Basic Questions by Beginner

[jerryyyyy]

Hi, have downloaded and installed the program trial version.  A couple questions:

1.  I am using the 32-bit version.  It says this is no longer supported.  Will this software work fully only on 64-bit machines?  if I probably will have a 64-bit main machine in the future but have resisted this because of a nuimber of other incompatibilities. If I buy the 32-bit, do I have to buy the 64-bit later? 

2.  I tried to follow the first basic tutorial on YouTube:

PixInsight Processing Example: NGC 1808 LRGB (Part 1/2)

It worked on my own data until the Dynamic background Extraction where instead of using the actual correction calculated in the example they loaded some other data to correct and miraculously the gradients corrected.  When I use my own calculated correction and execute it, nothing happens to the image.  Is this just the degraded 32-bit version or what am I missing. 

Thanks

[pfile]

the features in 32-bit are the same, it just runs out of memory when doing memory intensive tasks.

on DBE you need to set the correction method to subtraction. when the tool is in it's reset state there's no correction, it just generates the background model.

rob

[georg.viehoever]

1.  I am using the 32-bit version.  It says this is no longer supported.  Will this software work fully only on 64-bit machines?  if I probably will have a 64-bit main machine in the future but have resisted this because of a nuimber of other incompatibilities. If I buy the 32-bit, do I have to buy the 64-bit later? 

See http://pixinsight.com/faq/index.html section 2. No need to buy again if you switch OS or something else. You can even run it on multiple systems that you own without additional costs. Compare this to the expensive licensing schemes of some other applications...

Georg

[jerryyyyy]

Thanks.  I seem to be making progress.  I am not having problems running in 32-bit mode. 

I now seem to have the basic Dynamic Background Extraction process going.  It seem like I will need to run it more than one time.  Is this OK, or does noise accumulate? 

PS  Because these images are taken with a focal reducer they have a lot of vignetting, so I cropped them in CS5 and saved as Tiff 16-bit.  Is there any problem with using tiff RGBL versus FIT RGBL? 

PPS  Is there a pattern to sampling for DBE that is optimal?  5x5 in each quadrant? 

[pfile]

hi jerryyyyy

sometimes 2 passes of DBE are necessary. i'm not sure how much 'noise' enters the situation here - the backgrounds generated by DBE are synthetic 32-bit images. however as you get rid of gradients the amount of low SNR area you can expose gets better and so it may seem that noise is increasing.

are you taking flats? even if you have a focal reducer, flats are the right way to get rid of that vignetting. if you are trying to get rid of optical vignetting with DBE you'll never have as good a result as just using flats.

what is the origin of the images you have cropped? are you saying they were stacked in another program? or are you talking about cropping your subexposures? TIF vs. FITs should not matter for 16-bits, but if you are talking about integrated images it's probably better to save them in 32-bit floating point format. 16-bit images do not have enough dynamic range to capture all the tiny pixel values in an un-stretched, integrated image.

not sure about optimal sampling but the advice i've seen around here is to at least get the 4 corners of the frame if possible, and maybe the centers of the top, bottom, left and right edges.

rob

[jerryyyyy]

Thanks.  I am using Maxim to stack subs and I have good flats used by Maxim.  I have this nice Maxim Plug-in called Sky Flats Assistants that makes this pretty foolproof.  I am up early checking the night's run now and will run the assistant again just to make sure all is well. 

Problem I often have here near San Francisco is less than optimal seeing so I may get some sky-glow.  I am in a Red zone 35 miles south of SF and try to image as close to the apex as possible and have a dew buster to avoid dew that accumulates when the relative humidity gets near 100% as it does here almost every night.  It is bad when I image to the north right towards SF.  There may be nothing I can do about this with RGBL images.  I used some of my worst example to test PixInsight, which may have not been smart.  I am going on a long trip tomorrowand will try the techniques with some very clean images to make sure I know what I am doing. 

I am following the routines from the basic videos 1 and 2.  I have been stuck on the DBE but need to move onto the color balancing. 

Thanks again for the help. 

[pfile]

yeah i am in oakland and face the same problems, though the view to the north is better than to the south.

still those circular gradients look like flat issues. i think getting good flats is difficult. for my narrowband filters and my f/8 scope i don't have too much problem but recently when using an f/2.8 camera lens i had all sorts of problems. switching from "t-shirt" flats to sky flats definitely helped. it sounds like you are already there, though.