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Help with Imaging


Hazmat9

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I have a Celestron CPC-800 scope with a Starizona Hyperstar and an Orion G3 Deep Space Color camera.  I've seen photos online with this camera and I'm amazed, however it's nowhere close to what I'm currently getting.  First, I've been shooting and saving in JPEG since I have yet to master stacking flats, bias and dark frames.  But I'm not getting the colors nor definition which I think I should be getting.  I typically shoot 20-30 second exposures since I don't yet use a wedge, but I'm told that I should be getting pretty descent photos.  I shot this photo of Andromeda which I know has a lot of vignetting at a 20 second exposure which seems not to have a lot of definition.  The second photo concerns me which is a flat I shot 5 minutes after sunset at a 20 second exposure....it appears that the image is not uniform....can't figure it out.  The last shot is a JPEG file of the Dumbell Nebula which isn't too bad and still gives me hope.  Does anyone have any ideas.  Many Thanks, Steve 

Andromeda 2.jpg

flat test.jpg

Dumbell Nebula.jpg

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Hi, Steve, and welcome to SGL.

To me, the Andromeda photo looks out of focus. I think the dumbell looks a lot better. Are you using any sort of focussing aid (eg bahtinov mask)?

Flats aren't supposed to look flat (uniform)! They show where the light arriving on the sensor from a "flat" source is not even and use that information to even out the information in your image (your lights). I think it is probably too long an exposure.

HTH

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Focus is slightly out but also you really need to shoot in RAW and stacking is a must... JPEG loses too much information. Also you need various exposure time... from short 20-30 second up to even 5-10 minute subs to get the depth you want in a astro image.

 

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The Hyperstar system results in a very fast telescope which makes focus very tricky and this is evident in your images, especially the Andromeda one. As suggested, a Bahtinov mask would help you here but you would need to make up a dew shield extension to support it - no bad thing actually!

Stacking is vital to bring out details in your images but so too is image calibration so you really must address this to make any progress. Deep Sky Stacker would be a good (free) place to start as this will both calibrate and stack your images.

Your Flat frame is not ideal but I would not expect a uniform result (that it the whole point of a flat frame) - however, yours is not typical of a flat frame as it isn't showing a circular light variation. I suspect that you did not have a uniform light source for this flat frame and it is imperative that the illumination is equally distributed when it reaches the front of the telescope and that the exposure does not fully saturate the pixels.

Finally, guiding will help you long term but with your current short exposures, this is not the biggest concern and you should address the other issues first.

Good luck and ask away because as you can see from the replies from other SGL members, there is a wealth of information and help here.

Welcome to SGL.

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Hi Hazmat

1.Focus

2. Longer exposures. Try longer and longer test exposures until trailing becomes apparent. 

    Or get a wedge and Polar Align.

3. Flat looks overexposed. Should be no more than 50% .

4. Andromeda needs a mix of short exposures to show the detail in the core, and much !onger ones to show up the faint spirals.

Michael 

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Hi everyone and thanks for the recommendations.

First, I spoke to Starizona that sold me the Hyperstar and they recommend an exposure no longer than 25 seconds since I'm using a fork arm.  I will be getting a wedge in a month or so and will polar align which should help with longer exposures.  The flats were taken at 20 sec. exposures, I did cut the exposure time in half and it barely showed any light.  I took the flats 5 min. after sunset 20 degrees toward the east.   Focus has been an issue which I capture while running a loop with capturing software and adjust while viewing a bright star.  The only reason I'm shooting lights without stacking was because I was having issues capturing the flats.  I also asked Starizona how do I focus to shoot flats when the camera is mounted?  They suggested focusing manually like I have and put the scope away until the next session w/o moving the focus adjustment.....then set up the next time and shoot the flats.  I look forward to shooting raw and stacking, I do have stacking software and also Nebulosity 4.  This software has been an issue for me running on Windows 10 since it consistently locks up when I use the capturing program.  I will say this, using the Hyperstar has been an eye opener to what I've been able to see....some of my other plain JPEGs are fantastic, and what I see on the computer monitor is nothing I would be able to see with an eyepiece.  I hope to see more detail in the future once I get the stacking down.  Many Thanks and it's good to be here!  Best, Steve

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Indeed, you don't need longer exposures; stacking lots of 20s subs will give you much better results with the current setup.

