Equipment and accessories

Re: Thinking of getting a First telescope with astrophtography in mind?

WABarry — Fri, 14 Aug 2009 05:22:14 GMT

I think I can answer your question about Jupiter and Saturn in an 8" Dob. The answer is Yes and No. Yes, that image of Jupiter is not difficult to duplicate with a 5-8mm eyepiece in an 8" Dob on a night of reasonably steady "seeing". And No, the image of Saturn is going to be difficult to duplicate at the eyepiece.......you can see it as clearly (maybe even slightly more clearly), but it will not appear that large.....unless the seeing is near perfect and you can use a 3mm eyepiece or a barlowed equivalent. Jupiter's disk is quite a bit larger than Saturn's....especially now, with the rings all but disappeared. I would go ahead and get the 8" Dob (or even a 10" for that matter). You will not be disappointed in the views. On nights of steady seeing, you will be amazed at the amount of detail that is visible.

Do be aware that on nights of poor 'seeing' conditions, the best telescopes produce poor views. Some nights Saturn and Jupiter will be fuzz-balls with little detail.....other nights they will be so clear you will feel that you can reach out and touch them. Seeing conditions make a HUGE difference!

Your Dob will probably come with two fairly decent Plossl eyepieces.....a 25mm, and a 9mm. I would get a 2x barlow lens to increase your flexibility......turning your 25 into a 12.5, and your 9 into a 4.5.

Re: Thinking of getting a First telescope with astrophtography in mind?

chipdatajeffB — Thu, 02 Jul 2009 19:38:23 GMT

Not for astrophotography, despite what the ad text says.

It does not guide, it tracks. No telescope mount tracks accurately enough for time exposures over about 30 seconds at a focal length greater than about 1,200mm. You need an autoguider to keep updating the mount's position (several times a second) to make up for inaccuracies in tracking.

Furthermore, this is an alt-az mount, which means for exposure longer than a few seconds the field of view in the image will rotate, blurring the image.

If you want a first telescope, buy anything you want with an aperture of 6 inches (150mm) or larger.

If you want a first telescope for astrophotography, spend all you can afford on a heavy duty EQ mount and begin with a widefield refractor of about 80x480 mm, then move up to a bigger telescope later.

If you have not done any astrophotography, you should start out with the simplest and sturdiest, most accurate system possible. Otherwise you will be burning time and money recovering from frustration after frustration.

Is it possible to start out in AP with an 8" SCT on a so-so mount and actually make pictures? Yes.

Is it the right way to start? Not even close.

Go back and read the original posts here and heed the advice.

A starting system that's good for both visual observing AND astrophotography is easy if you're thinking widefield, harder if you're thinking dim DSOs, and complex (more accessories) if you're thinking both DSOs and lunar and planetary imaging.

The target and camera type are your first decisions. After that, the suggestions come easier.

Re: Thinking of getting a First telescope with astrophtography in mind?

HR8799 — Thu, 02 Jul 2009 19:05:07 GMT

What do guys think about these all in one Scope. hat have built in glider etc.

http://www.telescopes.com/telescopes/catadioptric-telescopes/celestronnexstar8se.cfm

Re: Thinking of getting a First telescope with astrophtography in mind?

HR8799 — Thu, 02 Jul 2009 16:41:12 GMT

Hey Tim , Sorry meant to say Tim Kerr !

Great post I like Method 4 as stated above and the idea that it can be used as an extra long and expensive Camera lens is cool. What Scope with built in CCD would you recommend? I'm using a Nikon D90. Could you write me a quick check list for Method 4? Thanks Dude !

Re: Thinking of getting a First telescope with astrophtography in mind?

tkerr — Thu, 12 Mar 2009 14:14:01 GMT

atomic7732:

Thanks for that issue, but the problem is, is that the eypiece can get to the center of the image, but the object in the eyepice will only show more than 50% when the eyepiece is at the bottom of the image.

Sounds to me like you're getting vignetting. This is because the camera is not properly aligned at the proper distance from the eyepiece. This is actually quite common with A-Focal photography through the telescope eyepiece. this is especially a problem when using short focal length Plössl eyepieces. There isn't much you can really do about it if you want to use higher magnifications. This is why most people usually only use A-Focal photography for the moon at lower magnfications with a larger/longer focal length eyepiece.

Re: Thinking of getting a First telescope with astrophtography in mind?

tkerr — Thu, 12 Mar 2009 14:06:46 GMT

atomic7732:

I don't understand the A-focal thing, it says some acronyms that aren't explained. It also says some things that don't make sense. Are you taking a picture with the camera infront of a telescope with an eyepiece on the camera?

Telescope...Camera.Eyepeice

Or is it, A camera looking throogh the eypice connected to the telescope

Camera...Eyepiece.Telescope

Which acronyms? There were only a few which are quite common. The others are file extensions and abbreviations.

EP = eyepiece (Ocular)
SLR = Single Lens Reflex. e.g. 35mm film camera
DSLR = Digital Single Lens Reflex, e.g. Canon EOS Digital Rebel
CCD = Charge-Coupled Device (Digital Camera sensor chip)
CMOS = Complementary metal oxide semiconductor ( a different kind of digital camera sensor chip)

.MOV and .AVI = three character file extensions for two different video file formats.
SPC900NC = the model of a WebCam. (aka. Philips ToUcam Pro III)

Alt-Az = Altitude and Azimuth
DOB = Dobsonian.
EQ = Equatorial Mount or GEM = German Equatorial Mount

DSO = Deep Sky Objects i.e. Nebulae, Galaxies and Clusters.

