NGC 5236 (M83) Southern Pinwheel Galaxy with basic equipment

[malau]

Hi All, my first "viewable" galaxy by using EQ3-2, no auto guider but drive motor only. DSLR (600d) in Sydney metropolitan area with serious light pollution area (with filter tho). Also process after DSS in short period of time (was in hurry as I was doing few things at the same time).

Mix of 800 and 1600 iso, ~520 light x 25 sec each.

Skywatcher 6" reflector

[cometcatcher]

Nice result David. Looks like you really put some time in on this one with 520 subs!

Some flats would help with the vignetting.

[malau]

Thanks for your suggestion. I would really love to get some flats but I cant leave my telescope in the balcony as I live in lower floor :P

btw how can you tell my pic has vingnetting?

In your opinion, with my DSLR in Sydney area (with CLS filter), how long (total) should I have for the light/sub frame?

[cometcatcher]

Notice the middle part of the photo is lighter than the edges? Most scopes have this to some extent. It becomes amplified with image stretching. You could always setup early and take the flats before you start the session, but you have to keep the camera orientation the same throughout the imaging session.

Sorry no idea on exposure for your circumstances. I think you are limited anyway being unguided if you are still using the EQ3.

[alpal]

Hi David,
Wow - 520 sub frames!
I have a feeling that there is better data in there than you think.
Make some flats up + at least 100 dark frames at the same temperature
& same ISO. ( that's 2 different ISO's- but DSS will handle it )
You might need to put the DSLR camera in the fridge to get similar temperatures.

cheers
Allan

[malau]

Really thanks for your help. You like my mentor teach me a lot.

If I have to take flat in the same session I guess will be very hard. I normally do it in my balcony after work which the sky is getting dim. I was considering use light box or something however I have the LP filter in my cam so I guess it may not working probably? I tried to leave the setting until next day and use the sunlight however I have to wait till weekend to do that.

Anyway :thanx:

[malau]

Hi Allan

I normally do 30 dark frame for each session so I probably have about 150 or so... or you mean each session 100 darks?

I agree with you about may have better data. I just feel I need to learn more about how to use PS to bring the detail up. I've tried different ways from online tutorial and now I guess I got a bit skill about it although may not be the best.

Btw I would like to also know in the pic you know the centre is much brighter than the edge and the changes are not smoothly... I mean if I zoom the actual pic (not the one I uploaded) I can see "square" in different color ... how can I make the brightness transit smoothly? Or it just DSLR problem?

[alpal]

Hi David,
so you're saying that you already have stacked 150 dark frames at the right
temperature into the photo you posted?
I just said 100 darks as a number but 100 should be enough for 520 sub frames
although purists would say that you need 520 darks.


The only way to stop the bright center is to take flats.
Do you know how to do that?

To learn Photoshop - I recommend Louie's videos here:

https://www.youtube.com/channel/UCJ5b6pFHBGe66vsuSaXb-0A


cheers
Allan