Astrophotography – equipment

Weekend Opportunism

Between a busy work week, family commitments and some so-so forecasts it wasn’t looking good for astronomy this weekend, but it turned out pretty well.

Friday Night:
Imaging-
Didn’t get out until about 10:30 but tried to make up for lost time by setting both the main scope going and trying out my 50mm lens on the Star Adventurer. I had high hopes for the 50mm lens- it’s another oldie (I’ve had it about 15 years), but online quite a few people are getting great results with them. Well- I’m not in that club (yet). The diaphragm only has five blades and although I stopped it down to f2.8 (it’ll open up to f1.8) all of my stars are pentagons and DSS is refusing to recognise them as stars- so no results from that. Fortunately, the main rig saved the day: I went for NGC6946 – The Fireworks Galaxy with my 200p. Throughout the session low clouds were interrupting the view, and around half the subs were lost, but the ones I did hang onto gave the result below. Over the summer I’ve picked up a second hand Canon 550d that has been home modified with a Peltier cooler and put into a metal case- it’s not pretty, but it seems to be effective. This is 13×4 minute subs and throughout this session it held the temperature down to around 7-8 degrees which I’m pleased with (a couple of degrees below ambient, my 600d usually runs about 10 degrees above ambient and is consequently much noisier). The target itself is quite a bit smaller than I’d anticipated- this is a crop of about 20% of the frame. Despite the small size- I think this is a lovely target- both for its colours and the asymmetry in the arms.

Observing-

Whilst the cameras were doing their stuff I had the Dob out on the following objects:

The Double-Double- I used Vega to get the finders lined up then dropped down to Epsilon Lyra to check out the seeing. It was a straightforward split, but I could see that the transparency was not great.

M13 & M92 – I often start with these and never get tired of them. In Binoviewers at about 260x they fill the field of view and appear 3 dimensional. For me these are the only types of objects that actually look better in the eyepiece than in a photo; I love the difference in their appearance- M13’s great with lots of features, but a bit of a mess with arms everywhere, whereas M92 is compact and very neat. Just wonderful.

The Veil – I was reading a thread on SGL recently which referenced a Sky and Telescope article on The Veil (https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/explore-veil-nebula/) . Using this as a guide, and with an Oiii filter a 30mm eyepiece (55x) and a coat over my head I managed to explore just about the whole thing. I’m a bit prone to hopping from object to object whilst observing, so it was great to really take my time in the tranquillity of the small hours and drink it all in with nothing but the odd clunk of a shutter release and that American woman with the nice voice who commentates on APT saying “Dithering started…” softly in the background. Ahhh… a very nice dither contemplating the remnants of a supernova.

I was on the Veil for over half an hour and loved every minute of it, but decided with to move on with the Oiii filter and go check out M27. This is normally not a problem, but by this point the transparency had deteriorated so much I was unable to hop to it. Altair was the only nearby star that was naked eye visible and despite several attempts I just couldn’t find the stars in the finder to hop up to M27. Reluctant to retire I switched up to the North East to check out M31 as the skies looked better in that direction. Before I could get to it a bank of cloud blotted it out. Time for bed…

Saturday:

I managed to pop out briefly whilst doing other things on Saturday evening and set the imaging rig running on M13. This was a bit of an experiment: I’ve imaged M13 before, but with my guide camera on a smaller scope using the short exposure method. Whilst I was quite pleased with those outcomes (see https://roslistonastronomy.uk/catching-up-on-images) , I wanted to see how it would look with more integration time and a DSLR chip. This is 22x 4 min subs plus calibration frames and I am really pleased with it. As a bonus for the last half-hour it was running I sat outside with Sam observing the sky primarily with Mark 1 eyeballs. After a while we were both able to pick out the Milky Way running up through Cassiopeia and Cygnus despite the local light pollution. A real pleasure!

Fun with my Bridge Camera

Some pics taken this evening with my Nikon P520, when I went out ‘bat hunting’ (NB all these images are cropped!):

Saturn single frame!
Jupiter Single Frame
Jupiter Single Frame – you can just see two bands!
Jupiter and Saturn
20 Jupiters and 30 Saturn images stacked out of 40 each, drizzled x3 to make them big enough to see!.
Sturgeon Moon Colour
And the Sturgeon Moon in Colour, stack of 10 frames.

T2 to 2″ adaptor

Hi Folks

After buying my nice new shiny UHC filter from Astrofest, when I got home I realised I hadn’t actually got any way of using it with my DSLR. If I attached it to my 2″ diagonal, I couldn’t get enough back-focus and if I connected the DSLR via a T2 adapter, I couldn’t connect the 2″ filter.

