KEJ

Thanks and I have never heard of that/him before.

This was more of a test last night, but with the 6.3 Reducer at 105mm or 107mm to the join, I had a FL of 1304mm when it plate solved(info in App and FITs header file), which I believe equates to the Reducer working at 6.4 which is possibly the best I'm going to get. Meade 2034mm FL 1304/2034 = 0.641 Sunflower Galaxy M63 Approx 27 million LY away and 100,000 LY wide. Not the best image as I only managed about 50mins of data last night and a fair amount of fringing on the stars(just can't get the staff). Captured using Meade 8" SCT with a 6.3 Reducer with a FL of 1304mm. ASI533 MC Pro, guided with the help of the ASIAIR. Bortle 6.

Managed to get a small break in the cloud. Steel ruler, 6.3 Reducer and A4 paper in hand, I took an approx measurement of 220mm FL, which I think equates to mine having or requiring a BF of 105mm or 107mm approx to the join between the Reducer and T-Adapter. Optical train should now be set and hopefully clear skies tonight. Thanks again for everyones comments and advice.

Brilliant and thanks once again. I will bring everything down and alter once again....... Job completed and now the wait for the weather......

Thank you also for the prompt reply and info. I have never tried the Sun trick and whilst the 105mm figure is mentioned, I was exactly unsure up to exactly where as previoulsy I had always measured to B from the camera sensor. So I guess all my various tests were pretty much 10-12mm out all the time. Thanks

Stuart hi Thanks for the prompt reply and info. 6.3 Reducer Is it safe to say the join, where the T-Adapter meets the Reducer or just step back into the T-Adapter collar a few mm ? I will have to take it apart to check. 3.3 Reducer I had a 15mm and 30mm tube/spacer that came with the adapter. I still assumed I would have to make allowances for the camera as I again assumed the older camera sensors could have been closer etc - fair point. Thank you

Not sure if anyone out there can give me a definitive answer on three hopefully simple questions. Background I have a Meade 8” SCT F10, ASI533 MC Pro camera and Hirsch 6.3 Reducer – see the attached. Q1) Back Focus Distance Does anyone know the correct back focus(BF) for this setup as I have heard values from mentioned from 85mm, 88mm, 105mm and 115mm, when measuring from the camera sensor to the Reducer? Q2) Measure to Where When measuring, the camera end is simple as I know from the sensor “C” to the top of the camera spacer “D” is 17.5mm. Should the measurement at the Reducer end be to point “A” or “B” on the T-Adapter ? Example Take the 105mm or 115mm BF figure I have used, now depending how you measure, to point “A” or “B” then that could be the approx. correct distance. Q3) Meade 3.3 Reducer In addition, I have a Meade 3.3 Reducer and once I know the correct point to take the measurement at the T-Adapter end is, does anyone know the BF distance for that potential setup as well ? (With the 3.3 Reducer I could also possibly try it with one of my planetary cameras which have smaller sensors & more out of interest). Hopefully thanks

You could be right........Its just that I have one and I was determined to try and get it to work. Parked up for the moment......

Mine will be going down a black hole if I can't sort it out. I'm parking the 3.3 issue for the moment, so back on the WO Z61 and maybe a crack at Venus/Moon with the Meade over the next few nights if its clear.

Thank you, yes I agree on that. I have been using picture as well previously.

So from last night a poor image

Thank you........

Blimey, thats interesting and I would have never in a month of Sundays figured that out. - thank you. So looking from above at the optical train, where the crack/join/seam is between the T-Adapter and Reducer? Your red line on the right hand side is say on the threads of the Reducer?

Thank you......I did read that previously. But I'm still trying with the 533 and that was going to be a try fallback with my planetary camera.

Once I know where to measure from, which I do now........I can at least concentrate on the getting the spacing correct.