Piggyback – Second Night – Cygnus

For the second night of weekend tests I decided to shoot Cygnus.  There were some good reasons to choose Cygnus.  I could see four or five stars in the constellation (ha ha, seriously it was that bad) but that was enough to give me a good idea that I was framing the North American and the Veil.  It was also near zenith and away from that dratted Radio Shack sign.

I tried the final filter, a Meade 4000 Nebular Narrowband.   Finally, a filter with a descriptive label!  Plus, I found a light curve for it:

Probably not much different than the others, but it seems higher quality and a little larger.  It is darker though (more narrow, perhaps), and harder to focus.  It took me about half an hour to find Vega in live-view.  Once in focus, I lined up Cygnus as best I could.

I’d left the wedge-pod set up from the previous night, and just dropped the scope on it again without realigning.  I told my timer to take thirty 1½ minute exposures and let it do its thing  for 3/4 hour.  Then I shot ten 1½ minute darks and a bunch of bias and flats.  I had to throw out 6 lights that were corrupted by airplanes, but stacked the rest to give me a 36 minute exposure.   Here it is, as well as a key I made for it from my previous star charting digital data.

Cygnus, 36 minutes, f/4.5 (50mm f/1.4 lens), ISO 800
(click each full size image into a different tab in your browser, and you can go back and forth between the image and the key)

Piggyback – First Night, with Filters and Guiding

In the last post I discussed some filter and balance enhancements I made to my piggyback setup.  This first night of testing it I started by trying out an unlabeled and ugly looking Lumicon filter.  The box said it transmits as follows: OIII (496) 96%, OIII (501) 94%, Hß (486) 92%.  It seems to transmit  Hα as well, since the California Nebula comes out pretty red in this 5.5 minute guided exposure (f/3.5).  There is a really bright Radio Shack sign not far from where I was pointed, and the filter was not able to block the glare well.

The next Lumicon filter was labeled “Galaxy” but that lettering seemed intentionally removed, like they were reusing an old mount.  Like the other, I’d removed it from the mount and placed it as a camera body clip-in of my own making as described in my previous post. Its transmission specs are OIII (496) 86%, OIII (501) 84%, Hß (486) 82%, Hα 95%.  I also added a hood to the lens in hopes of cutting down nearby light wash.

I tried two approaches with this filter, and both used a number of dark, flat, and bias frames stacked with multiple light frames.  First was three, 5.5 minute exposures, manually guided (ISO 800, f3.5).   The final 16.5 minute image looks like this after processing:

Next I tried ten 1.5 minute exposures, but did not guide the piggybacked camera with the main scope this time.  I had drift aligned the scope pretty thoroughly, however.  Here is the final 15 minute image (ISO 800, f3.5).  The stars look as good or better than the manually guided one, and the overall image a little better.  Yes, that’s the Pleiades on the right.  Seeing conditions were poor, with a limiting magnitude of around 3.

So the lesson I learned here is that I don’t need to manually guide when using the 50mm lens on my mount, if the mount is well-aligned and properly balanced.   That’s good, because after 16 minutes of manually guiding the scope I’m pretty done with that and ready for some autoguiding if guiding is needed.   In the next post I’ll talk about the second night of this configuration, using a different filter and a lot of unguided 1.5 minute exposures.

 

Piggy-backyard

To get me back in the swing of DIY enhancements and pictures, I came up with some goals besides “get a better camera.”  Better tracking, manual guiding, and use of filters seemed good goals.   Guiding a filtered piggyback camera appeared a good way to start.

Here’s the set up on the deck, with the 50mm f/1.4 on a small ball head piggybacked to the scope.  Lots of wires, including camera timer, paddle for dec/RA +/- guiding, heater, 12v supply, and focuser (not really needed for piggyback).  I need to add a heater to the camera too, I guess.

You can see the new bar on the bottom for counter-balance weights.  I looked to buy a dovetail system for this, but decided to make one out of a shelf bracket, sliding nut, and bolt with washers.  It didn’t take long and actually works pretty good.  Some of my tracking error in previous shots was likely due to lack of balance.

For the filters I had some 1.25 eyepiece filters from my dad (Hα, Hß, Oiii/UHC), but nothing I could mount on a camera lens.  Clip-in filters for a Canon camera body or lens are available, but pricey.  A little research and some measurements led me to the idea of making my own clip-in filters from the 1.25’s that dad had sent.  Unmounted, they are around an inch in diameter.

With a compass cutter and some foam left over from a dew shield, I started experimenting with making donuts to fit the filters on the inside and enough outside diameter to squeeze into the 42mm gap that crop sensor Canons have behind the lens.  The compass-knife I bought made quick work of this and I’m glad I didn’t have to cut a traced circle with an exacta knife.  It’s important to buy at least one new tool for a new project.

