Author Topic: Astrophotography / Telescopes (Read 999 times)

Tac · « **on:** November 15, 2007, 09:29:40 AM »

I have had a Meade LXD55 AR6 refractor (6") for some time now but had not used it for more than moon-watching because the Autostar mount was not working properly.

Last night, to my personal humiliation, we found out it was working perfectly and the error had been mine (the cage section that rotates left/right was...backwards. sigh. no wonder the scope could never align, it was receiving signals from me telling it that south was north.. hahaha)

So.. 'first light' was good. Scope pointed nicely to the alignment stars, it centered Mars dead-on the center of a 6.5mm eyepiece while I had a 2X barlow on (i know bad choice, i just had to try it) so i was impressed with the autostar.

Now, being a retarded nooblet, I need some help with the optics and a lil' photography.

First off, even with my 2X barlow and the 6.5mm eyepiece Mars still was nothing more than a little red dot on the eyepiece. I thought the scope could at least show you the planet.

I see a red dot half the size of this guy's picture:

I know nothing of optics so i'd like to ask you guys what I need to get to see something decent with the scope. I know most astrophotos out there are the result of CCD cameras crunching 100+ pics into one and using digital magnification to make the pretty pic

My first guess is I need a better barlow (i see some 4X ones out there) or such.

I have a 10mpixel 'pocket' digital camera and a 6mpixel digital that uses optical lenses (not an SLR but similar) and I'll be getting the adaptor for both to slap on the scope. But before I can use the cameras I need to be able to see something decent with the naked eye I think. Or maybe ill just buy http://www.amazon.com/Meade-Deep-Imager-AutoStar-Suite/dp/B0006FRYSK/ref=pd_bbs_sr_1/103-0626835-9445431?ie=UTF8&s=electronics&qid=1195140356&sr=8-1 or http://www.amazon.com/Celestron-NexImage-Solar-System-Imager/dp/B0002X5Q72/ref=pd_bbs_3/103-0626835-9445431?ie=UTF8&s=electronics&qid=1195140356&sr=8-3
to do the job. hopefully it can work to take a few mediocre nebulae pics.

CptTrips · « **Reply #1 on:** November 15, 2007, 10:45:05 AM »

TAC,

The rule of thumb for “useful” magnification under normal seeing conditions is about 50x per inch of aperture. For your scope that’s about a limiting magnification of 300x. In rare, perfect seeing conditions you might be able to go higher. On many nights, you won’t be able to even use 300x. You can magnify past that but it just gets blurrier with no additional information.

Your AR6 has a focal of 1219mm. with a 6.5mm eyepiece that’s 187.5x mag. With a 2x Barlow that’s 375x mag. So you are already pushing the practical magnification limit of your scope. To use higher magnification, you’d need more aperture or really, really good seeing conditions.

Mars is a tough object. It’s pretty small. Sometimes the surface is obscured by sand storms. Even at its closer approach this year (24 Dec), it’s still going to be pretty small. With a webcam (like a toucam plus Registax software) you can get some decent picture that you can enhance and enlarged. You can eek out more information from a processed wecam image that you could have seen from the eyepiece.

BTW, for planetary imaging, you are MUCH better off with a webcam type imager than a digital camera. You want to be able to catpure hundreds of sub second frames and filter out the ones blurred by atmosphere with software. That way you can stack and enhance the frames (maybe 2 frames out of every 10) that momentarily capture a bit of steady air.

Regards,
Wab

LePaul · « **Reply #2 on:** November 15, 2007, 10:51:58 AM »

Wabbit,

What's a good model for planet hunting? I've been surfing Amazon and checking the Meade's and other models. I know I want the computer/planet tracking stuff, but what else should i look for if I hope to take pictures?

The price range seems pretty huge so I thought I'd run it past ya

Can a good model be had for $400-500?

CptTrips · « **Reply #3 on:** November 15, 2007, 11:45:18 AM »

Quote

Originally posted by LePaul
Wabbit,

What's a good model for planet hunting? I've been surfing Amazon and checking the Meade's and other models. I know I want the computer/planet tracking stuff, but what else should i look for if I hope to take pictures?

The price range seems pretty huge so I thought I'd run it past ya

Can a good model be had for $400-500?

Hmmm. I can only tell you what I'd get. There are so many options and so many variables to consider. You'll have to weigh yourself.

400-500$ might not be possible. However, if you are mainly wanting to do solar, lunar, planetary imaging then you want a wedge mounted, eletric drive scope but it doesn't necessarily need to be computerized. Those are mainly naked eye objects and they won't be hard to spot visually and just point the scope at them. This option allows you to find some less expensive, older used scopes that aren't computerized. If it were me, on balance, I'd go with an older, used, pre-computerized 8" SCT , with wedge and drive.

Like this

(You might also check out Atromart.com)

You'll probably then want something like a Toucam webcam with adapter (~$130), Registax (Free), capture software like K3CCD or similar (shareware $?), Laptop , a good 2x barlow, a front-end mylar solar filter, eyepieces.

With that you could do enough visual, solar, lunar, planetary observing/imaging to keep you busy for years.

The computerized scopes come into usefulness when you are trying to find small, dark fuzzies like galaxies and dim nebulas. You can find those manually, people did for decades. For planetary stuff it’s not that useful. You do want an electric drive, but you don’t need computerized Go-To. That can save you some money.

Note: I used to lean slightly more towards refractors for causal users because they require less maintenance being a sealed system. But you can get more inches aperture per dollar with a reflector. And in the end, aperture is king. The main thing you have to do with a reflector is learn to align (collimate) the mirrors every so often. But it’s REALLY not that difficult.

