RACI help...

[jetstream]

I'm trying out the RACI that came with my SW120ED, on my VX10 dob. When I move the scope down the image goes sideways...or up... Also is the image of the moon for instance supposed to look the same as with the eyes? Is there some sort of adjustment or is this normal? Lost for now  

[Charic]

Using a standard finder scope of 9x50 at a roof aerial. the image appears to be upside down at  @ 45° from the vertical, if/when the telescope is near horizontal. Your image should/may appear to be the right way up, but at an angle. It sounds perfectly normal. Its how the telescope works, strange but true, until accepted!

[jetstream]

The moon was upside down in the right angle finder, with the terminator horizontal and black above it. So if I move the dob down the image looks like its going sideways...this is normal?

[Charic]

Not having used a RACI i assume the Moon should appear as if seen by the naked eye., rightway up!  Your saying your Moon is up-side down?   I know that the Newtonian, if viewed when horizontal, seems to play tricks with your eyes, but is perfectly normal. Someone with a RACI should check with their scope and give you a comparison.

[Charic]

.............for my reflector, Its to do with the angle the eyepiece is set at  with the telescope! If the eyepiece projects from the OTA at 45° then the image is displayed at 45°.  which  could cause confusion  when the telescope is level / horizontal especially for terrestrial viewing?  this makes you believe something is wrong?

[jetstream]

I mounted it and then turned it so I could view seated, finder EP towards me ( rotating scope in mount, diag tight), most likely 45 deg or so. Not sure what's normal, I hope some members that use then can fill me in.

[Dave In Vermont]

You do realize that the image in the finder will remain stationary as YOU move from behind to side to other side? I can't really see that you could achieve a 'wrong' FOV through a finder without having installed a new lens-group to shift it to a different configuration.

I would suggest you remove the finder from it's mount and use it in your hand. Learn what it does and the FOV (field-of-view) it gives you. Then re-mount it and align it during daylight on some distant object to show the same view the main scope does.

Keep us informed,

Dave

[Charic]

This Celestron support link also explains about telescope design and orientation.......... http://www.celestron.com/support/knowledgebase?article=http%3A%2F%2Fwww.celestron.com%2Fc3%2Fsupport3%2Findex.php%3F_m%3Dknowledgebase%26_a%3Dviewarticle%26kbarticleid%3D2219%26group%3Diframe&title=Why+won%E2%80%99t+my+erect+image+eyepiece+or+diagonal+always+give+right+side+up+images+with+my+scope%3F Although this is scope specific,   maybe the RACI behaves the same when horizontal?  Note when they talk about tube rotation on a Newtonian.  This is not for a Dobsonian!

[jetstream]

The image orientation was changing as I rotated the finder scope from towards me, straight up and then pointed to the other side of the scope. In my hand I could also change the moons orientation by turning it. Looking across the river here at some street lights and trees, the image was upside down, with the finder Ep straight up... this is all in relation to naked eyes BTW

[jetstream]

I just checked again...with the EP held straight up the images are straight up, but...reversed. I looked at a light with a building on the left of it/eyes, the finder shows the building on the right...all right side up. When I rotate it in my hands the image rotates. I wonder if this thing isn't a correct image finder? I should look in the diag housing  to see whats in there.

[Charic]

maybe........or just wait and get someone to align their RACI at a lamp post or similar and compare your result. The mind can play tricks, making you think there is something wrong. You won't be the first or last to have this dilemma

[jetstream]

I took a look, there is a nice thick mirror in there and re- assembled it does the same as my last post. Reversed.

[jetstream]

This Celestron support link also explains about telescope design and orientation.......... http://www.celestron.com/support/knowledgebase?article=http%3A%2F%2Fwww.celestron.com%2Fc3%2Fsupport3%2Findex.php%3F_m%3Dknowledgebase%26_a%3Dviewarticle%26kbarticleid%3D2219%26group%3Diframe&title=Why+won%E2%80%99t+my+erect+image+eyepiece+or+diagonal+always+give+right+side+up+images+with+my+scope%3F Although this is scope specific,   maybe the RACI behaves the same when horizontal?  Note when they talk about tube rotation on a Newtonian.  This is not for a Dobsonian!

Thanks for the input and that link Charic, lots to learn here for me....once again

[RichieP]

You don't have a RACI. You have a Right Angled finder so the image should be the right way up but flipped right to left.

A RA finder uses a mirror. A RACI finder uses a pair of prisms.

Richard

[RichieP]

I should add that the Skywatcher RA and RACI finders look identical from the exterior. You can only tell the difference by looking through it or (as you have done) dismantling it.

I bought wgat was described on eBay as a RACI but when I got it it was just RA so I had to send it back.

Richard

[Moonshane]

I was just about to make the exact point that Richie did above. basically you have a standard refractor view with a 90 degree mirror star diagonal. if you have a RACI on your dob, it might be better to swap them.

[Old Hairy]

Just had a look through a couple of finders, my Skywatcher RACI shows everything as seen with the naked eye, a no-name RA finder shows things erect but flipped left-right. Both have the cross-hairs at 45°. As Ritchie says, they look identical, the difference is internal. If you have a finder you're comfortable with move it to the scope you use the most.

[Peter Drew]

True RACI finders have a roof prism to correct the image orientation. 

[YKSE]

Gerry,

as others has mentioned, your finder looks like a regular right-side-up 90 deg one.

The up side of a RACI or a regular right-side-up 90 deg finder is where the eyelens pointing at. If you have enylens pointing horizontally, and moving the scope up and down, you will see the stars move from side to side in the finder as you've detected.

[Charic]

........I knew someone would help.........not many folk around that early in the morning? 

[jetstream]

Thanks everyone, the learning curve will now start...