After a bit of digging, I found this T2 to 2″ adaptor on eBay for the princely sum of £4.99. It arrived in 12days from China:-

https://www.ebay.co.uk/itm/2-to-T2-Adapter-M48-0-75-With-Thread-Black-Aluminum-Alloy-High-Quality-Durable/143111007190?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Here was my original DSLR to T2 to 2″ connection:-

 

Here’s the new version with the adaptor:-

I haven’t tried it yet but I can’t see why it shoudn’t work. I’ll let you know

 

My Astrofest shopping – 2″ UHC filter

Hi Folks
After hearing all the rave reviews about UHC filters I thought I’d buy one at Astrofest. I bought this one from 365Astronomy as their kit is usually good quality . Very reasonably priced at £52 (show price).
Here’s an interesting article on light pollution filters:-
See you on Friday

Flats light panel

Since I’m currently looking to change to a mono camera I thought it would be sensible to have a look at making the flats process easier.

I’ve seen a few posts over the years where people have produced a light panel and added A4 paper to the front giving a nice flat illuminated area.

I wanted to do something similar so I purchased a cheap LED panel on amazon and cut around the telescope circumference. I left the box around the panel and added Velcro to the inside to keep it flat against the outside. I also cut out the power inlet and on/off button.

Very pleased with the result ! I’ll keep it velcroed to the inside of the observatory.

Esprit 120

Esprit 120 Part 1

I decided to purchase this scope as it fits nicely in between the focal lengths of my other telescopes. I have read lots of reviews of the espirit range and quite honestly haven’t found any negativity at all. I purchased the scope from FLO and spent an extra little to have the scope optically bench tested. This will serve as an additional peace of mind and I’m really pleased I did so. 

On close inspection of the scope I can see this is a very high quality instrument with great attention to detail. 

It comes with all the connectors etc that you would require to start imaging right out of the box. I did purchase the field flattener at an additional cost as I plan to use it purely for imaging. If your doing visual astronomy the flattener isn’t required. I also received a m48 to canon adapter but not sure if this is normally included in uk sales or FLO just threw it in ? Either way very pleased ! 

The retractable dew shield is a great fit and works very well with the two screws to tighten over the tube. 

The focuser is of excellent quality and feels lovely to work it back and forth. The only other refractor I have is a takahashi Fsq 85 and I’d say this is of equal quality. The locking knob sits underneath the focuser. I wasn’t sure about the locking knob in the beginning as I’m used to using the screw type on the Fsq but this is growing on me and certainly locks things down tightly. 

I also like the camera orientation adjuster which enables you to quickly frame the object your imaging. Again slightly different to the Fsq but excellent. 

Visually the scope looks stunning with clean lines and I like the splash of green SkyWatcher have added to their scopes over recent months. 

The optics look awesome and I’m really looking forward to testing it out when the weather clears. I plan to use a full frame canon 6d to start with so this will be a real test of the scope/optics. Going by the look/feel of the scope I’m very confident it will pass with flying colours. 

Make no mistake this is a finely engineered scope, love it ! 

 

Pelican Nebula (Part 2)

Last week I posted an RGB image of the Pelican Nebula taken shortly after the full moon. The evening before (28/10) I’d had my first go at imaging with a Hydrogen Alpha filter, and a few murky evenings has given me the chance to process it and then learn how to feed it into the Red channel of the RGB image using Pixinsight. Updated image, along with the monochrome Halpha image, is below.

Really pleased with this output- because light pollution is suppressed by the filter I was able to expose for much longer (9 minutes per sub) and the red signal is correspondingly stronger. Once integrated into image you don’t have to “push” the software so hard to bring out the detail in the nebula.

Solar Image processing. Myths and Legends.

I have just read an (unattributed) article in April’s Sky at Night magazine on solar imaging, and I have to say, from my own experience I disagree with a lot of it!

It says

“— requires a monochrome high frame rate camera set-up” and “use of a colour camera is inefficient”

Who cares? There is plenty of light from the Sun, efficiency isn’t a problem!

It also says that Ha features change quite quickly. True. As do the atmospheric “cells” that cause image wobble. It suggests you take a 1000-1500 frame avi. The time this takes immediately cancels any advantage there might be from a high frame rate. When you stack all these, you get a blurred image. The only reason you would take so many frames is to reduce noise. Again there is plenty of light from the Sun, so this isn’t an issue.

It suggests that you might need a flat frame (possible) and that you take a defocussed 500-1000 frame avi to achieve this. Why? It is much easier and more accurate if you need a flat frame to simply blur an image you have already acquired.

My images use a £50 colour camera with a not particularly high frame rate. I find a good compromise is 200 frames. This takes around 7 seconds.

Click on “Solar” on the blog and judge for yourselves!

While still in Victor Meldrew  mode, in the same magazine there is a review of a new Skywatcher 20” goto dob for £5499. I am sure that this is a splendid scope, but following my earlier post it is worth remembering that it is only 1 stop faster than Rob’s new 14”! I am pretty sure Rob didn’t spend that amount on it! In fact, in the review there are pictures of M42 and the Trapezium. There is also a picture of M51 of recent discussion. They look nice, but I would invite you to compare the pics with these window-sill images with a scope costing £100 ish.

Moral – Just because something is in print does not necessarily mean it is correct. This is a hobby, it is whatever floats your boat. You can spend a fortune if that is what you want to do, but you don’t HAVE to!