M45 / Pleiades

[rjbokleman]

M45 turned out to be a much more challenging object to capture than I originally imagined. I figured: Big. Bright. Easy.

Turns out that using a short focal length (AT65EDQ @ 420mm) with a wide FOV with the amount of light pollution I have isn't easy at all. I'd been spoiled by my trip to VT and Plainfield, MA where the skies are nice and dark.

I'd been having issues with the AVX and this short tube with PHD. I'd get these odd DEC spikes that drove me crazy. I wasn't seeing this odd behavior with the SW100ED. (The SW100ED lighter than the AT65EDQ and its longer length tended to balance out this DEC issue better with the AVX defaults...so I learned later.) I worked with Andy via email and have figured out that I needed to use PHD 2.5 Dev 8 with a new DEC routine for anti-backlash. I also made a few AVX adjustments for anti-backlash discovering the defaults were 0%. They are now set at 70%.

The AVX Manual
There are two values for each axis, positive and negative:

• Positive is the amount of compensation applied when you
press the button in order to get the gears moving quickly
without a long pause.

• Negative is the amount of compensation applied when you
release the button, winding the motors back in the other
direction to resume tracking.

Normally, both values should be the same. You will need to
experiment with different values (from 0-99); a value between
20 and 50 is usually best for most visual observing, whereas
a higher value may be necessary for photographic guiding.

I also had a 1.25" adapter connected to my T-Ring on the Canon. That caused all kinds of vignetting that I'd seen before, but didn't take the time to really understand. I switched to a 2" adapter. Problem solved as the image train was being restricted causing serious vignetting in the image.

Last, but not least...how do you process an image with nebulosity like this without a modified camera and major light pollution? That took some time to figure out. I was so tempted to just purchased a CLS/LP filter and give it a go, but I think the processing learning curve turned out to be a better investment.

The other thing I learned from some folks on CloudyNights is that when you're imaging in such LP skies you may have to triple your integration time to get anything near close to what you'd get in dark skies. This is 3 hours over two nights. I really need at least 9 hours to get anywhere near some of the best M45 images out there.

I think this is a good start for now though...as the learning continues...

[Chuck]

Very nicely done Ron. Though I also have an AVX mount, I can't comment on anything as I still haven't even purchased my DSLR yet. I should be ordering it soon, the Canon EOS 7D Mark II, to start playing around with piggyback stuff. When I finally get started, I may need to pick your brain a little, if that's okay. Thanks for sharing.

---- Chuck

[Bruce D]

Looks great Ron! I never did get out that night, glad to see you did!

[AndyG]

Beautiful image, Ron! Certainly a challenging target with the bright (easily saturated) stars and the faint details in the nebulosity.

[rjbokleman]

Building upon the great success with NGC 869/884 Double Cluster with PI, I ran my M45 data through the same sequence..more or less.

I think this result is much better than the original and shows real progress, but *unfortunately* I forgot to include 20 Lights @ 120" ISO 400. So this is a stack of just the (47) ISO 800 images only or 30 * 120" + 17 * 300" or 2.4 hours total.

I'm going to go back through it again with PI and add the missing 18 * 120" or .6 hours.

[rjbokleman]

Bill,

Thanks! Here's my last try using this data. I think I've gotten everything out of this one I can. I've tried 3 times now using different tools. PixInsight by far does the best job...and here I was able to bring out even more of the reflection nebulosity and tone down the brighter stars a bit.

Santa brought me a Hutech IDAS LPS-DP1 filter to help reduce the 'Skyglow' in the future, so I'm hoping this will make a difference the next time I shoot M45 (or any other target for that matter). The processing has been a real 'bear' trying to get rid of the redish/brown tint and bring out the reflection nebula at the same time.

[Pete]

Another big WOW!