nikonshooter Loc: Spartanburg, South Carolina

Warren Keller has an excellent article on CCD Imaging techniques!

Something I didn't realize - and - it still doesn't make sense to me but worth trying.....is to take "darks" and use this info to subtract from "flats." If I read Warren right......the same process of subtracting "darks" from "subframes" needs to be applied to the "flats."

If you image "up" this is a good read!

http://www.skyandtelescope.com/astronomy-resources/astrophotography-tips/the-abcs-of-ccd-imaging/

Oknoder Loc: Western North Dakota

I only take dark flats if I end up with an exposure time of over five seconds for my flats to get to 25K adu. I have found this was only needed if I was shooting narrow band or if using the dawn sky to capture my flats. With a 5mm Ha filter though and a el panel requires +30s so these I do shoot dark flats*

Never had much luck with the dawn/dusk method, as the sky conditions changes so fast for accurate exposures, not too sure how accurate you really have to be. Sometimes I'm analysis like that, lol

nikonshooter Loc: Spartanburg, South Carolina

Early morning flats have really worked great for me. The sky in the north (absent clouds) where the mount is parked gives even lighting (given the scopes narrow FOV) and the exposures are so short there's not any significant light change during the taking of 100 plus. I also have softboxes inside but the light across the box - is not even. I can run a light meter across a flatbox and note a 1/2 stop of light variation and I have some good Elinchrom boxes. The boxes work....but for me, outside seems to be more consistent.

Oknoder Loc: Western North Dakota

I use an 16"x16" El-panel with a diffuser on a 1" standoff, pretty sure the spectrum is not exact but haven't noticed any Ill effect. My issue with dawn/dusk flats has to deal more with programming than actual timing. SGP can be programmed to take them at dawn, but what it does is remembers the length of exposure, gain/ISO and camera's angle of rotation then for each different frame it takes tests to figure optimal exposure length, by the time it calculates all the data and rotates the camera about, the lighting has changed so it skews the results. I just wait till I bring in the scope or simply point it vertical the place the panel on top and let the program go.

I thought the idea of a rotator would be a good idea, and it is nice for composition, but the issues with flats and the rotation of image frame so the dust donuts lineup had me pulling my hair out for a couple weeks. Now it's all good but look forward to being able to mount the panel somewhere, so I can train the mount to just point at it when needed.

Matthew

nikonshooter Loc: Spartanburg, South Carolina

Gotcha.

I bought Sequence Generator Pro a while back when I saw it demo-ed on the astro imaging channel. I have upgraded it with the updates but have not used it at all. I had gotten Astrotortillia figured out ....for plate solving and alignment issues. But even now find I am not using that either. IF, if, I am using the Atlas Pro which is about all I have been using lately - the PA and alignment routine is all but 15 minutes...by then I have synced 10 stars and polar aligned and ready for a night of shooting.

I will have to jump into SGP....it gets a lot of raves when the rains come again.

Oknoder Loc: Western North Dakota

I like it. And have only had a few minor complaints major one being having the add certain information multiple different times, and it can be a little bit confusing especially considering I use multiple different cameras with multiple different scopes. But all in all I love that it is able to control 95% of all the equipment that I use with little to no interaction from me once the sequence is set up and running. I love it if it fails tracking properly it stops operation and begins again a few times in hopes that it was just a random cloud, and if not it cancels the whole sequence and Parks the scope turns off all the equipment, and writes an error report. Maxim DL also does all of these things, and even a few more, but with a much higher cost and isn't as intuitive.

Since it is also able to interface with a digital logger's server-based power outlets it can turn on and off equipment when needed. The reason I use it for plate solving is so I do not have to even go outside unless there is an issue, that is as long as everything is already set up, plugged in and ready to go.

Matthew

nikonshooter Loc: Spartanburg, South Carolina

I need to come to you place and get lessons. I learn best with online video tutorials or better yet, hands on. They have detailed written instructions but that just puts me to sleep. So I have taken a pass on putting it to use.

Europa Loc: West Hills, CA

Sounds like a road trip!

Oknoder Loc: Western North Dakota

LOL I feel the complete rural nature of North Dakota might be a bit of a culture shock to the average person. It has taken me personally almost 10 years to be accustomed to the fact that if you need anything that involves any aspect of civilization it takes upwards of an hour to 2 to get there, and this is including such minor things as going to McDonald's or Walmart which everybody else seems to take for granted.

