DSO astrophotography on a very tight budget

[DennyD]

Hello, I am getting into astrophotography and just changed from using my smartphone to a dedicated astrophotography camera. My telescope is a Meade ETX-90RA with a ZWO ASI120MC-S and Nikon D40 DSLR. As much as I would like to upgrade to the ZWO ASI224MC  my budget won't allow it. Is the ASI120MC-S a good camera for DSOs? I plan on getting a. 5 focal reducer for my telescope. Any thoughts, help and advice would be greatly appreciated. Thank you. Denny.

[Stargazer33]

Hi, the ASI120MC-S is really a planetary camera. With a read noise of 4.0e it would be very noisy at long exposures. It's also got a relatively shallow well depth at 13000e which means the brighter stars will burn out in long exposures.

Having said that, sometimes stacking lots (couple of hundred or more) short exposures of 10 or 20 seconds gives pretty good results. 

At the end of the day you have to go with what you've got.

Good luck and hope to see your results soon.

[nfotis]

If you can use your Nikon, it should be a better option for DSO imaging. Larger sensor and pixel size, if I am not mistaken. It takes some effort, of course, to get good results (a guiding mount is necessary).

 

N.F.

[AstroRookie]

1 hour ago, nfotis said:

If you can use your Nikon, it should be a better option for DSO imaging. Larger sensor and pixel size, if I am not mistaken. It takes some effort, of course, to get good results (a guiding mount is necessary).

 

N.F.

Hello DennyD,

nfotis is right about the mount; no compromises there. I tried with an old Meade LXD75, and gave up. Then upgraded to the skywatcher EQ6-R Pro, and it's a complete different ballgame now. As I'm on a budget as well, the dedicated astro-camera will have to wait but the second hand 100€ canon 500d is definitely more then enough to start learning.

Enjoy!

AstroRookie

[nfotis]

I am in a similar situation, so I went first for a guiding mount (bought a used HEQ5) after I played with my used Skymax 127.

Initially, I am just dabbling in photography using my Canon DSLR, and I may continue later with a dedicated camera.

N.F.

[happy-kat]

I think your mount is an altaz mount so tracks in tiny left right up down keeping the object in the field of view but not following the earth's rotation. The mount and telescope with your asi120 are great for the Moon and planets and say small galaxies (many frames but say max 5 seconds) but for DSO I would piggy back it with your Nikon and probably the lens that came with it as many DSO are huge. The shorter the focal length of the lens the longer the exposure length before field rotation becomes evident, a 50mm lens may do anything from 15-45 seconds exposure length. Take raw files and that opens a whole new arena in processing but the essentials to get going are free DeepSkyStacker, GIMP, sharpcap, registax for example.

A remote trigger is required to not induce shake when using the Nikon or at least a timer delay.

Edited September 20, 2020 by happy-kat

[alacant]

Hi

Yeah, I'm sure it's doable. To ease the tracking, tilt the plate between the tripod and the base of the telescope mount to match your latitude and point it toward the pole.  (Many steps omitted here).

But, and IIRC, this makes the whole assembly unstable. Be sure to add weight below to prevent the tripod toppling and to balance the tube at the front against the DSLR.

Watch carefully to avoid the camera trying to fit between the fork;)

HTH

Edited September 20, 2020 by alacant