Zoom lens vs cropping

LennyLevino · Jul 29, 2023

What are your thoughts on replacing a standard zoom with 2-3 primes and then cropping in post (on a high/45mp+ camera)? Pros/cons?

For example, switching out a 24-105mm f4 for a 20mm (crop from 21-30), 40mm (crop from 41-60) and 85mm (crop from 86-135). Is the "prime look" still there after cropping? Is it worth the hassle?

Potential benefits I see are ability to use faster apertures at certain intervals and better image quality overall (although not sure if its still there after cropping). Negatives would be needing to switch lenses, (potentially) harder to compose (as you need to remember how you're going to crop the picture later when viewing it on your computer), and loss of pixels/resolution.

richj20 · Jul 29, 2023

LennyLevino said:
What are your thoughts on replacing a standard zoom with 2-3 primes and then cropping in post (on a high/45mp+ camera)? Pros/cons?

For example, switching out a 24-105mm f4 for a 20mm (crop from 21-30), 40mm (crop from 41-60) and 85mm (crop from 86-135). Is the "prime look" still there after cropping? Is it worth the hassle?

I've used 35mm and 50mm primes for 8 years. Normally I know pretty much where I want to crop when editing.

In both of these landscapes, I cropped the foreground, and the width of the frame was not changed.

35mm

50mm

Interestingly, with the 24-105mm zoom at 35mm, then 50mm. in order to preserve the width I wanted, I would have needed to crop out the foreground the same way

--
Richard

http://www.rsjphoto.net/

Klaus dk · Jul 29, 2023

When you crop from 20 mm to 30 mm equivalent field of view, you throw away 25 of 45 Mp.

I don't think the IQ is that much better with a prime.

And what about the gap from 30 to 40?

Good luck and good light.

LennyLevino · Jul 29, 2023

Klaus dk said:
When you crop from 20 mm to 30 mm equivalent field of view, you throw away 25 of 45 Mp.

I don't think the IQ is that much better with a prime.

And what about the gap from 30 to 40?

Good luck and good light.

Well, I just did some calculations. If shooting with a 61mp camera, you can crop 2x and be left with 16mp, or 2.5x and still have 10mp. For me, 16mp is great and 10mp is decent enough for most of my needs (small or medium sized prints, or cover a full 27 inch 4k monitor).

So lets say I had the following prime lenses:

20mm (crop up to 50mm)
40mm (crop up to 100mm)
90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

LennyLevino · Jul 29, 2023

richj20 said:
LennyLevino said:

What are your thoughts on replacing a standard zoom with 2-3 primes and then cropping in post (on a high/45mp+ camera)? Pros/cons?

For example, switching out a 24-105mm f4 for a 20mm (crop from 21-30), 40mm (crop from 41-60) and 85mm (crop from 86-135). Is the "prime look" still there after cropping? Is it worth the hassle?

Click to expand...

I've used 35mm and 50mm primes for 8 years. Normally I know pretty much where I want to crop when editing.

In both of these landscapes, I cropped the foreground, and the width of the frame was not changed.

Interestingly, with the 24-105mm zoom at 35mm, then 50mm. in order to preserve the width I wanted, I would have needed to crop out the foreground the same way

Great pictures, thanks for sharing!

I enjoy using a zoom when shooting landscapes. But that might be because I've never really considered cropping, and I've always tried to frame everything perfectly in camera before taking the shot. So every time I've used a prime lens it has been a frustrating experience.

sybersitizen · Jul 29, 2023

LennyLevino said:
... So lets say I had the following prime lenses:

20mm (crop up to 50mm)
40mm (crop up to 100mm)
90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

Not necessarily right.

Particularly in the cases where noise matters most (lower light), the cropped version would be visibly noisier if it was shot with the same camera settings as the uncropped version because it was made with less total light due to the cropping.

This can be demonstrated. Both of the images below started from the same source at a resolution of 6000 x 4000 pixels. Just a white background with digital noise applied. One was downsampled to 3000 x 2000; the other was cropped to 3000 x 2000. At any usable magnification, the cropped version is visibly noisier than the downsampled version.

Downsampled

Cropped

If you want to avoid that noisier cropped result you'd have to set up the shot using more total light than you would need without cropping. You'd do that by using some combination of wider aperture, longer shutter speed, and lower ISO.

I'll add that the downsampled result would likely preserve detail better as well, because downsampling typically can do that.

FingerPainter · Jul 29, 2023

LennyLevino said:
Klaus dk said:

When you crop from 20 mm to 30 mm equivalent field of view, you throw away 25 of 45 Mp.

I don't think the IQ is that much better with a prime.

And what about the gap from 30 to 40?

