Astro Photography Tool Focusing

[ThomasF1234]

So tonight I went out with my Sky-Watcher Evostar 102 and EQ3 SynScan GOTO mount and Canon 650D. I tried to capture some images of M44 with the barlow lens attached as i have just ordered an eye projection adaptor to avoid using the barlow lens. However, I could not get focused on the stars because I could not see them on the display screen on Astro Photography Tool. I was at 20" exposures at ISO 1600 , I even tried bumping up to ISO 12800 to try and find the cluster, and nothing showed up on the screen even when pressing the auto stretch button which just resulted in loads of fuzzy colours. The only way I knew the DSO was in view was by replacing the camera with an eyepiece to check. Does anyone have any suggestions on how to focus or even be able to see this object on the preview screen of the software?

 

Below is the final stacked result of what I got. I know it's not good at all but thought it might help give a better understanding of the issue!

 

Thank you!

[MarkAR]

Hopefully those blobs are stars which means you aren't too far away from focus.

Maybe try on the brightest star you can find first then taken M44.

[michael8554]

Were you using Live View, sounds like you were taking exposures?

If way out of focus the stars may be difficult to see as they're so spread out.

So get focus approximate right during the day, framing a distant landmark during the day - bottom of the garden is too close.

Lock the focuser. Then at night fine focus on a bright star near your target using Live View.

Michael

[StuartJPP]

I am not sure if infinity focus is possible on that combination as I am not familiar with it however a much quicker way to check focus would be on Venus or the Moon.

Since you are using a Canon 650D with a fold-out display I'd leave APT out of the equation for now and just try to focus by hand and watch the LCD screen. In fact I'd ignore the LCD initially and just use the optical viewfinder of the Canon 650D to make sure that you are getting the smallest point (on Venus) or something nice and clear on the Moon.

Once you know where infinity focus is you are just about there.

It looks like you weren't far away from infinity focus as the stars are at least showing up, though obviously bloated.

The thing to remember is that either the camera or APT in the "LiveView" mode is not taking a 20 second exposure otherwise your frame rate would be 1/20 frames per second, it is trying to simulate what a 20 second exposure would be like, but since the image is so dark, it basically looks black. Once stars are in focus you should be able to see something in LiveView, but only the brightest of stars.

[ThomasF1234]

7 hours ago, michael8554 said:

Were you using Live View, sounds like you were taking exposures?

If way out of focus the stars may be difficult to see as they're so spread out.

So get focus approximate right during the day, framing a distant landmark during the day - bottom of the garden is too close.

Lock the focuser. Then at night fine focus on a bright star near your target using Live View.

Michael

Thanks I did try focusing on a near by star in cancer. I was using live view on both APT an the camera screen. But since I couldn’t see Anything on the screen I decided to go ahead and just take some exposures to see what I got. Maybe after focusing on that star in cancer I shouldBe played around the focus more.

[ThomasF1234]

8 hours ago, StuartJPP said:

I am not sure if infinity focus is possible on that combination as I am not familiar with it however a much quicker way to check focus would be on Venus or the Moon.

Since you are using a Canon 650D with a fold-out display I'd leave APT out of the equation for now and just try to focus by hand and watch the LCD screen. In fact I'd ignore the LCD initially and just use the optical viewfinder of the Canon 650D to make sure that you are getting the smallest point (on Venus) or something nice and clear on the Moon.

Once you know where infinity focus is you are just about there.

It looks like you weren't far away from infinity focus as the stars are at least showing up, though obviously bloated.

The thing to remember is that either the camera or APT in the "LiveView" mode is not taking a 20 second exposure otherwise your frame rate would be 1/20 frames per second, it is trying to simulate what a 20 second exposure would be like, but since the image is so dark, it basically looks black. Once stars are in focus you should be able to see something in LiveView, but only the brightest of stars.

Thank you. Next time I get clear skies I’ll have a play around!

[ThomasF1234]

The problem with getting to infinity focus is that I couldn’t see the DSO at all even after focusing on a near by star (Through live view). Just to note the live view didn’t show anything like the picture was took and attached above 

.

Edited May 9, 2020 by ThomasF1234

[bottletopburly]

Invest in a bahtinov mask then use the Bahtinov aid in the tools menu in APT you just need to input your fl ,camera pixel size of camera  and diameter of scope then choose a bright star such as arcturus take a 6 sec exposure then place the bahtinov aid box over the bright star this will show how far out of focus you are then re adjust focus take another exposure until the aid says close or just look at the spikes lining up on screen , then focus will be bang on ,do you really need to use the Barlow ?.

[ThomasF1234]

26 minutes ago, bottletopburly said:

Invest in a bahtinov mask then use the Bahtinov aid in the tools menu in APT you just need to input your fl ,camera pixel size of camera  and diameter of scope then choose a bright star such as arcturus take a 6 sec exposure then place the bahtinov aid box over the bright star this will show how far out of focus you are then re adjust focus take another exposure until the aid says close or just look at the spikes lining up on screen , then focus will be bang on ,do you really need to use the Barlow ?.