Mostly what I did to learn certain individual features and how they affected the system as a whole, was to setup indoors which required to run some devices as simulators like the guiding and such, then run a sequence to make sure it functions properly through all phases, from centering on an object, which I use a large flat-screen TV. Seemed to work OK to test the auto focus, plate solving and to make sure it did a meridian flip, like it was supposed to.

I also like the framing and mosaic wizard and how it shows the orientation of the object within the frame or the ability to use an older image to center and orientate the camera which grants the ability to image objects on different nights with minimal cropping due to miss aligned frames.

Matthew

nikonshooter Loc: Spartanburg, South Carolina

Indeed - with the next two weeks looking grim - cloudy - rainy - crappy - I might as well fire up the Piper and start looking for water towers from here to there. Beats flying instruments......but that was back in the day when towns put their names on water towers.

I spent 6 hours plus processing time imaging M106 and M13 both the same night - M106 was focused but M13 (last target) was not. When you zoom in, all of my stars look like donuts. It is focus not collimation. Not too sure what happened - was using the Newt and I don't think the focuser slipped as it was locked tight - there wasn't any real significant temperature change either. I am puzzled! Anyone else had this experience. My guess when i slewed from one to the other "something" happened to lose focus. I should have taken a high ISO short exposure to check first - I will next time I go for more than one target in a night.

nikonshooter Loc: Spartanburg, South Carolina

It is getting bad when you start answering your own posts....but on closer examination both M106 and M13 were out of focus - this, I am afraid, was all user error. Imagine that - there is nothing wrong with the kit afterall!

Also, cannot count on FWHM working things out when using BY EOS for Nikon any more - back to the trusty Bahtinov mask!

Oknoder Loc: Western North Dakota

I have Backyard Nikon but its been a while since its use, does it measure the FWHM of a single star or does it pick an assortment? Are you focusing manually, or with an autofocuser, if manual a Bahtinov mask is an almost requirement. I know that with SGP it will only autofocus using FWHM as its primary measurement if Pinpoint is also installed, otherwise it uses HFR (Half Flux Radius) which I have found to give superior results. It also does not just use the measurement of one star but, depending on the parameters you set in the beginning, will use every star in the image up to a certain cutoff point from the edge of the frame. I believe mine is set to measure all the stars leaving 15% of the outer edge stars uncalculated.

I have a Newt that gets very little use, but with that and even my RC used to have issues with large movements of the mount. What I chased the cause down to being was a bit of mirror flop, for lack of a better term. With both scopes there were three clips on the primary mirror holding it securely to the cell. With my Newt when I first started I was getting odd three sided stars and found out the optics were pinched, the cure for this was to loosen those clips. That problem went away and I spaced a bit of a gap on my RC when it was first delivered. Well apparently I made the gap too large and the mirror would shift, especially after a Meridian flip, which required a refocus. Now I know to use either a piece of construction paper or a business card to measure the gap, and removing the paper after tightening the clip back down. Not sure if this could be an issue with your optics but maybe something to ponder on your next cleaning.

Matthew

nikonshooter Loc: Spartanburg, South Carolina

BYEOS uses one star as does APT when using FWHM.

I have three scopes

Vixen 81EDs is manual with crayford focuser duel
Newtonian is manual with crayford focuser duel
SCT has a JMI auto focuser and can be controlled by SPG

I have used the Newt on other nights with excellent focus so methinks I just didn't spend the time drilling down on the best possible FWHM number.

I wouldn't have a clue how to move the clips around....It it turns out to be something that collimation and/or focus cannot fix - I would have to put in hands of someone like you to fix.

Unfortunately, it will be a week plus before the weather prognosticators give me any home of clear skies!

Oknoder Loc: Western North Dakota

IDK about all that, if you can figure out the many buttons of a modern DSLR I have faith you could disassemble and reassemble a scope with roughly ten pieces. I used tape on the cells and vanes to assure proper replacement. I was scared the first time I stripped down my RC since collimation is tricky and I feared having the mirrors out of rotation with each other. In the end it was all unfounded as it didn't really matter, it was a PITA anyways.

Matthew

SonnyE Loc: Communist California, USA

And why I went the old fashioned way...
Me and Galileo... a tube with s shiny chunk of glass in the end...
:lol: :lol: :lol: :roll: :lol: :lol: