I Bought a Telescope and I Have No Idea What I'm Doing

Say you have spent two or three thousand on a telescope, a mount and a camera, taken your first three hundred frames, and found that the photograph is not in any of them. This post is for you, and you are not doing anything wrong.

Nobody mentions the second purchase. The equipment is sold as the hard part. Reviews compare optics, forums argue about mounts, and the assumption throughout is that good gear produces good images. Then the first clear night ends, you copy the files off the card, and every one of them is a dark gray rectangle with some dots in it.

Our recommendation

For most people the answer is Akastroid: one app for deep sky, planets, the Moon and the Sun, on Mac, Windows and Linux. You drop in your frames and it grades, calibrates, stacks, removes the gradient, calibrates the colour and sharpens, with no settings to choose. The usual route needs four to six separate programs for the same result.

On the same Orion stack, Akastroid’s automatic finish measured a signal-to-noise of 402 against 87 for Siril’s standard workflow, with a sky gradient of 2.6% against 21.6% (the full comparison). It is free to try on your own data.

Choose PixInsight if you want to control every step by hand and will spend months learning it, or Siril if you want free software and are happy to learn the steps. The rest of this guide compares them in detail.

What happened on that first night

Your camera did its job. The photograph is in those files, spread thinly across all of them. A single sixty-second exposure of a nebula contains mostly noise, some light pollution, and a very faint amount of the thing you were pointing at. That is what deep sky data looks like before processing. It looks the same for everybody, including the people whose images you were admiring last week.

Getting the picture out means combining the frames so the noise cancels and the signal does not, then correcting several things the sky and the camera did to your data. That is the second purchase, and you pay for it in weeks rather than money.

The list you get handed

Ask what to do next and you will be told something like this.

Capture the frames. Then DeepSkyStacker or Siril to calibrate and stack, loading your lights, darks, flats and bias separately and choosing a stacking method and a sigma value. Then GraXpert for the light pollution gradient. Then StarNet or StarXTerminator to separate the stars so the nebula can be stretched without them. Then PixInsight to stretch, deconvolve, build masks and put it back together, which is a program with a months-long learning curve and documentation written in signal processing vocabulary. Then BlurXTerminator, a separate purchase, because the built-in deconvolution is not the good one. Then Photoshop for the final curves and color.

Underneath all of that, YouTube and the forums, at every step, for weeks.

If you shoot planets it is a different chain of four: PIPP, then AutoStakkert, then RegiStax for wavelets, then WinJUPOS if your capture ran long enough for the planet to rotate. Each one is approachable on its own. The sequence between them is where people get lost.

Every program in those lists is good, which is why the advice is hard to argue with. The trouble is that each of the seven assumes you already know the other six.

Where most people stop

It is rarely a cloudy night or a disappointing mount. It is the eighth tutorial, with a telescope in the garage that cost more than the holiday they did not take, and the conclusion that they are the problem.

They are not. They bought a piece of equipment and were handed a curriculum with it.

What the workflow is

This makes the rest much less daunting. Take the seven programs away and the underlying job is eight operations:

1. Calibrate. Remove what the camera added, using darks and flats.
2. Grade. Find the frames ruined by cloud, satellites, a gust of wind or lost focus.
3. Register. Align every frame on the stars, to a fraction of a pixel.
4. Integrate. Combine them so the noise falls and the signal stays.
5. Remove the gradient. The sky was brighter on one side, and that has to come out.
6. Calibrate the color. Work out what white is.
7. Stretch. The data is linear, and the faint parts are invisible until this happens.
8. Sharpen and denoise. Carefully, and less than you want to.

That is all of it, and it is the same eight steps whichever programs you run them in. Each one is explained here in order.

Most of the decisions are measurements

Almost none of the decisions inside those eight steps are matters of taste.

The rejection method for combining frames depends on how many frames you have and how much they vary. Where the black point goes depends on what fraction of the image is sky: about 98% on a wide field, where the default in most software is roughly three times too high. That is why so many beginner images have gray backgrounds. How hard to deconvolve depends on your measured star width and signal-to-noise. Drizzle only helps if your frames were dithered, and that is recorded in the frames themselves.

An experienced imager answers these by eye in seconds. It took them years to learn, and what they are doing is estimating quantities, not making artistic judgments. Software can estimate quantities from data at least as well as a person can.

Those forty-odd parameters were never the craft. They were there because measuring the frames automatically used to be hard.

What to do this week

Do not start with PixInsight. It is the best tool in the field and the wrong first move, because you cannot learn processing from an image you never produced. Get a finished result from your own frames first, however imperfect, so you have been from sky to photograph once. After that you are improving something you have, which is much easier.

Check your capture before you blame your processing. Most disappointing first images are limited by the frames, not the software. Read why are my stars trailing, how long should subs be and what darks, flats and bias do. Those three will improve your next night more than any amount of processing skill.

Then pick a route that matches your constraint. If money is the constraint and you enjoy learning tools, Siril is free and very good; start here. If time is the constraint, there are now programs that measure the session and run the eight steps for you. The two routes are compared here.

Learn the theory afterwards, from the result. Change one decision and see what it does to the image. That is a faster way in than reading about deconvolution before you have seen it work.

Summary

You do not need to understand astrophotography processing to produce a good astrophotograph. You need to understand your capture, you need taste, and you need to be able to look at a result and say what is wrong with it.

The telescope was not a mistake, and the pictures are in those files. The usual workflow was designed by people who wanted to learn processing, for other people who wanted to learn processing. It is fine to want something else.

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We make Akastroid, which runs those eight steps from measurements of your own frames and lists every decision with the number behind it. It is free with every feature, with one export to try it on, works on the folder your camera or smart telescope already wrote, and never uploads anything. Read what it does not do before you decide. If the processing itself is what puts you off, see do you need to understand processing to get a good image.