Good luck and good light.

Click to expand...

Well, I just did some calculations. If shooting with a 61mp camera, you can crop 2x and be left with 16mp, or 2.5x and still have 10mp. For me, 16mp is great and 10mp is decent enough for most of my needs (small or medium sized prints, or cover a full 27 inch 4k monitor).

I think you are forgetting some things.

The sharpness of an even doesn't depend just upon the njuber of pixels on the sensor. It also depends on the lens resolution.

I don't doubt you'd be happy with 16MP if the lens was OK. But when you crop to 16MP from 61 (actually to 15.25MP) you are also thowing away lens resolution. So cropping to 15MP doesn't give you as sharp an image as a photo on a 15MP camera with a good lens. Instead it's like taking a 15MP Photo with a really bad lens - much owrse thtn your zoom would have been.

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

LennyLevino said:
So lets say I had the following prime lenses:

20mm (crop up to 50mm)

40mm (crop up to 100mm)

90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

And most of your images would look blurry.

LennyLevino said:
My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

Actually it probably would be worse than a downsampled image from a zoom lens, because most zoom lens are better than 1/2 the lp/ph resolution of most primes.

Guy Parsons · Jul 29, 2023

LennyLevino said:
What are your thoughts on replacing a standard zoom with 2-3 primes and then cropping in post (on a high/45mp+ camera)? Pros/cons?

For example, switching out a 24-105mm f4 for a 20mm (crop from 21-30), 40mm (crop from 41-60) and 85mm (crop from 86-135). Is the "prime look" still there after cropping? Is it worth the hassle?

Potential benefits I see are ability to use faster apertures at certain intervals and better image quality overall (although not sure if its still there after cropping). Negatives would be needing to switch lenses, (potentially) harder to compose (as you need to remember how you're going to crop the picture later when viewing it on your computer), and loss of pixels/resolution.

In the past I've thought about that approach but went zoomy anyway and enjoyed the simpler life.

If using primes and cropping then the logical set of primes needs to be spaced by about 1.4x (square root of 2) so the crops don't get too severe.

A set like 24mm, 35mm, 50mm, 70mm, 100mm etc would keep one happy. Unluckily the lens makers don't use logic in their choices of focal length, the focal lengths are determined by crowd nostalgia.

In the old days when I did try to live by primes, I found that the number of lens changes needed during a day was driving me crazy (and missed shots), so went to zooms when they become good enough.

Super convenient and surprisingly good quality is my backup compact camera a Sony RX100M6 where its "24-200mm" zoom does all that I need as I wander about. For more careful shots then M4/3 and f/2.8 zooms does it OK for me.

richj20 · Jul 29, 2023

LennyLevino said:
Well, I just did some calculations. If shooting with a 61mp camera, you can crop 2x and be left with 16mp, or 2.5x and still have 10mp. For me, 16mp is great and 10mp is decent enough for most of my needs (small or medium sized prints, or cover a full 27 inch 4k monitor).

So lets say I had the following prime lenses:

20mm (crop up to 50mm)
40mm (crop up to 100mm)
90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

After reading this, I realize that you are asking questions that can be satisfactorily answered by testing yourself.

I suggest you rent one (or more) of the above lenses and put it through its paces to see if you like the results.

LennyLevino · Jul 29, 2023

FingerPainter said:
LennyLevino said:

Klaus dk said:

When you crop from 20 mm to 30 mm equivalent field of view, you throw away 25 of 45 Mp.

I don't think the IQ is that much better with a prime.

And what about the gap from 30 to 40?

Good luck and good light.

Click to expand...

Well, I just did some calculations. If shooting with a 61mp camera, you can crop 2x and be left with 16mp, or 2.5x and still have 10mp. For me, 16mp is great and 10mp is decent enough for most of my needs (small or medium sized prints, or cover a full 27 inch 4k monitor).

Click to expand...

I think you are forgetting some things.

The sharpness of an even doesn't depend just upon the njuber of pixels on the sensor. It also depends on the lens resolution.

I don't doubt you'd be happy with 16MP if the lens was OK. But when you crop to 16MP from 61 (actually to 15.25MP) you are also thowing away lens resolution.

Sure, but when reading tests on lenstip, lensrentals etc it seems that many modern lenses can resolve much more than 60mp. So when they test a lens with a 30mp sensor and then a 60mp one, the lw/ph number will be significantly (2x?) higher on the latter. If resolution would stay the same no matter how many pixels your sensor had, then there would be no reason to have more megapixels.

But I get your point. I wonder how much lens resolution you lose though (if you use very high quality glass). Surely it cannot be 75%. Theoretically, it should be the same as using a 2x teleconverter. A smaller area of the glass has to supply a larger amount of pixels with information.

