Crop sensor astro photography

[horse.collier]

Have been looking into astro/night landscape photography. Besides the obvious requirements of tripod, remote shutter release etc,( which I posses) I have come across a possible pit fall.

My camera is a Nikon D7500 and have read in several places this isn't suitable due to the sensor size and there wil be too much noise. HNR etc will also be used.

I will be using as fast a lens as possible. ( Not purchased yet). Post production will be done using Affinity 2.

Is it worth me attempting to do that sort of photography and spending money on a suitable fast lens as well as time?

 

[LeeRatters]

My boy shoots with a crop sensor camera. Sony A6000.

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Usually with a 12mm f/2 lens.

A fast lens will make a difference as it'll allow a lower ISO which is always a good thing. You can stack multiple images though to reduce noise too which can be pretty effective. I use Sequator on Windows.

I use f/1.4 lenses and a tracker so noise isn't usually an issue for me anymore. I have shot at ISO 1600 and above before though on an A7 and as I said, once stacked and downsized for Web posting not an issue at all.

 

[wornish]

I shoot with an OM-1 camera which is M43. i,e a 2 x crop.
They are more than capable of shooting Astro images. Don't fall for the FF mafia view. Look at real-world examples.

As for time, then whatever format you use for Astro there is no shortcut. It needs practice and patience to get it right.
Oh, and the clouds to clear. I can guarantee that as soon as you purchase any new equipment for Astro the clouds will move in. It's a known law

 

[RichardC27]

I've done some basic astro with an APS-C camera. It doesn't make that much difference, getting as fast a lens as possible will make much more difference than having a FF sensor,

You could argue FF cameras aren't suitable for astro work, a medium format sensor would give you much lower noise etc. As above, don't fall for all the stuff you read online about how this or that camera isn't suitable for a certain genre of photography.

For example, I have a Fuji camera, and you'll read loads online about how Fuji AF isn't very good, it's not suitable for fast action etc and it's not true. I've shot loads of motorsport with a Fuji X-T4 and the AF is fine.

 

[benhben]

Ive shot crop sensor Fuji cameras for years and done many astrophoto sessions. The new crop sensor Fuji cameras (X-T3-X-T5) and other brands I am sure are more than capable of any type of photography. 99.9% of people wont tell the difference.

Tips to improve are:
1. Fast wide angle lens - I use a Samyang 12mm F2. This is available in various other mounts.
2. Tripod.
3. Take multiple images of around 20 seconds and stack them in starstax or similar software. This removes the noise.
4. Try a star tracker like the Move Shoot Move. Allows you to take 2 or 3 minute exposures without blurrring the skies.

Do not worry at all about your sensor size. Focus on good lenses and capturing techniques.

 

[sk66]

If you use a smaller sensor instead of a larger sensor, but everything else is the same, then the noise will be the same... i.e. if you crop the wider image from the larger sensor down to the same final image, the noise will be the same. The only difference will be in how well you can see the noise (image resolution).

Of course, this assumes sensors of equivalent design/generation.

But it is true that if you record the same image (composition), with the same exposure settings, the larger sensor receives/records more light and that does result in less image noise.

 

[LunaCat]

If you use a smaller sensor instead of a larger sensor, but everything else is the same, then the noise will be the same... i.e. if you crop the wider image from the larger sensor down to the same final image, the noise will be the same. The only difference will be in how well you can see the noise (image resolution).

Of course, this assumes sensors of equivalent design/generation.

But it is true that if you record the same image (composition), with the same exposure settings, the larger sensor receives/records more light and that does result in less image noise.

If the number of pixels is the same on both sensors then each pixel will be smaller so less signal and more noise.

 

[sk66]

If the number of pixels is the same on both sensors then each pixel will be smaller so less signal and more noise.

Per pixel yes, not per image/image area; and that's what actually matters.

The "larger pixels get more light and thus less noise" is only true if you consider the pixel as a standalone factor... and it is not. What really happens is that the smaller pixels mean you have greater resolution; and that lets you enlarge it more (i.e. 100% zoom), which makes the recorded noise more apparent.

 

[horse.collier]

Thanks for the advice chaps. Full steam ahead for a lens then.

Lunacat and sk66. had to read your comments a coupekl of times to understand, but am now in the picture....sorry long day

 

[LunaCat]

Per pixel yes, not per image/image area; and that's what actually matters.

The "larger pixels get more light and thus less noise" is only true if you consider the pixel as a standalone factor... and it is not. What really happens is that the smaller pixels mean you have greater resolution; and that lets you enlarge it more (i.e. 100% zoom), which makes the recorded noise more apparent.

