Focusing problem with ASI120MC

bersa81

Hello! I've just bought an ASI120MC for guiding and imaging, but it seems that I'm doing something wrong, I've searched the forum but I can't find any solution.

My setup:

- Skywatcher Equinox 80ED on Vixen Sphinx NexSXD modded

- 9x50 with helical focuser finder

- ASI 120mc + Canon 7D

- PHD2 + Nebulosity 3 software

My problem:

- I can focus with the provided lens (CCTV lens). When I try to focus with scope or finder I can't even get closer to anything focused. I've tried estending the focuser lenght (31,8 - 50 adaptor), or removing the adaptor from camera body and connect it "naked" to the scope. It should be a backfocus issue, but I'm not able to solve it myself moving in either direction (shorter or longer).

Does anyone have the same problem? How can I try to solve it?

riklaunim

You use the nosepiece ot T2 thread connection and it has to focus. For some refractors extension may be needed but still you should be able see image coming to focus when you pull the camera away from the focuser. Most finderscope should work unless they expect 1,25" camera body going inside (designed for QHY5 II)

bersa81

I've already tried the adapter that comes with the camera, but no image forming... Totally out of focus.

Sam@ZWO

you should try at it daytime or use the moon at night

bersa81

Already tried with the moon... I just see a glowing white light :( . I'd just like to find out in which direction should I move (I thing "out" or longer distance) and how to achieve the right one...

david staup

Try holding a sheet of paper behind the focuser when pointed at the moon at night. you will be able to find focus. measure the distance. that will tell you where the sensor should be placed.

riklaunim

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landbo

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bersa81

I've tried with an extension tube, but nothing... I Think I will try as suggested to find the focusing point of my scope.

paul777

I have an old LX90 (LX200 without GPS). I am new to digital photography but had taken a few pictures some years back using an Olympus OM10.

I am having a similar issue with my ASA120MC-S. I can get a preview on my computer with the supplied lens but I just get a dark screen when attached to the telescope. I have tried an extension tube (adjustable about 8-15cm) but no difference. I haven't even set up at night yet - I was trying to get things roughly right on day targets.

Any suggestions? I'm sure it is to do with the focal point and I just need the right length extension.

bersa81

Tried it with my CPC 9.25 and it gets to focus very well. I will try again with the refractor. I'm considering to use a Bathing mask...

farzad_k

Was there a conclusion to this issue? I tried the ZWO 120 on my ED80 and didn't get focus on the moon, just brighter screen on my computer capture software. The SWO works fine on my 8-inch SCT.

Farzad

phoenixke

Same issue here with 6x30 and with 9x50 Skywatcher. Any solution yet? My brand new ZWO ASI 120 is unusable as an autoguider, waste of money if not ....

s3igell

The design of SCTs allow one to dramatically change the Focal Point with it's Focusing Mechanism.

Refractors - not so much so...

Assume the Focal Point is FURTHER Behind the Focuser than your Extender.

That is why the previous post suggesting use of a sheet of paper to identify the actual Focal Point. Try it!!

paulus

I’m having the same issue with my setup. I have both color and monochrome of the ASI120. I use a Celestron 102SLT riding an AVX Mount. I also have an Orion 50 guidescope. I use them both with the guidescope without issue at all. They guide well. But I have to revert back to the dslr for imaging because the cam on my OTA won’t focus. I have tried the Orion 5123 to add 2 inches. I have done the Barlow and the 5123 trick and nothing. I dislike having to use the DSLR, but it just works. Is there a calculator out there that will calculate this? I can’t use my filter wheel until I figure out what the hell is happening.

Sam@ZWO

Paulus wrote:
I’m having the same issue with my setup. I have both color and monochrome of the ASI120. I use a Celestron 102SLT riding an AVX Mount. I also have an Orion 50 guidescope. I use them both with the guidescope without issue at all. They guide well. But I have to revert back to the dslr for imaging because the cam on my OTA won’t focus. I have tried the Orion 5123 to add 2 inches. I have done the Barlow and the 5123 trick and nothing. I dislike having to use the DSLR, but it just works. Is there a calculator out there that will calculate this? I can’t use my filter wheel until I figure out what the hell is happening.

the back focus distance of DSLR and 120 camera is different

you need to use one extender for 120 to replace the DSLR

I think the extender distance can be around 40mm