The images don't look that unevenly illuminated, I wouldn't worry too much about flats to start with.

I would get the basics nailed with the current setup before running out and adding further complications with a wedge.

1. get the focus right

2 stack a load of subs

win

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8 hours ago, Hazmat9 said:

The flats were taken at 20 sec. exposures, I did cut the exposure time in half and it barely showed any light.

Taking flats at dusk is tricky unless you've got automated software, it's surprising how the light level drops even over a few seconds.

A white laptop screen with some printer paper over it to dim it would be better if you've got one big enough, use exposures of  a couple of seconds and experiment with number of sheets of paper to achieve a flat that moves the histogram about a third to the right and remember not to take the camera off or alter focus before taking flats, I wouldn't worry about taking more than 16 for starters.

I'd also concentrate on getting all this working before complicating the issues with a wedge and guiding :grin:

Some imaging software like Maxim has a counter intuitive way of working where increasing the exposure turns the screen black rather than white when it's over exposed.

Have you got the latest Orion drivers for your camera as some early Orion Win10 drivers were a bit flakey.

Dave

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I use Hyperstar with an Atik camera and Atik's "Infinity" software. It turned me from an utter duffer into a credible astro-camera user in one first light session ,  albeit I might never become Astrophotographer of the year. My main focus is EAA to beat urban light pollution, but think I can assist. ...

With Hyperstar, you do only need extremely short STACKED exposures. Mine are typically 5 seconds on bright DSOs, and no greater than 30 seconds for dim. In less that a dozen stacks (total exposure probably under two minutes), I typically enjoy superb near live views but focus is critical. I believe focus is an issue here as your stars are a little bloated. It could be Hyperstar collimation, but I suspect that is less likely.  Don't fiddle with that until you have mastered exposures/focus. 

If an alt-az, you need no wedge, no polar alignment or autoguider as Hyperstar converts an f/10 scope to f/2 so images are typically generated 28x faster. It's easy once you realise Hyperstar breaks many conventional rules,  but almost every first light Hyperstar user suffers from overexposure and focus challenges because of what they have read in the (non-Hyperstar) camera/software instruction manual (and/or read in Forums). But sadly, some astro software is so complicated it is baffling for the new entrant trying to wrestle with other settings that add to confusion (like <gain> or <ISO>). My previous lifetime camera experience had been limited to a cell-phone camera. I needed simple, almost "point & shoot" software and a quality camera with operational simplicity. 

This advice won't help the OP,  but it may help others considering a camera purchase. I have tried most 'bundled' software packages and will sum up my experience by this single comparitive fact. SG Pro instruction manual 200+ pages; Nikon DSLR manual 200+ pages (that is before adding 'Backyard Nikon'); others also typically 200+ pages. Atik "Infinity" software 22 pages. Yes, merely 22 pages and that even embraces how to handle Internet broadcasting of your sessions! 

The key difference is that the Atik 'bundled' software is camera specific. This eliminates 90% of the complications and permits helpful pre-sets to be offered, albeit <gain> etc can be bespoke if you want to delve deeper. The FHMW focus tool is simple. OK, it does mean you are limited to Atik cameras, but they manufacture inside the EU (Portugal), are based in Norwich and the only criticism one ever hears is that the Atik range costs a little more than its Chinese rivals, but (IMHO) if more camera manufactures employed dedicated software developers and produced camera specific versions of bundled software then life would be so much easier.

