533MC + EFW + OAG-L

AymenAissa

Hi All !! I recently got hold of a 2" EFW, OAG-L and 174mm for guiding to be mounted to my existing 533MC Pro . I'm running through a challenge to achieve back focus and ZWO imaging train charts don't seem to cover this combo.

First of all, attaching the camera to the EFW is quiet challenging without using the T2 tilter. If we use the T2 then, we have Camera (6.5mm) + T2 (11mm) + EFW (20mm) + OAG-L (17.5mm) + M48 sensor tilt (5mm) = 60mm
If we use the M54 to M48 (comes with the EFW) + M48-M42 adapter to attach the EFW to the camera, then the 174mm can't reach focus even fully inserted into the OAG-L well and the overall back focus can never be reached
My assumptions are either the OAG-L and EFW combo are not meant to be associated with the 533, or there is a out of the box solution that i'm not aware of.

Appreciate your help to sort this out as this hobby is becoming a source of depression 😃

w7ay

AymenAissa I'm running through a challenge to achieve back focus and ZWO imaging train charts don't seem to cover this combo.

Did you search this forum?

https://bbs.zwoastro.com/d/16724-focus-issue-with-asi-174-mini-and-oag-l/4

Chen

AymenAissa

Hi Chen. I played with the prism and focuser, however, the focus point seems to be lower than the well depth. I tried pulling the prism up a bit to compensate for the distance and i was able to get the 174 focused however that generated a horrible vignetting where the lower screen is dark and the upper side is fully bright.
On top of that my main issue is that i can't reach backfocus (55mm) on the main camera using the imaging train mentioned above.
I now mounted the full setup on the Askar 400 (Backfocus not required) to test the OAG and added an extra spacer (16mm) between the main camera and the EFW to give the guiding camera extra room for movement. This way I could achieve focus on both cameras, however the vignetting is still present even when trying to lower the prism at its maximum. This is not letting me see more that 2 faint stars on my guiding 🙁

Tech@ZWO

AymenAissa I played with the prism and focuser, however, the focus point seems to be lower than the well depth. I tried pulling the prism up a bit to compensate for the distance and i was able to get the 174 focused however that generated a horrible vignetting where the lower screen is dark and the upper side is fully bright.

Check these two things
1 The direction of the ASI174 sensor and OAG prism are the same
2 Make sure the adapter on the telescope side was not block the OAG-L prism.

AymenAissa I now mounted the full setup on the Askar 400 (Backfocus not required) to test the OAG and added an extra spacer (16mm) between the main camera and the EFW to give the guiding camera extra room for movement. This way I could achieve focus on both cameras, however the vignetting is still present even when trying to lower the prism at its maximum. This is not letting me see more that 2 faint stars on my guiding 🙁

If you want to reach the 55mm back focus length,
You can replace the 11mm adapter on the camera with a M42 5mm tilt plate, then add a 1mm spacer to get 55mm back focus.

AymenAissa

Tech@ZWO Check these two things
1 The direction of the ASI174 sensor and OAG prism are the same
2 Make sure the adapter on the telescope side was not block the OAG-L prism.

I'm suspecting the second scenario is creating the vignetting.

Tech@ZWO If you want to reach the 55mm back focus length,
You can replace the 11mm adapter on the camera with a M42 5mm tilt plate, then add a 1mm spacer to get 55mm back focus.

Does the M42 tilt plate get bolted directly to the EFW ? so the order will be:
Camera ->1mm spacer->M42 tilt plate->EFW->OAG-l->M48 tilt plate->telescope ?

Tech@ZWO

AymenAissa Yes, and you also can put the 1mm spacer to any position you want.