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First attempts with nextstar 127 slt and Canon T2i EOS

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#1 bakernyc

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Posted 07 December 2020 - 12:22 PM

I'm slowly, slowly learning. First time out last night with my DSLR (canon T2i) hooked up to an nextstar (127) - no barlow. My images of mars seemed a little fuzzy and was curious if anyone in the forum would have an idea of the attribution. The collimation seems fine, in that I can see that very uniform donut patten on bright objects out of focus. I was shooting in manual with a 800 iso and 1/200, also shot at a 1600iso with 1/400 with similar results. Perhaps I'm just not getting the focus right? I'm trying to do it through the camera view finder which is hard. I'm picking up one of those Bahtinov focusing masks to see if I can improve the focus. Any thoughts looking at these images what I might be doing wrong? Also I'm planning to attempt a video capture tonight and try some stacking - but I still think the stills should be sharper? Thank you so much for your help - I'm super excited to learn more.

 

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#2 sg6

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Posted 07 December 2020 - 01:04 PM

The live view is probably more accurate for focus then the viewfinder - I found that out the hard way grin.gif

Next is the "collection":

Reads you are getting an image.

For planets you get a video, for Jupiter say 90 seconds. So at say 30fps around 2500 frames.

You load the video into Registax or AS3 and identify the best frame then tell the software to stack say the 20% that best match the good frame.

So your stack is the sum of only the good frames, well hopefully. Never trust software!!!!!

 

Then you process the result a bit.

 

Also usually a 2x or 2.5 barlow is used to get a larger final image on the sensor.

 

So back outside to freeze.



#3 bakernyc

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Posted 07 December 2020 - 01:15 PM

Thanks for the reply @Cosmos.. Yah it looks like I have a good exposure but there's really no detail. I was curious if anyone could tell from the images whether it seemed to be more a focusing problem vs something else? I was expecting a little more definition even on single exposure. 

 

I will try the focus through the live view tonight with a barlow to see if I can get it tighter. Past that I can make my first Bahtinov mask if it's still blurry and I'm not confident in focus. I'm just hoping I'm doing the right things so any more advice is welcome!



#4 Tulloch

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Posted 07 December 2020 - 03:40 PM

Hi there, it's certainly possible to create good quality images using Canon DSLR cameras, if you are creating the images in the correct way. The best way to use your DSLR to take images of the planets is by following the steps in this website, using the 5x zoom LiveView mode.

https://www.astropix...resolution.html

 

I imaged the planets using my Canon 700D with a 2x Barlow and a software program called BackyardEOS, which has a dedicated mode specifically for planetary imaging (as well as DSO imaging and other stuff). I was able to create images using this system which were comparable to those with my dedicated planetary camera (which I subsequently upgraded to), which you can see in the link below.

https://www.cloudyni...6-sct-test-two/

 

If you want to continue with your DSLR, I would recommend a 2x Barlow and BackyardEOS. 

 

Hope this helps,

 

Andrew


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#5 bakernyc

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Posted 07 December 2020 - 03:46 PM

Hey @Vanguard. Thanks for the reply. Awesome images of Jupiter and Saturn on that other thread. Inspiring! I'm going to take a shot with the barlow and some better focus practice tonight using live view. I was thinking I'd try a high frame rate view and then let registax have at it. For remote camera control I have the EOS utility off my laptop. I also dowloaded a trial of Backyard EOS which seems pretty capable. Thanks again and I'll follow up with results!.



#6 bakernyc

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Posted 07 December 2020 - 04:01 PM

Sorry meant @Andrew. I just realized the titles over the avatars is just your 'status' on the site. I'm 'Lift Off'. Great link btw on astropix - luckily I have the T2i with the 60fps crop mode. I'm going to try that!


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#7 Tulloch

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Posted 07 December 2020 - 04:42 PM

No worries, good luck!

 

If you haven't seen them already, these are a great set of tutorial videos to learn the processes. Note that Steve doesn't recommend using a DSLR, however the Canon system in LiveView mode is an exception to that rule ...

http://planetaryimagingtutorials.com/



#8 bakernyc

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Posted 08 December 2020 - 07:48 AM

Ok. So last night was a little better.  I have an EOS T2i so I managed to grab a short couple videos in crop mode, run them through registax (only about 2000 frames) and this was the output (attached). I think here are my next 2 problems to solve:

1) I'm not yet tracking the planet with the mount (alt/az that came with the 127 slt) so my videos are limited to mars passing through the field of view - I figure if I can get a good track on mars I can get a much longer exposure. It seems challenging to get things to tracking well and centered. Is there a way to tweak the tracking after it's setup to get things better centered?

