Photo – Sun April 21st 2018

Posted on April 22, 2018 by Benoit Guertin

After a weeks of clouds, rain and even snow, I finally get a sunny weekend without a cloud in the sky. With the warmer temperatures, time to take the telescope out. Unfortunately no significant sunspot happening on April 21. Just a small region (AR2706) on the western part of the sun.

Canon 80D (ISO 100, 1/400s)
Skywatcher 80ED (80mm F/7.5)

Sun with sunspot AR2706 (21-apr-2018). Benoit Guertin

Solar Eclipse – Post Processing

Posted on August 22, 2017 by Benoit Guertin

With the eclipse behind us, and all the gear put away it’s time to transfer and process the images to create something memorable. I decided to make a mosaic with some of the photos of the eclipse, as well as the visible sun spots. Click on the image below for a high-resolution version.

August 21, 2017 Solar Eclipse

The weather cooperated and I had the right gear to get some decent photos. Before the start of the eclipse, the sun presented two observable active sun spot regions: 2671 and 2672. This helped in achieving a proper focus and gave something to observe prior to the start of the eclipse.

Sunspot Region 2671 (right) and 2672 (left)

As I had installed and aligned my Vixen equatorial mount the night before, once I had proper focus with the camera, it was child’s play to start an automatic sequence of images every 60 seconds. Hence for the entire solar eclipse, it was hands-off and automated. I could simply glance once in a while at the screen or grab one of the hand-held solar viewers to look up.

58% Cover from the Montreal, Canada Location.

While the effect was nowhere near that of those in the path of totality, the light level and heat did drop at the peak of the eclipse. The brightness was lower, not like when there are high altitude clouds as the shadows were still sharp and well-defined. And the sun’s rays did feel cooler, a welcomed relief from standing under the sun for the last hour.

In the end, it was a fun experience, especially with the kids. And with over 150 images taken I decided to compile them into two formats. A time-lapse video and a mosaic as seen above.

The video was actually the quickest thing done. With Microsoft Movie Maker, it takes the Canon CR2 RAW files directly and stitches them together into a video. It actually took me longer to find a suitable soundtrack to the clip.

With that experience under my belt, I’m looking forward to April 8th 2024 total solar eclipse that will pass close to home.

Telescope: Skywatcher 80ED with Thousand Oaks R-G solar film
Camera: Canon Rebel XTi (450D)
Setting: 1/1000s at ISO 100

Sunspot 2529

Posted on April 16, 2016 by Benoit Guertin

Sunspots on the sun come and go. Count them for many years and you’ll soon find out that there is an 11 year periodic cycle when the solar magnetic activity peaks. We are presently in Solar Cycle 24 and on the tail end of the double peak of 2011 and 2014. So why would I want a solar filter when the Sun is heading into a quiet period?

Number of sunspots observed and predicted for 1995 to 2020

Well, just because the number of sunspots goes down doesn’t mean that there’s not good some great observing opportunities. Sunspot 2529 provided that perfect occasion to finally try out my new solar filter.

Sunspot 2529 (April 10, 2016) – Benoit Guertin

The above image was captured on April 10th, 2016 with on my Skywatcher 80ED with Canon 400D at ISO 200 and 1/500s. 19 frames were processed with Registax6. Sunspot 2529 is still visible today and may be there for another week as readings indicate that it’s quite stable.

There are various types of solar filter out there. They all essentially do the same thing which is to permit only a small percentage (roughly 0.001%) of the white light to pass through. Solar filters are not designed to allow observation of prominence and flares, special hydrogen-alpha narrow-band pass filters are required for that, but they do allow a view of sunspots and granulation if you happen to have sufficient focal length. By blocking out most of the sunlight, you can then safely observer or photograph the sun. Remember not to install your finderscope, and move the telescope away from the sun before removing the solar filter. Your telescope is a MIGHTY strong magnifying glass.

Shopping around there are generally two types of solar filter: glass and film. While the glass are more durable, the films offer just as good optical performance at a lower price, especially for larger aperture.

Thousand Oaks Optical R-G Solar Filter

Normally for anything in the optical path, especially filters, backyard astronomers are always looking for the smoothest and most parallel surfaces, but for solar film, it appears that the ripples from the loose film have no effect on the image quality.

The filter that I selected is the R-G Solar Filter from Thousand Oaks Optical. It provides a light yellow pleasant view of the sun, and works very well both visually and with the DSLR. I enhanced the yellow in the photo of the sun above, but it’s quite close to what can be seen and photographed.

Mark your calendars for May 9th 14:57UT, Mercury will transit in front of the Sun. The last time that happened was 2006.