A-focal is simply bringing the image of the moon or planet to focus with the eyepiece(EP) of your choice in your telescope. Then aligning your point and shoot digital camera over the eyepiece and taking a picture of the image that is projected through the eyepiece. Not as easy as it sounds,especially if your telescope mount doesn't have motors for tracking.

You can just hold the camera in your hand to do this if you want. Or you can use a tripod to hold the camera over the eyepiece, or you can buy a special mount that attaches to the eyepiece and holds the camera centered in position over the eyepiece. e.g. the one shown in the picture of the A-Focal imaging set-up.

To see the full size image in that post, just click the thumbnail image.

Re: Thinking of getting a First telescope with astrophtography in mind?

atomic7732 — Thu, 12 Mar 2009 13:48:08 GMT

Thanks for that issue, but the problem is, is that the eypiece can get to the center of the image, but the object in the eyepice will only show more than 50% when the eyepiece is at the bottom of the image.

Re: Thinking of getting a First telescope with astrophtography in mind?

chipdatajeffB — Thu, 12 Mar 2009 04:01:48 GMT

If you can't turn the flash off, then the next best thing is to direct the light from the flash away from the eyepiece and telescope. To do that, you could tape a piece of white card in front of the flash at an angle.

To avoid cutting out part of the field of view (which it sounds like your setup is doing), try this:

Set the scope slightly ahead of the target. The idea is to wait for the target to drift through the field of view of the telescope, then snap the photo when you can see the target through the camera viewfinder.
Place the camera on the tripod at an angle that matches the angle of the eyepiece.
Scoot the tripod-mounted camera into place directly over the eyepiece.
Watch for the target to drift into view.
Snap the shutter -- or, if your camera has a self-time, set that so that it goes off while you're not touching the camera ... that will minimize camera-shake-induced blur in the photo.

Re: Thinking of getting a First telescope with astrophtography in mind?

atomic7732 — Thu, 12 Mar 2009 03:22:17 GMT

I think while you posted, I got an image and i have 3 things.

I can't get my camera off of flash. I use a tripod, I don't have a mount. When I put it up to the eyepeice it has to be at the bottom to see the full image of the eyepiece. I wish i could put the picture up, but I can't. It is something like this:

The moon is about 1/8 the picture size and only about half of the moon itself, and the eypiece takes up a little less than a 1/4 of the size. THe rest is nothing.

Re: Thinking of getting a First telescope with astrophtography in mind?

DaveMitsky — Thu, 12 Mar 2009 03:06:03 GMT

Afocal can be defined as an optical system that does not form an image. Since the human eye ultimately acts as the imaging device, a telescope with an eyepiece is considered to be afocal.

Afocal astrophotography involves the use of a telescope and an eyepiece with a camera and camera lens held at the the focal plane of the eyepiece as opposed to prime focus astrophotography, where the telescope acts as the lens of an SLR camera or imaging device, and eyepiece projection, where the camera is employed without a lens but an eyepiece is used to increase image scale.

I believe your second description describes the situation except that the camera lens is in place in afocal astrophotography.

http://www.skyandtelescope.com/howto/astrophotography/3304331.html?page=2&c=y

Dave Mitsky

Re: Thinking of getting a First telescope with astrophtography in mind?

atomic7732 — Thu, 12 Mar 2009 00:43:42 GMT

I don't understand the A-focal thing, it says some acronyms that aren't explained. It also says some things that don't make sense. Are you taking a picture with the camera infront of a telescope with an eyepiece on the camera?

Telescope...Camera.Eyepeice

Or is it, A camera looking throogh the eypice connected to the telescope

Camera...Eyepiece.Telescope

Re: Thinking of getting a First telescope with astrophtography in mind?

jodoak — Wed, 24 Dec 2008 00:24:12 GMT

Tim,

Thanks for the information. I will look into those choices.

Re: Thinking of getting a First telescope with astrophtography in mind?

tkerr — Wed, 24 Dec 2008 00:20:39 GMT

jodoak:

Kevin,

I really want to do it right, so now I am reading and researching what I will need, at a reasonable price. I don't think I need to spend over $5000 to accomplish that. I have time to put my plan together as it will be several months before I even place orders for equipment.

With $5000.00 budget I would consider a Celestron CGE or Losmandy G11 or Titan mount, with a 9.25 or 11" SCT.

Re: Thinking of getting a First telescope with astrophtography in mind?

jodoak — Wed, 24 Dec 2008 00:15:52 GMT

Kevin,

I really want to do it right, so now I am reading and researching what I will need, at a reasonable price. I don't think I need to spend over $5000 to accomplish that. I have time to put my plan together as it will be several months before I even place orders for equipment.

Re: Thinking of getting a First telescope with astrophtography in mind?

Kevin Bozard — Tue, 23 Dec 2008 17:23:33 GMT

jodoak:
Tim,

I do this hobby strictly for my own enjoyment, not for research or in the hopes of making some discovery.

I now want to share it with my wife and my two grown boys.

My early intentions were much like yours. I got into imaging the night skies just to have visual documentation of the objects I've observed with my telescopes. It all started with a Kodak 3.2 mega pixel point and shoot camera, taking afocal shots through the eyepiece. An Orion Starshoot Deep Space Imager, three web cams, and a Canon DSLR that came later, I'm still attempting to meet my original goal of capturing decent images for documenting my efforts.