Match telescope and camera

[Derek Astro]

I have a Skywatcher Startravel 102 AZ3 telescope and want to use it along with a Canon 600d camera .  All the pictures look so simple when they are attached to oneanother, but after a number of frustrating days I find that I have been unable  to get any sort of picture on the camera's screen, all I get is a blank screen.  I have tried getting a picture of surrounding trees etc with no success.   I have tried a number of combinations between  the telescope and camera with no success.   I guess I am making a very simple error and would welcome any advice.   Thankyou. 

[fozzybear]

how are you attaching the camera to the ST102? and have you any photo's of the scope and camera attached to help resolve this.

" I have tried a number of combinations between  the telescope and camera with no success".  What do you mean

 

[Alexp]

I am honestly not sure how well your setup will work together with a DSLR camera and how much knowledge you have already built up in astrophotography.

Afaik your mount is not motorized, which means you will not be able to take long exposures as your mount can't track objects in the sky automatically to counter Earth's rotation. I guess it depends on what you want to shoot? Maybe it is possible to shoot some objects by taking many and quite short exposures (half a second --> if you are not familiar with the 500 rule, google it to find out what that is, your camera has an APS-C sensor which means you must take a crop factor into account for the 500 rule), but I am sure there are many more qualified people here that may have a better answer than I have.

Apart from that, how is your camera connected to the scope? Are you using something like this 2" adapter or this 1.25" adapter?

If the screen is blank does that mean black or white? It seems like you may be overexposing completely or are shooting in some other mode than manual? If you want to delve into astrophotography, you will always take pictures in manual mode. Concerning the ISO of your camera it depends I guess. With my scope and my tracking mount, when shooting objects like galaxies or star clusters I was able to take 180 seconds exposures with ISO 400 or ISO 800. If you want to take pictures of the Milky Way, you will need a much shorter focal length and shoot at a higher ISO.

Also, set the focus to manual instead of automatic. Before you actually start taking any pictures, it's important to be in focus of course. Here it is quite helpful to google Bahtinov mask. Apart from that you can simply try liveview and change the focus until you believe you have the smallest stars on your screen (I'd say though this is the least effective mode on achieving focus).

If you are not yet familiar with astrophotography you should also google image stacking and calibration frames, there is tons of information available and many programs (Deep Sky Stacker, for example) are free to use. 

 

[fozzybear]

1 hour ago, Derek Astro said:

I have tried getting a picture of surrounding trees etc with no success

The OP has tried during daylight as above so to me maybe an issue as per say My ST80 and needed to add a 50mm extension into the Focuser to achieve focus 

[Alexp]

16 minutes ago, fozzybear said:

The OP has tried during daylight as above so to me maybe an issue as per say My ST80 and needed to add a 50mm extension into the Focuser to achieve focus 

You may be right there. I believe it's either that or the camera may have also been completely overexposing? Either way it would be interesting to find out how the camera is connected to the scope

[michael8554]

Hi Derek

The ST102 has a focal length of 500mm.

That means that the images you want to capture are in focus 500mm back from the lenses at the front of the telescope.

So roughly measure 500mm with the diagonal removed.

The 600D has a sensor that is 44mm back from the lens mounting flange.

Assuming you have bayoneted a T2 Adapter to the flange, the sensor is now 55mm back.

So 500mm - 55mm = 450mm gives you roughly the position the front of the T2 adapter  needs to be positioned.

You'll probably find you need a long T2 threaded spacer.

They come in standard lengths, so juggle lengths with the focuser roughly half way out.

Michael

 

[Derek Astro]

Thankyou for responding to my post.  The camera is attached to the telescope by a 1.25 inch T mount.  I tried getting focus by using the live view option  on the camera and get focus in the normal way.  This did not work so I then tried manually holding the camera and move it backwards  anf forwards in line with the lens tube to try and get some sort of picture to determine if I needed an extension tube and what length it shoud be.  I still could not get any picture.  This was all carried in daylight looking out of a window at objects at least 0.5 of a mile away.  I would have expected some sort of picture on the camera screen.  Could there be an issue with the camera settings, but there is no problem when viewing the camera screen when a normal camera lens is fitted? 

Attached are two pictures, one showing the camera attached to the telescope, the other shows the white camera screen with no sign of any features showing. 

[fozzybear]

24 minutes ago, Derek Astro said:

Thankyou for responding to my post.  The camera is attached to the telescope by a 1.25 inch T mount.  I tried getting focus by using the live view option  on the camera and get focus in the normal way.  This did not work so I then tried manually holding the camera and move it backwards  anf forwards in line with the lens tube to try and get some sort of picture to determine if I needed an extension tube and what length it shoud be.  I still could not get any picture.  This was all carried in daylight looking out of a window at objects at least 0.5 of a mile away.  I would have expected some sort of picture on the camera screen.  Could there be an issue with the camera settings, but there is no problem when viewing the camera screen when a normal camera lens is fitted? 

Attached are two pictures, one showing the camera attached to the telescope, the other shows the white camera screen with no sign of any features showing. 

What ISO setting are you using as 800 is a starting point for the 600D

 

Edited February 27, 2022 by fozzybear
added text

[michael8554]

Hi Derek

Why are you using LiveView ?

During the day you find focus using the visual viewfinder on the back of the DSLR.

14 hours ago, Derek Astro said:

I then tried manually holding the camera and move it backwards  anf forwards in line with the lens tube to try and get some sort of picture to determine if I needed an extension tube and what length it shoud be. 

Did you make the measurement I suggested, instead of trying those random movements ?

You can use the diagonal while you're trying to see if focus is possible, but it's best to remove the diagonal when imaging, as every unnecessary lens/mirror/prism in the light path attenuates the light reaching the camera.

Michael

[Bluemoonjim]

The diaganol needs to go and then its a case of getting your camera sensor in the right position in relationship to focal length of scope.
Michael's explanation above nails it. You will need relevant camera adaptor and probably spacers.

[Derek Astro]

Hi Michael

Not one to be beaten,  I followed your dimensions to get focus but still got a blank white screen when using the Live View Option.  However picking up on your point about using the view finder at the back of the camera EUREKA  I can now take photographs, through the telescope, not perfectly focused, but can be worked at.  It would appear the Live View shooting option cannot be used as I originally intended. Thanks for getting me on right road.

Derek 

[michael8554]

Hi Derek

Set the 600D up just like you'd use it during the day, with a lens on, and check LiveView is working.

Then put it on the OTA,  LiveView should work.

Michael

[Derek Astro]

Hi Michael

Thank you for your help.  I followed your instructions and YES  it works, with Live View shooting.  I now have a fully operating system, just want some clear nights now.  Thank you again.

Derek