This LRGB image is the result of 3 hrs of imaging with many lost subs due to cloud and some RA imbalance issues. Probably only 1.5hrs with most of those softened by clouds. This results in a noisy and more washed-out image than I would have liked. Still, compared to my first attempts, 14 yrs ago, it’s not bad.
Imaged with the ASI1600MM-Pro, ZWO filters, Lacerta Komakorr Coma Corrector. modified Orion Optics 250mm Next on the CEM70G.This was first-light for my refurbished scope. I had the mirrors re-silvered in 2020, I flocked the tube and replaced the focuser for a Skywatcher low-profile Crayford. I’ve just finished making a brace for the rings – to stop ring wobble – which it does very well. The Lacerta Komakorr Coma Corrector is a big improvement over Skywatcher 0.9 CC. Sharpness has improved across the image, its very noticeable.
I should try and revisit this target again and give it the time it deserves now that my equipment can capture more detail.
Some of my earlier attempts:
A guided session using an HEQ5. Manual focusing is a bit dodgy so lots of detail lost.
An early guided session using my HEQ5.
Taken with a Canon 350d, OO 250mm on an EQ5 unguided.
Taken with a modified webcam using my OO 250mm on an EQ5.
I had a few things to crack like the differential flexure and misting up of the camera that trashed a lot of the subs I took in a 3hr session. As a result, at first when I processed the image I lost all the colour but revisiting the data and being more careful I have been able to bring out a lot more detail and colour. All things considered this is not a bad image – noisier than I would have liked but we can’t have everything.
If you pixel-peep the image you can see the smaller stars are elliptical left to right. This is the result of a high frequency oscillation in the RA axis of the CEM70 that I have fixed by a board swap out.
I have been fascinated by astronomy ever since I was a boy (even making a telescope with simple lenses) but it wasn’t until 2005 that I really started taking astronomy and astrophotography seriously. But as is common with me, my interest peaks and wanes with extensive periods of inactivity (often associated with challenging work commitments and I now suspect metal health dips).
M13 is a very bright object and so it’s been an obvious target over the years. This post contains images taken over the years with different equipment and improving results and techniques.
The Toucam was a basic way to start astrophotography long before low-cost CMOS cameras existed. The Toucam was a CCD webcam that produced surprisingly good results for planetary images. With the long exposure modification (and Peltier cooling) you could even attempt some deep sky imaging. It had a very small sensor with just 640×480 pixels. Getting a target on to the chip was a real challenge.
I remember being very pleased with the results all things considered; using the large Newtonian on a wobbly over stretched EQ5, manual focusing, basic polar alignment, star hopping and lots of 1-5 second images.
By 2010 I had invested in the HEQ5, a Canon 350d DSLR and a guide camera. But even the HEQ5 is pushed to its limits by a fully loaded 250mm reflector. Good results were possible but exposures had to be short when the DLSR really needed longer, it was a challenge even for bright targets. This led to some frustration that ultimately meant the hobby was parked for several years.
In 2020, when lockdown really started to bite, I restarted my hobby and invested in a new small Newtonian, the Bresser 150mm f5, that was better suited to the HEQ5. This allowed substantially better-quality guiding and the shorter focal length was more forgiving. It was worth taking longer subs and building up the data to get a deeper image.
For this image conditions were not great and I did not take enough subs to control the noise (dark hours are short in early summer).
(If you pixel-peep you will notice all the stars are D shaped. This is because the focuser tube extends into the light path when the scope is used with the Skywatcher 0.9 Coma Corrector. I eventually resolved this by sawing off 16mm of the focuser tube!)
At the back end of 2020 I decided to comit more to the hobby updating my 250mm Newtonian with re-silvered mirrors and flocking. In early 2021 I replaced the focuser for a more robust low-profile Skywatcher focuser. At the same time, I purchased the CEM70g and finally after some 15 years or so I had a mount that could handle the weight of the 250mm easily! Swapping out the DSLR for a dedicated mono camera has allowed a much more detailed, deep and less noisy image. This final image shows just how far the globular cluster extends.
This is my first image of this season after a long break. It’s the result of two nights of roughly 1hr total for LRGB, 2hrs Ha and 5hrs Oiii. I’ve been practicing with methods to combine the images… This final image is LRGB normally processed combined using a star mask and pixel math with an HOO image. The result is fairly balanced but the regions extensive Ha is not as pronounced as I would like. I seem to have bit of light leakage in the corners, some I managed to clone out but I need to track down the source.
LRGB subs were 30sec @ gain 0, Ha and Oiii subs were 120sec @ gain 200.
ASi1600mm pro and filter set, scope was the OO250 newt.
Even at 30 seconds and 0 gain I still manage to clip some stars.