Please correct me if I'm wrong.

FingerPainter said:
So cropping to 15MP doesn't give you as sharp an image as a photo on a 15MP camera with a good lens. Instead it's like taking a 15MP Photo with a really bad lens - much owrse thtn your zoom would have been.

FingerPainter said:
The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop? Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

FingerPainter said:
FingerPainter said:

So lets say I had the following prime lenses:

20mm (crop up to 50mm)

40mm (crop up to 100mm)

90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

Click to expand...

And most of your images would look blurry.

FingerPainter said:
FingerPainter said:

My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

Click to expand...

Actually it probably would be worse than a downsampled image from a zoom lens, because most zoom lens are better than 1/2 the lp/ph resolution of most primes.

LennyLevino · Jul 29, 2023

richj20 said:
LennyLevino said:

Well, I just did some calculations. If shooting with a 61mp camera, you can crop 2x and be left with 16mp, or 2.5x and still have 10mp. For me, 16mp is great and 10mp is decent enough for most of my needs (small or medium sized prints, or cover a full 27 inch 4k monitor).

So lets say I had the following prime lenses:

20mm (crop up to 50mm)
40mm (crop up to 100mm)
90mm (crop up to 225mm)

In this case I'd be covered from 20-225mm.

My main concern is just how bad the image quality, noise etc will be after cropping 2-2.5x. But if I'm only viewing it at 100%, then it should not be worse than a downsized image from a zoom lens, right?

Click to expand...

After reading this, I realize that you are asking questions that can be satisfactorily answered by testing yourself.

I suggest you rent one (or more) of the above lenses and put it through its paces to see if you like the results.

sybersitizen · Jul 29, 2023

LennyLevino said:
FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Yes. Look at my posted example.

LennyLevino said:
Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Let's return to your actual proposal, which is to end up with the same composition obtained in two different ways: one with an uncropped image and one with a cropped image.

If you always look at the cropped version at a smaller size than the uncropped version, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

LennyLevino · Jul 29, 2023

sybersitizen said:
LennyLevino said:

FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Click to expand...

Yes. Look at my posted example.

sybersitizen said:

Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Click to expand...

If you always look at the cropped image at a smaller size than the uncropped image, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

Those were great demonstration pictures you posted. Thanks for that.

I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI) or when viewing pictures on social media etc. If I only shoot at ISO 100 with a tripod and expose correctly.

But let's see tomorrow when I have a chance to test it.

sybersitizen · Jul 29, 2023

LennyLevino said:
sybersitizen said:

LennyLevino said:

FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Click to expand...

Yes. Look at my posted example.

LennyLevino said:

Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Click to expand...

Let's return to your actual proposal, which is to end up with the same composition obtained in two different ways: one with an uncropped image and one with a cropped image.

If you always look at the cropped version at a smaller size than the uncropped version, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

Click to expand...

Those were great demonstration pictures you posted. Thanks for that.

I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI) or when viewing pictures on social media etc. If I only shoot at ISO 100 with a tripod and expose correctly.

Depends on the size of the prints ... but the bar for social media is easy to clear if that's how the results will be used: small images viewed at small sizes.

LennyLevino said:
But let's see tomorrow when I have a chance to test it.

LennyLevino · Jul 29, 2023

sybersitizen said:
LennyLevino said:

sybersitizen said:

LennyLevino said:

FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Click to expand...

Yes. Look at my posted example.

sybersitizen said:

Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Click to expand...

Let's return to your actual proposal, which is to end up with the same composition obtained in two different ways: one with an uncropped image and one with a cropped image.

If you always look at the cropped version at a smaller size than the uncropped version, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

Click to expand...

Those were great demonstration pictures you posted. Thanks for that.

I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI) or when viewing pictures on social media etc. If I only shoot at ISO 100 with a tripod and expose correctly.

Click to expand...

Depends on the size of the prints ... but the bar for social media is easy to clear: small images viewed at small sizes.

sybersitizen said:

But let's see tomorrow when I have a chance to test it.

Click to expand...

Yes. After all its the same as comparing full frame sensors to APS-Cs and MFT, right? Mounting my full frame lens on a 16mp MFT camera should get the exact same picture as cropping the full frame 61mp picture 2x.

Guy Parsons · Jul 29, 2023

LennyLevino said:
I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI)

Whether upsizing, downsizing or cropping then when printing it is the original camera pixels per inch of print that matter.

Aiming for 300 or more of those camera pixels per inch puts it in the super fussy and good for very close examination class. Aim for 200 as a minimum original camera pixels per inch and the print still is good for the usual close viewing. If it gets down to something like 150 per inch then it looks soft up close but step back and all is good.