Thanks I’ll have a look into them. The only reason I had the Barlow on is because I’m waiting for the adapter to allow the camera to look straight through the telescope.

[david_taurus83]

What adapter are you waiting for? T ring?

A rough idea of where the focal plane sits is to measure from where the lens element is to the sensor position of the camera. Should be 1000mm on your scope and will give you an idea if you need any spacers as well.

[ThomasF1234]

42 minutes ago, david_taurus83 said:

What adapter are you waiting for? T ring?

A rough idea of where the focal plane sits is to measure from where the lens element is to the sensor position of the camera. Should be 1000mm on your scope and will give you an idea if you need any spacers as well.

The adapter is the Tele-Camera Adaptor for Eyepiece Projection  which just fake today. Sorry this is probably a stupid question but what are spacers?

[david_taurus83]

Sounds like your trying to attach your camera to an eyepiece or barlow and take an image through the diagonal. That's not the best way to image through the telescope. You should be able to connect the camera directly to the end of the drawtube and take an image that way. Like this:

 

Do you have one of these?

 

[ThomasF1234]

10 minutes ago, david_taurus83 said:

Sounds like your trying to attach your camera to an eyepiece or barlow and take an image through the diagonal. That's not the best way to image through the telescope. You should be able to connect the camera directly to the end of the drawtube and take an image that way. Like this:

 

Do you have one of these?

 

Oh I see! Thank you so much! I think this could be the solution and yeah I do have a T-Ring

Edited May 9, 2020 by ThomasF1234

[david_taurus83]

1 minute ago, ThomasF1234 said:

Oh I see! yeah I do have a T-Ring

Should go straight onto the end of the drawtube or attach onto the thread of the adapter on the drawtube. Then you need to measure from the lens to the camera sensor mark and you are looking for 1000mm. Heres where you might find you need a spacer if theres not enough travel on the focuser to come into focus.

[ThomasF1234]

7 minutes ago, david_taurus83 said:

Should go straight onto the end of the drawtube or attach onto the thread of the adapter on the drawtube. Then you need to measure from the lens to the camera sensor mark and you are looking for 1000mm. Heres where you might find you need a spacer if theres not enough travel on the focuser to come into focus.

Does this look about right? Also sorry but for the measurement which lens is it and how would you measure to the sensor?

Edited May 9, 2020 by ThomasF1234

[david_taurus83]

Measure from the glass at the front of the scope to the sensor mark on the camera body.

Also, if you remove that middle section can you screw the t ring onto the end of the drawtube?

[ThomasF1234]

13 minutes ago, david_taurus83 said:

Measure from the glass at the front of the scope to the sensor mark on the camera body.

Also, if you remove that middle section can you screw the t ring onto the end of the drawtube?

There aren’t any threads to do that on the end of the drawtube so I have to use the Tele-Camera Adaptor Eyepiece Projector to attach the T Ring straight on. Sorry for all the questions but when your measuring does it matter how far In or out the focus Wheel is?

[david_taurus83]

Do any of these screw off? The ad for that scope states direct SLR attachment so there must be a way.

[ThomasF1234]

3 minutes ago, david_taurus83 said:

Do any of these screw off? The ad for that scope states direct SLR attachment so there must be a way.

The only way I can get the camera attached is using the eyepiece projector and as seen in the picture below the t ring is smaller than the end of the drawtube.

[david_taurus83]

I see now. On the adapter you got today, can you unscrew the 1.25" adapter on the end and insert the 2" section. You might be able to use that. You can use it as it is but with the 1.25" barrel you are restricting the amount of light that can get to the camera, if you see what I mean. You would end up with dark corners and edges.

[ThomasF1234]

5 minutes ago, david_taurus83 said:

I see now. On the adapter you got today, can you unscrew the 1.25" adapter on the end and insert the 2" section. You might be able to use that. You can use it as it is but with the 1.25" barrel you are restricting the amount of light that can get to the camera, if you see what I mean. You would end up with dark corners and edges.

I get you I’ve done that and it fits perfectly! Just the last question though should I focus in and out in order to get that 1000mm or should it be 1000mm with the focus wheel all the way in?

[david_taurus83]

No, not all the way in. If you can get roughly 1m from the glass to the camera body and you have an inch either way to play with you should be fine.

[ThomasF1234]

12 minutes ago, david_taurus83 said:

No, not all the way in. If you can get roughly 1m from the glass to the camera body and you have an inch either way to play with you should be fine.

Okay thank you so much! Think I’ve pretty much got the idea!

[ThomasF1234]

15 hours ago, david_taurus83 said:

Edited May 10, 2020 by ThomasF1234

[Look left]

Also one of the best ways is to use EOS Utility for the Canon Camera. This will give you the ability to choose ISO and time easily and allow live view, once you ve done it and got some focus etc especially with Bahtinof mask then close down go into APT and check it out - at least then you know you have everything is OK .