Zooms unnecessary with high megapixels & crops out of primes

Now and then people say they don't need primes anymore seen the high iso's of nowadays and that a f2.8 zoom is fast enough with ISO 6400-25400 etc...

But in fact we can turn this statement otherwise : zoom's aren't necessary anymore as we can crop easily with all those megapixels.
Do you find the quality equal or do we lose sharpness by this?

For example i'm just back from a carsafari, I forgot my 70-200 2.8 and took only pics with 35L & 85 1.8.

For close pics I used only 85 1.8 (shows with eagles,...) and can take crops of which the quality is very decent as prime quality is excellent.
Offcourse the not too long primes to be able to crop

I dont fully understand how a person can replace a prime with a zoom or vice versa.

I love hearing comments of people loving their 35L and dont regret selling their 24-70L...huh????

IMO a person will become a better photographer shooting primes while being forced to foot zoom and learn composition. On the same note that same person will be able to use their composition skills and now use the power of the zoom to vary the perspective.

Many birders crop their photos aswell as spend $$$$$ for high quality long primes and zooms. Megapixels are helpful if you have enough to play with. A 10mp camera cannot be a nice tool if your consistently being aggressive in cropping photos. So high MP can be our friend.

There's more to it than low-light performance. Fast primes offer large apertures (for shallow DoF), that zooms can't. Zooms offer versatility, and IS..which short primes don't have.

You're not going to crop a shot of an airplane at an airshow with a 35L, and crop it to a decent, viewable shot.

It's not only or even for a lot of people mainly about quality. Many people visualise by seeing the exact framing in a DSLR viewfinder.

Back in the 1950s, when you couldn't frame very accurately with rangefinders, cropping was much more routine than now.

Apart from that, who wants to spend the time cropping everything in post, or trying to figure out what part of the frame caught your fancy 3 weeks ago on the other side of the world?

I think it is the other way around... zooms make cropping unnecessary.

if you really think about how the camera works, it's not the megapixels that grant great cropping ability, it's the size of the sensor. The megapixels only determine the size of the image generated by the sensor following after processing of the image. The higher the megapixels, the higher the "density" of the image (higher number of image area per amount of sensor size), but the actual quality of the image is determined by the sensor size.

Take, for example, utilizing a crop sensor and a full frame. You use the 1.6 field of view crop factor because the sensor on an APS-C camera is 1.6 times smaller than the sensor on a full frame--this achieves the effect of making an image from an APS-C camera appeared more "zoomed in", which people may view as a valuable attribute; however, the reality is that cropping the final image from a full frame sensor down to 1.6 times it's original diagonal length achieves the exact same effect as taking a picture with an APS-C camera. The only advantage of an APS-C camera is that you are able to achieve high density images more easily (high number of megapixels per area of sensor). Due to the squaring effect (linear increases in length amount to exponential increases in area), in order to retain the same resolution you get from an 18MP APS-C camera, you'll need to have a full frame sensor that outputs to ~47 megapixels (hopefully I did that right).

Until we get a 47MP full frame (which is pretty inpractical), the 18MP APS-C will continue to have a "resolution advantage" (although be careful with the term "resolution", its actually a politically incorrect term, "pixel density" is more correct) over full frame cameras. This arguably makes them better for taking giving one a range advantage with the 1.6 FOVCF, but, for the reasons I just explained, density only helps so much, as you're typically more limited by the sharpness of your lens. If density were more important than sensor size, we would all be using cell phone cameras with ultra high megapixels (okay maybe not, but you get the point).

All of this being said, does the statement "zoom's aren't necessary anymore as we can crop easily with those full frame sensors" hold much water? In a way, yes it does, granted that you're willing to live with an image that does not live up to its full potential. again, pixel density aside, cropping the final image is effectively exactly what we do with APS-C cameras; however, if you have the ability to zoom in (or shoot at longer focal lengths), you retain the (relatively) full quality of the image whist not having to move in closer to your subject. Also, different focal lengths meter a scene differently (subject to background ratio), and obviously grant different depths of field.

Let's see someone zoom out via crop...

I have a question concerning this :

In past I always took .cr2 reduced size RAW's to save some space (even with a 32GB card). Now I have put the setting again to full RAW.
Reason was that I thought if I take crops of full RAW's instead of smaller .CR2 raws that the quality of the image (density,details,sharp​ness,...) would be better than taking crops of a smaller .CR2 RAW

So this isn't the case as both are taken with fullframe sensor ?

brennanyama wrote in post #15056977
if you really think about how the camera works, it's not the megapixels that grant great cropping ability, it's the size of the sensor. The megapixels only determine the size of the image generated by the sensor following after processing of the image. The higher the megapixels, the higher the "density" of the image (higher number of image area per amount of sensor size), but the actual quality of the image is determined by the sensor size.

