Comparing DSS and Nebulosity stacking

Looking more into focusing. Another cool gadget would be this motorized focuser - though I don’t really have a problem with too much shaking when I focus the telescope. But this is something I would like to have for my camera when I make photos through a lens.

But I’ll get to try out lots of new gadgets soon:

• The focal reducer already arrived at work
• The DSUBS cable should arrive tomorrow
• The GPS unit for the Nexstar remote should arrive tomorrow

Can’t wait to try them out (especially DSLR Shutter with the DSUBS cable). Unfortunately, the focal reducer will probably reduce the range of the telescope even more with the camera attached.

I took flats and flat darks tonight - but it’s cloudy again. So, I won’t be able to shoot more pictures my last night here :-( Only back in San Jose with all the other lights and such, too bad!

In the absence of taking new pictures, I played more with the ones from a few nights ago.

First, I wanted to compare DSS stacking with Nebulosity stacking:



DSS stacked:



Nebulosity average stacked:


Nebulosity std dev (1.5) stacked:



Ignoring the diagonal lines of Nebulosity (I need to buy a license for it - I’ll probably end up using it anyway), the images are quite different. The Nebulosity pictures have some greenish hue towards the upper left corner - the DSS stack doesn’t. There shouldn’t be any hue at all (Lyra is next to the milky way). But somehow the Nebulosity pictures look much richer.

Zoomed into the main stars of Lyra:

1. DSS


2. Nebulosity (average stacked)


3. Nebulosity (std dev stacked)


The resulting colors are quite different. Vega itself is blue with DSS ad red’ish with Nebulosity - the DSS color seems to be much more realistic. On the other side, delta2 lyr is red with DSS and blue with Nebulosity - and in reality it’s red.

Somehow, Nebulosity seems to have mixed up the color palette (in the originals, the colors are correct) and introduced this strange hue.

But I still haven’t made much progress with post-processing of the pictures themselves...

Comparing various processing techniques

Well, I actually woke up late enough (1:30) but forgot about the fog... So, no combined shots for now :-(

Pre-processed all images. Here are the results after some basic post-processing (background color adjust, DDP Stretch - I tried Sharpening and Noise reduction too, but they don’t seem to have any impact):



Comparing different noise corrections:

1. None


2. With explicit darks


3. With camera noise reduction


Can’t see much of a difference, but you can clearly see the vignetting.

So, here are the 2 different noise reductions with and without flat correction:

1. Noise reduced with explicit darks:


2. Noise reduction from the camera


The vignetting effect is clearly visible - shows how important it is to take the flats (though next time I need to take them the correct way - with ISO 100 and proper shutter speed).

But there isn’t a visible difference between the two different noise reductions. I guess that doesn’t matter too much.

Now, I have to get better with color corrections (so far I just applied some default post-processing steps). And also I have to do a better job in focusing. The following is a zoom into this image:


I guess, that’s where I have to figure out how to do computer-supported focusing - don’t think I can do it better with the naked eye (the strange diagonal line is from Nebulosity - still don’t have a license).

After playing with all those tools, I’ll probably stick with DSS, Nebulosity and I hope that DSLR Shutter will work with my DSUBS cable. These are fairly simple and should work for me for some time. Nebulosity has a lot of manual pre-processing that I could use if DSS fails.

Just got the notification that the focal reducer was delivered (to work) and that the DSUBS cable will arrive on Thursday. Can’t wait to try it.

Also got a reply from the Avistack guys - seems as if it’s not that easy to load .mov files. But considering that I am not able to take a movie of the moon that’s not overlit, I won’t need this any time soon anyway.

Have to figure out what pictures I want to take tonight.

… actually not - it’s completely overcast.

So, I’m reading more on focusing. I am somewhat surprised that nobody came up with a mixed software/hardware solution that does this automatically. All solutions rely on doing the correction to achieve focus manually.
For the telescope, a Bahtinov mask sounds like a fast way (or these are way cheaper) - but need to measure the outside diameter of my telescope. Or Stilletto to get really fancy. Not sure what to do when I just want to take photos with a lens and not the telescope.

Taking more photos - skies without light pollution are addictive!

Tried to process the movies in Avistack. But even after installing the avisynth server, KRSgrAVI.dll and KRSgrAVI.dlm - and even after installing the 64-bit version of the dll, still doesn’t work. Will send an email to the forum.

But the good news is that I got MaxIm working with my camera! The user interface is HORRIBLE, but I managed to create a sequence (delay, break, ISO, shutter speed)!!!! But there doesn’t seem to be a way to move the mirror up (plus delay) before taking an image. The only way to do that seems to be to use the BULB setting and cable and move the mirror up at the beginning and then run the sequence. I hope I get my DSUBS cable sooon to try that out. In the meantime I’ll try to figure out how “mirror up” works with my D7000. Unfortunately, that means that I have to take the pictures individually with the remote sensor until then.

While reading more about this I found some software that can combine pictures that have different parts of the image exposed correctly (Nik HDR Efex Pro). This together with bracketing could allow me to take some pretty nice photos of the ocean at night with the moon and the stars. Will try this out tonight.

