Wide field astrophotography (low budget)

These astrophotos were taken during holiday trips to the Canary Islands (2005, 2006). I wanted to gain some experience with astrophotography, but at a minimal budget. So I bought a Orion min-EQ equatorial mount (including Astrotrack drive, total cost ca. 150 euros, manufactured by SkyWatcher) to track the stars, and used a Minolta 600Si analog SLR (with film Kodak Elitechrome 200) to acquire images over exposure periods of 4 to 8 minutes. A small review of the min-EQ is given further below.

Constellation Cygnus stars wide-field astrophotography
Head of Cygnus (the swan). North America nebula (NGC7000) clearly visible (click on image for full size).
Part of the Veil Nebula (a supernova remnant) is just visible at right of/below the center.
The tiny red dot in the upper right corner is planetary nebula M27 (Dumbbell Nebula).
Location: La Palma (Canary Islands), September 2005. Precise location (uses google maps).
[Minolta 600Si with 50mm/f1.7 @ f2, 4 minutes exposure, Kodak Elitechrome 200. Scanned with Minolta 5400, processed with Paint Shop Pro 8 and PixInsight LE 1.0]


Constellation Orion stars wide-field astrophotography
Orion. Barnard's loop clearly visible (click on image for full size).
The bright patch at right of the center is M42, the Orion Nebula (APOD). The three central stars form the belt of Orion.
Location: La Palma (Canary Islands), January 2006.
[Minolta 600Si with 50mm/f1.7 @ f2, 8 minutes exposure, Kodak Elitechrome 200. Scanned with Minolta 5400, processed with Paint Shop Pro 8 and PixInsight LE 1.0]


Constellation Auriga stars wide-field astrophotography
Auriga. Star clusters M36, M37, M38 are visible (click on image for full size).
Location: La Palma (Canary Islands), January 2006.
[Minolta 600Si with 50mm/f1.7 @ f2, 4 minutes exposure, Kodak Elitechrome 200. Scanned with Minolta 5400, processed with Paint Shop Pro 8 and PixInsight LE 1.0]


Constellation Zodiacal light Zodiac stars wide-field astrophotography
Zodiacal light (click on image for full size).
Location: La Palma (Canary Islands), January 2006. Precise location (uses google maps).
[Minolta 600Si with 28mm/f2.8 @ f2.8, 8 minutes exposure, Kodak Elitechrome 200. Scanned with Minolta 5400, processed with Paint Shop Pro 8 and PixInsight LE 1.0]


Constellation Sagittarius stars wide-field astrophotography
Sagittarius (the Archer) and center of the Milky Way, indicated by a blue 'C' (click on image for full size).
The center of our galaxy is hidden behind dust clouds; a supermassive black hole is believed to be positioned there.
Location: Tenerife (Canary Islands), August 2006. Precise location (uses google maps).
[Minolta 600Si with 50mm/f1.7 @ f2, 8 minutes exposure, Kodak Elitechrome 200. Scanned with Minolta 5400, processed with Paint Shop Pro 8 and PixInsight LE 1.0]





Short review of SkyWatcher min-EQ

The min-EQ is by far the cheapest motorized equatorial mount available. Given a price of ca. 150 euros (including motor, an Astrotrack Electronic Drive), it makes a well-built impression. It is very compact, well-suited for travel (travel box not included).

I only used it for wide-field photography, not to mount a telescope. The images shown above are those which turned out best; many other images suffered from star striping. One reason for inaccurate tracking was temperature dependent speed of the AstroTrack drive (which is not crystal controlled). Speed change of 7% was observed when temperature was reduced by 10 degrees centigrade. So I replaced the Astrotrack drive with the EQ-1M drive (which is crystal controlled) which indeed has a very stable and accurate rotation speed.

Nevertheless, I was never able to acquire satisfactory images with a telephoto lens (135 mm): jagged star striping occurs. So I measured the periodic error of the min-EQ/EQ-1M, and found a periodic error of ca. 200 arcseconds peak-to-peak. The period was ca. 870 sec. A collegue of mine measured periodic error of his min-EQ/EQ-1M, and also arrived at ca. 200 arcseconds peak-to-peak.
This level of periodic error is very high (a high-end equatorial mount will display a periodic error of no more than a few arcseconds), and explains why telephoto imaging failed.

I conclude that the min-EQ is only suited for wide-field imaging (50 mm and shorter).
As such it offers good value for money.

Min-eq equatorial mount skywatcher
Min-EQ with Minolta SLR mounted. This mount was adjusted by the author, to include a polar finder and adjustable counter-weights (the product has no polar finder and a rather heavy (ca. 2 kg) counter weight). A mini ball head (Manfrotto 484) was used to give some directional freedom to the camera. Click on image for full size.


Min-eq equatorial mount skywatcher Min-eq equatorial mount skywatcher
For polar aligning, a standard finderscope (which belonged to a 5 inch telescope) was 'inserted' between the mount body and the counterweight-bar; that required drilling a hole in the finderscope's post and adding a 'headless screw' and long nut. Click on images for full size.
Aligning the finderscope with the mount's axis required adjusting the scope's two screws.
Find a rock or so to put the mount on, otherwise you have to lie on your back during polar aligning! (had to do that in the Sahara desert ...)





Planets, stars, etc.


The "seeing" over Holland

Moon Lunar Clavius DMK Barlow

Lunar astrophotography with a DMK camera



[Images are copyright P. van de Haar. This page was last updated on June 19, 2008]


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