Best DSLR or ILC for Night Sky Imaging?

Started Nov 8, 2017 | Questions
kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: Best DSLR or ILC for Night Sky Imaging?

rnclark wrote:

Just to be clear, the dpreview comparison above is more about the changing lenses used than the sensor. DPreview changes focal length while keeping f-ratio constant. That means lens aperture area changes between cameras, thus the light delivered to the sensor is changing, and that means the amount of photon shot noise is different due to the lens, not the sensor.

Download the images and look at the exif to see what focal lengths and f-ratios were used. The Sony 7RII is full frame, so the use the longest focal length and largest aperture area.

Well the 100D was 50mm f/5.6 = 8.9mm aperture

7Rll was 55mm f/5.6 = 9.8mm aperture

X-T2 was 56mm f/5.6 = 10mm aperture

So I tried a bit of an experiment tonight with the same ISO and exposure time and focal length and f-ratio/aperture between the Fuji and Canon. (35mm f/4.5, ISO 6400) Partly cloudy and was shooting at a few gaps between the clouds. Pretty awful night really with poor seeing. But just wanted to see if noise would be the same according to your it's only aperture that counts theory.

Just 100% crops of the camera produced jpgs...

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rnclark Senior Member • Posts: 3,755
Re: dpreview comparisons: Are they kidding?
8

kiwi2 wrote:

rnclark wrote:

Just to be clear, the dpreview comparison above is more about the changing lenses used than the sensor. DPreview changes focal length while keeping f-ratio constant. That means lens aperture area changes between cameras, thus the light delivered to the sensor is changing, and that means the amount of photon shot noise is different due to the lens, not the sensor.

Download the images and look at the exif to see what focal lengths and f-ratios were used. The Sony 7RII is full frame, so the use the longest focal length and largest aperture area.

Well the 100D was 50mm f/5.6 = 8.9mm aperture

7Rll was 55mm f/5.6 = 9.8mm aperture

X-T2 was 56mm f/5.6 = 10mm aperture

Maybe look again. I downloaded the raw and jpeg files for the dpreview comparisons and extracted data directly from the files. Here are the results:

ISO___Exp_time__f-ratio__FL,mm__LensArea_______Camera____________lens
12800__1/5000____f/5.6___85.0____191_____Canon_EOS_5D_Mark_II__EF 85mm_f/1.8
12800__1/5000____f/5.6___50.0_____62.6___Canon_EOS_80D_________EF_50mm_f/1.4
12800__1/5000____f/5.6___56.0_____78.5___Fujifilm_X-T2________Fujifilm_XF56mmF1.2_R
12800__1/2500____f/5.6___55.0_____75.6___Sony_ILCE-6000_______FE_55mm_F1.8_ZA
12800__1/2500____f/5.6___50.0_____62.6___Canon_EOS_REBEL_SL1___EF_50mm_f/1.4
12800__1/2000____f/5.6___19.9______9.9___Olympus_XZ-2__________-
12800__1/5000____f/5.6___55.0_____75.6___Sony_ILCE-7RM2________FE_55mm_F1.8_ZA

So not only are the lens collections areas all over the place, but the exposure times vary too. That means the light delivered to the sensors are NOT the same. There is a factor of 19.3 in aperture areas (thus the mount of light that can be collected per unit time), and a factor of 2.5 in exposure time.

Then I checked the Sony a6000 and Canon 5d2 as they seemed surprisingly noisy. I brought the raw files into photoshop and with my default settings (and this means no vibrance, no clarity, no adjustments for exposure, dark, highlights, etc. Just some nominal noise reduction (documented on my web site) - nothing strong and most of the settings are the default settings when I first installed photoshop. This is what I get:

dpreview raw results are so bad I couldn't make my conversion as bad when I tried. Middle is dpreview comparison web page, left is full resolution CS6 ACR conversion, on the right is theconversion from the left enlarged to match the sizes in the dpreview web site.

