reach if you use different lenses. It all depends upon whether or not the lens stays constant in the comparison made.
    Post edited by donaldejose on
  • ben_dmbben_dmb Posts: 87Member
    donaldejose - remember the teleconverter option too.
  • PB_PMPB_PM Posts: 4,412Member

    @PB_PM: The question is about reach and sensor size and not about the general benefits of FX.
    .
    Which is exactly what I've talked about the entire time. I'm not saying FX is inherently better, never did. My point has been, and always will be, that DX does not inherently provide more "reach" aka magnification, simply by having a smaller sensor. It's simply a matter of the physical characteristics of optics. There is no argument here, it's a matter of facts. If people want to ignore the science of optics that's their problem not mine.
    If I take a good photo it's not my camera's fault.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    <.<i> If people want to ignore the science of optics that's their problem not mine.
    but if we just stuck to facts , NFR would die over night
    there is every chance of thread overtaking the D400


    Post edited by sevencrossing on
  • hawkdl2hawkdl2 Posts: 56Member
    PB_PM is absolutely correct. There is no inherent "reach" advantage in shooting DX vs FX with lenses of the same focal length. The only argument for DX is that the quality, not the number, of pixels on image may be superior to the pixels on image form a cropped FX sensor. That resolution from DX sensors were, and may still be in some cases, superior to the the DX-area of an FX sensor does not equate to a conclusion that DX sensors have a "reach" advantage. The only point of contention should be whether the DX-area of current FX sensors sensors, such as the 15MP "DX" area of the D800 sensor is superior or inferior to the current 24MP DX sensors. And I presume all would agree that is not just a matter of pixel numbers.



  • PB_PMPB_PM Posts: 4,412Member
    edited January 2014
    Exactly. I never questioned the pixel pitch advantage that DX bodies have, purely the argument that DX provides more magnification! Apparently making that point makes me an FX fanboy.

    To me, having FX provides both framing types in one body. Is it perfect? No. Does it have more pixel pitch than the D7100? No. Can both camera types get the job done? Yes. There has been no contention on my part to suggest otherwise, despite others putting words in my mouth.
    Post edited by PB_PM on
    If I take a good photo it's not my camera's fault.
  • donaldejosedonaldejose Posts: 3,393Member
    edited January 2014
    Interesting question, is the 15mp DX area of the D800 sensor superior to the 24mp DX area of the D7100 sensor? According to DxOMark data the DX area of the D800 sensor would have acceptable noise at 2853 ISO while the DX area of the D7100 sensor is only acceptable to 1256 ISO. Clearly the D800 DX area is superior if you have to shoot in low light. However, if you can shoot both at ISO 200 I would expect the extra 9 megapixels to provide the D7100 with a visible advantage. Perhaps someone knows if this it true or not?

    Of course as ben_dmb points out using a teleconverter will also put more megapixels on the subject and is a good solution if it does not degrade image quality too much.
    Post edited by donaldejose on
  • IronheartIronheart Posts: 3,017Moderator
    edited January 2014
    If we want to talk physics and science as PB_PM suggests, lets take a look at real world example:

    For this example assume the following: You need 1000mm equivalent at f/5.6 and you have to carry it 10 miles into the wilderness over a field of boulders to get your shot, and you have to go alone. Capital expense is irrelevant, you can choose whatever you want as long as you get 1000mm at f/5.6.

    With FX you will have to carry a 35+ lb lens into some rough terrain, as the only lens I can find to do this is the Sigma 200-500 f/2.8 with a built-in 2x teleconverter. With DX you get to take a 10lb 400mm lens and a 1.7 teleconverter (you get a bonus of 1/2 of a stop and 20mm) With CX you could take the 80-400 f4.5-5.6 for a mere 3.5lb

    So which one would you take? I know how heartyfisher would answer :-) So go ahead, use whatever lens and teleconverter combo and sensor size, as long as you get to 1000mm equiv. at f/5.6. My point here is that there are places where DX will get you that FX wont. My next post will talk about a situation where DX again has the inherent advantage, from a scientific viewpoint, regardless of cost.
    Post edited by Ironheart on
  • hawkdl2hawkdl2 Posts: 56Member
    Ironheart - I respectfully suggest you are missing the point PB_PM and I are trying to make. You can get the same weight and "reach" advantage by putting your light[er] weight DX lenses on your FX camera and shoot in DX mode, or crop later. The ONLY issue if whether you will be satisfied with the IQ of the image from the, say, 15MP D800 sensor vs. the image you would get from whatever DX camera you would intend to use. And that is a matter of evolving camera sensor technology, not an inherent "reach" advantage of DX vs. FX.
  • IronheartIronheart Posts: 3,017Moderator
    I'd take the 24mp DX over the 16mp DX (D800 crop) any day of the week. I was primarily responding to sevencrossing's comment:

    There little or nothing that can be on Dx that cannot ( at a price) be done with FX
  • MsmotoMsmoto Posts: 5,396Moderator
    I suppose I could start a new thread on this, but as it relates to the issues of DX vs. FX, crop factors, etc., I will drop this here: I had a motorcycle shot of Josh Hayes (D4, 400mm f/2.8, TC-20EIII) and wanted to print it on aluminum. At the time I could not find the original due to a glitch in Lightroom, so I downloaded the 2000 pixel size from my Flicker photostream. This was then made into a 20" x 40" print was is an eye stopper…..seen here:
    Motorcycle_For _Print Example Image

    And, this came from the original here:
    Josh Hayes in Six1

    See the crop, then imagine the cropped size was uploaded to Flickr as 2000 pixel JPEG, then downloaded by me, edited and exported as a TIFF for printing on aluminum. All this suggests to me, unless one is going to wall sized prints, the arguments of quality, DX vs, FX are far more academic than of any real practical value.
    Msmoto, mod
  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    All this suggests to me, unless one is going to wall sized prints, the arguments of quality, DX vs, FX are far more academic than of any real practical value.
    I think it is a lot more complicated than that
    It not only depends on which DX camera compared to which FX Camera
    it also depends on subject matter and lighting conditions
    In good lighting conditions which a subject were the detail in highlights and shadow are not too important you may not need FX or probably ever as DX

    It is when the condition get tough that FX cameras start to earn their keep

    In a landscape with subtle colors and tones, if the highlights are blown and the shadows clogged, the size of print is irrelevant

    at low ISO values the IQ of the D7100 does seem to be coming very close the a D800 and if I was recommending a camera to an keen amateur the D7100 would be a the top of the list

    but for most professional shooting a wide range of subjects in a wide range of conditions I suggest a tried and rested D3s, a D4 or the fantastic D800


    Post edited by sevencrossing on
  • heartyfisherheartyfisher Posts: 3,181Member
    edited January 2014
    I have been fairly amused and confused by this thread ... its seems incredibly obvious to me that the DX format has the reach advantage over FX. but since there are so many people arguing the opposite (and they are not trolls ! ) then what is interesting to me is that there must be something / some factor that is as yet unquantified by both sides. Some how this factor is being looked at from different directions. Looking forward to having this thread discover what that factor is ! :-)
    Post edited by heartyfisher on
    Moments of Light - D610 D7K S5pro 70-200f4 18-200 150f2.8 12-24 18-70 35-70f2.8 : C&C very welcome!
    Being a photographer is a lot like being a Christian: Some people look at you funny but do not see the amazing beauty all around them - heartyfisher.

  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    Looking forward to having this thread discover what that factor is ! :-)
    My belief is, we all have a differ definition of the word "reach"

    Reach : To sail with the wind abeam.



    Post edited by sevencrossing on
  • spraynprayspraynpray Posts: 6,442Moderator
    Or: Reach - involuntary gagging reflex bought about by too much talk of FX superiority over DX in this thread.

    LOL! =))
    Always learning.
  • WestEndBoyWestEndBoy Posts: 1,456Member
    edited January 2014
    I have been fairly amused and confused by this thread ... its seems incredibly obvious to me that the DX format has the reach advantage over FX. but since there are so many people arguing the opposite (and they are not trolls ! ) then what is interesting to me is that there must be something / some factor that is as yet unquantified by both sides. Some how this factor is being looked at from different directions. Looking forward to having this thread discover what that factor is ! :-)
    Heartyfisher, I think that you have hit the nail on the head. Sevencrossing, you have hammered the nail in. I have been reading all the comments in this thread and thinking about them while trying to stay out of the discussion. Believe me when I say how hard that was. Also, I appreciate every contributor to this thread. Without disagreement, the advancement of knowledge is impossible and this thread has highlighted our disagreements while being civil.