Here is the end result.  Pictures of actual nebulae will follow in my next post!

 

 

 

Camera Apart (late 2013, early 2014)

As I’ve mentioned from time to time, my Canon 1000d is modded in order capture more red light.  In September 2013 I first disassembled it to remove filter LPF2, which has a transmission curve like the graph the right, cutting transmission of reds and IR:

This went well (i.e. the camera booted and took pictures when I was done).  I left LPF1 in place, as is typical.  But I didn’t replace LPF2 with anything.  Typically one replaces LPF2 with a filter that cuts UV and IR beyond the H-α wavelength.  I think the idea is that you need to transmit H-α but _still_ aggressively cut IR otherwise your images can capture unfocused IR that has been refracted into the visible spectrum.  So anyway, my stars looked bloated and I wondered if it was this effect.  So I got an Astrodon filter from Hap Griffin that has a curve (black line) that looks like this:

6 months after I took the camera apart to remove LPF2, I replaced it with one of these AD40Ds.  Here is the scene of the crime:

 

 

 

I just came across these pictures today and realized I never went into the story in detail, so now you have it!  Did it improve my images?  I think it did, though I wish I had done some before and afters. Looking at my images from that time, maybe I’ll try to recreate the California Nebula image to see if it’s much different.  Drive correction is next on my list to try to get the stars smaller.

My thanks to Gary Honis and his fabulous resources for these DIY DSLR mods.

Lagoon Nebula

This year’s camping trip to Medicine Lake was planned to coincide with the new moon.  Unfortunately it ended up coinciding with a rash of wildfires around the state.  I was able to get this image of the Lagoon Nebula early on in the trip before the smoke got really bad.

6 Stacked 30s Exposures Canon 1000d modified/C8

International Space Station

I had big plans last night to drive down the coast and try to get a picture of the ISS transit of the moon during the eclipse.   I was packed and ready with scope, camera, and SW radio for a time signal.  Unfortunately the coast was shrouded in fog and high clouds, and after consulting GOES-West and some web cams, I decided not to risk the drive down PCH to get to the centerline.  My research did get me intrigued about the idea of capturing an ISS lunar or solar transit, though, and introduced me to a great website for this and other events.

Tuned as I was to what the ISS was up to, I noticed it would be nicely visible from our house yesterday evening.  I took this picture almost as an afterthought, so I didn’t set up the shot very well.  The green blotch reflection of the full moon, below the bright ISS dot, is a good lesson in the flare potential of wide open fast lenses.  Or that you need to take the UV filter off for such shots.

50mm f1.4 1/80 Sec ISO 3200

New Lens

Since I’ve been shooting a bit of camera piggyback on the scope, I’ve decided to take lenses a little more seriously.  All of my previous lens pictures have been using the 18-55 or 55-200mm Canon EF zoom lenses.  Not particularly fast, and with a lot of lens elements.  I just got my first fast lens in the mail, a second-hand Canon EF 50mm f/1.4.   Anxious to test it quickly, I took it out on the deck tonight and shot toward Vega.  This is a handheld shot of Lyra and vicinity, Canon T3 50mm f/1.4, 1/40th sec ISO 6400.  No post processing, just the jpg from the camera. (click it to show the full size)

With my eyes I couldn’t see much more than the summer triangle, (though not dark adapted).   So I’m pretty happy with the lens.

Medicine Lake #2

Next one from the Medicine Lake camping trip, also within Cygnus (because that’s where the trees were not).  The Veil Nebula.  Same exposure info as the previous post.

 

Images from Medicine Lake

We planned this year’s camping trip to Medicine Lake to correspond with the new moon. Here is the first of four objects I shot.  This is the North American Nebula at f/5.6 200mm 9minutes (18 exposures of 30sec each).  Piggy back.

 

Using my Work Skills for Play

The problem with the new latitude digital setting circle is that it’s in decimal degrees rather than degrees/minutes/seconds.  I made a table of bright stars with the converted formats, and started thinking about sketching in constellation diagrams.

Orion using stars from the HYG database

Then it occurred to me that since I have the knowledge and software to make maps of the earth, maybe I could make a star chart.  It’s been fun to try my hand at uranography.  There are a number of star databases out there, and it’s not hard to convert RA and Dec into longitude and latitude and plot and project them with GIS software.

These maps are quick and dirty, but I have some ideas about how I’d like the perfect star chart to look and the data I’d like it to contain.  (Hint: Like any good GIS analyst, I hate Degree/Minutes/Seconds).

I did take the time to vary the size of the stars by magnitude and the color of them by the color index.  Here are all of the stars from the HYG 2.0 database brighter than 7th magnitude in a sinusoidal sphere projection.  How many do you recognize?

Stars brighter than Mag. 7 (HYG 2.0)