Shocked, I'm shocked and stunned that the dpreview results are that bad. I would bet my 5-year old granddaughters could do better than dpreview with the raw converter. This illustrates what I've often said, that images like these are comparison of raw converter algorithms and not about the sensors. My already low view of these kinds of comparisons just sank through the floor. It was quite trivial to produce a far better image than the dpreview comparison page. I couldn't try the 80D or Fuji because I only have CS6 and ACR in CS6 won't open them.

dpreview web page:

https://www.dpreview.com/reviews/image-comparison?attr18=daylight&attr13_0=fujifilm_xt2&attr13_1=canon_eos5dmkii&attr13_2=canon_eos80d&attr13_3=sony_a6000&attr15_0=raw&attr15_1=raw&attr15_2=raw&attr15_3=raw&attr16_0=12800&attr16_1=12800&attr16_2=12800&attr16_3=12800&normalization=full&widget=1&x=0.6844401079033461&y=-0.6993156544054749

BUT WAIT. That is not all. The gains (ISO levels) are set differently with each camera by the manufacturer, even within each manufacturer. So the same ISO DOES NOT MEAN THE SAME SIGNAL. For example, the 5D2 at ISO 12800 has a range of 0 to 460 electrons. An 80D has a range of about 0 to 230 electrons. So the same magnitude noise in the 80D image means a factor of two smaller noise in electrons.

To compare images properly, the images need to be calibrated to the same signal level. That means same incident light level onto the sensor, and the output comparison images MUST BE on the same scale. This is not done in the dpreview site nor on most other review sites.

Your other posted image that you said was not 14 mm f/5: the exif data shown says 14 mm f/5:

14 mm f/5 in the exit data

So I tried a bit of an experiment tonight with the same ISO and exposure time and focal length and f-ratio/aperture between the Fuji and Canon. (35mm f/4.5, ISO 6400) Partly cloudy and was shooting at a few gaps between the clouds. Pretty awful night really with poor seeing. But just wanted to see if noise would be the same according to your it's only aperture that counts theory.

Just 100% crops of the camera produced jpgs...

Is this a raw conversion using dpreviews settings on the canon image? As I show above, the color splotches originate in the raw converter, not the sensor. Better settings like I show above would make a far better image. But even with the poor conversion, the canon image shows fainter stars than the fuji. It looks like the fuji image is heavily filtered, either in the raw data in the camera, or in the raw converter. So there is no realistic comparison here. If the canon image were converted better, the canon would look better making the two images much closer, as one would expect from real sensor data.

Here is the deal. All recent sensors from all manufacturers have reasonably high quantum efficiency, typically around 60% +/- 10%. And read noise at high ISO is pretty small, around 2 electrons or so. At these levels there is very little difference between sensors for short exposure of a minute or less in real world imaging. The technology is pretty mature. Sure there is room for improvement, but it is quite small in he scheme of things. The differences between cameras seen on review sites from dxo, dpreview and others is mainly dues to varying light levels delivered to the sensors, and now it is obvious that raw conversion algorithms and basic settings move things all over the place. That leaves open the problem of a biased review, intentional or not, by some poor settings in a raw converter.

Again, the differences in making a nightscape image, the main topic here, has more to do with the lens collecting the light, not the sensor.

Analogy: Internet discussions about camera sensors are like people standing around holding buckets and claiming how big and shiny their buckets are, and not about the quality and amount of water they fill their buckets with, when the water is what they drink. "Hey look: the water in your bucked has green, red and brown splotchy things floating in it." "Oh that doesn't matter because my bucket is bigger and shinier than yours!"

sharkmelley
sharkmelley Senior Member • Posts: 2,146
Re: dpreview comparisons: Are they kidding?

Roger, it's very interesting what you've shown with those DPReview images. Very enlightening.

I agree with you on that Canon vs Fuji night sky test - the Canon is showing more stars. Like you I suspect the Fuji data is being filtered somewhere along the line.

Mark

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swimswithtrout Veteran Member • Posts: 3,264
Re: Best DSLR or ILC for Night Sky Imaging?

kiwi2 wrote:

Here are some 100% crops from my Canon 100D and X-T2 of the camera produced jpgs with all the default settings at ISO 6400...

Is there anyway to turn off the Fuji's horrendous in camera High ISO  noise reduction?
That is the worst ,over smoothed "plastic" photo I've seen !! It looks like an oil painting, not a photograph.

JimH123 Senior Member • Posts: 1,905
If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

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swimswithtrout Veteran Member • Posts: 3,264
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

JimH123 wrote:

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

I totally agree !!!

But the OP and most everyone else here can't accept that fact. Unfortunately, 99.9 % of the users here think that "Astrophotography" is just a WA shot of the MW with a noisy foreground.

