45 minutes of M31 from Central Texas

Started 5 months ago | Discussions thread
OP Saabster Regular Member • Posts: 274
Re: 45 minutes of M31 from Central Texas

JamminHyaku wrote:

I am trying to learn some astrophotography and am quite confused, this is a 250mm focal length correct? This picture I took at 400mm, or around 640mm in crop mode, and it is still very small. Did you have to crop a ton in order to get this image?

I am trying to figure out if I should try a telescope or if my 100-400mm lens is capable of achieving similar results. This is just one frame as I didn't stack anything here

Yes The Redcat series is a 250mm FL scope/lens. Yes I cropped the image. When I get home I'll post the full frame version so you can see how much I cropped out.

In answer to your question, I'd get a telescope. While the Lens is good, it will have a few shortcoming that a decent refractor won't, that will make it easier to deal with the images.

Camera lenses typically have coma so the stars will not be round at the edge of the field, some will only have 30% of the center usable and the rest comma shaped stars. They'll also have a lot more false color that even a good doublet will have which makes for bad purple and green fringing around stars.

The focuser on a telescope will be much better and easier to keep in focus with out focus creep let alone zoom creep on some lenses when pointed upwards for many minutes.

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