A 300mm telephoto vs a 6 inches refractor

The Tamron SP 54 is a 300mm telephoto lens, with an aperture of 54mm. I took a 60 seconds of exposition image of M42 in Orion. A few months later I took a 15 seconds image of the same field through a 6 inches Sky-Watcher non-apo refractor.

The comparison throws some interesting conclusions:

1.- A 150mm lens gives more resolution than a 54mm lens. Stars are fainter in the 6 inches refractor picture.

2.- The light captured by a 54mm lens in 60 seconds is nearly equivalent to the one captured by a 150mm lens in 15 seconds. Nebulosity appears practically equal in brightness in the two pictures. The lower image is a full frame, meanwhile the upper one is cropped at 25%.

Both images were taken using an unmodded Canon DSLR camera, EOS 450D (or Rebel XTi) and an EQ6 equatorial mount.

M42 with point & shoot digicam

It is interesting to explore the possibilities of some common devices such as digicams and binoculars. I have been reprocessing some old stuff from March. I took 474 single exposures of M42 in Orion through the binoculars with my Exilim digicam. Using a stacking software, all these subframes may become aligned and added accurately, resulting into a 4 minutes long exposure single shot with a perfect star-tracking. I reckon I didn’t use any kind of equatorial mount or motorized tracking. Just an steady tripod. Orion belt passed accros the field of view of the binoculars 3 times. In every gap, I corrected manually the FOV to get M42 inside it as longest as possible.

M42 last night

Last night I could enjoy a really clear night sky at Manaluna Observatory. Meanwhile some of my partners were working hard to complete the Messier Marathon, I took 3 series of no-tracking shots through Vixen 12×80 binocular to M42 in Orion.

The truth is that what I could see through binoculars was much more brilliant and detailed than the next image by far. I think my Casio Exilim digital pocket camera is a bit insensible to dim light …

Trapezium is visible as a spot. The 20″ separation among its components is too close for my binoculars to resolve it. Remember that 20″ is the apparent diameter of Saturn.

M42 through binoculars

M42 is the brightest nebula in the sky. It becomes visible even under light polluted urban skies. I took some exposures of M42, the Great Nebula of Orion, using my Vixen 12×80 binoculars and stacked them up. No tracking, even manual. Just shift-and-add method. This is the result; up to magnitude 12 stars are visible and the core of the nebula is also evident:

Orion belt

Orion is the most important Winter constellation in Northern Hemisphere. In its center we find the “Orion belt” and beneath, the “Orion sword”. The nebulas located in the area show red colors: horsehead, flame and M42 are visible in this shot.