With the prices of all of the new CMOS based, cooled sensors, in 4/3 / APS-c format dropping down to less than the price of a FF camera. the day of the dSLR for AP is over.

landscaper1
OP landscaper1 Veteran Member • Posts: 3,471
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs
2

swimswithtrout wrote:

JimH123 wrote:

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

I totally agree !!!

But the OP and most everyone else here can't accept that fact. Unfortunately, 99.9 % of the users here think that "Astrophotography" is just a WA shot of the MW with a noisy foreground.

Actually, trout, the OP (that's me) has long realized that a dedicated CCD camera mounted on a telescope is the best method for producing images of star fields.  In fact, I realized that long before I ever aimed a DSLR at the night sky.

However, that's NOT what I wish for my subject matter.  Forgive me for having a personal preference that is at odds with how you seem to think it ought to be done.  I had no idea someone had anointed you as the foremost authority on the subject of night sky photography.

I'll readily admit some of my night sky images have noisy foregrounds, but I feel entitled to proclaim, "Hey, I'm a beginner at this!"  I can count the number of nights I've been out shooting on the fingers of both hands and still have a 2 or 3 fingers left over.  I know I'm getting better, but I also know there's still much for me to learn.  That's why I ask questions.

-- hide signature --

Landscaper

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kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: dpreview comparisons: Are they kidding?

rnclark wrote:

Your other posted image that you said was not 14 mm f/5: the exif data shown says 14 mm f/5:

14 mm f/5 in the exit data

I did?

https://www.dpreview.com/forums/post/60388001

Do you mind pointing out where I supposedly said that?

If you are just going to start making things up now, who knows what else you have just made up?

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kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: Best DSLR or ILC for Night Sky Imaging?

swimswithtrout wrote:

kiwi2 wrote:

Here are some 100% crops from my Canon 100D and X-T2 of the camera produced jpgs with all the default settings at ISO 6400...

Is there anyway to turn off the Fuji's horrendous in camera High ISO noise reduction?
That is the worst ,over smoothed "plastic" photo I've seen !! It looks like an oil painting, not a photograph.

Noise reduction was on 0 of a scale from -3 to +4. I'll try and find time shortly to make a new copy from the RAW with -3 noise reduction and see what it looks like. But personally I prefer the smooth X-T2 image over the noisy 100D image.

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kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

swimswithtrout wrote:

I totally agree !!!

But the OP and most everyone else here can't accept that fact. Unfortunately, 99.9 % of the users here think that "Astrophotography" is just a WA shot of the MW with a noisy foreground.

Ummm... "Let's suppose someone is interested in doing night sky photography (sky plus landscape foreground)"

https://www.dpreview.com/forums/post/60352669

As for me, doing deep sky astrophotography holds very little interest as images of those deep space objects are freely available online at much better quality than I would ever be able to achieve. So I don't see the point of spending large sums of money and time trying to pursue them. But if others want to, that's fine, that's their thing. We all have different tastes and interests. It would be a boring world if we didn't and all thought the same.

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swimswithtrout Veteran Member • Posts: 3,264
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

kiwi2 wrote:

Ummm... "Let's suppose someone is interested in doing night sky photography (sky plus landscape foreground)"

https://www.dpreview.com/forums/post/60352669

As for me, doing deep sky astrophotography holds very little interest as images of those deep space objects are freely available online at much better quality than I would ever be able to achieve. So I don't see the point of spending large sums of money and time trying to pursue them. But if others want to, that's fine, that's their thing. We all have different tastes and interests. It would be a boring world if we didn't and all thought the same.

It's no different than Milky Way photos. Every lens, ever angle has been covered 100,000's of times +++++

JimH123 Senior Member • Posts: 1,905
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs
1

kiwi2 wrote:

swimswithtrout wrote:

I totally agree !!!

But the OP and most everyone else here can't accept that fact. Unfortunately, 99.9 % of the users here think that "Astrophotography" is just a WA shot of the MW with a noisy foreground.

Ummm... "Let's suppose someone is interested in doing night sky photography (sky plus landscape foreground)"

https://www.dpreview.com/forums/post/60352669

As for me, doing deep sky astrophotography holds very little interest as images of those deep space objects are freely available online at much better quality than I would ever be able to achieve. So I don't see the point of spending large sums of money and time trying to pursue them. But if others want to, that's fine, that's their thing. We all have different tastes and interests. It would be a boring world if we didn't and all thought the same.

Actually, looking at online pictures of the objects is not that interesting.  It is the pursuit that is interesting.