    However, after all of the above comments and Heartyfisher and Sevencrossings most recent comments, I think now is the time to express my view.

    I think it boils down to this:

    A 300mm lens at F/4.0 on an FX sensor will produce a similar depth of field and field of view as a 200mm lens at F/2.8 on a DX sensor (I used http://www.similaar.com/foto/dof/dof.php for my DOF calculation). Effectively, they are "both the same".

    Neither option has more "reach". How many "pixels are on the bird" depends on the camera model. A D610, D7100, D5300 and D3300 will all be identical in this regard with the above respective DX/FX lens.

    So what are the other important variables:
    1.
    Low light performance. FX sensors are almost always superior but in the above example is on an F/4.0 lens. The DX with the F2.8 somewhat compensates. How closely it compensates will depend on the sensors involved.

    2.
    Weight. This is hard to say. 300 is generally heavier than 200 but F/4.0 is generally lighter than F/2.8. The answer will depend on the lens being compared.

    3.
    Lens Cost. Would a DX 200mm 2.8 be cheaper than an FX 300mm 4.0? Dunno. The answer will depend on the lens being compared.

    4.
    Camera Cost. A D610 is certainly the cheapest FX and is more expensive than the D400, the most expensive DX. Did I say D400??? I am so sorry. D7100.......

    5.
    Lens quality, particularly resolution. This answer again, will depend on the lens being compared. This also seems to be the hardest test to perform. I believe that a superzoom's point and shoot's failings would be most apparent in this area, which is why serious birder's don't use them.

    I am sure that I have missed some factors, and I welcome hearing what they are, but my conclusion is as follows:

    To say, "this lens/camera combination has more or less reach" is a meaningless statement, as it does not specify what it is being compared to. If one says "X has more reach than Y", then we have something to discuss. To say that "DX has more reach than FX" is a misleading statement because as this thread has demonstrated, nobody agrees on the definition of reach. I could not find a definition in http://www.oxforddictionaries.com/definition/english/reach and Oxford has a reputation for being the gold standard of English dictionaries. Even if someone can come up with a definition quoted somewhere, someone else can come up with a definition quoted somewhere else that is different and most readers will be confused even if we all get together and vote on the definition. All you can say is that DX has a narrower field of view but to argue that a narrow field of view is superior without considering the other variables is also misleading. However, if someone argues that I get a narrower field of view with the same megapixels but at a cheaper cost but with lower lens resolution, then we can have a discussion.

    So perhaps when somebody says "reach", we should substitute "field of view" for "reach" and see if the statement still makes sense. If somebody says, "X has more/less reach" without specifying "Y", we should ask what "Y" is.

    My "two bits".


    Post edited by WestEndBoy on
  • donaldejosedonaldejose Posts: 3,393Member
    I believe sevencrossing is correct as to why the debate continues: just different definitions of the word "reach."

    Msmoto provided a really great practical example; but I would like one more bit of information. Her wonderfully dynamic image starts as a 16mp image from her D4. Not 24mp from a D610 or D7100 or 36mp from a D800. She reduces it to 2,000 pixels and prints it 20 x 40. Now just what is that 2,000 pixel size she refers to from flicker? I see no such size on my flicker account. I am assuming it is 2,000 pixels horizontally across the image so her original flicker photo was about 2,000 pixels by 1,335 pixels for a total of 2.67 megapixels in the image she started with. Then she cropped that to less than 2 megapixels. So her final 20 x 40 image contains less than 2 megapixels and is stunning. Sort of proves KR's statement of not needing more than 6 megapixels for poser size prints, doesn't it? Also sort of proves another of KR's statements that the bottom of the line D3300 with its 24mp DX sensor is all one really needs even for poster size prints: the reason to pay more is not for increased image quality but for factors which make an advanced user able to more quickly capture the image they want to get (such as quick access to functions through dedicated buttons rather than a complex menu, larger easier to view viewfinder, portrait orientation shutter release, more fps, etc). KR isn't completely nuts!

