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DPChallenge Forums >> Tips, Tricks, and Q&A >> Astrophotography Question?
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 12/27/2004 10:32:29 PM · #1
Ok i have the attachment to the telescope. I've tried taking photos of the moon but they all seem to come a slightly blurred,
With the new lenses i tried it too Canon EF 90-300mm and they are coming out blurred too.
Is this a techinc problem or is it the weather, the sky is clear but it's winter time here, it's really cold but clear sky.
Please do help.
 12/27/2004 10:33:52 PM · #2
remember that the earth spins, so if you make too long an exposure, the moon will blur/streak.
 12/27/2004 10:37:09 PM · #3
I'm using high iso like 400 or 1600, and the exposure is of 1/100 or 1/240 i now that but thanks for reminding. just don't really get it why it's happening.
 12/27/2004 10:45:36 PM · #4
If your tripod isn't sturdy enough or you're pressing the shutter by hand, you'll get some shake.
 12/27/2004 10:46:57 PM · #5
i use the timer. and the tripod is just fine.
 12/27/2004 10:48:00 PM · #6
Can you post one with EXIF data?
 12/27/2004 10:50:09 PM · #7
i'll post an example. just a second.
 12/27/2004 10:59:35 PM · #8
Taken with the telescope, 1/100 iso 1600 and self timer. click here for image.
 12/27/2004 11:05:34 PM · #9
It looks like there is either a little focus error, or you're just seeing atmospheric turbulence. What is your elevation above sea level, and how far above the horizon was the moon (in degrees, approximately)?

You need very good seeing to get the best clarity/detail in astrophotos. It helps greatly if you are at high elevation, and if the object is well above the horizon.

Focusing can be frustrating, and it's not always possible to get perfrct focus with just the viewfinder. A hartman mask may help, especially if the 'scope has larger aperture (>150mm).
12/27/2004 11:12:16 PM · #10
Sorry kirbic but i don't know the answers to those questions. i'm rather new at this. but i live near the mountain but it's just at the beging of the mountain and the sea is a little bit far away but it seems i'm almost at it's level. a bit up. The moon was just above me.
What about that hartman mask, whats that?
And i've heard a lot about mirror lock whats that too, is it useful?
 12/27/2004 11:51:01 PM · #11
The soft focus may be a result of not shooting fast enough. When you add a massive telephoto, like a telescope, unless the tripod is actually tracking the movement, you still need to shoot the inverse of the focal length.

At 300mm you need a minimum of 1/450th (300x1.5for most digis).

With a tripod, you get much better stability, but astrophotography really puts a strain on the idea of being still because both objects are really moving so much faster than we even can fathom.

Try shooting faster, see if it make a dif.
 12/27/2004 11:51:41 PM · #12
Here's a link that explains about the Hartman mask.
If you're nearly at sea level, remember that you are looking up through nearly all of the atmosphere. The higher up you go the less atmosphere you are looking through, and the better the seeing will be.
Same with objects near the horizon. Close to the horizon, you are looking through a lot more atmosphere than directly overhead. that's why the moon look dimmer, and orange near the norizon, the blue light has mostly been scattered.
When you look up at the stars, if they are twinkling visibly, the seeing is relatively poor. If they appear steady, with only slight twinkling, the seeing is better. If you go to very high elevation (3000m?) you will see almost no twinkling at all.
 12/27/2004 11:58:13 PM · #13
What kind of scope are you using?

It looks like either focus error, poor atmospheric conditions, poor optics or some combination of the three.

I shot this @1/125 through my 80mm f6 refractor. It's not the best, but it's pretty good.

Moon Shot

Message edited by author 2004-12-28 00:00:14.
 12/28/2004 12:02:11 AM · #14
I'm using meade etx 70.
Thanks everyone i'll see what i can come up but not tonight.
Thanks everyone.
 12/28/2004 12:06:28 AM · #15
Looks like a combination of focus and lack of an equatorial tracking motor (your tripod doesn't follow the apparent movement of the sky). This eclipsed moon was taken through a Celestron telescope- 2000mm (x1.6 crop factor), 1/4 second exposure, ISO 400 at an altitude of maybe 100 feet:

12/28/2004 12:13:02 AM · #16
Shooting the moon at high zoom tends to result in blurry images mostly due to poor seeing (assuming all other items on the checklist can be accounted for). Seeing is the term kirbic used appropriately to describe what amounts to atmospheric turbulence. A good site for checking when will be a good time for viewing or photography is //www.cleardarksky.com/csk/

I've also had trouble getting sharp focus with my 10D mounted to my 8" SCT (f/10). Of course, the only eyepiece that fits in the adapter tube is 19mm or higher magnification... Need somehow to fit a wide-angle eyepiece in there...

Through the scope, a remote microfocuser would be ideal, and the standard focusing knob on most scopes is horrendous. SCT's are always a pain due to their design (mirror shift).

Of course, tracking is a major issue. A smooth motor drive is best for astrophotography, even if just the moon. Otherwise you're chasing and getting ahead of it to get the right composition.

With such a drive I was able to capture this composite of six images (shot through my 300 f/4 lens, not the scope), each about 30-60 second exposures: //www.noestudios.com/photo/astro/m42_new_composite.jpg

There's a lot of technique and general technical issues involved with astrophotography, but it can be very rewarding. Look around on the net for info and keep it up! It's fun!
 12/28/2004 12:17:18 AM · #17
here is an excelent site for the ETX users, TONS of good info

Weasners ETX site

James
 12/28/2004 12:25:37 AM · #18
Originally posted by Discraft:
I'm using meade etx 70.
Thanks everyone i'll see what i can come up but not tonight.
Thanks everyone.


one last thing to check.... do you have enough counter ballance on the scope, you need to offset the weight of the camera by adding weights to the front of the scope, usually placed on the underside of the OTA near the front of the scope.

James
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