Same could be said about climbing Mt Everest, since others have already done it and pictures exist of what it looked like.  For those into mountain climbing (not me), it is the pursuit that they are after.

Anyway, I have already spent the money on telescopes, mounts and various cameras.  So the money pain is now behind me.  What is fun is to actually capture for myself what I see that was taken with bigger telescopes.  I realize I can never equal what they can capture, but I can certainly see those objects.  Well, maybe not all the objects since Hubble can see things far, far beyond what I can see.

It is also nice to know that the state of home viewing with sensitive cameras gives us better views of the night sky than professionals had less than 100 years ago.  And their film cameras has no where near the sensitivity of today's cameras.

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kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: Best DSLR or ILC for Night Sky Imaging?

swimswithtrout wrote:

Is there anyway to turn off the Fuji's horrendous in camera High ISO noise reduction?
That is the worst ,over smoothed "plastic" photo I've seen !! It looks like an oil painting, not a photograph.

I used Silkypix for the RAW as it's the raw editor that I downloaded from the Fuji site and perhaps gives me closest to native control. I minimised every slider I could under the noise tab.

Here is a crop of the resulting jpg...

And for comparison the 100D image with noise reduction minimised as well with a new RAW edit...

As I said yesterday, it's the lack of colored chrominance noise from the Fuji that appeals to me and makes it easy to clean up in post.

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Trollmannx Senior Member • Posts: 5,461
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs
1

swimswithtrout wrote:

JimH123 wrote:

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

I totally agree !!!

But the OP and most everyone else here can't accept that fact. Unfortunately, 99.9 % of the users here think that "Astrophotography" is just a WA shot of the MW with a noisy foreground.

No comment - trying to be polite...

With the prices of all of the new CMOS based, cooled sensors, in 4/3 / APS-c format dropping down to less than the price of a FF camera. the day of the dSLR for AP is over.

No - not at all.

My Atik 490ex deliver clean images - but the image sensor is small (10x12.5mm) giving a limited field of view, and the dear little thing MUST be tethered to a computer.

In my case I love the standalone DSLRs - just put the camera with lens on a star tracker and let loose. Get a wider field as the image sensor is bigger, use modded cameras to capture more of that lovely Ha light faster. All is easy and convenient and relaxing.

And my DSLRs fit behind my telescopes too, just a turn and we are ready to go.

DSLRs need no tethering and no need for longer exposures to keep read noise down (my Atik noise level is 8e and the DSLRs are more like 2e).

My Atik is idle (at least for now) and my DSLRs are going strong...

The days of the DSLRs for astrophotography are not over...

rnclark Senior Member • Posts: 3,755
Re: dpreview comparisons: Are they kidding?
1

kiwi2 wrote:

rnclark wrote:

Your other posted image that you said was not 14 mm f/5: the exif data shown says 14 mm f/5:

14 mm f/5 in the exit data

I did?

https://www.dpreview.com/forums/post/60388001

Do you mind pointing out where I supposedly said that?

If you are just going to start making things up now, who knows what else you have just made up?

You said: "Well the 100D was 50mm f/5.6 = 8.9mm aperture"

But you have posted so many images, perhaps I misinterpreted which one it was.  And even i I did make a mistake regarding which image you were referring to, that doesn't mean everything else said is wrong.   I am fine with everyone checking and confirming what I said, but accusing someone of making things up is outrageous.  I've been trying to help you, but with an attitude like this, I'll no longer respond to you.

Roger

Selene Senior Member • Posts: 1,258
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs
2

Thanks and thanks again Roger and Landscaper for starting this thread.  I am very new to this.  As I live in a very light polluted place with lots of trees, I do most of my night sky photography elsewhere. Thus, being able to use a camera and lens is convenient for me. I am intrigued by astrotrackers, but I am still very much a beginner who has learned a lot from this discussion even though many on here understand technical details much better than I do.  I like to kind of think that I am using night skies as parts of scenes I want to shoot.  I am sure others have done many of the same shots, though sometimes I have been in places that aren't so heavily traveled. I appreciate that some of you who know so much, like Roger, are willing to help some of us learn.  This is the great benefit of these kinds of forums--I can ignore the ones that are way over my head, while trying to get as much as I can from those I can follow.  Thanks again for a most interesting and informative thread.

1llusive
1llusive Senior Member • Posts: 1,571
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

JimH123 wrote:

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

Hey Jim, do you have the FCD1 or FCD100 glass in your ES ED102? Great scope, but judging from your upper corners you may have focuser sag.

