Gina

There's a hole in the clouds so I'm off out to the observatory to open the roof and point the scope at the hole

Now have the Esprit on the EQ8 with the camera, EFW2 and OAG plus FF attached and all connected up. Everything is working except the remote focuser which is suffering from bad USB connection on the Arduino Nano. If I wiggle the plug it will connect but it won't stay connected whatever I try. These mini USB connectors are just not up to it!! Think I'll see if I can sort out an alternative tomorrow. Anyway, I cna probably manage with manual focussing tonight - if the cloud clears at all and doesn't turn into thunderstorms!

I'll see what I can do and the see what it can do

Seems I need a FLO M48 to T2 adapter - that should do the trick. A short test should show if the PA is good enough for unguided imaging with the Esprit though.

Just measured up the actual rig and the distance from OAG to camera face is 53mm. Add 6.5mm camera back focus gives 59.5mm + 10 FF adaptor gives 69.5mm. Specified back focus is 54.9mm so error is 69.5 - 54.9 = 14.6mm That's even worse!!

I've looked back through this thread and yes, I did have the 1600 camera working with the Esprit and FF BUT it was with the OAG and EFW2 in the optical path. Strangely the focus seemed consistent across the field! The back focus was 11mm out!! ie. image sensor at 65mm from the optical face of the FF rather than 54mm. Could it be that the back focus of the Esprit field flattener is really that tolerant? Seems unlikely. Looks like there could be some night sky with just partly cloudy tonight so I might just set up the Esprit and just take a frame or two and see how good the focus is. I can use SharpCap for this and eyeball the result immediately.

Yes, and I've been looking into that as I think that would be my preference too. I seem to be missing and adapter though Strange because I'm sure I had the 1600 camera on this scope with the field flattener and if so the adapter can't be far away! Rather tired today and maybe not quite with it as I had a late night or rather an early morning from imaging (or trying to) last night.

Does anyone have any preference as to which sort of imaging they would like to see me do? If so, please say

Been thinking about what I shall do next time there's a clear night - tomorrow is looking hopeful. Several options :- More Ha data on a DSO I've already imaged OIII data on a DSO already imaged Ha on a DSO I've not tried with this rig 55mm f1.8 lens and Ha on much larger area of Cygnus area - needs lens bracket and focuser parts printing Esprit on the Crescent and Soap Bubble in Ha Some options depend on the ambient temperature. Options 4. and 5. seem the most exciting I think the PA might be good enough for imaging with the Esprit without guiding. If so it will save me either turning a new EFW2 camera ring or fitting up a guide scope. I am also rather keen to see if I can catch the Soap Bubble. I seem to be getting star shape problems on one side of the image with the current 135mm lens. This seems to get worse as time goes on in an imaging rig. I suspect it could be partial dewing of the lens but not sure. The dew was very heavy last night and the rig was pointing almost straight up which could well mean dew falling onto the lens more on one side.

Here is a 120s Ha sub of the Crescent Nebula area of Cygnus. Again gain of 500 and temperature -25°C. Histogram stretched. Full frame.

I'll have a go at that later One thing I'd like to do is change over to the 55mm f1.8 lens and do a mosaic of the whole Cygnus area so that I can see where everything is Might not even need a mosaic.

Yes. I don't know why it happened earlier this evening - that was all I had running. Then it just suddenly started working alright again! Modern computers are pure "Black Magic" and I'm not referring to chocolates!!!

I'm trying to decide on whether to stop at 50 Ha subs or go on to the full 100 as I did with the 30s subs. 50 will already be twice the total time of the 30s runs and I've heard it said that the rule of diminishing returns applies. I'm think I'm still in the experimental phase. There's the decision of many short exposures or fewer longer ones too.

APT working now and I'm capturing 120s Ha subs of IC 1396. Gain reduced to 500 with temperature of -25°C. This is a single sub histogram stretched.

Tried another reboot and SharpCap is working but APT isn't.

I didn't - tried running APT on 10s exposures - finished the exposure and locked up showing BUSY. No image display. There's a few bits of cloud about but I think it's clearing - now the gear won't work!!!! AAAARRRGGGHHH!!!