I had to think about that. I can see what you mean but I think it depends on the subject; if it were a blanl canvas then I might agree but imagine the subject had detail on the scale of the pixels, so that each detail (like a star point) fell on just one pixel. In other words although your combined area is the same regardless of the number of pixels the gathering area per feature is less. Lets not go down a rabbit hole though!

 

[wornish]

Per pixel yes, not per image/image area; and that's what actually matters.

The "larger pixels get more light and thus less noise" is only true if you consider the pixel as a standalone factor... and it is not. What really happens is that the smaller pixels mean you have greater resolution; and that lets you enlarge it more (i.e. 100% zoom), which makes the recorded noise more apparent.

This is undoubtedly rabbit hole territory.




There is some good info here

https://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

 

[Tysonator]

My boy shoots with a crop sensor camera. Sony A6000.

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Usually with a 12mm f/2 lens.

A fast lens will make a difference as it'll allow a lower ISO which is always a good thing. You can stack multiple images though to reduce noise too which can be pretty effective. I use Sequator on Windows.

I use f/1.4 lenses and a tracker so noise isn't usually an issue for me anymore. I have shot at ISO 1600 and above before though on an A7 and as I said, once stacked and downsized for Web posting not an issue at all.

You son has some very good astro photos on his IG page.

I have been wanting to do Astro for a while now and just do not know where to start !
I have tripods, timer on the camera, so I can use my Sony A6600 with 18-50 f2.8 lens, or my canon R7 with 17-70 f2.8-4 lens
Is it all about pointing the camera in the right direction for the Milky way ! ?

 

[sk66]

I had to think about that. I can see what you mean but I think it depends on the subject; if it were a blanl canvas then I might agree but imagine the subject had detail on the scale of the pixels, so that each detail (like a star point) fell on just one pixel. In other words although your combined area is the same regardless of the number of pixels the gathering area per feature is less. Lets not go down a rabbit hole though!

If you have a detail that only falls on a single photosite there is nothing to discriminate it from being noise itself.

I used the term photosite to differentiate it from an output image pixel. Because what an output pixel actually is, in both color and luminance, is determined through complex algorithms using the information of surrounding pixels (demosaicing). And if the surrounding information is unrelated, it results in errors (noise).

 

[sk66]

This is undoubtedly rabbit hole territory.

Yes.
As a standalone "engineering" consideration larger pixels always win... but in reality no one consideration stands alone, there are always interactions/tradeoffs.

It wasn't that long ago that I was a bit surprised to realize that the gains in DR capabilities have primarily been coming from cameras with sensors of even higher resolution (smaller pixels). It turns out that the primary reason for that is smaller photosites are actually more sensitive to light; they have a smaller full well capacity, and a lower conversion gain requirement (requires fewer photoelectrons to be equally full)... combine that increased sensitivity with improved (lower) read/switching noise and you get increased dynamic range (farther into the darks). And the smaller FWC isn't a problem because the available light is divided between more photosites (i.e. each gets less of the total).

So what really ends up mattering in terms of image noise (shot noise) is total physical area/sensor size; not the total area used to record the scene, but rather the total area remaining after editing/cropping. The pixel resolution then determines how much you can magnify it (physical size at 100%), and therefore how apparent the noise is at that magnification.

 

[wornish]

.............

I have been wanting to do Astro for a while now and just do not know where to start !
I have tripods, timer on the camera, so I can use my Sony A6600 with 18-50 f2.8 lens, or my canon R7 with 17-70 f2.8-4 lens
Is it all about pointing the camera in the right direction for the Milky way ! ?

Its a good start.

Start with something bright , the Moon is up right now and is easy to focus on. It's actually very bright so normal daylight shooting settings work. You can do it hand held with a fast enough shutter spreed.

Then perhaps go for some of the brighter constellations. These again are well within the capabilities of your gear. Getting sharp stars is the first challenge.

At the stage you are at there is no need for any specialised kit. Go outside and give it a go.

Taking a shot of the Milky Way is not as easy as it sounds, needs lots of practice first.

Good Luck

 

[LunaCat]

If you have a detail that only falls on a single photosite there is nothing to discriminate it from being noise itself.

I used the term photosite to differentiate it from an output image pixel. Because what an output pixel actually is, in both color and luminance, is determined through complex algorithms using the information of surrounding pixels (demosaicing). And if the surrounding information is unrelated, it results in errors (noise).

Hmm.

 

[LeeRatters]

You son has some very good astro photos on his IG page.