1llusive
1llusive Senior Member • Posts: 1,571
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

Trollmannx wrote:

swimswithtrout wrote:

With the prices of all of the new CMOS based, cooled sensors, in 4/3 / APS-c format dropping down to less than the price of a FF camera. the day of the dSLR for AP is over.

No - not at all.

The days of the DSLRs for astrophotography are not over...

Agreed. You can buy a QHY 247C (Sony IMX193) for $1,999. Or, you can buy a Nikon D5300 for $400. Same sensor, and practically speaking, same results.

https://www.highpointscientific.com/qhy-qhy247c-color-cooled-aps-c-cmos-astronomy-imaging-camera

We will likely never reach price parity due to economics of scale.

With mono, things change. There are solid reasons for going mono. But those cost even more money, skewing the equation further. They simply are not going to nudge DSLRs out of existence for astrophotography. They both have their place.

kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: dpreview comparisons: Are they kidding?

rnclark wrote:

You said: "Well the 100D was 50mm f/5.6 = 8.9mm aperture"

But you have posted so many images, perhaps I misinterpreted which one it was. And even i I did make a mistake regarding which image you were referring to, that doesn't mean everything else said is wrong. I am fine with everyone checking and confirming what I said, but accusing someone of making things up is outrageous. I've been trying to help you, but with an attitude like this, I'll no longer respond to you.

Which is strange because you must have realized that was in relation to this....

Me; "I have always used the noise comparison here at dpreview with any potential camera purchase to gauge its usability for the nightscapes I like to do. It shows me what the market has to offer at the particular moment as far as noise goes and what to avoid"

You; "Download the images and look at the exif to see what focal lengths and f-ratios were used. The Sony 7RII is full frame, so the use the longest focal length and largest aperture area."

When I pointed out that it was actually the X-T2 that had the (slightly) larger focal length and aperture...

Me; "Well the 100D was 50mm f/5.6 = 8.9mm aperture. 7Rll was 55mm f/5.6 = 9.8mm aperture. X-T2 was 56mm f/5.6 = 10mm aperture."

(100D and SL1 are different names for the same model of camera)

...you told me to "Maybe look again." as if somehow that would negate the fact that you were wrong about the 7RII having a larger aperture. Nice try though.

So yes I find it strange that you would go to the trouble of creating a screen capture to accuse me of being misleading about an image that clearly had EXIF info available.

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kiwi2
kiwi2 Veteran Member • Posts: 4,398
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

Selene wrote:

Thanks and thanks again Roger and Landscaper for starting this thread. I am very new to this. As I live in a very light polluted place with lots of trees, I do most of my night sky photography elsewhere. Thus, being able to use a camera and lens is convenient for me. I am intrigued by astrotrackers, but I am still very much a beginner who has learned a lot from this discussion even though many on here understand technical details much better than I do. I like to kind of think that I am using night skies as parts of scenes I want to shoot. I am sure others have done many of the same shots, though sometimes I have been in places that aren't so heavily traveled. I appreciate that some of you who know so much, like Roger, are willing to help some of us learn. This is the great benefit of these kinds of forums--I can ignore the ones that are way over my head, while trying to get as much as I can from those I can follow. Thanks again for a most interesting and informative thread.

Don't be fooled. What Roger is leaving out in his formulas, is the inverse-square law. Light fades the further it has to travel. A longer focal length lens may have a larger aperture, but then the light also has to travel further over the focal length of the lens. For diffuse light subjects, it comes back down to f-ratio as the gauge of brightness.

That's why photographers and camera metres use f-ratio to calculate exposures rather than calculating aperture.

f/5.6 on any lens, be it 10mm or 500mm, is roughly the same amount of light reaching the sensor.

ie. Have a look at the EXIF of these two photos I have just taken out on the back lawn with the same shutter speed and ISO and f-ratio of f/5.6 and shot within minutes of each other...

The 10mm has an aperture of 1.7mm and the 500mm shot had an aperture of 89mm.

So where did the massive amount of more light from the larger aperture go as both photos are similarly exposed? (if anything, the larger aperture shot is a bit darker and underexpose)

In the wider angle shot, the light after passing through the front element only had to travel 10mm to the sensor. (loosely speaking. from the point of convergence technically) In the telephoto shot, the light had to travel 500mm to the sensor. That's why f-ratios are used as the constant/relative brightness of a lens.

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