CanonYouCan wrote in post #15056851
But in fact we can turn this statement otherwise : zoom's aren't necessary anymore as we can crop easily with all those megapixels.

This is equal to the statement that electronic zoom is equal to optical zoom. It is somewhat disturbing that in photography anybody would set electronics equal to optics.

CanonYouCan wrote in post #15056851
But in fact we can turn this statement otherwise : zoom's aren't necessary anymore as we can crop easily with all those megapixels.
Do you find the quality equal or do we lose sharpness by this?

In the past doing this (cropping an image and pretending it was the same as zooming in) was known as 'Digital Zoom'. It was rightly sneered at by anybody who knew the slightest thing about digital imaging. Nowadays it is seen only on the cheapest and nastiest of bottom-level consumer P&S cameras, normally those found in cereal boxes.

CanonYouCan wrote in post #15056851
But in fact we can turn this statement otherwise : zoom's aren't necessary anymore as we can crop easily with all those megapixels.
Do you find the quality equal or do we lose sharpness by this?

Well in some cases this might be true... An ultra wide angle probably doesn't need to be a zoom as the zoom ratios are generally poor on such lenses anyway and the impact from cropping won't usually be too severe.
But, by no means on my standard walkabout 15-85mm can I expect comparable image quality by taking a photo and cropping at 15mm, than I can by taking a photo at 85mm.

Ah offcourse I forgot, correct, cropping is digital zooming and this is lower quality, I remember when I bought bridge camera's that I always chose max optical zoom 12x or 18x at that time as I knew digital zoom wasn't interesting

But I +- managed reasonably well taking some crops of 85mm prime shots, didn't lose too much sharpness,... probably cause it's out of a prime image.

And what about my second question, is making a crop out of a full RAW image higher quality than out of a smaller .CR2 RAW, or what is the actual difference, or is it the same as they are both fullframe images ?

hollis_f wrote in post #15057110
In the past doing this (cropping an image and pretending it was the same as zooming in) was known as 'Digital Zoom'. It was rightly sneered at by anybody who knew the slightest thing about digital imaging. Nowadays it is seen only on the cheapest and nastiest of bottom-level consumer P&S cameras, normally those found in cereal boxes.

hollis_f wrote in post #15057110
In the past doing this (cropping an image and pretending it was the same as zooming in) was known as 'Digital Zoom'. It was rightly sneered at by anybody who knew the slightest thing about digital imaging. Nowadays it is seen only on the cheapest and nastiest of bottom-level consumer P&S cameras, normally those found in cereal boxes.

I just spent almost $400 for an SX260HS. It has digital zoom, which is near impossible to use. I think it is a marketing department gimmick. Is the SX260HS a cheap and nasty bottom-level consumer P&S? If so, it is in good company. The S100 and G1X both offer digital zoom.

CanonYouCan wrote in post #15057148
And what about my second question, is making a crop out of a full RAW image higher quality than out of a smaller .CR2 RAW, or what is the actual difference, or is it the same as they are both fullframe images ?

The mRAW and sRAW images are given in pixel dimensions that are not the same as the "pixel" dimensions used for the sensors used in current EOS cameras, which have sensels rather than pixels. For a black and white image, there isn't much difference, but for a pure red image the mRAW might be close to the resolution of the full camera sensor. This is because only 1/4 of the sensels are R(ed). The mRAW OTOH has RGB for each pixel - the camera interpolated all the R pixels for not much loss.

(Sort of. In recent Canon cameras, R is closer to orange, but it's the principle I want to demonstrate.)

In general, though, a 22Mpx raw file will demosaic to about 22Mpx of RGB image. And of course mRAW and sRAW have fewer pixels. So if you chop the middle 3/4 out of any of them, for example to simulate a 135mm focal length when you only had a 100mm lens, you lose 25% of the resolution. The mRAW and sRAW won't "catch up", but will get 25% worse than they were, which was usually worse than the full raw.

One more thing: I want to warn you off storing mRAW and sRAW long term. By all means, they are useful for agencies and media to save on bandwidth, but they should immediately be converted to standard TIFF or JPEG. Software support for mRAW and sRAW has been patchy.

EDIT - it *is* also true that cropping also "blows up" any softness in the lens. There are too many different lenses to generalise, but I will say I see this with some of my lenses on 1.3 crop vs. full frame. However, it is clearly possible to build a lens sharp enough for this not to matter, so in *theory* this isn't relevant. I suspect it *is* relevant with your 85mm f/1.8.

Simple. Pick a subject and take a with 70-200mm f2.8 at 20mm. Now take same shot with your 35L. Then do same with 85mm f1.8. Crop whatever and post here. You will have the answer in like 5 mins of your time.