22 replies to this topic

[MrNeil]

Hi all,

 

I finally got a chance to try my DSLR with a lunar shot last night, I am a complete newbie so feel free to rip me to shreds as I can learn as much as possible from you very friendly and knowledgable folk here 

 

My camera is a Canon 600d Astro Modded with a Celestron Nexstar 6SE, 6.3 Reducer, Light Pollution Filter and used ISO @ 100, 1/8 exposure. I took 40 dark frames with 130 light frames after removing any bad shots. The RAW files were converted in Siril, stacked in Deep Sky Stacker and processed in GIMP.

 

Playing with different settings and arrived at the exposure looking at the live view after setting the ISO, with a red glow around the image subject I slowed the shutter speed until the glow was minimal, should I ignore this and just go with what others say at around 1/250, guess this is part of learning with the astro mod.

 

The images appeared to become black and white or stay very very red, converting the file from Siril appears to be the better route as color is retained but no where near the levels of red, would love some detailed knowledge here to remove the red but keeping subject true colors.

 

Anyway heres the final jpeg obviously reduced in size for this post.

 

Edited by MrNeil, 01 June 2025 - 07:46 AM.

[matt_astro_tx]

Nice job and congrats on the first image!  Ditch the LP filter, it's not doing you any favors.

[MrNeil]

Thank you Matt, you always have great advice

[Borodog]

Agreed. An LP filter is completely unnecessary on the Moon, and will destroy the color balance even in an unmodded camera. What you need is a simple UV/IR cut filter. Since the camera's built in CCM is no longer appropriate since it's been modded, I would take the RAW images into RawTherapee to convert them to PNGs before stacking. You'll then have to carefully white balance in post. You may have to employ some tricks to deal with the terminator even then.

[scottinash]

Good capture.  Thanks for sharing. 

[MrNeil]

 

OK, so last night I managed another go but with the recomendations in this post, I think theres a marked improvement but Im also aware that my image now looks over processed, more like a painting in comparrisson to say Mike's images that look like the real thing and make you want to reach out and touch it.

 

By removing the LP filter and using the white balance feature in GIMP I can remove the red, but then giving it life again is where I over process posibly, I also notice a couple of areas that look over exposed even though I purposly shot under with an ISO of 200 and exposure of 1/80, of course this could be down to the quality of the camera as I also tried to stack only 10 frames in place of the 100 below, surely the more frames would introduce more differences but there wasnt really much change in the result.

 

Anyway, for my second attemp im pleased with improvements and looking forward to any further advice I can get 

Edited by MrNeil, 03 June 2025 - 11:33 AM.

[RCLARK28]

Good job!

There is hope for me still. I begin my journey this summer with some good seasoned local observers and I hope I have as good of an outcome as you.

Thaks for the share.

[Borodog]

Definite improvement. The image is definitely over-exposed. We can't know whether this was done during capture or in post-processing unless you link the raw stack.

[MrNeil]

Hi guys,

 

wow didnt expect replies so soon!

 

Thanks RCLARK28, good to see you Mike and thanks for the reply and taking time to look.

 

I didnt know I could!   I hope Im not breaking rules as I uploaded it to my gallery and will link to that. Let me know if its obtainable or I need to change how ive done it.

 

 

Neil

[MrNeil]

I think this may be a good lesson to myself and any newbie, looking at whats happening here I may be caught up in trying to mimic too closely what Ive seen in videos and heard in conversations, I have tried to get the exposure balance meter to drop to -1 to ensure an under exposed image, in truth in setting this I may be guilty of setting the shutter speed too slow, and in increasing the shutter speed to darken the image even if it sets the exposure balance to -3 may be the way to go here.

 

Of course, (Note to self ) spending an evening or two playing further with the settings to find a sweet spot rather than using the time as an imaging session will help too! Impatience and getting to know your camera behaviour I would say is key into coaxing that awesome image to emerge from the screen. You have all given me great advice to start from and I think learning from those points forward until im comfortable will help to an easier time in post-processing and in deep sky imaging further down the line.

 

Thanks to everyone who took time to read or comment

 

Neil

[matt_astro_tx]

I suspect your collimation is off or possibly you have considerable tilt.  Notice how the image is sharp at the terminator but blurry and doubled at the limb...

 

 

It is a fine image otherwise!  It sharpened up nicely with some wavelets.  Other than that all I did was a manual color calibration to balance the colors, eliminating the red tint, and then a small histogram stretch.

 

Edited by matt_astro_tx, 04 June 2025 - 06:59 AM.

[MrNeil]

oh Matt,

 

Thanks so much for this, your so right!

 

I can see the blur in your version, I have never done collimation as when I blur a star it formed a doughnut, but seeing this makes sence as the righht side of the doughnut is slightly thicker and ignorantly thought it wouldnt affect the image. I know its not a level issue as I always level the mount each time I use it. So this will be useful experience in itself, but now I see what you have done with the same stack I will practice more, can I ask what software you used please, the difference is night and day, astonishing and as you say the image itself is really quite good and one id be proud of when I can produce processing like you have.

 

You my friend are an absolute star 

[MrNeil]

Still not at the level of Matts processing and more practising and experience to come, but I have restacked the image which for some reason has now omitted the multiple edging, I have then used tools which roughly match what Matt has used from within GIMP and followed his guidance, I still have blurring around the edge and will attempt collimation when clear skies return. Stretching the histogram proved somewhat difficult as to stretch meant destroying the image, one to practice! Of all the video's and internet articles I have read, Matt's simple advice for processing beats them hands down. A remarkable improvement to build upon.