Let me know if I can help further.

Regards,
Wab

moot · « **Reply #4 on:** November 15, 2007, 11:48:41 AM »

Some more data points for your consideration.
http://uplink.space.com/postlist.php?Cat=&Board=askastronomer
Post pics when you get it going...

CptTrips · « **Reply #5 on:** November 15, 2007, 12:01:38 PM »

Also, here is a older discussion of some of the variables for you to consider:

linky

Wab

ChickenHawk · « **Reply #6 on:** November 15, 2007, 12:05:20 PM »

AKWabbit, have you taken any images of Comet 17P/Holmes yet? I'm curious to see what kind of image your setup can get of this very interesting phenomenon.

I meant to get some prime focus pics through my 4" Meade but only had time to use my telephoto lens on the camera. Even so, it's clearly visible:

Canon 20D f/5 10.00s ISO 800 70-300@70mm

Tac · « **Reply #7 on:** November 15, 2007, 12:10:51 PM »

Wab,

Im a total noob when it comes to this and I dont really understand the eyepiece/magnification math yet.

I guess my concern is that no matter what I do the only thing ill ever see through the eyepiece when pointing at mars or jupiter/saturn is a little dot that I can hardly see any features through.

as for the camera... well, i really would like to spend more time taking pics of a nebula than a planet so I was looking at something that would let me do both.

What would you suggest I can get thats not so expensive?

I only have:

LXD55 mount (autostar 1 GOTO)
AR6 tube

Eyepieces that came with meade anniversary kit:
2X barlow
6.4mm
9.7mm
12.4mm
15mm
20mm
26mm
32mm
40mm
Blue/Red/Green/Lunar filter

moot · « **Reply #8 on:** November 15, 2007, 12:23:28 PM »

Holmes' been dimming pretty quick these last few days...
An interesting bit about it: Its halo of dust is now bigger in volume than the Sun.

ChickenHawk · « **Reply #9 on:** November 15, 2007, 12:29:36 PM »

Quote

Originally posted by Tac

I guess my concern is that no matter what I do the only thing ill ever see through the eyepiece when pointing at mars or jupiter/saturn is a little dot that I can hardly see any features through.

I think you'll be surprised at how much better viewing Jupiter and Saturn are then Mars. Mars is pretty small.

That's a pretty nice setup you have there. With the right camera, you could get some nice results.

If you want to see something no one alive has ever seen before and likely never will again, check
out Comet 17P/Holmes.

CptTrips · « **Reply #10 on:** November 15, 2007, 01:04:21 PM »

Quote

Originally posted by Tac
Wab,

Im a total noob when it comes to this and I dont really understand the eyepiece/magnification math yet.
.......

The eyepiece/ focal length math is simple. The resulting magnification is equal to the focal length of the Primary component (i.e. you front lens) divided by the focal length of your eyepiece. So looking up the focal length of your scope I saw it was 1219mm. You said you were using a 6.5mm focal length eyepiece. So that’s 1219 / 6.5 = ~187.5x. If you slapped on a 2x Barlow it simply multiplies the magnification so a 2x Barlow would make it 187.5 x 2 = 375x. So with your objective lens, 6.5mm eyepiece, with 2x Barlow you are getting 375x magnification.

As I said, Mars is a tough object even in my 12” LX200. Your view of Jupiter (best next June) or Saturn (best next Feb) will be much more impressive. I bet it does great on the moon (might consider getting a minus violet filter) and with the proper solar filter would be great on sunspots.

As for a camera that does great for both planets and deep sky stuff, that’s a difficult thing to achieve. It’s like designing a plane that is as fast as a FW190 but has the low speed maneuverability of a SpitV. If you can get a reasonably priced adapter for the camera you already have, I’d start with that. You just have to realistically understand your limitations. At first, it’s fun just to get any image at all. As you get more experience you and decide it’s something you want to stick with, you can always upgrade your equipment later. Sunspots (with a proper filter), and lunar shots are what I suggest you start with. They are big bright objects that are good to cut your teeth on. You can start getting reasonably pleasing results right off the bat.

Regards,
Wab

moot · « **Reply #11 on:** November 15, 2007, 01:05:51 PM »

Relative scales of planets as seen from Earth right now (Uranus is closer than Neptune 19:30 IIRC), with the moon on the left, magnification is 400x.

Below Mars are Mercury, Uranus, and Neptune.

CptTrips · « **Reply #12 on:** November 15, 2007, 01:09:04 PM »

Quote

Originally posted by ChickenHawk
AKWabbit, have you taken any images of Comet 17P/Holmes yet? I'm curious to see what kind of image your setup can get of this very interesting phenomenon.
[/IMG]

CHickenHawk,

Wow thats a cool shot. Yeah, Holmes is all the buzz now. I've been so busy last 2 months, I've hardly touched the scope. I mght get to take a peak this weekend.

I'm hoping I'll get a lot of sky time come Dec. December is pretty much going to be devoted to Mars. I want to get at least 1 really decent shot. This is the best approach we're going to get for the next 16 years.

Regards,
Wab

moot · « **Reply #13 on:** November 15, 2007, 01:16:06 PM »

Hehe while we're at it, another cool pic: Daylight picture of the moon's and venus' crescents next to each other.

CptTrips · « **Reply #14 on:** November 15, 2007, 01:25:13 PM »

Quote

Originally posted by moot
Hehe while we're at it, another cool pic: Daylight picture of the moon's and venus' crescents next to each other.

Now THATS a nice one.

Wab