First look at M42 with the big Newtonian

[Kanadalainen]

January 5, 2019

My first good look at M42 with the big dob some images of the moon using Canon 60D DSLR

Exciting, as we had a beautifully clear and still night – the first really grade “A” observation chance in a very long time.

Location: Home in the suburbs – Bortle 7 or 8
Equipment: 14.5” f4.5 dob (368 mm aperture, 1655 mm f.l.), Canon 60D unmodded, GSO 2” 2x barlow
Seeing: Very good
Transparency: Good to very good
Steady atmosphere.
Temperature: -6*C
Time: 9:00 pm to 11:00 pm
Cooling time: 40 min.
Magnification:
1. 92x with an 18 mm ES82 (no paracorr this evening), exit pupil 4 mm, FOV = 0.9*
2. 151x with an 11 mm ES82 eyepiece, exit pupil 2.4 mm, FOV = 0.5*


This evening was a bit of a surprise, coming on the heels of a miniature snow storm. Around 2 pm the skies broke and cleared to a spectacular and rather warm winter day. In anticipation, I assembled the big dob in our sun room and did a quick collimation, using my new Hutech collimation tool. Around 5 pm the sun had dropped below the horizon and the wind slacked to nothing. I am mainly a DSO guy but I decided to try my hand at taking a few moon images with the dobsonian and my new 2X GSO barlow, rigged in series to my Canon D60. I am using an Optolong CLS-CCD filter to help sort out the local LP, and decided to leave it in their while I tried my hand at manual focusing.

After dinner, I moved the scope out to my patio, and attached the Telrad. I took a ranging shot of the moon using my 18mm after allowing to scope to cool for 40 min or so. Then I plugged in the Canon to the focuser, and set up my live view (just 1X). Focusing a camera with a rotary focuser was a first for me. Its not easy, but not impossible. I was a bit surprised how long I could leave the shutter open with a 320 ISO setting. I played with the shutter and ISO for a while until my live image view was reasonable (more below)


M42 and M43 – (nebulae in Orion) – Fantastic! This view, even in my heavily light polluted skies in the city, were easily up there with my better observations with the XT10. At 151x with a 2.4mm exit pupil, I could see the E and F stars within the trapezium (ABCD stars). Visualizing E and F for me is kind of the hallmark of decent seeing, so this was an unexpected treat with a first light on M42 with the 14.5” dob. The probiscus minor and major were very evident in M42, trailing off to long wispy wings. M43 was also quite prominent. I didn’t use any Paracorr or filters for this observation, although a Paracorr would have been a good idea.

Imaging the Moon

My field of view with the GSO 2X barlow was not very large, considering my effective focal length was now doubled to ~3310 mm. I’m guessing the effective magnification might be over 200x. I was able to jump around to various parts of the moon and play with focus.

An afterthought would have been to use the 5x and 10x function in live view on my D60 to try and get better focus. I’m not super satisfied that I did justice to the focusing, but it’s a first effort, I’m OK with it.

After 11 pm, my fingers were freezing so I dissembled the scope and covered up the optics, brought them in, and went straight to bed.

Thanks for reading to the bottom.

[Bigzmey]

Looks like 14.5" DOB is performing well for you Ian, Hopefully, you will get some moon-free clear skies soon.

[notFritzArgelander]

Yeah, f4.5 is kind of an awkward spot for deciding on Paracorr use. At f5 I don't bother. I know I need it at f4.

Great night! Thanks.

[Kanadalainen]

Thanks not_Fritz and Andrey,
Looking forward to more of Orion this winter, its a great segment of the sky.

[prowler75]

Sounds like a great night out, Ian!
I can imagine M42 presented quite a show with a 14.5" Dob. Nice pics you were able to capture of the moon too!

Craig

[bladekeeper]

Good stuff, Ian, and fun images too!