More DS vs Standard Experiments

I followed some excellent advice I received from the Yahoo PST group and spent a good deal of time setting up the DS filter on the scope.  I found that the "sweet spot" for the SolarMax II had the tuner hard up against the pin.  I carefully removed the pin and repositioned it 5 holes away in the middle of the tuner slot.  This gave me extra capabilities when it came to tuning, although at the other end of travel, the image was too dark to see.

Visuallty, I could really see a big difference with the DS in place--much more surface detail was visible, but prominences seemed a little fainter and not as detailed.  I took the following images for comparison.  I cropped then to about 25% of size, and oversharpened them to exaggerate differences.  Here is the DS image:

And here is the standard image:

The DS image had more features and a more balanced look.  The standard seems better focused, which highlights one of the issues I'm having when imaging.  The DS is very hard to focus optimally.  Unstacked, you have a real sense of "snap: as the scope reaches focus.  I don't get that with the DS and I seem to be hunting for he least hazy image position on focus.  I should point out that this is only an issue when imaging.  Visually, focus using the DS is sharp and clear.

DS vs SS PST--part 2

I tuned the filters visually, rather than trying to adjust them via the imager.  Here are two more images to compare after that process:

PST-DS:

PST-SS:

The edge detail looks better in the SS, but much more detail is visible in the DS image.

The difference between SS and DS when using the scope visually is very apparent.  Operating in DS mode, visual images have much more detail and contrast.  The images don't capture this difference quite as well.  However, for speed of comparison, the above images were smaller stacks (500 as opposed to 1000) and captured at 640 x 480 as opposed to 1280 x 720.

Single vs Double Stack PST

My goal was to compare the scope operating in both modes.  Here's the DS image:

And here is the SS image:

I found DS harder to focus; I'm not sure if the image is actually better....

I suspect the problem is with tuning the SolarMax filter.  I tuned for this image via the imager itself and this might not be the optimal way to tune it.  I'll try again, this time with visual tuning.

PST Double Stack

I came home today to find this package sitting on the kitchen counter:

My double stack filter had finally arrived!  I hurriedly opened the box and found the following case inside:

It felt impressively heavy.  I opened it and found a beautiful piece of engineering inside.

I lifted the filter out.  Like the PST, it feels like a solid, high-quality product.  The build and finish were impressive. Here is a view, looking into the back of the filter.

Fitting to the PST was simplicity itself.  It screws right into the threads on the lens hood.  The fully-assembled instrument looks like it means business!

The DS PST is obviously too long for the cutout in the Coronado case.  Increasing the size would require cutting  the foam and reducing the cushioning between the scope and the case at both ends of the instrument.  My plan is to store the PST and the filter in their own cases and assemble them each observing session.

I can't wait to try it out!

AR 1575 and some long filaments

AR 1575 has the potential to create M-Class flares, but it looks quiet in this image.  Captured and processed with my usual workflow.

Observatory Part 10

Insulation!  I am insulating the roof and walls of the observatory to reduce heating in direct sun and also to reduce condensation.  This is just R5 polystyrene and I have installed it rather crudely, but it will do the job and (most importantly) it is very inexpensive. The next step is to install the rest of the studs and to install the drywall to give the interior a more finished look.

M27 -- The Dumbell Nebula

I captured this image last night with a Nikon D40 DSLR, running at 3200 ISO.  Only about 4 of the captured images were actually stackable, so this image represents around 3.5 minutes of actual imaging time. The resulting image was, of course, very noisy.  Noise reduction has softened the image somewhat.

SLR imaging is a cheap way to get into deep sky captures, but it is far from perfect.  The D40 does not have mirror lock up, so I had to cover the scope aperture when I began the exposure, otherwise the vibration caused by the movement of the mirror in the camera causes distortions in the star images (they usually look like little chevrons).  It takes about 5 seconds for the scope to damp down the vibrations after the shutter has been opened.  I stacked the images with DeepSkyStacker, which does a much better job with DSO images than Astrostack.  Histogram stretching was performed in Astrostack, with final processing in Windows.

If you decide to try imaging with a DSLR, I would also remove the strap.  When I started imaging, I noticed that stars were showing very anomalous and varied shapes.  At first, I blamed tracking, but ti turned out to be the breeze moving the camera strap and causing vibrations!