What's The Best ISO For Astrophotography (ISO Invariance)

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[NebulaPhotos]

Well done Alyn! I'm glad you did this video so I didn't have to 😜 You did a very nice job of explaining the major concepts in plain language and how they relate to astrophotography. I think your lead-up explanation of exposure stops and then the visual difference between ISO100 pushed 5 stops vs. ISO3200 at 04:51 is especially effective, and will hopefully get more people thinking about this in the correct way, and not just insisting to me that it's as simple as: higher ISO = higher noise. Also, that's an epic filming location for your talking head stuff!

[mikemosier]

You will continue to produce information for all of us even in your absence. I hope that those stars swallowed you up and we can all continue to hear you speak through them.

[davidpeeters]

Rest in Peace man, you've taught me so

[lucas.rabelo]

17:40 - Sony a7iii has a function called "Bright Monitoring" that enables you to see in the dark before the shooting without changing the ISO. Just assign a custon button. Thank you for the video!

[michalkubecek]

Good video, I just have two comments on it:

1. You mention that higher ISO means lower dynamic range. While true, it's important to realize that simulating higher ISO by underexposing and correcting in postproces does exactly the same. When you underexpose by e.g. 3 EV, it means that you only use 1/8 of the available range, i.e. lose 3 bits (or 3 EV) of dynamic range. And when you check the graphs of dynamic range by ISO, in the intervals of ISO invariance you can see exactly 1 bit (or 1 EV) of loss for each ISO step. Which is not really a surprise, considering that in these intervals you essentially just choose if it's camera processing chips or your software in PC who does the multiplication or division, the values produced by the sensor are the same. In other words, dynamic range is not really an argument for underexposing and correcting in postprocess, the only reason to do that is to prevent clipping.

2. People often tend to think that an ISO invariant camera automatically means it's better. This is not always true, all it means is that the sensor has only one actual gain value and every other ISO setting is simulated by multiplying or dividing the values from the sensor by a constant - i.e. exactly what the exposure correction in postprocess does. While more convenient, it does not always mean a multi-gain sensor could not achieve better results (in the sense of less noisy image) for a particular combination of exposure settings. Often the reason for using a multi-gain sensor is to get better results in some parts of the range, it would be easier and cheaper to use just one gain and simulate everything else by recalculating in firmware.

[DaveMcKeegan]

Fantastic video as always Alyn and thank you so much for recommending my video :)

[marinaamgad]

I realized that my whole photography life was a lie after watching that video...yeah that makes sense Alyn. Great presentation! :)

[CraigLively]

Finally!.. This is the first video/article I've found which explains it to my satisfaction, as a photographer (and as a Sony shooter). Seems like most people seem to get bogged down in more of the technical aspects of it all, causing me to involuntarily tune out. You spoke to us as a photographer, rather than an engineer, and I followed you from beginning to end. Thank you.

[Stillfilm]

This was so useful Alyn. I've struggled with articles about ISO invariance but you make it so very clear and understandable. Thank you so much.

[jackdeangelis]

Good explanation, in fact the best I've seen. As I use a Fuji XT-2 I've come to set the ISO at 1600 for everything and adjust in post with the exposure module (Darktable). Works great. I'm pretty sure that Sony developed this technology and Fuji uses the Sony sensors (although they don't like to admit it). One additional point - while the noise stays the same the dynamic range does not. As you increase exposure (in post) the dynamic range decreases. (You covered this later in the video!).

[franconebbia]

Por fin un fotógrafo que nos enseña técnicas, valores y todo tipo de tips con seriedad y estudios en el campo y en la edición.

[derekthomas]

Thanks for another really informative & useful video. “Protect the highlights & increase the dynamic range will be my new mantra”!

[raphaelcoelho]

I couldn't agree more. It is exactly how I choose my iso. I just add that I reduce the iso if I am doing a single shot or stack images. If it is a panorama I reduce too but keep an iso where I still can see the composition in each shot.

[Coolpado]

Finally, a clear and complete explanation about ISO invariance. I’ve got a Sony a7III and I’m gonna do it from now on.
Thank you very much, Alyn!😊😉

[willjmarston]

This is turning my head upside down on my go-to astro camera settings, incredibly useful info! Looking forward to trying this out.

[Paulus]

I've been trying to get my head around ISO invariance for months but couldn't grasp it. That was until I just saw this video which explains it perfectly. Thank you. i also own an A7iii (bought after watching many of your videos). It's nice to know I have the tools, if not yet the skills, to attempt astro photos like yours.

[tjayay]

Thank you so much Alyn! Your repetition is perfect for teaching new concepts. I learned so much from this video - even what a full stop is pertaining to ISO.

[puckco]

Thank you very much. I think this was one of the most important videos I watched the last years. A7iii.

[BillyVerden]

Great Video as Always! Very informative! In your video you mentioned you could raise your iso to it's highest setting to compose then lower it back down to the minimum invariant iso.. what I do on all my Sony cameras is turn off the live view setting effect.. to compose.. then turn it back on for the shot.. I have setting effect on/off as a toggle on one of the programmable buttons. If you know your manual settings are correct and you are going to shoot all low light.. you can leave live view setting effect off the whole time. Works for me.. your mileage may vary.. lol.

[Phil_fandbethere]

Many thanks for this Alyn - I've learnt something new today! And the best news for me - my camera is an XT-1 😁. So I never need to worry about ISO ever again - Auto ISO for me from now on 🥳🎉