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Advice on Pleiades and DSS

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#1 Simon D.

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Posted 14 January 2020 - 06:50 PM

I’m planning the above for my next target, using a Canon 500mm f4 and unmodded Canon 5D IV, on an HEQ5, unguided.  I can get up to 2 minutes, which should be enough on a bright target. A couple of questions.  1) on this target, do folks take a second set of lower exposures to combine so they dont blow out the stars, or do you not worry about it? 2) if you do take a second set of lower exposures for the star cores, is there a way to automatically stack them in DSS with the other exposures to have one HDR image, or do you need to stack them separately  and combine after in Photoshop. PS I’ve downloaded a trial of Startools, so if that can merge the 2 sets, please let me know.  Thx



#2 Gipht

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Posted 14 January 2020 - 07:48 PM

I recently did Pleiades with at 330mm focal length, with a 70mm refractor using 2 minutes subs.  My results were fairly good for star color, with the brighter stars clipped.  At 500mm with a smaller aperture, my guess is that you will do better  in that regard then I did.  If you decide to take a second set at a reduced exposure  time, you can stack them  separately and then blend  them, or you can stack them all as one stack.  DSS allows you to click which light frames to stack, or you can group your stacks together.  Group tabs  appear at  the bottom  once you enter the first set of lights.  If you stack them separately, you probably will want to select a single reference frame in one of the stacks so everything can be overlaid easily.  To do this, right click on the desired light frame and a drop down menu will appear with reference frame at the top.

 

Here  is a link to a youtube video on HDR combine in Star Tools:  https://www.youtube....h?v=WqYim2phWLo

 

The darker your skies, the better the results will be.

 

Good luck!


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#3 JDShoots

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Posted 15 January 2020 - 12:45 AM

I did the same thing, 500 f4 unmod'ed unguided, except Nikon.  I shot at 5.6 with 60 sec subs, all 2 and a half hours of it.  There is a lot of dust out there, so plan for a lot of subs.   I suppose if you are in a dark site, that is less important.  

 

A point to note with the StarTools trial version, you can't save you finished image.  I missed that when I tried it the first time.   But I liked it so I bought it, and used it on M45, this was my first attempt at The Pleiades, and second target using startools.  

 

This image was the first time I saw these huge diffraction spikes(but it was only my 4th target ever), I like them some people hate them.  They are a byproduct of the blown out stars and stopping down a little.  But these stars are so bright.  

I was also surprised to see the "straight" lines in the nebulosity, thought I made a mistake, so watch for that too:)  

 

Have fun! 

 

original.jpg



#4 the Elf

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Posted 15 January 2020 - 06:27 AM

This is an unmodded Canon 800D at ISO 400, scope is f/6. As I post the link I see the description is wrong. It is 19x 4 minutes. Going to correct when I'm home. No shorter subs involved. The cores of the brighter stars are saturated but I don't mind. If you image at ISO 400 as well you can probably use 45sec or so at f/4. For other ISOs correct accordingly. For my non ISO invariant T3i I used 2 minute subs at ISO 800.

http://elf-of-lothlo...eiades2018.html

full res linked in the description



#5 Simon D.

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Posted 15 January 2020 - 03:51 PM

This is an unmodded Canon 800D at ISO 400, scope is f/6. As I post the link I see the description is wrong. It is 19x 4 minutes. Going to correct when I'm home. No shorter subs involved. The cores of the brighter stars are saturated but I don't mind. If you image at ISO 400 as well you can probably use 45sec or so at f/4. For other ISOs correct accordingly. For my non ISO invariant T3i I used 2 minute subs at ISO 800.

http://elf-of-lothlo...eiades2018.html

full res linked in the description

That’s super helpful.  Thanks.  Love your processing on it too. 



#6 Simon D.

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Posted Yesterday, 08:22 AM

I did the same thing, 500 f4 unmod'ed unguided, except Nikon. I shot at 5.6 with 60 sec subs, all 2 and a half hours of it. There is a lot of dust out there, so plan for a lot of subs. I suppose if you are in a dark site, that is less important.

A point to note with the StarTools trial version, you can't save you finished image. I missed that when I tried it the first time. But I liked it so I bought it, and used it on M45, this was my first attempt at The Pleiades, and second target using startools.

This image was the first time I saw these huge diffraction spikes(but it was only my 4th target ever), I like them some people hate them. They are a byproduct of the blown out stars and stopping down a little. But these stars are so bright.
I was also surprised to see the "straight" lines in the nebulosity, thought I made a mistake, so watch for that too:)

Have fun!

original.jpg


Thanks. Which ISO did you use?

#7 JDShoots

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Posted Yesterday, 09:39 AM

Thanks. Which ISO did you use?

ISO 200.  60" f5.6 and still had clipped highlights in the large stars.  

160 lights, 35 darks, 41 flats, and 130 bias frames.  



#8 Hesiod

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Posted Yesterday, 11:47 AM

I take a picture of Pleiades last fall (eos1100d @ ISO800, 230mm @f/4.2), with my rudimentary camera took 120" subs; probably could do better on brighter stars through a more accurate use of masks but was too lazy

gallery_215679_10936_1060600.jpg

 

I was more interested in the surrounding dust, so was more than willing to sacrifice the brightest stars for the sake of simplicity.


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