Helping me to shot andromeda

Started 2 months ago | Questions thread
OP jjuncal Junior Member • Posts: 44
Re: Helping me to shot andromeda

Hey Dan!

Thank you so much in taking time to read me and providing me so much useful information!

Dan Paris wrote:

1. focal length selection ?

200mm is fine for the Andromeda galaxy, which is quite large (more than 3 degrees, about 6 times the moon !).

Speed is important, so a teleconverter is not a good idea I think.

OK perfect! I didn't know it was so large in the frame.

Btw how dark is your sky ? Is the Milky Way easy to see ?

Sky isn't the best. I'll be located in Galicia northern east Spain.

on the website it's yellowish surrounded by cities which won't really help.

3 years ago I managed to get a descent picture of the Milky Way, reason why I was hopping to make something interesting there.

But It won't be a problem in moving and finding a better place with better (absence of) light.

You have also to be aware that it's not possible currently to shoot the Andromeda Galaxy (best period starts in September).

Ok, I wasn't aware of this... I guess it's because it's moving higher in the sky. good to know it will let me more time to gather infos.

Right now, to get some training, you may try the Pinwheel galaxy (M101) in Ursa Major. While much smaller than Andromeda galaxy in angular size, but with 200mm you could still get some interesting details :

Or, if you shoot early enough in the night, you may try the Orion nebula which is larger and brighter

Ok I'll take look for practicing !

Of course I imagine the more gathered light the best but should I not exceed a certain number of iso?

ISO does not change the sensitivity of your sensor. Raising the ISO too much would lower the dynamic range hence you'll loose star colors.

You have a dual gain sensor so you need to shoot above the threshold for the second amp. According to the data on (Bill Claff) there's no need to go higher than ISO800.

Thanks so much in taking time to check this information to me and explaining why it's important! it's really helpful!

4. How many white/black frames?

About 20 frames is a good start.

Here's the result of 18 frames at ISO800 with a Pentax K-1 Mk II + Samyang 135 at f/2

If you can about the same number of dark frames and flat frames is best. Depending on your stacking software, you may need to shoot also bias frames.

Ok... reading here and there, I saw many people focusing just on white/black frames and not giving so much importance to the other ones. Good to know! thanks!

any technics to find it fast and focus properly ?

For focus : the more accurate is to use a Bahtinov mask (that you can cut/3d print yourself easily). Otherwise point a bright star, use the liveview at max magnification, rack back and forth slowly till you are confident where best focus is.

ok. I was thinking in creating my own bahitov mask on some cardboard after not being able to find one descent and cheap on amazon.

If your lens have some field curvature, it may be a good idea not to take a star in the center of the frame.

Ok great! as I've been mainly shooting wide angle never thought about this detail!

To find it, are you familiar with the constellations ? I would say that if the sky is dark enough it should be pretty obvious to the naked eye once you know where it is.

good luck !


Thanks again in taking your time to investigate and providing me such useful information. I really appreciate.


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