Climbing higher on the learning curve

[Pete]

Friday, 20 Nov 2020

Tonight’s focus is upon getting darks and flats functioning on SharpCap Pro. Flats from last try didn’t work so ran another set in the afternoon. Turns out they didn’t work either.

17:00 Attempted M15 at 1 m, 4X, -15C, 200 Gain. The core’s badly blown out and can’t get Wednesday’s flats working. Also the software isn’t able to auto-align even though the field is filled with bright stars. Darks are working. Tried again. 60 X 15 sec, 4X binning, Gain at 200 and 4 sec PHD2 guiding using the piggyback Orion long tube. Getting better.

Wanted to see what a large stack would look like. Been using M74 as another imaging standard . Lot of false starts to discover camera icing at -15C. Turned off the cooler and hit it with the observatory hair dryer. Thought it through a bit more and concluded that without flats it’s a waste of time.

Mars @ 20:00 or thereabouts. Seeing isn’t great but an occasional individual frames looks clean. Imaged 6000 X 1/1000 sec. SharpCap offers a lot of options and somehow the imaging was set to SER rather than ASI format – cannot be processed.

NGC 1275 – the Perseus galaxy cluster. 79 X 1 min, 4X binning, -10C, 4s guiding. Didn’t evem try to use autoalign, and just as well. The guiding jumped sometime during the run and the subsequent unaligned stack was very blown. My expectation of instant color masterpieces has gone by the wayside and following Roger’s instruction was able to run the FIT files thru ImagesPlus3. Which can do a really job of clean-up.

Observatory closed for the night at 22:50.

Conclusions and lessons learned:

There are many permutations possible with darks and flats. There are many variables including temperature, exposure, binning, color format, image format, camera gain plus more. And the saved files are just identified by a time stamp. Standardizing upon -15C, 4X, RAW16, FIT and 200G to simplify things with the prime focus 14” It seems that SoftCap will select appropriate darks and flats with more info when selected from within the program. But it’s near impossible to figure out what file to use for ImagesPlus processing.

On Saturday the 2600 was taken in and disassembled for subsequent cleaning and recharging of desiccant. (2 minutes in a microwave beats the SBIG required 4 hours in a 400° oven.) This should address dust motes and frost.

The software author responded to my forum query on the flat problem. Couldn’t try for flats because it takes a day or two for the desiccant to be fully effective.

Didn’t think there’s be a learning curve this time around.

[Bruce D]

Pete i really like the "galaxy zoo" shot. The vastness of the solar system or even our own galaxy are not sufficient to diminish my sense of self importance, i really need a good galaxy cluster to make me feel like the insignificant speck that I am. Thanks! LOL

[menardre]

Pete

I like the galaxy zoo too. I will have to give it a try someday.

Your star look nice and round and sharp so tracking and focusing must be good.

Regarding the blown out globular. That is a typical problem with stretching something that has bright core. To combat this I use an ArcSinH stretch. This type of stretch stretches the dim portions of the image more than the bright. So the outer stars get brighter but the core does not. I just pull the 'Power' slider from far right to far left. For globulars I then use a "HDR Pre-Stretch Scale' using the 'nth Root X'n scale function. Pull the 'Factor' slider slightly from right to left. This will push the dimmer objects even more without amplifying the core.

From your images looks like you solved the blue cast problem. Did you do anything special?

I use SGP for all of my imaging. It was very easy to create a DARKS and BIASES library. SGP can set the file name based on parameters that you select. So all of my dark file names automatically look like "Dark UG 4M -20C. The 'dark' is automatically applied, I supply the dark type (in this case UG short for Unity Gain), and SGP supplies the imaged exposure time (4M) and temp (-20). My library consists of Unity Gain versions and High Dynamic Range (HDR) settings. For each I have 30sec, 1M, 2M, 4M, and 5M. And for each of those I have 0C -10C and -20C. Sounds like a lot but you can do this during the day and just let it run. I could also have a different set for 1x1 vs 2x2 binning, but I almost always utilize 1x1 binning.

Roger

[Pete]

Thanks for the continued support Rog.

The strange colors may be from using RGB24 rather than RAW16 color format. And may also have been associated with undetected icing at -15C.

I'm a hands-on kind of guy and not into automated imaging. ASI dedicated software and SoftCap both do live stacking so that one may appreciate the image capture live. So this is the software focus for the moment. The objective isn't to get great images, but to get good images that satisfy me with a minimum of processing effort.

The 4 pages of notes taken when you walked me thru ImagesPlus3 are right here at hand. Got 'em memorized now but still check that I'm following the Maynard Sequence. With my extra long focal length the star size reduction function is a real winner. Although one can't live without ArcSinH stretch either. What I do miss in ImagesPlus is the Levels control found in Photoshop. Is there an IP equivalent that I've not yet discovered?

Working through the darks and flats. Once that's taken care of I'll be experimenting with my focal reducer/field flatener. And then in about a months time I hope to drop the Hyperstar on and experiment with 14" f/2 imaging of larger objects. This huge color chip is indeed a wonderful device.

[mark.m]

Pete:
Thank you so much for posting all of these "learning stories." I've pretty much decided that the replacement for my ageing SBIG camera is going to be the monochrome version of the camera that you're using. All of these experiences that you're going through are all things that I won't have to repeat.

All I need now is for Sony to start shipping those sensor chips to the camera manufacturers so that they can build the cameras so that I can get one!

- Mark M

[Bruce D]

Mark I had my camera (same as Pete's) back-ordered at OPT for almost 3 months and I finally cancelled, they did return my $$ promptly. I'm going to try ordering directly from ZWO if I can-

[Pete]

With the big chip there are a whole lot of setup options. Today I removed the OAG. Will guide strictly with the unused scope. Also installed a focal reducer to see if the chip vignettes at around f/8. And also rebalanced with the dew shield as without it one it's hard to tell f you're imaging the edge of the shutter. So it's playing around with setup as well as with software.