Milky Way Lucky Shot

We spent a few days at a cottage in the mountains. Very dark skies overhead although hemmed in by forest. I was delighted to see the milky way easily although not as vivid as in the image above. That is the result of four 30 second shots at ISO 1600 through the canon 18-55mm lens at 18mm f/3.5. This was just the camera on tripod, no tracking, no zoom.

Cassiopeia is lost in the profusion of stars but it was clear in person. Andromeda shows just above the trees right of centre. In one of the sub-exposures I caught a late perseid meteor just above Andromeda. I saw another one around the same time. For the image below i took the sub where i caught the meteor, duplicated it so i had three copies then fed it to Siril. Besides the usual process I used the ASINH transform to move the black point about half way.

The Cradle of Andromeda

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This unimpressive goody is the only legacy of a cold hour with a new lens. I like this part of the sky with Cassiopeia and Andromeda. I was hoping to get the stars against a bit of blue background but this is the best i could do in post processing. The original was done 4 seconds 18mm f/4 ISO 1600. I boosted the colour a lot and brightened it with the windows photo tool.

The lens is a used Sigma DC 18-200mm f/3.5-6.3 on a Canon t3i. It’s not my favourite lens: the glass itself may be ok but the zoom is stiff and yet it will collapse the zoom if it’s left pointed up. There is a zoom lock but that’s stiff and hard to find. It’s easy to knock it off focus and the focus changes as you zoom.

My worst problem last night was the cold though. I’m used to working a lot by feel in the dark and numb fingers are not much help that way.

Meanwhile Back in Nikonia

I was out one night earlier in the month trying to image M31 with the Nikon P900. The results were pretty dismal. Below are my three best tries. The first one is from a starscape video so 25 sec ISO 100 and the others are ISO 6400 1/2 sec. In each case you can see the Andromeda Nebula as a smudge. The smudge is pretty blocky in the video frame. I looked at a number of the frames and they were similarly blocky so i doubt that stacking would make a difference. So the Nikon makes night sky photography easy and fun but not that rewarding – the sensor is just too small.

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Adrom-Encore

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I was out again last night with my 135mm lens but without a dew heater so I got better resolution on M31 but not as sharp as it could be. This is a combination of 8 not-too-smeary shots at with the canon t3i at 135mm f/5.6 75 seconds ISO 1600. I stacked and stretched it with pixinsight following Alan Hall’s book then decoloured and dimmed it with the windows photo tool.

The image below is 8 shots at ISO 3200, 37 seconds, 135mm. I did this hoping the lens would get less smeary between wipes. I haven’t decoloured it and the crop is a bit different but, if anything the longer subs are better.

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Androm-again – And Is She Stacked!

19-10-24 stacked M31-cropped

I am pretty pleased with this result. Eleven images 60 seconds each at f/3.5 ISO 800 shot at 50mm and cropped. Processed with pixinsight using guidance from Alan Hall’s book. After stacking with pixinsight The image had a greenish tint and I eliminated that by using the color slider in the windows photo tool, then used the brightness slider to reduce brightness a bit. That’s a crude tool but i’m happy with the result.

Above M31 you can see M110 and the greyer “star” below it is M32. The two brighter stars midframe are v Andromeda and 32 Andromeda. Near the bottom center us u Andromeda.

Below, for reference is IMG_3963, one of the 11 frames stacked to generate the picture in its original size and roughly cropped to match the above.

I now have a 135mm lens which I intend to try on the next good evening. Assuming I can do 60 second exposures I would need higher ISO to get the same brightness because the lens is f/5.6 rather than the 3.5 I was using for the above. According to this I think the brightness ratio is (5.6/3.5)^2 or about 2.5 so I will try ISO 1600 for 75 sec and if that’s no good, ISO 3200 for 37 sec.