Problems as soon as it starts to get dark - again No image in SharpCap. Rebooting - see if that cures it - I've already tried restarting SharpCap.

Away from ∞ I think.

Rig cleaned and reassembled, attached to EQ8 and connected up. All functions tested OK, moved Home mount position 2 or 3 degrees anti-clockwise to line up with my N mark. I'll check position of Polaris when it's dark enough and further adjust as necessary. Means the DSO's should appear in the FOV when slewed to from CdC. Another warm night forecast and lots of moon so I plan to try longer NB exposures with lower gain to reduce the noise at higher temperature. Always assuming the forecast clear night becomes true.

Thanks Just been reading that thread from 2015 which shows the confusion but it does seem the consensus is that filters add to the focal distance from the flattener (or whatever). Good - adding a mm is no problem - saving a mm would be virtually impossible.

Did forget something - filters change the optical path length but I can never remember whether it's more or less and however I work it out I get it wrong! Astrodon filters are 3mm thick and change the focus be 1mm. Maybe that will not affect things for this size of sensor. If it means it moves the focus further away I could turn an extra mm onto the camera ring for the FW.

I only need an OAG for scopes - with good PA that I now have, I can do without for lenses. Might even try without on the Esprit. Yes, I've been looking at the TS OAG and was going to post about it. I was trying to make out just what the threads were on each side but I found it confusing. As for 3D printing, I already have a design I was going to use with a debayered DSLR but I've given up on that project - life's too short!! But I don't think plastic is stiff enough for optics for imaging. It really needs machined aluminium but that would be a lot of work. Anyway, I have another solution for the Esprit scope, that involves much less machining - just a replacement camera ring for the Atik EFW2. This has a rectangular groove in the edge to take the grub screws that allow this ring to rotate to change the camera angle but hold it fast when tightened up. I can save 11mm if I do away with the T2 female to female connector ring and place the camera right up against the FW. To achieve this the camera rings needs a T2 female thread rather than a protruding T2 male thread. I had to bring the rig indoors anyway because I saw a great big dust bunny last night so need to do a spot of cleaning so with it all apart I did some more measuring. With the OAG screwed onto the 10mm thick adapter for the field flattener of the Esprit, the EFW2 + OAG gives a thickness of 38.4. 10 + 38.4 + 6.5 = 54.9mm. Distance from optical face to focal plane of FF is 54.9mm - an exact match This is with the camera against the EFW2 which could be achieved with a new EFW2 camera ring with a T2 female thread/hole as mentioned above.

The so-called 10mm optical length OAG has arrived but it isn't! It's 19mm and exactly the same as the one FLO sell and the one I've got. I did come with a whole heap of adapters and extension tubes of various lengths though which may be useful. Don't think I can be bothered to send it back - it was half the price of the FLO one so I might be able to sell it at a profit

I've now realised why the DSOs were not appearing in the middle of the view when slewing to target from CdC - I think I must have moved the azimuth a couple of degrees or so when I adjusted the PA last night. That means the Homed mount is no longer pointing due north after the azimuth adjustment so it's no longer star aligned. AstroTortilla left me with an enormous PA error! It's a wonder I could do much good imaging even with guiding! I think the first thing to do tonight is to adjust the mount Home position to bring Polaris to the centre of the FOV. And no! I'm not using AstroTortilla to plate solve - I'm so disgusted, I've dumped it - I no longer have any confidence in it! Maybe the new version has solved the problems but my confidence in it has been destroyed, and that's that I'm afraid. I'll see how I feel when I go back to longer FL with telescopes but I hope to be using Linux by then. I believe INDI or KStars or PixInsight or ekos or whatever has plate solving anyway.

Thank you DP and Rich When I used AstroTortilla I found results were not repeatable and it drove me up the wall! What with repeated iterations of plate solving on a view to the east and then to the south, with adjusting the mount in between, and not really getting anywhere anyway, I just gave up having lost hours of clear sky I could have used for imaging!! PoleMaster has saved my sanity and well worth the money