Merlin66

Wait until the Amazon Celestron reducer arrives........ I hope it does live up to expectations......(I see Adorama are selling at exactly the same price)

Hmmm "No name brand" v's Commercial established vendors - Celestron/ Meade etc. (Could be they are using others rejects? or what?) I'd like to think that the branded product (with original warranty) would be much better.

Moonshane, That shows a typical failure for the front filtered element.... I’d be interested to see the issues with the diagonal mirror and the final blocking/ sort filter.

Dave, That’s a little surprising..... I’ve been involved in solar and solar mods for over ten years, as yet I’ve only seen one final/ sort filter with any signs of deterioration. I’d like to see any images you may have of the issue..... 99.9% of the problems I see are associated with the front filter within the BF assembly.

We all have had differing experiences.... Most of the SCT optics nowadays are very comparable. A star test (or even a Ronchi star test) will quickly show any issues. The OP was looking for info on the x0.63 reducers used in SCT's rather than the telescopes themselves......

Yeah, I'd like to think Meade's "issues" with the x0.63 are a thing of the past.....

Sara, Normally it's just the front filter element which is affected..... The rear blocking/ sort filter doesn't seem to have any long term issues.

The Meade and the Celestron reducers should be similar....But My original Meade x0.63 reducer is "Made in Japan" and has the focal length around 240mm. This works well with all the non-HD SCT's. I've also tested previously a Meade x0.63 reducer which was marked "Made in China" which had an incorrect focal length, around 88mm - similar to the x0.33 reduce design....... It is believed an initial production batch when moved to China, was assembled with the wrong lenses. I would double check the actual focal length to be 100% sure. No issues with the Celestron brand.

Indeed you are correct. The original Lunt ITF filter was replaced recently with an RG glass filter. This unfortunately still seems susceptible to deterioration.....

Unfortunately the design of the ITF filter (the one we're talking about) in both the Coronado and the Lunt can result in failure. Sometimes this can be months or years.....it doesn't depend on usage as much as the possibility of moisture ingress through the failure of the side epoxy seal. Best advise I can offer is to keep the blocking filter diagonal in a seal Tupperware container with a silica gel pack when not in actual use. No guarantees.... (Easier to see this failure in a blocking filter diagonal but difficult to pick up on the PST blocker which is usually securely glued to the Black Box (Thank you Meade!).)

I’m sure it will assist with remote focus control. I use it on all my scopes. Works well.

I think the optical path length may be different to a basic prism diagonal......

As suggested, a prism diagonal is probably the way to go....

Then there is some seriously wrong with our analysis of your problem. I don’t know what else to suggest.

OK Last suggestion..... Move the focuser inwards about 25-30mm and see if the Lodestar will come to a focus. (Ignore the imaging camera for the moment.)

Hmmm As everyone has already confirmed - you need a spacer between the OAG and the filter wheel. For testing, the 21.5mm spacer you mentioned would be a good start.

Alex, A perfect addition to this discussion!! All we need now is for Rodd to submit an image of his set-up for comparison.

Not my images, (from a previous SGL thread) but you can see how the OAG can be tested during the day......

https://astronomy-imaging-camera.com/products/accessories/zwo-oag/ If the EFW is 20mm and the backfocus on the camera is 17.5 (assuming a T to T adaptor) this would infer a 37.5mm distance It could be that you need a spacer between the OAG and the filter wheel (or one between the filter wheel and the OAG) to bring this up to around 50-55mm to produce a focus at the guide camera. Sounds like the guide focus could be too close to the top of the OAG body to allow the Lodestar to go inward. The lodestar needs 12.5mm plus adaptor

If you can get an acceptable image from the Lodestar using the main telescope focusser then other than verifying the distance - see my previous message - I don't know what to suggest.

Hmmmm If the focus travel is longer than the backfocus of your OAG>Fliterwheel>ASI 1600 then you should have found a Lodestar focus - somewhere. Have you tried the Lodestar on another telescope to verify the settings - exposure etc. I use the Lodestar (under PHD2 - Latest Ascom driver) to guide my spectroscope using a "similar" oag set-up on a C11 at f10.........

I understand... That's why I suggested focusing the Lodestar (using the telescope focusser) first - just to confirm 100% it's seeing the light beam and can indeed focus on your system. Then review the imaging camera to see how far you have to move the telescope focusser to bring it into focus - the difference is what you need to address with the Lodestar positioning.

I assume your set-up is OAG>filter wheel>ASI 1600..... Roughly what's the distance from the centre of the OAG to the imaging plane? 55,60mm?? Does the Lodestar "usually" work OK? ie when imaging on it's own? If everything else checks out I'd work backwards - ignore the imaging camera for the moment and get the lodestar to focus.... then move the Lodestar in/out the OAG until it's close to your measure 55-60(?) and retest the Lodestar focus when it works OK, then look at the imaging focus .... one small adjustment to the imaging camera, one small adjustment to the Lodestar - repeat until success.

I currently use the ZWO ASI 174MM for solar imaging, and I'm awaiting delivery (on back order) of an ASI 183MM to use on the shorter focal length scopes (to give easier full disk images) I use FireCapture V2.6 for acquisition, AutoStakker V3 for quality stacking the AVI files and Registax 5 (I find it better than Registax6 at times) for the application of wavelets.

SharpCap or FireCapture work well with the ASI cameras. Yes, you can run effective "live view" - just change the exposure to show sufficient detail. (I use an ASI 174MM with a SM60/ED80 for solar imaging, but about to buy a ASI 183MM)