Just Call Me Galaxy Bill

19-09-23 closeup

I’ve been trying to photograph M31, the Andromeda Galaxy, for a while and this is my most gratifying effort to date. I was in a fairly dark location tracking with the ioptron Skytracker and the picture was taken with the Canon T3i and 50mm lens at f/3.5 ISO 400 and 120 second exposure. I had done a series of 60 second exposures at 800 ISO with the idea of stacking them but that hasn’t worked out so far. The brighter stars near the bottom of the image are v Andromeda to the left and 32 Andromeda to the right. It’s interesting that the little parade of stars near v And. and the little squad above 32 And. are actually there. Some of those stars are getting down to magnitude 10 or 11.

The image below from stellarium shows the two groupings and also shows the real extent of M31 which is only hinted at in my image. Oh, and in the stellarium image you can see a small puff above Andromeda which is M110, a satellite galaxy of M31, also barely visible in my image.

19-09-23 stellarium andromeda

The image below is the uncropped version.

Tracking Andromeda

M31ButHow

That’s M31 – the Andromeda Galaxy – front and center. Mirach and Alpheratz are toward the bottom. This is a combination of five images shot at 10 seconds f/4 ISO 1600 using the Canon t3i with 50mm f/2.8 lens. The five images were combined with DeepSkyStacker then brightened with the Windows Photo tool. The sky was visually dark although it shows blue-grey above.

The Camera was mounted on my new-to-me ioptron Skytracker. I didn’t have a lot of luck aligning the tracker with Polaris, my vision is pretty poor at night, but I’ll keep trying.

Cr*p – I AndroMissed

I was out last night with a new 50mm Canon lens aiming to get multiple exposures of M31 in Andromeda but i blew it on several levels. First and worst, I pointed the camera with SkyView on an iphone rather than hanging off Cassiopeia the way i did the last time.

19-09-10 androMissedIt2 In any event I was way off with the wrong part of Cassiopeia in frame and Andromeda off to the right. The stellarium clip below shows what i was looking for which would have put andromeda right near the center. Pointing with the phone is cute but it’s not trustworthy.

19-9-10 androMissedIt

Then I was all over the map with my exposures. In the previous outing at 55mm I got a smudge at f/5.6, 10 seconds, ISO 1600. I should have started there adjusting for the faster lens. Maybe f/4 6 seconds ISO 1600. Lastly, I had only jpegs being produced which are no good for stacking.

Also, the lens may be faster but, while the center stars are pretty good, the stars near the edge are smeared – this could be a defect or just need stopping the lens down a bit.

So: Next time try to bracket Shedar in Cassiopeia and Mirach in Andromeda at 50mm. Expose for 6 sec at f/4 ISO 1600. If It’s a good evening I could try bringing my laptop and checking with the plate solver but that’s a lot of risk and setup fuss.

The two samples below were shot with the Canon T3i 50mm lens at f/2.8 ISO 1600, 4 seconds on the left and 6 on the right.

UPDATE: I accidentally found something super encouraging. The plate solving web site, shows you images uploaded by other users in the neighbourhood of your shot. One of them looked like andromeda so i clicked it and got the results below. I’d be delighted if i got anything like this and the field of view is almost identical to mine(24.8X16.6 degrees vs my 24.7X16.5). So, if i can capture enough light i can get an acceptably sized image. I don’t think it was taken with the same sort of setup i’m using(50mm lens on a canon aps-c body) because the pixel scale is different, 25.5 arcsec/pixel vs my 17.2 but still it’s very encouraging. I see another shot with similar but distinct parameters(24.4X15.7 degrees, 15.3 arcsec/pixel).

These may be done with more sophisticated setups and tracking but i suspect they are single images. I don’t think anyone would upload stacked images to a plate solver.

Well: somewhat less encouragingly I was able to identify the camera as a Sony ILCE7RM2, a $2500 full frame mirrorless camera. Also, that shot was a 401 second exposure at 85mm f/2.2. So to get that much light i would need to stack maybe 100 shots with my camera. still, image size is not the barrier i was afraid of.

Another example, below from a tutorial(for which thank you) also shows andromeda at 80mm equivalent focal length. This was made from a stack of 25 light frames. Andromeda and Half Dome – Nikon D800e, Nikon 85mm f/1.8 G – ISO 6400, f/1.8, 6 sec.

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To get that much light I would need 100 shots at f/4 6 seconds ISO 6400. (Or I need to get my darned tracker working)