2) I cannot for life of me see anything when I connect the Barlow. I have a 2x celestron omni barlow where you can detach the barlow lens and screw into the camera adapter. Tried that, tried using it as. Tried getting everything set and quickly adding in the barlow. I'm not sure what I'm doing wrong but I couldn't get anything to show through the liveview once the barlow was attached. Going to try during the day today but that was a bit frustrating last night...

Excited on the progress but seems a way to go!

Thanks,

E

Attached Thumbnails

  • mars_v2.jpg

Edited by bakernyc, 08 December 2020 - 07:49 AM.

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#9 RedLionNJ

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Posted 08 December 2020 - 12:09 PM

If you're not tracking at all with the 127mm Mak-Cass, then inserting a 2x barlow, while the right thing to do, is going to amplify the problem easily by an order of magnitude. The field will be substantially smaller, the image will be substantially darker (and likely way out of focus) and it will zip across the sensor before you have time to even achieve a decent focus.

 

You need good tracking to operate at upward of f/20.

 

Additionally, since M-C scopes are not generally collimateable, there's not much you can do about fine collimation. Having a good looking out of focus donut (even on a star) means very little. Having it on an extended object (planet) means nothing at all.  The best test of collimation is an in-focus, 2nd or 3rd magnitude star. The first diffraction ring should be concentric and continuous.

 

The 60 fps mode of the T2i isn't that great. It employs lossy compression, degrading the potential results by quite a bit.  You're better off using 25-30fps via BYEOS in so-called 'planetary mode'.  The resulting AVI from this can be fed into AutoStakkert where AS will quality-order all the frames, then build a reference image from the best few percent. Whatever percentage (or count) of frames you then specify will be aligned and stacked with respect to this reference image. You do lose a bit of resolution using a color AVI vs a raw AVI or SER, but there's no way around this with the Canon.

 

When building your stack, it's a common misconception by non-practitioners to only align and stack a very small number of the very sharpest frames. That's simply wrong. You need a decent number of frames to build up a reasonable signal-to-noise ratio (planetary imaging is synonymous with noise) - preferably in the thousands. The hope is that the signal part of the data will be distributed in a nice gaussian pattern within the noise. Then when you apply the wavelets from Registax (or deconvolution from any other app), the noise gets integrated into the signal, "crisping up" the output.

 

The focus doesn't look too bad in your last attempt, there. You could try drizzling during the stacking process to see if you can pull out more detail.

 

Focusing with poor tracking and no hands-off mechanism (and worse, by moving the primary mirror) is majorly painful.

 

Good luck!


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#10 bakernyc

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Posted 08 December 2020 - 12:58 PM

Thanks @RedLion - really helpful comments. Tonight I'm going to try and get a good track on mars first and then get the barlow going, I'll toy with the video setting options. The majorly painful set of activities you describe is exactly what I've been doing so far! If I can get a good track and live view that should help with the focusing I need to do on the telescope.


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#11 RedLionNJ

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Posted 08 December 2020 - 02:07 PM

Thanks @RedLion - really helpful comments. Tonight I'm going to try and get a good track on mars first and then get the barlow going, I'll toy with the video setting options. The majorly painful set of activities you describe is exactly what I've been doing so far! If I can get a good track and live view that should help with the focusing I need to do on the telescope.

I started out approximately where you are. I did have a little more aperture (at that point it was a  portable 10" LX50 on a wedge), but exactly the same DSLR. One by one, I upgraded the components over the years.  My avatar on the left was taken with the Canon T2i, using BYEOS on a 12-inch SCT.

 

Good tracking, hands-off focusing - those two will go a long way. Not sure what kind of aftermarket Crayford focuser is available for the 127mm, but if there is one, it'll be much appreciated by the imager. Physically touching the scope to tweak focus, then waiting for it to settle in order to judge - this is too intense and frustrating a process for many people. I would count myself among them.


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#12 bakernyc

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Posted 08 December 2020 - 04:35 PM

Thanks - encouraging. I think my first upgrade will be from the DSLR to a ASI462MC. I want to go slow though, otherwise I'll miss the fundamentals. Tonight it's the 127 SLT, solar system aligned to mars, canon T2i, 2x barlow (lens only), live view to the computer with EOS movie recorder, will try both 60fps crop mode and zoomed in 30 fps mode. Run through autostakkart, and so on. I should check BYEOS it seems for the capture...



#13 Tulloch

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Posted 08 December 2020 - 05:37 PM

The 60 fps mode of the T2i isn't that great. It employs lossy compression, degrading the potential results by quite a bit.  You're better off using 25-30fps via BYEOS in so-called 'planetary mode'.  The resulting AVI from this can be fed into AutoStakkert where AS will quality-order all the frames, then build a reference image from the best few percent. Whatever percentage (or count) of frames you then specify will be aligned and stacked with respect to this reference image. You do lose a bit of resolution using a color AVI vs a raw AVI or SER, but there's no way around this with the Canon.

