Cropping, megapixels and sensor size

[PicLiz]

Hello...Could someone explain to me about the relationship between the amount of mp and cropping. If you have a full frame sensor with 24 mp and one with 45 mp will the 45 mp sensor provide more detail in post processing, so therefore a better image? Also, is cropping in post processing about the same result you get when using a smaller sensor to begin with? I hope that makes sense.

(I have been reading about this, but am still confused. I thought I wanted a bridge camera, but ended up sending it back and decided I will use my em5 mk3 as a "bridge" camera with an all in one lens. I am thinking about getting an older full frame mirrorless camera as I have never had a full frame, and have recently discovered that shooting in raw and using lightroom is the way to go! I like to shoot birds, wildlife at the park, my dogs and family indoors and the occasional landscape when on vacation.)

Thanks for any help.

 

[ahaslett]

At one time, I was regularly shooting MFT 16Mpix, MFT 20Mpix & Sony FE 61Mpix. I now mostly switch between 20Mpix and 61Mpix. I've also shot FT 8 & 12Mpix and FE 36 & 42Mpix.







Essentially you are right that cropping is the same as shooting with a smaller sensor but otherwise the same settings.

For example, the FE bodies can be made to produce an APSC RAW crop from their sensor, which they do automatically if you mount an APSC lens on an FF body. That gives 61/1.5/1.5 ~= 26Mpix resolution and the DR of an APSC sensor. That's remarkably close to what you would get mounting the same FF lens on an A6xxx E-mount APSC body.

If you crop further to MFT size and aspect ratio, you get the DR of an MFT sensor and about 15Mpix, so about the same as an older MFT sensor like my GM1 or EM1.

Things get a bit more complex if you buy an older DSLR body because some of them had sensors significantly worse than modern sensors. For example older Canon DSLRs had DR a bit worse than modern MFT bodies, despite being 4x the area. Unless you bought a really expensive EF lens, OM Pro and Panasonic Leica lenses are usually better than standard range EF lenses. Modern lens technology has advanced as much as sensors.

So, if I shoot an OM5 with the PL 25/1.4 attached at say f1.4 1/100s and an A7CR at 50mm f2.8 1/100s, I get similar images but with different aspect ratios and likely more detail and "pop" in the FF image, depending on the FF lens used. I have a CV 50/2 APO Lanthar, which is a better lens than the PL, so that would deliver.

In theory if the MFT body was at ISO 200, the FE one would meter at ISO 800 in auto-ISO but that depends so much on jpeg settings and metering. Both sensors are relatively ISO invariant and I shoot RAW, so it's the aperture and shutter speed that matter, since ISO only affects exposure via metering against jpeg output.

Does the difference between MFT 20Mpix and FF 61Mpix matter? Well yes, otherwise I wouldn't have both. It only matters photographically for what I shoot when I am shooting landscape (detail and DR) or a high DR scene (like an interior with light streaming from windows) Since I'm a RAW shooter, I can claw back quite a bit of the difference by using a Custom UniWB to reduce the loss of exposure headroom from jpeg metering.

IS makes quite a bit of difference when shooting handheld in low light, for example inside churches. My OM5 will beat my A7Riv at that every time. The A7Riv needs a tripod.

Lenses matter a lot - for example veiling glare around windows, LoCA etc. The best MFT lenses are pretty good (but expensive), although there are fails like the OM 20/1.4.

The other advantage of FF is that zooms start getting big and expensive below about f2.8, and primes below about f1.8. Compare the weight and cost of a PL 12-35/2.8 with a PL 10-25/1.7 or an OM 17/1.2 with an OM 17/1.8. A f2.5 FF lens provides about the same light gathering and subject isolation as a f1.2 MFT lens with the same angle of view (because the entry pupil is the same diameter and you are the same distance from the subject). MFT has the advantage that low light AF depends on f-stop, so shooting at f2.8 for MFT beats f5.6 for FF.




Shot with a Viltrox 35/1.2 LAB FE lens

There is no 17/0.6 MFT lens, so the shot above required an FF body. The Viltrox cost me £770 new discounted, a used OM 17/1.2 Like New from mpb is currently £499 or discounted to £1,099 new. The Viltrox is 910g and the OM 390g.

Diffraction depends on depth of field, so it's the same photographically for any sensor size whatever misleading comments people make about MFT providing greater DoF (apart from that point about low light AF).

TLR There is no magic that makes FF always photographically better than MFT in any way that matters. You need to compare use cases against specific gear to make choices, in my case every time I pack my bag.

Hope that helps.

