philhilo

I have a trip to the Med soon and South Africa later in the year. I am contemplating putting together a travel set up. I was thinking a SW Star Adventurer Pro + DSLR + small refractor.I bought a WO 66 with this in mind but have realised it is still going to take up a lot of space and weight with the flattener/connector set up (it is however a great scope so no regrets). I am now thinking Samyang/Rokinon 135mm as the scope. Am I going to be disappointed with the results, is it worth the ~£700 it is going to cost with a 2nd hand lens + new mount + tripod + ball head? I currently image with 200mm Newt and the WO 66 using a DSLR in a bortle 8+ backyard. Cheers.

Bright stars are fine, but I never get much otherwise apart from noise (I did mention it to Ivo and he suggested I checked the settings - cant remember which ones, however they were optimal). There are suggestions there might be a fix for this in the latest beta 3.85.3 out yesterday but I haven't checked/had a star to check it with.

From experience another reason DSS can baulk at a set of subs is having one that is radically different to the others - it has happened to me more than once when I have shot multiple targets and got an image into the wrong batch. DSS then only processed a few of the subs, got to the different one and didn't do the rest. Very baffling till I went through the subs when more awake!

I definitely don't waste clear skies on darks, or I get to a point where I can do no more and leave it with APT to finish up the darks - come back in the morning. Had wondered about light getting in around the mirror of the Newt, I tend to chuck the scope coat on so that's going to be pretty dark combined with the lens cap. I am trying to build a darks library but have just changed DSLRs so its start again time.

Jeepers had me going there for a moment. Definitely a beginner but thought I had that covered off!

I do dither but was beginning to wonder via research if there was any point in the bias with dithering. I did read that one set was enough. Flats - I have already figured that they aren't going to change unless the camera orientation changes. My thoughts around darks makes me wonder if the time of exposure is in fact irrelevant - is it just temperature critical, the temperature being a factor of the time/ambient. I did read that sensor temp can lag a long way behind the temp read out which is in fact the chip temp. Also use of warm air blowers used to bring the whole lot UP to its likely final temp. I can see the logic in this but wonder if in a situation where time is of the essence if its benefits are more than negligible.

I should set up my kit list, however a lowly Canon 650D, recently modded - hooray, and added an IDAS LP D2 filter and wehay the nebula are actually there, not just 'fake news'. Yes I was beginning to consider storage - huge piles of calibration frames that are surely redundant once a master has been made (I am building a calibration library but researching furiously before I bin stuff).

Hooray, and apologies for the panic. Looked back through the files and discovered there was a shot of M45 in the set. I shot two targets last night, but not sequentially as I was cloud dodging. When I looked at the files APT had labelled them in such a fashion that they went into the folder interleaved, thus I had to sort them visually off of small tiles (whilst doing breakfast, fielding small children etc). During that process one ended up in the wrong folder and that is what lead to DSS rejecting 90%, rather than rejecting one outlier as you might expect. So moral of the story is when shooting multiple targets check the files very closely and DSS does not always respond in an expected way to bad data in. Thanks again everyone for their help, cheers.

Thanks for that. I wondered about that (been there ages ago and it was a focus issue, but this looks fine - just done M45 from same session and no problems but obviously much higher in the sky out of the murk), with the detection at 20% most were 50-70 stars detected, and some 250. Now I have pushed the star detection threshold down to 10 or 5% and it is picking up 250+ stars, although looking through the files 6 or 7 have 3 or 4 times that amount. It is still rejecting the bulk of the subs. Is it processing those and rejecting the others, do I need to split it into 2 batches? Can I see which subs it is rejecting and which it is processing? Cheers.

And my second question, why does DSS sometimes throw out perfectly good looking data? Thought I was having a great night and with over 2 hours of the Horsehead and it only wants to use 6 or 7 of the 44 subs, and they look fine, seeing was pretty grim but that's not been a problem before, baffled.

Using DSS is there a way of telling it to reuse use masters it has already made when reprocessing data? Such as the master flat, or master dark, rather than it churning through everything when you redo a set of lights?

So to closure. Had a 30 minute clear sky/availability slot tonight, and threw everything into checking the new scope/flattener/focus issue - family/work/life permitting. Standing staring at the darkening sky straining until I could make out polaris - pa. Next - capella - 1 star align and get an eyepiece in there and it was looking sharp so the OTA is OK. Quickly switch the flattener and camera in - gutted no focus, aha, haven't taken the nosepiece off the flattener. Fumble fumble, tough to dismantle as several adapters are very thin or hidden and I screwed the whole thing down hard to take the flex out. Surrounded by expensive bits of kit perched on slopey wet plastic as I wrestle the next bit off. At last nosepiece out and reassemble. Argh, mount swivels whilst screwing the whole assembly back on to the drawtube. Quick realign to Capella and manual focus as no Bhatinov for this yet - it looks OK on the camera at x10. Fingers crossed. Then hook up the laptop to mount and camera, and GOTO M31 (I know should have stayed with Capella to check focus further), and a quick 30 second image whilst looking at watch counting down the minutes, and...….its looking OK, the focus seems OK, at last after weeks of faff and many £££ it looks OK without getting up close, hooray! After that a series of high ISO images to try and get decent centring before realising that the lack of balancing was killing the tracking (I normally massively overload the mount with a 200mm reflector and DSLR and guidescope and telrad but have it nicely balanced and it guides just fine, so figured it cant be that bad with this little thing, wrong!) and I was out of time - and the fog rolled in 5 hours earlier than forecast. I had hoped to put up a nice image of M31, however, below is the single unguided 30sec frame of M31 that the little WO 66SD finally delivered, and I think it is OK considering the tracking was all over the place, (ignore the colour, haven't yet sorted processing images from the modded camera). As my son said, "Dad, why do you choose to do things that are so hard?" Thanks all, merry Christmas, and clear skies!

