Sat, 04/30/2022 - 01:34

Hello, I have already observed several variable stars through binoculars and I wanted to know more details about the difficulties of observing through the telescope. I say this because of the narrower field of view. Should I use a set of eyepieces for observation? I say this in relation to the field of view. If anyone can give me some advice I would appreciate it. Thanks.

American Association of Variable Star Observers (AAVSO)
Widest possible field of view

Hi Marcelo,
I think each of us has had his/her own experience regarding observing through different instruments.

What I think is that the more instruments you put between your eyes and the sky, more sources of potential errors will appear.
It is not the same to observe with the naked eye than through a telescope.
You have an almost unlimited field of view eith the naked eye and a generous one when using binoculars.

My advice is that the field of view should be as large as possible, as long as the variable is comfortably detected. That usually means that it should be between 1 and 4 magnitudes above the limiting magnitude (limiting magnitude will depend on the instrument and also magnification, and it will vary from night to night).
It is important to take the chance of having all comparison stars in the same field of view, without any need of star hoping to a different field and consequently having to trust in your visual memory.

Of course, if the variable is too faint and in a crowded area, you will have to use higher power and won't be able to choose, but we can't have everything. I think it is important to be able to adjust. Each particular target will require a different approach, but the rule of allowing for the wider possible field of view, is an important one.
Changing eyepieces will also change the background brightness and this may affect your estimates. I would always use the same magnification to make your estimates, to avoid any potential jump in the results as a result of that change. If the variable star range is too large, this may not be possible though, but it is a recommendation.

I hope this helps.