 

When building your stack, it's a common misconception by non-practitioners to only align and stack a very small number of the very sharpest frames. That's simply wrong. You need a decent number of frames to build up a reasonable signal-to-noise ratio (planetary imaging is synonymous with noise) - preferably in the thousands. The hope is that the signal part of the data will be distributed in a nice gaussian pattern within the noise. Then when you apply the wavelets from Registax (or deconvolution from any other app), the noise gets integrated into the signal, "crisping up" the output.

Thanks Grant, I was unaware of the difference between frames in the the 60fps "Movie crop" mode and the 30 fps standard LiveView modes. The quality of the jpg images in the standard Live View mode is very high, with a compression ratio of just 16% (which I have confirmed with my images from my 700D). Not sure what it is for the 60fps, it is possible to measure it using some online tools, I just can't find them now.

https://kuvacode.com...ve-view-quality

 

Thanks @RedLion - really helpful comments. Tonight I'm going to try and get a good track on mars first and then get the barlow going, I'll toy with the video setting options. The majorly painful set of activities you describe is exactly what I've been doing so far! If I can get a good track and live view that should help with the focusing I need to do on the telescope.

Yes, in order to get high quality images you should/must track the planets on the screen. Alt/Az tracking is fine, it's what I use too smile.gif. I did another study about how many frames you need to stack to get a good image with both the Canon DSLR and ASI224MC, the DSLR needs about a quarter of the frames that the ASI224MC did for a similar result, which is fortunate since the Canon can only capture at about a tenth of the speed as the ASI.

https://www.cloudyni...sct-test-three/

 

Thanks - encouraging. I think my first upgrade will be from the DSLR to a ASI462MC. I want to go slow though, otherwise I'll miss the fundamentals. Tonight it's the 127 SLT, solar system aligned to mars, canon T2i, 2x barlow (lens only), live view to the computer with EOS movie recorder, will try both 60fps crop mode and zoomed in 30 fps mode. Run through autostakkart, and so on. I should check BYEOS it seems for the capture...

I would strongly recommend using BYE, it's free for a month and gives you much greater control of the camera (once you learn how to use it of course smile.gif). If I was starting again I would go with the ASI462MC camera also, seems to have better sensitivity than the 224MC.

 

Andrew


Edited by Tulloch, 08 December 2020 - 05:38 PM.


#14 bakernyc

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Posted 09 December 2020 - 08:41 AM

Hey guys (or girls) - Got the tracking, barlow and BYEOS working last night. Also did some video in the T2i crop mode. I didn't have a long session but out of the couple minutes of video I got (and given the atmosphere up here in CT last night) I was really happy. I think it's going to cloud up for a few days.

Here's some quickly stacked images from the videos last night. The lighter one was from a video using the T2i crop mode. The darker one was from BYEOS. I'm still getting used to the software but really cool to see the progress here!!

Attached Thumbnails

  • mars3.jpg
  • dec_8.jpg

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#15 Tulloch

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Posted 09 December 2020 - 06:24 PM

Nice images, certainly an improvement there :).

 

For Mars you can easily image for up to 5 minutes per video without worrying about planetary rotation to increase the number of frames to stack, I normally try stacking a range of values and see which one comes out best. In AS!3 you can stack up to 4 different percentages at a time, I like to try 10%, 25%, 33% and 50% and see which one comes out best. 10% is usually too noisy and 50% is usually too soft (too many blurry frames), but it doesn't take long to do them all and see which one works best. You can also reduce the size of the image to stack using the slider bars on the image window so you are not stacking empty space which will speed up the process.

 

The online jpg image quality checker is here, it would be interesting to run a single frame through this tool for the 30 fps and 60 fps captures, for my 5x LiveView frames in BYE, the quality value came out at 98%.

https://www.imgonlin...peg-quality.php

 

For focusing, I don't have a hands-off electronic focuser, but I find this works well for me...

https://www.cloudyni...ser/?p=10194236

 

Andrew



#16 bakernyc

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Posted 09 December 2020 - 07:35 PM

Love the focuser idea - I've seen a few approaches of adding 3d printed knob extenders and such. Roger that on a larger sample size. Bit of a break tonight with the weather.



#17 bakernyc

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Posted 23 December 2020 - 11:48 AM

Just following up on this thread. I ended up grabbing one of those focuser motor kits for $60, drilling a hole in one of the plates it came with and mounting it under the dovetail using the existing screw. I then replaced the focuser knob and the motor head with some gt2 gears and a belt. This was a combo of a couple different articles I found out there - worked great for the SLT and now I don't have to touch that focuser!

IMG_5313.jpg


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