Laurin Dave

Hi John .. I believe the reference point (RA centre on the Mesu diagram) for the offsets is the intersection of the RA and Dec axes.. which for your mount looks to me as the point between the two RA bearings.. rather than where it looks to me that you have it (just below the dovetail clamp) you need vertical and horizontal offset of this point from the centre of your pier ( to add to your pier Offset measurements) ..and the GEM offset which is the distance from the reference point to the centre line of your scope .. HTH And that I’ve understood your diagram .. looking on my phone Dave

All very nice Carole and congratulations on your "Top Pick" ... Here's another Veil.. 5 minutes each RGB and 150 minutes each Ha and Oiii, ASI1600, major crop to remove dodgy stars caused by tilt and spacing, sorting that out will be a task for when it gets dark at a slightly more sociable hour. Dave

Thank you Pierre, I got one of the screw adapters from Astrojolo then discovered it didn't fit , I shall investigate the Geoptik adapter. Dave

Having just bought a GT71 and Flat 6A-III I'm hoping that the info on the attached will help.... https://www.firstlightoptics.com/reducersflatteners/william-optics-adjustable-flat6a-iii-08x-reducer-flattener.html https://williamoptics.com/2019-all-new-adjustable-flat6aiii-t-mount-not-included However on the FLO page there seems to be a discrepancy between the "Adjustable Distance" (7.1mm for the GT81) and the backfocus distance quoted of 60.1mm which to my mind would give an "Adjustable Distance" of 5.1mm.. (ie 60.1 -55) whereas on the William Optics page the "Adjustable Distance is quoted as 7.1mm which is consistent with the backfocus quoted there of 62.1mm. I'd assume that the WO page is more up to date and therefore suggest you try 62.1mm with the flattener adjustable distance set to 7.1mm and see how this works, hopefully pretty close.. Mine GT71 is set to 9.1mm and I shall be testing soon .. HTH Dave

North American and Pelican Nebulae in HOO with RGBish stars from Monday night. 90 minutes Ha and Oiii and 5 minutes each RGB. Samyang 135 at f4, ZWO Nikon connector, EFW and ASI1600mm. I just set it running at 11:30 and went to bed, consequently the Oiii was somewhat out of focus ... "fixed" this with Starnet by removing the Oiii stars and replacing them with the Ha ones. Also the ZWO connector isn't great (does anyone know of a better solution) and there's tilt (and most likely spacing) issues with the stars but apart from that I'm pretty pleased with the outcome. Also of note is that for once there are no microlensing issues with the ASI1600. Thanks for looking Dave

That looks fabulous Adam. well done on a great job Dave

low enough though

Rather good I'd say given how low it is

Take a look at these Ron.. https://www.firstlightoptics.com/adm-losmandy-type-d-series/adm-losmandy-dovetail-for-optical-tubes.html there's one for a Celestron 8", FLO should be able to be able to find out if it's the correct one .. If its similar to my Meade then just a few allen screws to undo (which no doubt will be imperial) to take it off the forks then remove four of the screws that hold the mirror and corrector plate assemblies on and screw the dovetail on using use the same holes and new screws (which should be supplied).. HTH Dave

Hi, in the manual ( https://inter-static.skywatcher.com/upfiles/en_download_caty01416868621.pdf ) it states that the field flattener back focus is 75mm so it should be 75mm - 44mm (Canon backfocus) - the thickness of your M48 to EOS adapter Dave

All four are very nice and many congratulations on your AN potm .. very well deserved it’s stunning Dave

And mine..

An amazing image Tom and Olly .. Even better online than it was on Olly’s wall Dave

No dovetail it's held onto a Losmandy bar with 4 screws

Indeed it is Richard, very nice... Dave

Ditto.... mines just been taken to pieces too... Maybe a spacers would lift the JTD high enough to work, something like these perhaps https://www.firstlightoptics.com/adm-misc-mounting-accessories/adm-universal-adapter-block-uab.html , or maybe needs to be custom made.

Your family gathering was clearly a success in more ways than one Olly! For the stars somewhere slightly to the left of the middle for me .... for the nebulosity further to the right so maybe be worth seeing what adding a bit of Starnetted Ha to a left of middle version looks like.. Couldn't resist a fiddle … It'd be something like this I think (Red channel from the right one added in blend mode lighten to Red channel in a 70:30 blend of L and R) Dave

Mine stays around ambient, maybe 1 or 2 deg C higher in direct sun but nothing to worry about, as my wife discovered last week once inside it feels much cooler than outside as you're out out of the sun.. Dave

Maybe the position of the shutter (by moving the stop brackets or whatever they’re called) needs to be adjusted so that it goes a bit further back .. I’d compare the overlaps at the top and bottom ..

Given the very limited data you have in this I think you’ve done a great job here. I’ve tried some big mosaics and have had the same issues.. lots of data helps as does ruthless culling of poor data .. I ended up processing each panel separately matching background levels before combining in APP.. Still wasn’t entirely happy so will capture more data next time the targets come round .. as for cropping if you have Photoshop or Afinity does layers then you can create an image with a rectangular crop out in the lower left by cropping your base image, duplicating it a couple of times cropping the duplicates to suit then pasting them back over the cropped base image and using the move tool to align them .. reduce opacity in the overlying layers for alignment then increase back to 100% flatten and you have it.. Dave

Looks to me like there are two things going on.. a) ASI1600 microlensing around 51 Cygni which in your case isn't that bad and which you cant do anything about and possibly b) a reflection of 51 Cygni from the sensor glass back to the filter and then back again creating the large spaced out donuts. Suggest you try turning the filter around and see if that makes a difference and also see if it is the same on all filters and also with no filter. Dave

I also had a very poor experience with DFO.... Whatever mount you get I'd see what it does out of the box with your Scope/Camera combo and get advice on here if needed before spending money on tuning it. As for the Samyang 135 there's a thread on here about using it showing the excellent results that are possible

It’s a “Canary”.. monitors temp and humidity has video and lets me know when it thinks there’s someone in the dome ie when the trees cast moving shadows on the dome.. mounted on an upturned bookend my son made many years ago

Here’s mine.. much the same as Steve’s.. the board screws on to 4 wooden blocks which are stuck to the dome with plastic padding ..

Looks like you used a step size of 10 with the Epsilon.. it might be different with a different scope ... RayD has a done a couple of his Simplified Astro videos on setting it up and explaining all this much better than I can... its giving me a headache