Friday, June 14, 2013

Seeing and Saturn

The environment really makes a difference when it comes to planetary imaging. Here are two images of Saturn; the first from a windy night with poor seeing, the second from last night--calm and good seeing.

Windy, Poor Seeing

Calm, Good Seeing
The differences are dramatic. With better conditions the artifacts at the ring-tips are gone, there's more ring structure, Saturn's limb and cloud belts are better defined, and the polar vortex can be seen. Contrast is higher, too. (Differences in color balance are due to processing, not the conditions.)

Now imagine if the seeing had been excellent. Maybe some day I'll have a third image that illustrates that.

(Both images were created using a Point Grey Chameleon, Celestron C925 XLT, and TeleVue 2X Barlow, FireCapture and Registax 6.)

Thursday, June 6, 2013

Clouds, WOW, Focal Reducer

The abysmal spring of 2013 continues with clouds, clouds and more clouds. My plan to attend the Wisconsin Observers Weekend this weekend has fallen through because of weather. The first night is being clouded out as I type this, Tomorrow night is forecast to be partly cloudy (at best) and Saturday night is forecast to be rainy (50% chance) and cloudy.

Worst. Spring. Ever.

But anyway, I did manage last week to shoot some test images with my .63 Celestron Focal Reducer.  I fiddle with my adapters until I got a spacing of about 104mm (I think), and here's what I got:

Flat Field test
This is taken using a Celestron 925 XLT and Celestron 0.63 Focal Reducer/Flattener. The camera is an SBIG-ST8300M with filter wheel (total back focus 38mm). Spacing was provided by a Celestron SCT-to-T adapter #93633-A (about 58mm).

The above full-field image is six 10 second exposures (2x2 binned) aligned and stacked, then given a stretch by Images Plus. The scope was not even roughly polar aligned and was unguided. I was also shooting through overhead power lines. Yechh.

I think it's fairly flat, at least flat enough to make me happy. Some vignetting is present, but it's about the same as found when imaging without the FR. I will probably tinker with the spacing in the future.

What's nice is that this setup gives a much more solid connection between the scope and camera. I look forward to using it SHOULD THE FREAKING SKY EVER CLEAR. Really, no, I'm okay, but thanks for asking.