A

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[jthomas39]

I will use my Z6 (and my Z6 iii, they are the same size sensor). It's a full-frame ("FX") 24 MP camera, and can shoot "DX" mode or with DX lenses. That's APS-C size, approximately a 1.5x factor. The FX or DX are Nikon names for the two sizes.

~~~

Z6

Z6 full size: 6048 x 4032 pixels.

Z6 in DX mode: 3936 x 2624. 6048/3936 = 1.537, so the quoted"1.5" multiplier is approximate, but "close enough".

There's no difference between cropping the center of a full size image in an editor to the 3936 x 2624 size, or switching the camera to DX mode and shooting that smaller size image directly.

~~

Advantages of the full size crop: There's lots of room to move the crop to re-frame the scene. Good for birding with fast moving birds, for instance.

Advantages of the DX APS-C shooting: The camera uses this smaller area for exposure and for white balance and for focusing, so it can be more accurate. The scene fills the viewfinder, so it's easier to compose the scene, too. The file sizes are smaller, saving some storage space.

~~~~

Z7

The Nikon Z7 series is a 45 MP full frame camera.

Z7 full size: 8256 x 5504

Z7 in DX mode: 5408 x 3600. This DX photo has more pixels, so bird photographers like it.

~~~~~

4K displays:

My PC display is a 27 inch, 4K monitor, 3840 x 2160 (note the 16:9 view, a less tall format than the FX or DX 3:2 modes.)

So I sometimes resize the photo in the editor output, to be 3840 wide. That doesn't leave much room for cropping a Z6 DX image, which is just 3936 wide. When shooting, careful framing helps!

 

[John Crowe]

Yes a 45MP FF sensor shows more detail than a 24MP FF sensor. This has nothing to do with RAW file post processing.

APS-C versus FF depends on the number of pixels involved. My Canon APS-C, which is smaller than all other APS-C cameras delivers 32.5 MP. My 50MP FF Canon when cropped to match my Canon APS-C delivers only 19MP. If I can't match the APS-C camera by using a longer lens on the FF, then I shoot the APS-C.

I have used APS-C alongside FF for more than half of my digital years so that I don't have to crop full frame images.

 

[ishwanu]

If you have a full frame sensor with 24 mp and one with 45 mp will the 45 mp sensor provide more detail in post processing,

In general, yes.

so therefore a better image?

More detail is usually considered better.

Also, is cropping in post processing about the same result you get when using a smaller sensor to begin with?

In general, yes.

II thought I wanted a bridge camera, but ended up sending it back and decided I will use my em5 mk3 as a "bridge" camera with an all in one lens.

That's fine if it works for your purposes.

I am thinking about getting an older full frame mirrorless camera ... I like to shoot birds, wildlife at the park, my dogs and family indoors and the occasional landscape when on vacation.

Are you thinking about buying one with a 45MP sensor and cropping it to 20MP instead of using your Olympus? Or do you intend to keep and use both formats?

 

[PicLiz]

I want to keep my Olympus with one good all around lens, as I would like a camera I can pick up and go with and not think about what lens to bring.

I am looking at a Z7ii, Canon R6ii, and Canon R7. There are some nice new bundles with these cameras out there with prices comparable to used.

 

[PicLiz]

Beautiful photos. This is a lot of information! I did not know you could aps-c cameras or vice versa.

 

[PicLiz]

So when you are looking at the images from these two cameras and you have them cropped and processed like you want them - can you tell which image came from which camera?

 

[ahaslett]

I want to keep my Olympus with one good all around lens, as I would like a camera I can pick up and go with and not think about what lens to bring.

I am looking at a Z7ii, Canon R6ii, and Canon R7. There are some nice new bundles with these cameras out there with prices comparable to used.

The 12-45/4 plus an FL-LM3 make the EM5.3 a pickup & go body. It really is a nice lens and you can see from my gear list I have a lot of lenses!




An OM5, but that’s the same body

A

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[PicLiz]

Did you mean to have photos in this post?

 

[PicLiz]

I actually have the 12-40 f2.8 and that's what I was thinking about keeping!

 

[ahaslett]

Beautiful photos. This is a lot of information! I did not know you could aps-c cameras or vice versa.

E, R & Z mounts all have APSC lenses, although E mount has far more APSC and FF lenses than R or Z. Look at the manuals to see how they handle APSC crops from FF.

I tend to crop in post, but I do have a button to do in camera APSC RAW on both my FE bodies.

Some Sony users have an APSC tele zoom for when they want reach without weight. I tend to switch to MFT for tele (40-150/2.8 and 300/4). I went all out at 100-400mm GM on FE, plus the tiny, cheap and rather weird Samyang VAF 100mm T2.3 Cine to extend a bit from 70mm. At 280g it literally punches above its weight, although it really needs to be stopped down to f2.5 at least, so it’s only an MFT 50/1.2 equivalent.





I can’t comment as between R and Z mounts, but Z has more access to 3rd party lenses, just not nearly as many as L or E.

