Kiwi_Brad

Does anyone have experience with this. I am keen to get one due to its long back focus as I use a DSLR and OAG. I have heard backspacing needs to be very accurate for it to correct properly but that is all good. I have heard it can introduce come aberrations as well though so interested in hearing peoples opinions after using it. Or any other recommendations with a long back focus for use with DSLR. I just use a SW130PDS at the moment. thanks

No it does I had never thought about trying this to be honest. I will def see what I can do. Just always thought I wouldn’t be able to reach focus with it that early but will have a play around! Again great idea thanks.

Great thank you to all it will be spacing of my baader cc. I am outside it’s backspacing and with a DSLR I can’t get any mess with my OAG. Sadly. Thank you for your help everyone.

I blacked those screws, loosened the mirror clips and shortened the focuser tube. it seems to be pretty good now in terms of spikes. I do still see on the sides or corners where n a defo used star the edge of the star missing. Is this a misalignment of the secondary and focuser tube? diffraction pattern is looking quite tidy and the additional spikes have gone. Longer spikes on one axis than the other though why do I have the top quarter or more of the outer ring missing? this image is the centre of the fov

Yes I will blacken the cut screw heads tonight. I think the only things I have done that could be causing it are those screws or the focuser tube but of course that was there before but now with a darker flocked tube and a lot of stray light being dealt with it is more directed into the focuser tube and creating the spike? Maybe… stretching. I will cut the tube slightly and blacken those screws and report back. Thanks

I have just replaced the eyepiece clamp to a compression ring so it wasn’t in those images but was in the latest close up stat image of Acrux. Hopefully it will help as it is much better. I know I am outside the backfocus limits because of using a Nikon DSLR and OAG. I can’t find one smaller than 11mm which I use now. So probably have to accept some issues through the corners. One day I will find money for a new camera! Thanks

Thanks for that I do think you might be right. It protrudes quite far. I have heard of people shortening the tube but the focuser itself really isn’t overly great but not sure I want to spend the money on that as an upgrade. I certainly could trim a good 20mm off it … 🤔

Below is some images of the scope and my most recent collimation then star test. I think I have resolved most of my issues given my back spacing problem until I get a dedicated camera. Focus looks better but still an extra diffraction spike just not split now. I read and fixed this as the secondary mirror holder not be square to the OTA tube itself. So measure from the edge to the edge of the tube it was out about 2mm. Also my laser collimated badly needs collimating so didn’t use that at all. Don’t have an image across the whole field but any comments on collimation welcome. Thanks

Just after some help with my 130PDS. I have taken it apart cleaned, flocked and added a few 3D printed parts. Including a secondary mirror holder. I have attached an image before and after the rebuild. I was trying to help the primary mirror clip issues around bright stars mostly. I have clearly introduced several issues into my images in doing all these. I believe I have aligned the focuser tube and secondary and collimated suitably well but I can’t tell the different between pinched optics bad collimation and the thousand other things I could have introduced. The two images are both of the southern pin wheel and a single frame. Different exposures but you can see the differences in the images. The second image is using the L-enhance filter. I have a pds130. Eq6-r mount and use a Nikon DSLR which I am not convinced is all nice and square within itself let along the focuser tube. I guide with an OAG and ZWO220mm mini (seemed to make my guiding worse from my 120mm). I am just outside the recommended back spacing due to my OAG etc. About 59mm to a Badder MPCC coma corrector. Corners seem to be doing different things and now I have an extra diffraction spike?! If someone could have a look at the images and give me some guidance that would be appreciated. Thanks Brad

Pulse guides are 0.70 I usually switch up exposure on guiding from 1.5-3 depending on conditions. I had excellent conditions last night but guiding would still blow out to 1.1 in some spots of the sky. Bad moon glow as well. Was guiding better during all 53 minutes of dark sky. Just wish the mount was a bit more consistent.

Hi everybody. Just a quick updated. The above methods fix most of the issues for this mount for me. The end cap nut was far to tight and a quick work adjustment using a voltmeter to pick out high spots worked well. it is consistent now but still not great numbers. Comfortable around .7” mark but does drop right down to .5. This just get ruined by large erratic spikes. Short of pulling it apart to rebuild it (still under warranty so won’t do that yet) seems to be the best I can get out of this iteration of the mount. Any suggestions welcome. Cheers

I have now slackened off slightly the nut against the roller bearing in RA after have trouble balancing and this has significantly helped that process. Slight adjustments on the meshing of both axis and using a ammeter confirmed there is no binding or backlash. It will be interesting to see how it goes now being a brand new mount and have those minor issues before like many other if these easy tweaks fix it. Cheers

Thanks Michael. Yes it was on the finished pec curve was all very nice except one patch. Has done it twice I will try once more and post an image of it. I am guessing it’s binding but I don’t identify it on slew so may need some help. I have found a few settings in PHD which were wrong including saying I have as calibrating at Dec -60 so maybe those few little changes will help also. RA is still very tight. I would say there is some level of stiction there. Does anyone know how to help that like that end shaft cap in DEC which was over tightened. Thanks

sweet thanks for that that’s where I calibrate now so all good. I always let PHD pick the guide star it just never picks multistars now for some reason. thanks for the info. Always appreciated.

Thanks Michael Good to know I am not doing anything weird contributing to errors. Ran GA after that time because I was recording PEC Curve. Which was great except one patch of vertical movement so I scrapped it. Clearly something going on there. The multi star guide is odd as I always have that on and didn’t touch it at all. It never seems to work with OAG even if I can see multiple stars. Is there a way to force it? The following nights numbers were much worse which was frustrating as I have no idea why. I’ll get a couple of hours tonight to just go through it again. Can someone confirm for calibration what RA and Dec I should be looking to do this at. I thought it was easy or west and low to horizon? Thanks