And I was reading more about the strange lighting on my pictures (brighter in the middle and less and less towards the edges). This is probably vignetting (didn’t think I would encounter that with these simple shots). And the only way to get rid of it is to take some flats right after sunset. I’ll try to remember to do that this evening (maybe have to do that while we are at Dr. Statti’s). On some website, they mentioned a “super sky flat” technique. This would avoid having to do the flats in the evening, but I’m not sure if this only works for less stars. Maybe I’ll try both tonight.

So, program for tonight:

1. Take flats plus flat darks in the evening
2. Take lights with noise reduction of Vega
3. Take lights without noise reduction of Vega
4. Take darks
5. Take “super sky flats”
6. Take some bracketed shots of the beach, sky and moon (I probably have to move further back for that)

And then I can make 4 sets:

1. noise reduced with flats
2. noise reduced without flats
3. lights with flats and darks
4. lights and darks

And then compare.

And then try to combine the beach photos to one.

OK, back from the beach. Unfortunately, I couldn’t take the bracketed shots because the moon is too high (if I’m motivated enough, I might go out later when the moon is lower).
But I got all the other shots, plus some shots from saturn - though they have a very bright background as it was low on the horizon.

The first decent photos

Started post-processing the pictures from last night. Deep Sky Stacker had absolutely no problem to stack the images (at some point I saw a star count of 150 something on the screen!)
So, stacking was fairly straight forward!

Then I tried to load that picture in Nebulosity for further processing, but I first had to store them in the FIT format. Either DSS can’t store correctly 32bit or Nebulosity can’t read it correctly. So, for now I have to do with 16bit.
But I’m still struggling with the post processing. Nebulosity has a couple of default steps that make the picture look better, but it’s not very impressive. Plus the resulting picture has a very bright background in a circle, but at the edges it’s almost black. I’m sure that’s not from stacking as the photos had HUGE overlap.

Downloaded RegiStax to stack the moon movie. And then I had to download a converter that converts my movie to an .avi file. But somehow I can’t see anything in RegiStax when I load the movie. Maybe it’s too long? Also, I should have taken the movie with a much smaller apperture. There are almost no details from the moon - it’s just very bright, white.

So tonight (if the weather allows): 

1. take another film of the moon with proper apperture, and 
2. take two series of the same object - one with automatic long exposure correction, one without.

The more I read about MaxIm DL5 (or its predecessor MaxDSLR), the more I whish I could use it on my Nikon. It seems to be pretty awesome for focusing, taking images...

Sch...!!!! A complete session for nothing. I set my camera on JPEG - assuming that it would make a RAW copy in the second flash drive. BUT NO! It created a JPEG copy in the second, so I ended up with 2 JPEG’s of each photo but no RAW. Well, tomorrow again.

I tried taking two movies: from the moon and Saturn. The moon movie is still WAY bright (even though I chose the smallest aperture). Saturn is almost not visible at all.

First photo shooting on the beach

Read more about astrophotography. By surfing for some programs/equipment I found a GPS for the Nexstar that sets location and time automatically - ordered that!
Then I was reading more about taking photos through the telescope and read about focal reducers. Ordered one for the Nexstar - hopefully that will improve my pictures.

Took the camera out to the beach at 10pm. I used the 50mm f1.4 lens. Boy! what a difference it makes not to have all the city lights!!!

But I’m still struggling with all the settings that I have to adjust. First, I forgot to set the lens to manual focus (and was wondering why on some images there were no stars and on others there were). Then I realized that I took the first set of the big dipper with ISO 100.
Also, it was surprising to see how little of the sky the 50mm lens takes. I was afraid that it would span WAY too much. But I can’t even get the entire big dipper or swan on the photo.

And I took some photos with automatic dark correction and some without to try it out. But I should probably take the same set with and without to really compare the effect (vs. taking a separate set of darks and correct afterwards).

1. Big Dipper - ISO 100 - With Long Exposure dark correction
2. Deneb - ISO 400 - With Long Exposure dark correction
3. Altair - ISO 400 - Without Long Exposure dark correction

I also took a movie of the moon to try to stack moon “pictures”. Let’s see how that works.
And then I took some random pictures (not to be stacked or such) - some of them actually look very nice!

Comparing Nikon Camera Control and ImagePlus Camera Control

Couldn’t sleep and tried out some more things:

First: compare taking pictures with Nikon Camera Control to taking pictures with ImagePlus Camera Control:

The process is much better with ImagePlus - unfortunately, it still stops or crashes way too often.

Then I took pictures from IC 1396 and M 11 (the M11 with ISO 6400 and ISO 400 - to compare details vs. brightness).

Trying out ImagePlus

Got my demo version of ImagePlus. I like the approach for post-processing: set everything up (as with the other programs, default parameters pretty much work). And then let it run through all the steps to final, combined image. Way less manual intervention. But the resulting image doesn’t seem to be as convincing as the ones from DSS or Nebulosity.

Also, I could easily connect my camera to ImagePlus (connect, live view). Trying to figure out how to control it now. It’d be awesome to have a proper control program that takes care of all the images, breaks... Unfortunately, ImagePlus crashes A LOT! I can connect (most of the time). I can do basic things like “Live View” or even focus. But when I try to take a photo, download it … it throws at least an error message or crashes and I have to re-establish the connection.

I purchased a DSUBS cable - several of the camera control/image acquisition programs seem to need that for connecting to the camera.