1171 replies to this topic

[avarakin]

A lot of people send their DSLRs for modification, so I don't see a reason why people won't be willing to send a backplate of their scope for drilling the hole.

[Mert]

What FWHM do you obtain after this modification/upgrade?
What is the subframe exposure time?

[HoloTheWolf]

You made a very sturdy mounting on the backplate! Now is the time to take orders for us, poor RC8 owners
Wish I had the option doing the same!

I concur with Mert. Do you have any interest taking orders? 

[Mert]

Just another question popping up in my mind:

did you cut off the threading from the back of the mirror cell

to get closer with the plate??

 

The more I look to your solution, the more I like it!!

 

CS,

Mert

[nateman_doo]

I concur with Mert. Do you have any interest taking orders? 

Step into my office.... 

[nateman_doo]

What FWHM do you obtain after this modification/upgrade?
What is the subframe exposure time?

I haven't a clue.  Stars just looked better

 

 

Just another question popping up in my mind:

did you cut off the threading from the back of the mirror cell

to get closer with the plate??

 

The more I look to your solution, the more I like it!!

 

CS,

Mert

I didnt modify the back plate at all other than the small holes I drilled.  If you had to sell the scope without the adapter plate, you can just simply plug the tiny holes.  We still need back-focus, so this gives you more options in terms of back-focus.  

 

In fact, I just ordered some longer factory screws that should put the factory collimation screws all the way to the surface of the plate itself so you dont have to reach in their anymore.  Will install and update pictures.  35mm long screws.  I hate to throw off the collimation by taking the factory screws out, but the hours saved in the long run bringing the screws out farther I think will pay off over the life of the scope.  (plus it gives me a chance to clean my mirror)

[nateman_doo]

A lot of people send their DSLRs for modification, so I don't see a reason why people won't be willing to send a backplate of their scope for drilling the hole.

honestly I never thought of that.  That is absolutely true.  I wont really need the backplate until the part itself is cut, so I only need the stock plate for an hour at most to indicate it, drill it, flip and countersink.  Mount stuff and its back out the door the next day. 

[nateman_doo]

Here are the longer screws.  The steel spacer takes up all the slack in the screw to have the same amount of threads, so it should be no different.  If these spacers prove inefficient, I can always turn some on my lathe.  These were actually purchased just to give some uniformity. 

 

[jd200]

Not in the least.  I just use the single smaller of the M90 extension tubes and its less than 10mm extended out for perfect focus.

I'm with Mert.  That's very interesting to me.... I use the CCDT67 focal reducer from AP with spacing for a .7 reduction - shooting at f/5.6...  I have the 1" extension tube that came with the RC, the tilt ring shown above and behind that a Moonlite focuser.  With that arrangement, I have been almost running OUT of back focus space.  I have my camera/filter/OAG pushed all the way into the drawtube and the Moonlite focuser racked in with only a few millimeters left to get to focus.  I recently had a custom 1/2" extension tube made for me to replace the 1" so that I can have a little bit more play in the Moonlite focuser.  If I added the piece you made onto the back of my RC, I don't think I could achieve focus...

 

That said/asked - your adapter looks like an incredible feat of engineering and machining.  Wish I could achieve the same separation with my scope!

JD

[Mert]

Yes, I had the very same problem running out of backfocus space adding a rotator,

filter slider with the CCDT67 reducer.and a tiltplate.

Finally I got myself a 10mm M90x1 extension to mount everything.

Right now I reach focus with only some 10 mm backspace left over to move in/out.

[nateman_doo]

This was tested with that very focal reducer.  Cant see it in the picture cause its in the focuser tube. 

 

It extends roughly 1" directly above the scopes stock threads.  

[nateman_doo]

Helps that I made my own custom filter drawer 

[Mert]

Well done, good job

[nateman_doo]

Well done, good job

 

zero backfocus issues.  (these pictures pre-date the collimation plate)

Also learned to anodize on these parts.  I have a few of them if anyone was interested, but they are drilled specifically to QHY OAG's.  Id have to machine a new front plate for any other method.  I did make one for a redcat:

 

Edited by nateman_doo, 22 June 2022 - 09:46 PM.

[Mert]

It's great when you have your own workshop!

[nateman_doo]

Here are the new screws installed:

 

MUCH easier to collimate reaching the screws.

So my process is place as fine of a red laser as you can find (farpoint astro) and beam the light directly at the center of the circle on the secondary by adjusting the plate itself.  Then aim it right back on the laser with the secondary screws.  Check that the laser is still in the secondary circle and then again with the laser back on itself.  walk the 2 together.  Then all that is left is to collimate the primary.  I can't really use the DSI model since I dont want to touch the focuser or the secondary since they are perfectly aligned, so just move the primary until you get the flattest field you can get.  I realize these are still mirrors made from Chinesium... but still a much better image then I have ever had on this scope.

 

 

While I had it apart I made a 1" baffle extension on the lathe, and cleaned all my mirrors.

These scopes have so many design flaws.

[nateman_doo]

It's great when you have your own workshop!

100%.  

[nateman_doo]

That extension seems to work really nice.  With the scope at the point of focus, there is no light leaking to the sensor around the secondary.

 

https://imgur.com/MBnKSVn

 

[nateman_doo]

 

Just took this in the Cygnus Star Cloud.  Ironic it was able to plate solve. 

[nateman_doo]

Now if I can keep the guiding under control it should produce a decent image:

 

 

Round stars in all corners. 

[nateman_doo]

[Mert]

Excepcionally flat

[nateman_doo]

My refractor is 10x worst than my RC using the same software.  Its clear that I have some work to do with it as well. 

[Mert]

How long was the exposure for the image in Astap?

[nateman_doo]

300 seconds on the Fireworks Galaxy.