In summary, most new entrants focus only on the decision which camera. My advice before purchase is consider all aspects including what software, what computing power and even what display. You can review most software before making a camera purchase either by downloading a trial copy and/or instruction manual. If you are intimidated by its apparent complexities, then my advice is choose another make of camera that offers bundled software that you do consider manageable.

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Thank you so much for all of you help.  I really thought I was seeing things w/ the shot of Andromeda being so circular, however I thought I was in focus when I was aligning in loop mode.  I did several weeks ago build a lightbox which I haven't tried yet, however I will take folk's advice and not worry too much on flats right now.  The scope was checked and collimation adjustments made at Starizona this past summer with the Hyperstar.  Again, the software I'm using is Nebulosity 4 for tweaking the jpegs, but haven't had good success using it for ascom capturing without the program crashing, therefore I've used the Orion Starshoot software that came with the camera which seems to work fair.  Best, Steve 

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As steppenwolf suggested above, you would need to add a dewshield to the scope, effectively extending the tube-length beyond the camera. You would then be able to add either a bahtinov or Y mask onto it for focussing. My favourite trick: forgetting to remove it before I start imaging!

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... or you can cut a B-mask in two, and place them around your hyperstar adapter. The B-mask should have a central hole for this to work.

I think that with your setup (hyperstar), you're really jumping in at the deep end. Your system is so fast that focusing and collimation are supercritical. I don't think I'd ever go that route. But hats off if you get it to work.

Good luck

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HyperStar is not as easy to use as Starizona wants you to believe...
Here is some nice info about how and why: HyperStar Alignment and Use V3 9-25-15.pdfHyperStar Alignment and Use V3 9-25-15.pdf
As it has been said above: HyperStar needs very short exposure times, because of the fast f2. A 'normal' f6 telescope would need 9x longer (6:2)² exposure time to get the same results...  Obviously the core of M31 in your image is already burned out, so 30 seconds is a long time for an Andromeda sub.

Stacking of may short subs will be neccessar, and a Bahtinov mask is a must...

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I ordered a dew shield and a Bahtinov mask and will give it a try.  Great read thank you Waldemar!  There isn't much info on Hyperstar other than what I've had to piece meal together.  I'll post again once I start working out my focusing issues.  Best, Steve 

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I think a split Bahtinov ought to work. Or a Y mask, also split.

I'm not sure I'd go for a wedge yet. They are, in the main, terrible things to set up. If you're not using a permanent setup my feeling would be not to do it. If you don't, in the end, get on with the Hyperstar you'll have thrown a lot of money at it.

It's a very fast system and should do pretty well with stacked and calibrated short exposures in alt-az. Sort the other issues out first, I'd say.

I'm glad to see that Starizona have changed some of their claims about the Hyperstar. I have no problem with their comparing 90 minutes in a 4 inch F5 with 90 seconds in a 14 inch Hyperstar. They have comparable focal length so the comparison is valid. Claims based on the F ratio rule (2x2=4 versus 10x10 =100  and then 100/4 = 25x faster) are absolute tosh.  The SCT with Hyperstar and the SCT without are not taking remotely the same picture so the comparison is meaningless.

Olly

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3 minutes ago, ollypenrice said:

I'm not sure I'd go for a wedge yet. They are, in the main, terrible things to set up. If you're not using a permanent setup my feeling would be not to do it.

Agree with Olly here, I tried imaging with mine on a wedge on a tripod and never got good results, it really needs to be on a permanent pier and an hour spent getting it drift aligned.

Dave 

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  • 4 weeks later...

Unfortunately, too late I purchased an HD wedge, got a great buy on a new on off Ebay for 260.00 including shipping.  I've put the thing on but haven't tried it yet.  And, to make things possibly worse, Santa brought me Celestron Star Sense.  I've heard the set up issues and nightmares w/ polar alignment and a wedge.  Does anyone know off hand if the bugs have been fixed in the Star Sense program before I open the package?  Otherwise, I can move the topic to another forum.   Happy Holidays, Steve

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