I have been wanting to do Astro for a while now and just do not know where to start !
I have tripods, timer on the camera, so I can use my Sony A6600 with 18-50 f2.8 lens, or my canon R7 with 17-70 f2.8-4 lens
Is it all about pointing the camera in the right direction for the Milky way ! ?

Thanks. The hardest work is getting him to actually upload some photos! He's started an A level photography now.

Also, see below

Its a good start.

Start with something bright , the Moon is up right now and is easy to focus on. It's actually very bright so normal daylight shooting settings work. You can do it hand held with a fast enough shutter spreed.

Then perhaps go for some of the brighter constellations. These again are well within the capabilities of your gear. Getting sharp stars is the first challenge.

At the stage you are at there is no need for any specialised kit. Go outside and give it a go.

Taking a shot of the Milky Way is not as easy as it sounds, needs lots of practice first.

Good Luck

Good advice there ^

You want to keep your lens pretty much wide open really. You want your shutter speed as long as possible without star trails - that will vary a little depending on focal length and how fussy you want to be at 100% I'm guessing somewhere between 10-20 seconds. Then you just need to crank up the ISO to get the exposure. To combat the noise, shoot 6 or so identical images straight off and use software to stack them - I use Sequator, free for Windows.

The moon will get you used to being outside in the dark and right now Orion is a lovely target and at a nice time of the early evening. Easily shoot and still have a good night's sleep

There's a good few of us on here with plenty of experience between us.

 

[Tysonator]

Thanks. The hardest work is getting him to actually upload some photos! He's started an A level photography now.

Also, see below



Good advice there ^

You want to keep your lens pretty much wide open really. You want your shutter speed as long as possible without star trails - that will vary a little depending on focal length and how fussy you want to be at 100% I'm guessing somewhere between 10-20 seconds. Then you just need to crank up the ISO to get the exposure. To combat the noise, shoot 6 or so identical images straight off and use software to stack them - I use Sequator, free for Windows.

The moon will get you used to being outside in the dark and right now Orion is a lovely target and at a nice time of the early evening. Easily shoot and still have a good night's sleep

There's a good few of us on here with plenty of experience between us.

What direction do I point the lens, and do I need to Cosmos App for direction help ! ?

 

[LeeRatters]

What direction do I point the lens, and do I need to Cosmos App for direction help ! ?

Well I use Stellarium but I know where I want to aim for constellations anyway pretty much. Ursa Major will be north ish, Cygnus is north west right now early evening. Orion (much like the Milky Way in the summer - and the sun!) travels east to west across the southern sky.

Really depends on what your want to photograph? Just the stars? A landscape? A building? You either have to wait until the constellation you want is in the right place or just shoot the night sky in general. Most people aim for a recognisable or popular part of the night sky but you don't have to.

 

[Tysonator]

Well I use Stellarium but I know where I want to aim for constellations anyway pretty much. Ursa Major will be north ish, Cygnus is north west right now early evening. Orion (much like the Milky Way in the summer - and the sun!) travels east to west across the southern sky.

Really depends on what your want to photograph? Just the stars? A landscape? A building? You either have to wait until the constellation you want is in the right place or just shoot the night sky in general. Most people aim for a recognisable or popular part of the night sky but you don't have to.

The Milky way photos on the net I have seen are amazing, so perhaps I will start with Milky way

 

[LeeRatters]

The Milky way photos on the net I have seen are amazing, so perhaps I will start with Milky way

I think the Milky Way core is visible from the end of this month. For something like a whole 8 minutes initially in the early hours before dawn.

It's not really at its best until April or so really. Right now I'd be concentrating on Orion in all honesty. Such a good easy constellation and at a very convenient time in the evenings.

I like my Orion landscape images just as much as my Milky Way ones in all honesty.

 

[wornish]

This is one very big crop sensor just to show what's possible. Taken with my iPhone last night, Looking South West.
Orions Belt and Sword



handheld.


Betelgeuse at the top Rigel at the bottom

No fancy gear needed.

 

[southernsteve]

There is no reason why you can't shoot with a crop sensor, but you do need to consider the amount of light hitting it. The rule of 500 will give you a max shutter speed before light trails appear. I only shoot a single frame at the moment, haven't got into stacking yet, and my star tracker is still in its box, but this is what I've achieved with a Nikon D500 and Tokina 11-16mm lens at 11mm, f/2.8. 20 seconds, ISO 3200 and a play around with basic Lightroom adjustments.

Cap Blanc by Stephen Webb, on Flickr