Asi224 mc used with ASIAIR plus

[steve t2]

Does anyone know why I can’t see anything but Grain and noise and no stars once I have the camera with 2.5x power mate installed in c11 diagonal  everything powered up no caps left on etc ?

[bosun21]

Probably due to having a focal length of 7000mm and such a small FOV. The exposure and gain settings could also be wrong. Try it out on a planet to achieve focus and ensure everything is working as it should.

[steve t2]

Hi thanks for reply, what would your suggestion be to gain a larger fov for this camera and telescope?

[Elp]

Don't use the Powermate, not to start off with anyway.

SCTs aren't ideal for capturing massive targets due to their long FLs and narrow field of views, I don't particularly like using my C6 visually manually for the same reason. The small chip size of the 224 also makes this even more difficult, it's best reserved for planets only, you can do the moon but you won't get much FOV into each shot.

What are you trying to image?

Edited December 24, 2023 by Elp

[steve t2]

Hi , my goal is to image planets and moon only. I’m not too concerned about observing. Do you think I should at least be able to see stars using that camera with the power mate removed and just having it input directly in the diagonal? 

[Carbon Brush]

A suggestion, if you haven't tried already.
Go out during daylight to view distant horizon objects.

It is immediately obvious when exposure is too long or gain too high - a white screen.
Reduce exposure and gain until you see 'less than full white'.
In daylight you should be able to get video. No wait for seconds to minutes while the image arrives.

Struggling to get anything to focus lets you know if you have the camera at the correct distance.
You can even hold the camera in mid air behind the scope and look at the rapidly updating screen.

Once you have the camera in the right place to focus, leave it there.
As the light fades you can increase exposure time to view the horizon.
Then go for an easy target like the moon and work up from there.

HTH, David.

[Elp]

You should be able to see stars but from my experience at even 1500mm you'll be surprised how much blank space devoid of stars there is, more so if you're not in focus and I believe this is your issue. Forgivingly though, an SCT has a large focus range so you might find you'll be turning the focus knob for a while before you see anything, and if you're not tracking the target you'll find it quickly disappears out of the field of view.

As suggested, get rough focus during the day. Or at night use the moon as it's quite large.

On planets when I'm certain they're on the camera chip, I'll make the exposure reasonably long like 1s or so so it's a white dot, then focus as small as I can get it, if it's Jupiter you can assess the edge of the dot until it's a crisp white edge, you're in or near fine focus. Then dial the exposure back into the milli seconds until you can see dull surface detail and fine tune based on when the seeing freezes, you'll find when looking at it live the object will wobble constantly due to atmospheric air turbulence (seeing).

Edited December 24, 2023 by Elp

[steve t2]

Hi thanks both of you for that help I’ll give it a go

[bosun21]

Another thing is to consider dropping the diagonal as they are not needed with a camera. They only increase the light path. Place the camera directly into the back of your scope and if using the powemate place that directly into the scope and then the camera. 

[Elp]

With an SCT I think the diagonal is wise as usually it needs a long back focal distance if imaging straight through. With the F6.3 reducer this is around 105-120mm (larger scope is slightly different distance), without I'd expect it might need the diagonal to eat up some of that distance, you can also swap a visual eyepiece to roughly gauge the point of focus prior. With the PM the distance will be increased further back.

Edited December 24, 2023 by Elp

[bosun21]

2 hours ago, Elp said:

With an SCT I think the diagonal is wise as usually it needs a long back focal distance if imaging straight through. With the F6.3 reducer this is around 105-120mm (larger scope is slightly different distance), without I'd expect it might need the diagonal to eat up some of that distance, you can also swap a visual eyepiece to roughly gauge the point of focus prior. With the PM the distance will be increased further back.

I don't know a single serious imager who uses a diagonal with a focal reducer or not. It will degrade the image slightly and while imaging every little bit counts.

Edited December 24, 2023 by bosun21

[Elp]

And rightly so, how would you even attach the diagonal to the back of the reducer? (I'm sure there's a way) I was simply referring to when I use the reducer for straight through imaging what backfocus distance I have to the camera. Without the reducer (which you should not be using for planetary) this backfocus distance might be longer which a diagonal is useful for to take up a lot of that distance. Finding focus with the standard visual back > diagonal > camera with a 1.25 inch nosepiece attached to the front of the camera is easy, the Powermate makes it more difficult but not impossible as it becomes more difficult to keep the target in the centre FOV (a good motorised mount helps).

FYI, you can use a focal reducer on a camera through a diagonal, I've done it when doing solar though the signal is much higher than on night targets (different setup with required filters). I have also imaged with my C6 native, F6.3 reduced and F2 Hyperstar so know the equipment.

Edited December 24, 2023 by Elp

[bosun21]

6 hours ago, Elp said:

And rightly so, how would you even attach the diagonal to the back of the reducer? (I'm sure there's a way) I was simply referring to when I use the reducer for straight through imaging what backfocus distance I have to the camera. Without the reducer (which you should not be using for planetary) this backfocus distance might be longer which a diagonal is useful for to take up a lot of that distance. Finding focus with the standard visual back > diagonal > camera with a 1.25 inch nosepiece attached to the front of the camera is easy, the Powermate makes it more difficult but not impossible as it becomes more difficult to keep the target in the centre FOV (a good motorised mount helps).

FYI, you can use a focal reducer on a camera through a diagonal, I've done it when doing solar though the signal is much higher than on night targets (different setup with required filters). I have also imaged with my C6 native, F6.3 reduced and F2 Hyperstar so know the equipment.

Agreed. I found that the best additions for planets are a flip mirror and an accurately set finder. Especially with a small sensor like the 224. They can remove a lot of the frustration in centering the planet.

[Elp]

A flip mirror is one of the best things for astro especially when visual or EAA type imaging at the same time, more people should use them. I find my Rigel Quikfinder easier to use than a finder for me personally as it can, kind of, be used with both eyes open so is more comfortable to use, it's main use scenario is because it has angular sized reticules so finding objects via star hopping is easier. The Celestron SCTs also have the upstanding corrector plate cell housing up front so you can butt the Quikfinder relatively square up against it and velcro a strap around it and the ota for quick assembly.