    I am still waiting for the D400 but if it doesn't surface this year I probably will get a D7100. Now that we have a series of very excellent and reasonably priced lens (such as the Tokina 11-16mm f2.8, the Sigma 18-35mm f1.8 zoom, the Sigma 35mm f1.4, the soon to arrive Sigma 50mm f1.4, the Nikon 85mm f1.8, the Nikon 105mm macro or the Tokina 100mm macro, the Nikon 70-200 f4, the Nikon 300mm f4, etc) I should be able produce everything I want at an image quality greater than I will ever need by swapping those less than $1,000 lenses between an FX and a DX body. The DX body will give each of the FX lenses more "reach" so the Sigma 35mm f1.4 becomes a DX 50mm extremely sharp normal with great bokeh; the Nikon 85mm f1.8 becomes a very sharp DX 130mm portrait lens; the 105 macro become a 150mm macro lens for creature which fly away when you get too close, the Nikon 70-300 f4 becomes a 105-450 mm zoom for wildlife, and the Nikon 300 mm f4 becomes a 450mm prime for birding. A 1.4 teleconverter can extend that range further by turning the 300mm f4 with teleconverter (420mm) into a 630mm DX telephoto for birds and wildlife (if the combination works well!). By using two bodies I can cover the range from 11mm to 450mm (or 630mm) without spending more than $!,000 on a lens. Thought of another way a DX body with a very high quality sensor allows me to get double duty out of all FX lenses.
  • spraynprayspraynpray Posts: 6,442Moderator
    @donaldejose: Don't forget the 2x crop option of the D7100 too.
    Always learning.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    so the Sigma 35mm f1.4 becomes a DX 50mm extremely sharp normal with great bokeh; the Nikon 85mm f1.8 becomes a very sharp DX 130mm portrait lens; the 105 macro become a 150mm macro lens for creature which fly away when you get too close, the Nikon 70-300 f4 becomes a 105-450 mm zoom for wildlife, and the Nikon 300 mm f4 becomes a 450mm prime .
    and here we have the cause of some of the confusion

    It does not matter what camera you put a lens on, the focal length remains unchanged

    If you move a 300mm from a D800 to a D7100 it is still a 300m lens it does NOT magically turn it self into a 450mm lens

    Yes the field view will change but it is still a 300mm lens

    and as the D7100 has different sensor to the D800 there will be other changes but the focal length remains unchanged

    Yes what mean is EQUIVERLANT, but why do DX users want to think in FX terms
    when I moved from large format to 35 mm, I did not think of a 50mm lens being an equivalent of a150mm lens







    Post edited by sevencrossing on
  • snakebunksnakebunk Posts: 976Member
    Of course sensor size and reach are related.
    The D7100 has more reach than the D610 because it has much higher pixel density, not because the sensor is smaller.

    Imagine that you use a D610 in DX crop mode. Imagine that you fill the frame with a bird. Now imagine that you switch to regular FX mode. Does the reach change? No, you will only get extra pixels around the bird.

    I think this example is the best I can do to explain why reach is not related to the size of the sensor.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited January 2014
    snakebunk" The D7100 has more reach than the D610 because it has much higher pixel density, not because the sensor is smaller.

    If this is the case, does the D800 has more "reach" than the D600, the D4 the Df or the D300 ???

    To answer my own question. it just depends of your definition of "reach"
    Post edited by sevencrossing on
  • donaldejosedonaldejose Posts: 3,393Member
    spraynpray: Yes, teleconverts and the 1.3 crop mode on the D7100 DX are additional factors. In my example you can turn the 300mm f4 into a 600mm using the "crop" feature of the D7100 and you have "full frame" autofocus, However, you do lose pixels and are looking at a smaller image (the viewfinder doesn't enlarge your image as it could if it were an EVF).

    sevencorssing: Of course the focal length of the lens remains the same and all you are doing is looking at a smaller part (angle of view) of the image that lens projects. The point of making the comparison to 35mm for those of us old enough to think that way or to FX for younger people is just to make a quick mental math comparison to wide, normal, portrait lens common designations. Those of us who spent years with 35mm still think that way. Like in the US we still think yards, feet and inches rather than metric dimensions. Just us old fogies.

    My point is and always has been quite simple. We are used to thinking of using a different lens when we want to get closer to the subject if we cannot simply zoom with our feet. We should expand that box. If we are shooting with FX we also should think of simply swapping camera bodies to achieve the same effect. The new 24mp DX sensors are so good both in megapixels and in ISO ability that I think an FX user can now think of them as a way to expand the effective range of the lenses he or she already own. Whether you call that "expanding the range of your reach" or "narrowing the angle of view" or "multitasking lenses with equivalent mm" or whatever doesn't really matter. The point is the same. I believe it is now a good option.
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