In my previous two posts, I noted my standard setup for backyard imaging:
- Celestron NexStar 8SE;
- stock alt-azimuth mount;
- an iPhone XS Max phone running Night Cap software;
- the Phone Skope smartphone adapter; and,
- a 25mm Celestron Plossl.
My last set of targets for the night was stars. Although my thinking was more like:
Okay, the moon is easy.
I’ve got a handle on planets.
Now I need to figure out how to do stars.
There’s a guy online named Loren Ball who can do an amazing job getting asteroids, and his stars are always pinpoint perfect. His technique is to use a hand-held magnifying glass to get his stars in focus, and then snap away. He sets his iPhone for ISO 8000, does 10s bursts in Night Cap, has documented all the buttons he pushes to do that, and then stacks 18 images in Nebulosity. Easy peasy lemon squeezy, it seems.
Nope, not even close. I had a few early shots about two months ago that I was happy with, and it seemed like I was on the right track. I took a stab at the Lagoon Nebula and got this on June 8th:
But getting back to that point has proven challenging. I thought I would start with a very simple object — Polaris. Nice, big, bright, can’t miss it. I followed Loren’s button-mashing order to the letter, set my ISO to 10K, and reduced duration to just 5s (the recommended time to start with). The brightness can present some challenges with the lighting in the image, not to blow it out, but it’s easy to see on the screen.
And at first blush, I was okay with it. The other stars aren’t pin points, but it seemed okay. Until I posted a few shots online, and people noticed that the “circular” field of view wasn’t quite circular. It’s a bit warped downward to the left. Which apparently meant my camera wasn’t perfectly centred over the eyepiece (although I think it meant my eyepiece was a bit crooked more than the centreing was off — my new adapter pretty much CAN’T be uncentred, it’s molded specifically for my camera, it lines up perfect every time). Loren’s view was that I wasn’t actually at 10K ISO. Except the app said I was, the ExIf data says it is. Not sure how I would know if I wasn’t, or how to check otherwise. Hmm…
M82 showed me a faint galaxy but the stars were elongated:
The stars really showed up as elongated for the Mini Coathanger cluster:
I tried to get clarification online about what those elongated stars meant…I thought I had already reduced the number of variables to focus on technique, as Loren kept saying I was being too complicated. But I had reduced to a single eyepiece, a 25mm Plossl, gives me about 80x magnification which is relatively easy to work with. The new adapter should have given me perfect centreing if I put the lens in right. I used the magnifying glass to pinpoint my stars, so I should have been in focus. So what did elongated stars mean? Did it mean I was getting subtle star trails at 5s?
The response was almost immediate — the centreing was off, so I wasn’t getting flat stars, not a drift / star trail problem. And my focus. Loren repeated, again, that I should use the magnifying glass, but I *had* done that, which I told him, but he kept repeating it, saying I wasn’t listening, and it finally just pissed me off. I had followed his instructions to the letter, even made a checklist to do it. When I’m frustrated, I appreciate someone offering help, but if they’re not listening to what I’ve done and instead just telling me to just do the same thing over again, it moves past help and well nigh into condescension, and just added to my frustration. At that point, I’m better off going on my own because that kind of rote help is not help at all. And to be honest, I’ve found the two groups I was using somewhat unpleasant in recent weeks for some of the conversations in it, maybe it’s the heat. Whatever. I unfollowed four astronomy groups and moved my focus to my own stuff and a couple of email groups I use. One of the guys on FB who was actually quite helpful is offering feedback through DM, so hopefully I’ll figure this out in stages. In the meantime, I’ll share my other results.
A very light M10 globular cluster:
Some of the stars in M18 (an open cluster) were okay:
I like the “W” cluster, but you have to cock your head to the right to see it:
I tried twice for Albireo and the second one split the star properly, but neither were great:
I got a bunch of stars in M39 (open cluster again), but still elongated:
M2, a faint globular cluster, is the type that suggests I’m not actually getting up to 10K for my ISO — there should be other stars in those fields.
I liked the look of Epsilon Pegasus which I hadn’t seen before:
M12, another globular, gave me slightly better detail:
But when I tried stacking it, it didn’t improve anything:
I *really* liked M23, nice big open cluster, lots of stars and not as elongated (but I don’t know why!). Stacking didn’t change the outcome:
The target that Loren had suggested for me to try was M25 since it has so many stars in it. And as soon as I published it, the guys online said “You’re not centred” (see dialogue above). Which is true, obviously. So I need to work on my centreing some more (or more likely, the vertical-ness of the EP in the adapter).
Stacking didn’t do anything to help, even with 20+ pics of 5s each. Need to work on that, but as I said earlier, that’s a later priority. I moved on to the Blue Snowball. And, while I can’t say I got anything amazing, there IS something blue in there:
I tried for the Bubble Nebula, but got nada for the nebula. Even the stars around it aren’t great:
Dumbbell Nebula? Nada. Eagle? Lots of stars, no nebula.
I tried for the Swan Nebula, and I did get a faint bit of fuzziness near the bottom.
For the Veil? Nada. Hmm…Maybe I’m NOT at 10K ISO. Hmm…On the other hand, I looked at the Wild Duck Cluster for the first time. And I think it looks really cool with a lot of potential for the future.
When I figure out the right technique, Wild Duck and M25 will be my test subjects. And maybe the Lagoon Nebula again. See if I can get some more colour.