So print "quality" really depends on how it is likely to be viewed.

Example a 2x crop on a 20MP image leaves you with a 5MP result and that is quite good enough for a 10x8 inch or A4 print but not so happy if stretched to A3 size.

It does not matter what interpolation is involved you cannot get away from the fact that the crop only contains information worth 5MP in that case.

LennyLevino said:
or when viewing pictures on social media etc.

That is by far the least demanding quality concern of all.

LennyLevino said:
If I only shoot at ISO 100 with a tripod and expose correctly.

No need to get too fussy, use a raw file and a good raw converter, such as DxO Photolab which seems to have the best noise reduction available.

LennyLevino said:
But let's see tomorrow when I have a chance to test it.

Testing is the only way to see what will work for you.

sybersitizen · Jul 29, 2023

LennyLevino said:
sybersitizen said:

LennyLevino said:

sybersitizen said:

LennyLevino said:

FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Click to expand...

Yes. Look at my posted example.

LennyLevino said:

Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Click to expand...

Let's return to your actual proposal, which is to end up with the same composition obtained in two different ways: one with an uncropped image and one with a cropped image.

If you always look at the cropped version at a smaller size than the uncropped version, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

Click to expand...

Those were great demonstration pictures you posted. Thanks for that.

I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI) or when viewing pictures on social media etc. If I only shoot at ISO 100 with a tripod and expose correctly.

Click to expand...

Depends on the size of the prints ... but the bar for social media is easy to clear: small images viewed at small sizes.

LennyLevino said:

But let's see tomorrow when I have a chance to test it.

Click to expand...

Click to expand...

Yes. After all its the same as comparing full frame sensors to APS-Cs and MFT, right? Mounting my full frame lens on a 16mp MFT camera should get the exact same picture as cropping the full frame 61mp picture 2x.

Not exactly (for one thing, the aspect ratios are different) ... but close enough.

LennyLevino · Jul 29, 2023

sybersitizen said:
LennyLevino said:

sybersitizen said:

LennyLevino said:

sybersitizen said:

LennyLevino said:

FingerPainter said:

The noisiness of an image depends on how much light is captured in it. If you crop your 61MP image tp 15MP, you will have thrown away 3/4 of the captured light. Your cropped image would be as noisy as a 61MP image taken with two stop less exposure.

Click to expand...

This makes sense on one level. But wouldn't this only be true if you downsized the original (non-cropped) version to the same size as the crop?

Click to expand...

Yes. Look at my posted example.

sybersitizen said:

Let's say the original image is 10k x 6.1k pixels, and you print it at full size. Then you take a pair of scissors and cut away 3/4ths of the picture, leaving only 10k x 1.6k intact. Where is the additional noise coming from? The part you leave hanging is still untouched.

Click to expand...

Let's return to your actual proposal, which is to end up with the same composition obtained in two different ways: one with an uncropped image and one with a cropped image.

If you always look at the cropped version at a smaller size than the uncropped version, you won't see the additional noise. Of course all the detail will look smaller as well, and some of it won't be visible at all. But If you're happy with that, you're fine.

Click to expand...

Those were great demonstration pictures you posted. Thanks for that.

I can understand the concept intellectually, but I'm still questioning whether it'll be noticeable in the final prints (still at 300 DPI) or when viewing pictures on social media etc. If I only shoot at ISO 100 with a tripod and expose correctly.

Click to expand...

Depends on the size of the prints ... but the bar for social media is easy to clear: small images viewed at small sizes.

sybersitizen said:

But let's see tomorrow when I have a chance to test it.

Click to expand...

Click to expand...

Yes. After all its the same as comparing full frame sensors to APS-Cs and MFT, right? Mounting my full frame lens on a 16mp MFT camera should get the exact same picture as cropping the full frame 61mp picture 2x.

Click to expand...

Not exactly (for one thing, the aspect ratios are different) ... but close enough.

Well if you crop it to the aspect ratio of MFT

Arek Halusko · Jul 29, 2023

SO much restriction vs zooms and the image quality is negligible if the zoom is of high quality glass. Why restrict yourself and carry many lenses.

grsnovi · Jul 29, 2023

LennyLevino said:
Is the "prime look" still there after cropping?

Take a look at the 1st and 3rd messages in this post. In your opinion is the "prime look" there in the 1st image? Compare with the uncropped image in the 3rd (which was the original - although unedited).

LennyLevino said:
Is it worth the hassle?

Not for me - I'd rather have a 2nd camera/lens than carry a bunch of lenses. That said, as you realize: if you need f/1.8 you aren't going to get it from a zoom that only opens to f/4.

Zoom lens vs cropping

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