Yet another QHY268M...

[tooth_dr]

...I am not using the QHY filter wheel like the other guys with this camera so just wanted to share my initial experience.

 

I already own an Atik EFW3 2 x 7” and unlike the QHY version i can’t bolt my wheel to the camera.  I’m attaching it via an M54 to M42 threaded adapter (with an M42 to M48 adapter on the M42 male thread of the EFW).

The back spacing for Epsilon 180ED is 56mm to the M54 corrector and I’m allowing another 0.7mm for the filter glass, so I’m aiming for 56.7mm

The M54 to M54 adapter I have is 8.7mm thick, added to a 22mm EFW3 gives 30.7mm, leaving 26mm to work with.

The camera uses 12.5mm plus the additional 5mm adapter that screws directly onto the camera.  With this 17.5mm accounted for I was left with 8.5mm.

Despite having amassed quite a lot of spacers, I hadn’t very many M48 items, but was able to find a 5mm M48 extension.

In the box of the 268 are several unthreaded M54 ‘washers’ of 1mm and 3mm thickness.  I was able to use one of the 3mm spacers under the threaded M48 spacer.

Loosened and removed the M48 threaded adapter:

Placed 3mm M54 washer onto camera body:

 

The three sizes of included bolts didn’t fit (too long or too short).  I found some SS bolts I bought a while ago that were 3mm longer than the standard short ones - no hacksaw needed.

The remaining 0.5mm was made up using a red Baader M48 shim.

I can see that Takahashi do an 8mm M54 extension piece for a very reasonable £23, so I plan to buy this to minimise the camera sensor to filter distance. I’ll add it onto the existing scope side M54 adapter, replacing the 3mm spacer/washer on the camera body and the 5mm M48 extension piece.

Whether this works in practice is yet to be determined but on paper it’s ‘right’.

I also plan to use the 268M on my 250px but will need to include an OAG in the imaging train.

Initial assessments suggest it will work.  It’s 57.5mm +\- 1mm from the M48 shoulder on the MPCC. The EFW is 22mm, camera is 17.5mm and ZWO OAG is 16.5mm.  The flush filter wheel fittings add 0mm, and allowing 0.7mm for the glass, I’m coming in just under 56.7mm. I again can use the M48 baader shims as required 👍🏼
 

The weather is another story now 👎🏻

Thanks for making this far

Adam  

 

Edited February 1, 2021 by tooth_dr

[Allinthehead]

Congrats on the new camera.

Just fyi, the backfocus for the Epsilon according to Takahashi is 56.2mm.

[tooth_dr]

44 minutes ago, Allinthehead said:

Congrats on the new camera.

Just fyi, the backfocus for the Epsilon according to Takahashi is 56.2mm.

Thanks Richard. I can add in a 0.3mm shim if required.  I've done a search and cannot find anywhere listing 56.2mm, only 56mm.  Where did you see this?

There is a tiny lip on the corrector. Do you measure from that lip or from the broad flat surface (if you follow)

 

Edited February 2, 2021 by tooth_dr

[tooth_dr]

Lip:

 

 

[Allinthehead]

https://www.takahashiamerica.com/blogs/technical-support/camera-systems-and-back-focus-untangling-the-gordi/

Afaik it's from the broad flat surface.

[Xiga]

Congrats on the new camera Adam! Can't wait to see what you do with this and the 2600mc working in tandem. 

If all goes to plan, i am hoping to have one of these myself in the not too distant future. When i get a chance to use it.... well, that's anyone's guess 🙄 😋

[tooth_dr]

3 minutes ago, Xiga said:

Congrats on the new camera Adam! Can't wait to see what you do with this and the 2600mc working in tandem. 

If all goes to plan, i am hoping to have one of these myself in the not too distant future. When i get a chance to use it.... well, that's anyone's guess 🙄 😋

Cheers Ciaran. Can’t wait to see your images from the camera.  Weather is pretty dire. 

[Xiga]

1 minute ago, tooth_dr said:

Cheers Ciaran. Can’t wait to see your images from the camera.  Weather is pretty dire. 

There won't be many, that's for sure lol. I will be hoping for more quality over quantity. 

ps - Yay for 1,000 posts for me! 😅 Holy moly, i've just noticed your post count 😳 

[MarsG76]

Congratulations on the new astroimager... looking forward to seeing your photos exposed through it.

[AstroVagabond]

I'm about to place one on order. Your post is very helpful. Congratulations!