Jump to content

Banner.jpg.b89429c566825f6ab32bcafbada449c9.jpg

Blank Images


Reubeng

Recommended Posts

Hello, I am completely new to this, and have kind of jumped in at the deep end.

Me and my brother wanted to do some astrophotography so he bought the scope and I got the camera.

I have a canon 600d.

He has a celestron compustar 8" without the y2k chip (he's a bit mad about not having it... even though the seller stated it did)

but we tried to take some images tonight for the first time and all the images came up with the same set of RGB dots on them and nothing else. (using a laptop to live view the image and to change the settings)

Now I have got home and am looking at the images in lightroom and these dots are not showing up.

I thought these dots were a sensor problem with the camera and they still could be, but when opening the images in Lightroom the dots show for a second then disappear.(see image)

a1fc079322.jpg

When looking through the Telescope with the eyepiece we can see things clearly but when attaching the camera it is just black with these dots in the same place every time. Taking an image with 

the camera lens cap on displays the same dots.

So if anyone could help me diagnose what these dots are and why we are not getting anything through the telescope i would be very grateful.

Thank you 

Link to comment
Share on other sites

have you altered the focus from eyepiece to camera if not then that is your problem you need to find a bright star then focus the camera on it.the camera focuses at a different focal point than the eye piece.

Link to comment
Share on other sites

Coloured dots are usually dead pixels on the sensor chip.

These are normal...the darks will eliminate them.

I can only think your exposure time is not long enough and maybe the ISO setting is too low.

Also, the focus for the eyepiece will be different from the camera. Try focussing the camera on the Moon or something bright like a distant streetlight...or even something in the daytime.

If you are trying to image stars way out of focus, you may seem to be getting blank frames.

Link to comment
Share on other sites

So the sensor chip is nothing to worry about? and isn't something i should get fixed ?

And it seems like the we are way out of focus then?

The focus comes from the telescope not the camera yea?

Thank you for the rapid replies and help it is much appreciated. 

Link to comment
Share on other sites

First it sounds like the camera is not at the focus of the scope, aim the whole lot at the moon and then adjust to get the moon as a sharp image in the camera. Then make sure that the focus cannot be adjusted.

The whole camera needs to be set to manual, absolutely nothing is to be set by the camera.

Scope is an 8" SCT, so a long focal length and a dim (very, very dim) image on anything other then the moon.

The camera will have to be set to something like ISO 800, Exposure 20 seconds as a start.

The scope came out in the 80's so I doubt that anyone gave a fig about y2k then, also I would expect it to be the software not the chip that altered.

Not sure what you expect to image, not the full capabilities of the scope. However being an SCT I would expect you to have problems as the long focal lengtth will amplify any innaccuracies and errors in tracking and movement.

For DSO imaging you need to get several exposures of longer then the above and then stack them then finally process. For good DSO images the sat in front of a computer time will exceed the actual getting images time by a lot.

If the moon will fit on the camera then go for the moon first, you can do that as a normal picture, ISO 100, 1/100 second. If too bright try 1/250 sec in effect alter the exposure time to get the exposure.

A Canon can/will do a noise reduction exposure. If you take a 20 second shot of the sky, then the Canon will also do a 20 second exposure of "nothing". The then take this noise reduction exposure off of the real exposure. If this is being done then block off the viewfinder at the rear as it alow light through and gives a false result.

You will have to aim at bright things with the scope+ moon, M42 and M45 come to mind.

Planets are taken by aiming at the planet (Jupiter) and taking a video. You then drop the video into Registax and process in that. This is easier and you should get a result in around 10 minutes, bit more instant. The scope is actually better suited to planetary imaging. Many use a webcam for planetary imaging, they are meant to take videos, small, lighter.

Link to comment
Share on other sites

The focus comes from the telescope not the camera yea?

How could the focus come from the camera with the lens removed?

Are you using 'prime-focus' = no telescope eyepiece, or 'eyepiece projection' = + telescope eyepiece.

Mostly here, unless stated otherwise, it will be assumed that it is 'prime focus' with no telescope eyepiece. 

The attached pdf is from Vixen with Pentax, but it helps to clearly explain the differences and the different bits of kit involved.

Eyepiece_Projection_Camera_Adapter_User_Guide.pdf

Link to comment
Share on other sites

There could be numerous things going on here, focus, exposure time, ISO etc and without knowing exactly how you were set up its difficult to say where the issue lies. There are some really good tutorials available online, this is one I have done for a website http://lothianastronomy.co.uk/dso.php

Spend some time reading different tutorials, it will help you understand what went wrong. Be patient, stick with it, it will all come together eventually.

Good luck

Sent from my iPhone using Tapatalk

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.