Sky-Watcher EvoGuide ED50

[AlYev]

Thank you! The guarantee is not worried. I see that remove is possible. But I don't know how to do it.

[AlYev]

I want to achieve focus in this composition. Then change from 3-6 mm to 2-4.

Edited December 15, 2018 by AlYev

[AlYev]

The previous question is no longer relevant. Cut off 30 mm from the side of the lens. All the necessary eyepieces reach the focus.  It remains to move the diaphragm.

[AlYev]

The diaphragm has an internal diameter of 40 mm. it is now 40 mm from the edge of the nearest lens.  How far should I move the diaphragm? Let me remind you, the aperture is 50 mm, the focal length is 242 mm. 

[AlYev]

Classic 10x50.

[AlYev]

The diaphragm was shifted by 11 mm. with the help of a barrel from the eyepiece 30/80. Put barrel on the table. On top put the tube and pressed. Painted over the entire surface to the diaphragm with a black marker.

[AlYev]

Now the aperture should not be cut.

Edited December 22, 2018 by AlYev

[AlYev]

Purchased for maximum magnification zoom eyepiece 2-4 mm. Increase with it accordingly 61-69-81-97-121х. The field of view of 0.4 - 0.8 degrees.

[AlYev]

I assume to use such mount.

[happy-kat]

Your window ledge mount looks good for the job.

[AlYev]

I can't check mount in yet. The area between the rings is too narrow. Waiting for the Miller.

[Miguel1983]

On 03/01/2019 at 15:04, AlYev said:

I assume to use such mount.

Looks like you got a hot neighbour across the street ? 

All joking aside, nice adjustment job ?

[cuivenion]

On 03/01/2019 at 13:59, AlYev said:

Purchased for maximum magnification zoom eyepiece 2-4 mm. Increase with it accordingly 61-69-81-97-121х. The field of view of 0.4 - 0.8 degrees.

Are those custom built tube rings?

[AlYev]

ghYes, I ordered the rings to the local Miller.

[AlYev]

14 hours ago, Miguel1983 said:

hot neighbour across the street 

The weather here does not contribute to the observation of the sky. We have to look through 3 glasses.

[AlYev]

initially, I had the idea to make a binoscope with a fixed interpupillary distance. Print on 3D printer detail, as in the figure. The detail of this positioning between two 50ED. Pull it all off with some kind of tie. In the base of the detail insert the nut under the photo screw 1/4-20.

[kirkster501]

Posted in wrong thread.  Apologies.

 

Edited August 7, 2019 by kirkster501

[JEM_svca]

On 03/06/2018 at 06:21, DRT said:

 

 

Ok, here is some more info that you guys might find useful...

• The tube has an outer diameter of 56mm and an internal diameter of 52mm.
• There is approximately 21mm of travel in the focuser.
• The tube has a female thread that accepts the body of the focuser. It would be possible to shorten the tube if you had the means to re-cut the thread inside the tube or find a shorter focuser with the same thread or a very sort adapter. Sorry, I have no means of accurately measuring the pitch of the thread but it looks like some sort of standard metric fitting to me.
• The lens cell and green retaining ring unscrew to reveal a 16mm male thread on the OTA. The green ring eats up a minimum of 3.5mm of that thread. The lens cell has a 10mm deep female thread. This means that you could remove 2.5mm from the front of the tube and both would still fit provided you did not destroy there thread on the OTA.
• Alternatively, you could dispose of the green ring and remove 6mm from the front of the tube and re-attach the lens cell without the retaining ring.

I was seriously considering that final option when something struck me! ?⚡?⚡

I have been fitting the Baader T2 prism using the 1.25" nosepiece. The Baader "T2" Prism has...wait for it...a T2 fitting on both sides!!  

I unscrewed the nosepiece and screwed the prism directly onto the T2 thread on the back of the focuser and my prism is now 4mm closer to the objective so I should now be able t reach focus on infinity. Bingo!

Here are some pictures that might help you visualise some of the above...

Back of OTA with the focuser removed to reveal a female thread. Internal diameter appears to be 52mm to thread diameter perhaps M53?

Focuser male thread and OTA female thread are approximately the same length so modification to shorten the OTA here would require the OTA thread to be extended/re-tapped.

 

Green retaining ring fully retracted leaves 2.5mm spare thread when objective cell fully engaged.

Objective end male thread on OTA is 16mm deep, 12mm when green ring retained in place. Green ring therefore eats 4mm of the OTA length.

The lens cell has a 10mm deep female (M56?) thread. Shortening the OTA by 6mm ad not using the green retaining ring would give 6mm of additional inward travel.

 

The Baader T2 Prism lightbulb moment! ?

 

 

It will hopefully be clear tonight so I will give this a go and report back ? 

DRT,

I was able to get infinity focus with my Evoguide 50 using the Baader T2 32 mm prism diagonal with the Baader screw-lock eyepiece holder.  The optical length of this holder is about 3 mm shorter than that of their twist-lock holder.   The diagonal was attached directly to the T2 thread on the end of the focuser as shown in your photo.  That being said, I get a lot of stray light bouncing off the inside wall of the focuser tube when there is a strong light source outside the field of view.  This seems to cause a significant reduction in image contrast.  I would like to be able to paint the inside of the focuser with a matte black paint to reduce the light reflection but I can't seem to get the focuser unscrewed from the end of the tube.  I was wondering how you were able to remove it.  Did you find any adhesive on the threads?