 

 

 

 

[matt_astro_tx]

Thanks for the kind words.  Your new image is looking much better!  I do all my processing in Siril, which is what I used on your image above.

 

Regarding tilt, I was referring to sensor tilt, not the tilt of your mount.  I'm not sure if that was understood or not.  Sensor tilt happens when your camera's sensor does not sit precisely parallel to the focal plane of the telescope.  This can result in misshapen stars or portions of the frame being slightly out of focus.

 

Siril can easily measure sensor tilt using an image you've taken of a star field.  Below is an example of an image of mine which I asked it to analyze tilt on.  (Note that I don't really have that much tilt; but I ran it on an a heavily processed image so it *thinks* I have a lot of it.

 

 

However for your case I am thinking the blurry limb might have just been a stacking artifact because you were able to make it go away in your second stack.  It is most likely a combination of collimation and stacking...

[Borodog]

Hi guys,

 

wow didnt expect replies so soon!

 

Thanks RCLARK28, good to see you Mike and thanks for the reply and taking time to look.

 

I didnt know I could!   I hope Im not breaking rules as I uploaded it to my gallery and will link to that. Let me know if its obtainable or I need to change how ive done it.

 

 

 

Neil

It says I don't have permission to view your link.

[matt_astro_tx]

It says I don't have permission to view your link.

Yeah I just had to right click the large image and do a save as.  It's a tiff image.  Which is a no-no on CN!

[MrNeil]

To be honest it wouldnt let me upload .tif, maybe a blip so I had to change it to upload, felt a bit strange at the time.

 

So at my early stage of processing and before I learn too much in GIMP would you say Siril is more dedicated to Astro and generally better for what we need, I ask because I have been recomended so many different software that now have 12 apps on my desktop including Siril that I was using to convert RAW CR2 files and really want to slim it all down and learn what is going to help best.

[matt_astro_tx]

Yes Siril is far superior to GIMP for astronomy processing.  It is a dedicated astro app.  It's what I use.

[MrNeil]

Thanks Matt, I had a play with collimation last night and found half hour clear sky to get some more shots as well, So ill find a tutorial or something to go through Siril properly and get to know it using the new images and skills you have taught me. You were right about the tilt, I had no idea that could be a posibility so I will check that whilst going through Siril, again, thanks so much for all your help and Mike too, Im learning heaps and looking forward to doing you both justice with some great shots

[MrNeil]

So, this thread has rapidly turned into a fault finding thread for beginners, I found a 2 hour slot 2 nights ago and tried my collimation adjustments for the first time, I have read many articles and watched videos on the subject and felt quite comfortable. I then took an image of the moon and processed yesterday where I saw I hadnt really made much difference and there is still some blur as well as some improvement in other areas, I will put the image at the bottom here.

 

So needless to say I have researched more into collimation since, If you are new to the hobby and like myself have read up on collimation, please check the below link as it differs from advice and videos I have seen, I completed the first part without issue but as the rest of the post describes that was only part of it, I will be trying this out but we are not expected to have further clears skys for a few days.

 

@Mike, At the moment I have not tried star shots and the tilt feature in Siril is looking for them, once I have the collimation where I am happy I will do that and test the tilt.

 

https://www.cloudyni...-a-photo-guide/

 

[matt_astro_tx]

That latest picture is looking really good!

[MrNeil]

Thanks for that Matt,

 

I played with my collimation again and I think its improved further but practice will make perfect. I held out for the full moon and wow, it becomes a completely different beast and to be honest I much prefer the moody, lonely and even cold looking shots prior and post to full moon.

 

I played with Siril but really struggling with lunar, although I love the wavletts in there, so my processing is still across different software, this of course may well change when I start star and DSO's further down the line. I did a practice shot using a Bahtinov Mask but focus was way off so that one needs work before I even start.

 

So I think the below is an improvement although posibly the over use of the wavletts helped it gain detail, I still aspire to Borodogs lunar shots that are so clear, well toned and focused, it may be that my astro modded camera is holding me back where by scaling the colour balance takes away the natural colours and something I need to practice further with. I see there is a feature in Siril, Photometric Color Callibration but that now relys on Plate Solvingthat my shots are missing some info it needs, shame but ill keep looking for the best way to filter the reds and leave natural colors.

 

Edited by MrNeil, 13 June 2025 - 05:48 AM.

[Borodog]

Many people consider the full Moon a tough target and they often just skip it. I confess that if I shoot the full Moon these days I am usually going for aircraft transits (or a lunar eclipse). A "proper" image of the full Moon is very low contrast because it is so bright. To pull the greatest amount of detail you have to artificially enhance the contrast, which I am totally fine with. Everything is an artistic choice.

 

Regarding "natural colors", there's no such thing from a modded DSLR or a dedicated astronomy camera. The easiest thing you could do to get close would be to use a special UV/IR cut filter that approximates the camera's original filter you removed, and then use the camera's own color correction matrix. The most accurate would be to image a Macbeth chart with your rig and use specialized software to calculate and apply a CCM to your images (there are some threads on the forum about this). But I don't see the need. Regular astro cameras and UV/IR cut filters (the kind that still pass 90%+ of Hα) do not produce "natural" colors, but nobody really complains about that. Do the colors look natural? Then that's close enough for astrophotography, and that usually comes down to processing.