A

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[Bill Ferris]

First and foremost, you can do good photography with whichever brand and model camera you choose. The factors that have the greatest impact on the quality of a photo are your choice of subject, light, perspective, framing, depth of field, rendering of movement, and moment to press the shutter release.

Understanding how a camera and lens affect those factors helps you to find a system that's compatible with the kind of photography you want to do. With that in mind, let's have a look at your questions.

Hello...Could someone explain to me about the relationship between the amount of mp and cropping. If you have a full frame sensor with 24 mp and one with 45 mp will the 45 mp sensor provide more detail in post processing, so therefore a better image?

All other factors being equal, increasing the pixel count does result in a more detailed image. How much more detail? The square root of the ratio of the two pixel counts tells you the maximum increase in resolution as a percentage.

• 45/24=1.875
• SQRT 1.875=1.36930

A 45MP sensor can produce an image with 37% more resolution.

What does that mean? How will it translate to the images you make? It's a difference that will probably not be readily apparent when comparing two photos in their entirety but should be discernible when comparing 100% views of the photos; when pixel peeping.

Also, is cropping in post processing about the same result you get when using a smaller sensor to begin with? I hope that makes sense.

Yes. Not only are the two photos made with the same number of pixels but, more importantly, they're made with the same total light energy.

(I have been reading about this, but am still confused. I thought I wanted a bridge camera, but ended up sending it back and decided I will use my em5 mk3 as a "bridge" camera with an all in one lens. I am thinking about getting an older full frame mirrorless camera as I have never had a full frame, and have recently discovered that shooting in raw and using lightroom is the way to go! I like to shoot birds, wildlife at the park, my dogs and family indoors and the occasional landscape when on vacation.)

Thanks for any help.

Bear in mind that a larger sensor camera has the potential to capture and use more light to make a photo, but there's no guarantee it will. If you get a full frame camera, it will be important to pair it with a lens that can realize the potential of the sensor.

 

[ahaslett]

I actually have the 12-40 f2.8 and that's what I was thinking about keeping!

That’s a nice lens too, and more general purpose. I just find it a bit front heavy on my OM5.

I got the OM5+12-45/4 as a kit for £950 after all discounts, cashback etc. The 12-40mm has been in my bag a long time. At f5.6, my copy of the 12-45/4 is better than my copy of the 12-40/2.8 mk i.

A

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[PicLiz]

Have you ever used one of the 14-140mm Panny's or Olympus lenses on your em5?

 

[ahaslett]

Have you ever used one of the 14-140mm Panny's or Olympus lenses on your em5?

Sorry, no.

I was going to get a used 35-100/2.8 mk i but the shop also had a used (very battered) 40-150/2.8. There was a discount on new ones that day, so…

I really am happy with the 40-150/2.8 and I don’t mind field lens changes (mostly).

The 14-140s are very popular - if you post about them on the MFT forum there will be responses, from Jeff at least.

A

--
Infinite are the arguments of mages. Truth is a jewel with many facets. Ursula K LeGuin
Please feel free to edit any images that I post

 

[PicLiz]

That photo is composed beautifully.

 

[John Crowe]

When viewing at the same enlarged size on your screen, yes. When printed at 16" x 20", maybe not so clear. Printed at 24" x 36" quite likely. For even larger prints, yes, this is when the 45MP really makes the difference.

I am specifically thinking in terms of filling the frame. If one starts to crop each image a lot, then of course the 45MP image will make a bigger difference in even smaller prints.

 

[PicLiz]

Thanks for your answers. Your gallery is impressive!

 

[PicLiz]

When viewing at the same enlarged size on your screen, yes. When printed at 16" x 20", maybe not so clear. Printed at 24" x 36" quite likely. For even larger prints, yes, this is when the 45MP really makes the difference.

I am specifically thinking in terms of filling the frame. If one starts to crop each image a lot, then of course the 45MP image will make a bigger difference in even smaller prints.

This is helpful, thanks. I am trying to decide between the Canon R6ii and the Nikon Z7ii. I just went to Best Buy and handled them and they both feel pretty comfortable. The Canon is supposed to have superior auto focus and the Nikon of course has more pixels. Unreliable autofocus can be frustrating, but I don't want to feel like I missed out on image quality as I will crop my bird shots a lot. But I will not be blowing them up really large, if at all. I have looked at lenses and feel I can get what I want in either brand...hence analysis paralysis. I am not a very talented photographer, but my photos really matter to me.