Two swans and a new "zoom" lens

Hey, the great attraction last night was Comet SWAN – but I did capture the above image of the well-known constellation Cygnus the Swan with my new zoom lens as it (the heavenly swan) plunged into my trees to the West.

Earlier I saw the other swan- COMET SWAN – and it was COOL. But at that point I didn’t know how to use the zoom lens, so there are no pictures. Most of this post is about is my learning curve with the new zoom. As for Comet SWAN it was easily brighter, larger, and greener/bluer – than nearby M13 and it had a faint,but detectable tail. It really caught the attention of the three scheduled visitors to Driftway Observatory. I wasn't entirely surprised because I had read a report earlier in the day that it had suddenly brightened two magnitudes and thought it would make a nice target for my new zoom lens. My guests had great fun learning how to find the comet with binoculars and then move up about 7 degrees to also locate the globular cluster, M13 – then we looked at both objects in the 15-inch and , of course, what looked similar in binoculars looked quite different in the telescope.

Anyway – Comet SWAN was a fun object that I did NOT catch with my Color Hyper MallinCam video camera and new lens I bought for astro astronomy. And it's the lens I want to write about. But. If you want more on Comet SWAN, I suggest you go here- what I want to share while it's fresh in my mind is the zoom lens experience which fellow newbies to video astronomy may find interesting.

By near midnight the new lens was bringing me views like this one of M45, the Pleiades:

but it was a real challenge to get there. Here are the bare facts on the lens:

Fujinon - C-Mount - 7mm to 70mm - Zoom - Manual-Iris- F1.8 - $125 – Adironasack Astronomy -

The facts looked attractive to me. I roughly calculated that this would give me a 4-40 degree field and it is delivering something in that neighborhood – well, check out the view of Cygnus and friends – I think it delivers a wider view than I anticipated. And the zoomed-in view of the Pleiades is pretty cool IMHO. But the lens held several surprises, not all of them pleasing. Frankly, I'm trying to decide if I should send this one back and get a lens of a fixed length, but I need to do more experimenting.

I should have been forewarned. When it arrived earlier in the day and I opened the box and looked at it, I discovered three little protrusions – 1/4-inch posts – sticking out at various points. What?

Turns out they are locking screws. See, you adjust the amount of zoom, then turn the little post to lock it. And you adjust the focus, then turn the little post to lock it. And you adjust the iris and turn the little post to lock it. Neat, but I didn’t have a clue why this was important.

The reason is this is NOT what I think of as a zoom lens – at least in my short time with it – it's more like having multiple fixed lenses. The operative word here is focus. I had the apparently naïve assumption that you would simply set the focus to infinity, point the lens at the sky, and zoom in and out at will. Nope!

Every adjustment of the zoom calls for an adjustment in focus – an oh-so-delicate adjustment that in three hours of serious toying with it I got more exercise then I get in a week of walking. See, the only place I could quickly attach the lens was about 12-feet from the DVD screen I was using for a display, so I had to keep walking back and forth between the two and it was a bit frustrating.

No big deal? If you haven’t used a set up like this you might consider focusing trivial. It isn't for two reasons. First, when the image is just a little out of focus it vanishes from the screen entirely. And second, to get a decent image to work with I need to do a 2-second integration – which means you focus a tiny bit, then wait two seconds for the result – nothing like the intuitive kind of continuous focusing you do when observing visually.

When the new cables – on order – for the DVD arrive they should cut down on my exercise, but I still fear the delicate focusing will be a challenge. In any event, it's not going to work exactly as I had hoped. That is, I'm not going to be able to show folks a constellation, then quickly zoom in on a special feature, such as a cluster or nebula, as I had thought.

One of the question marks in this respect is just how deep the lens can go. I found that if I open it wide and do a 6-second integration (exposure), it's seeing some fairly faint stuff. But when I pointed it in the genral direction of the Andromeda Galaxu - M31 - I was shocked at how little an impresion it made. (Anyone have any suggetsions to improve this, let me know. I'll keep trying, but first impressions were disappointing. ) Twelve seconds would give better results, but I think for that I'll have to have it piggybacked on the LX90 or whatever. (For these first experiments the camera was fixed - not tracking.) Without any tracking, 12-seconds was showing streaking – especially as I zoomed in.

AND there was streaking at the wider points as well – that is, like a cheap, wide-angle eyepiece, as you move out from the center of the field of view you certainly lose sharpness. (That's being gentle.) OK, well how much can you expect from a $125 piece of glass? And the answer is, I don’t have a clue.

My old photography instincts rebel against zoom lenses anyways. That is, my photography started half a century ago when zoom lenses were viewed as toys that couldn't deliver. That's changed now, but old ideas die hard. So I'm wondering whether a fixed lens might deliver a better image. And I guess the bottom line is I need more experience with this baby. If I back off the iris to about half way I lose significant light, but I seem to get a sharper image – which again, is what I expect from my out-dated photography experience. So maybe I can find a good balance between the amount of zooming, the iris setting, and the length of exposure.

And that is what those little protruding posts are all about – find a setting you like and save it – and maybe somehow mark some key settings so you can easily jump to them – or at least get close.

Whew! Yes, I'm still having fun. Yes, I like the results. But boy do I have a lot to learn about this video astronomy business! Meanwhile, here's a shot I took as I running out of steam lat night. It's pretty close tto a binocular view of Taurus and I love the "home plate" or "house" astrerism near the center that has three nice pairs of stars in it.

Oh - and the star colors, they're real, I think! I was surprised by how vivid they were. Some of my shots with this lens look like Christmas lights. On the image below I did a quick random survey on several of the stars and found the color I see on the image certainly fits roughly with the spectral type of the particular star. That's why I assume the color is real. By the time the image gets to the Web this color is a bit diminished, but still obvious,