Ta-da, the nosepiece came off the OVL flattener (vice + silicon oven glove + filter wrench) to reveal M48 female threads. Studying the RVO catalogue it appears that I can get an SCT female to T male (10mm optical length) then a female T to M48 adapter (0mm optical length). E-mailed RVO to see what they think of this plan. I see that Blue Fireball in the USA do single SCT to M48 adapter so that's a longer time option - many more clear nights with the new OTA leering at me. Here's hoping it all happens before M31 disappears for me. Thanks again all. Phil

Alas no. Tried and it won't move, and RHO thought it wasn't removable.

Yes the shoulder is up against the back of the adapter, and the end of the nosepiece is flush with the threads that go onto the SCT thread on the back of the drawtube. I would guess the nosepiece is a standard length and the adapter internal length is the same.

The nosepiece of the flattener was all the way down inside the adapter and jammed against the threads, the flange on the flattener was now sitting flush on the top of the adapter and the adapter was screwed as far down the threads as it would go - flush to the back of the OTA. Depressingly I can't see anyway of getting the lens closer to the drawtube, short of taking something off the length of the nosepiece, and something off either the thickness of the ring on the adapter that screws down to hold the adapter or the threads it screws onto - and I don't actually know how much closer the lens needs to be to achieve focus, less than a cm I suspect, it is close but no cigar.

Update part 2. The adapter arrived, the flattener went into it, the moon looked good, but alas not in focus. All parts were screwed together until metal met metal and the moon was nearly in focus, so close.....but only nearly :'-( Back to square one. Guess I will have to wait for an original or find a flattener with a removable nosepiece (or butcher the flattener and adapter somehow to take a cm out of the length).

Update after talking to RVO (who recommended the flattener for this scope but they cant know everything) they are sending me an adapter which will screw onto the external 'SCA' thread on the end of the focuser tube which will then receive the 2" nosepiece of the flattener. It will arrive tomorrow, after tonights lovely clear skies...… Hopefully this will not put the flattener so far back that I cant focus, fingers crossed. As for the filters I am slowly being dragged towards filters with the 8+ skies here and a modded DSLR. Most nebula I simply can't image, M42 is it currently. I can just about do 150 sec subs overhead, which in 90 mins had M33 just about peering out of the fog when processing. Role on my filter before I cave in to a cooled astrocam!

No, just a ruler. I see you are Birmingham south, not far from me in Solihull and the joys of JLR and the airport (thus I am awaiting my LPS D2 filter like yours)!

OK, apart from great excitement when I thought ENS (7 miles away) might have THE flattener, but out of stock. The end of the focuser tube is threaded -outside thread dia 50mm, inside 44mm. I thought the flattener was going to slide inside the focuser, does this mean I can remove the nosepiece off the flattener to reveal an appropriate thread? I have tried but nothing happening by hand so far.

Wasn't sure where to put this, but as it seems to be a newbie error then here it is. Decided I wanted a travel OTA and something wider than my 200PDS. Saw a WO Zenithstar 66SD doublet at a good price on ebay and wehay it arrived. Great reviews from a few years back, looks good. Have now discovered it takes 1.25 or 1.6 inch accessories ..... not the 2 inch flattener I ordered from RVO. Research shows they made a 1.6 inch reducer flattener in the early/mid noughties. I got it for astrophotography, is there a solution, is there a secret source of 1.6 inch flatteners for f5.9 refractors, can I get a 1.25 inch flattener or would a 1.25 inch flattener work with an APS-C sensor on a DSLR? Or am I up a creek and should I stick it back up for sale, lick my wounds and get something more modern. Cheers for any assistance (especially any suitable flatteners!). Phil

I did but it went very very quickly - before I got to look at it!

I was just thinking, that's a great tip re laser pointer (I have lost whole nights where I had polar aligned not on polaris, doh) ...… then I realised basically where I am aimed at most of the time is the flight approach for Birmingham International Airport, and they aren't going to be pleased with me shining a laser pointer at the aircraft, even if benignly. We have regular problems with idiots in this country shining laser pointers at aircraft trying to blind the pilots, now a jailable offence.

Thank you everyone for the advice so far, some suggestions confirming what I thought , some others that were totally new. An EQ6 mount isn't actually a big expense as I would sell the HEQ5 Pro (and I have an EQ5 doing nothing) - probably only a couple of hundred in it second hand. 2nd hand cooled astro cams seem to be as rare as hens teeth - people have nowhere else to go so they stick with them - and they kick in at £800 plus filters, so probably more like £1500, one to save for. Or a modded DSLR plus filter plus new software. Will definitely go look at Startools. The Canon TS OAG (had to look that up) - interesting, reduces the amount of kit required, weight on the mount, and should reduce set up time, always a good thing. I would be interested to see reports on this. One thing it would help with is alignment. It was definitely easier before I started using the finder as the guidescope, then I added the Telrad, but this doesn't seem to have been the silver bullet, still groping around trying to find the selected alignment stars. Thanks all, and will be back now winter is here and I have more free time - lots more time to think between clear skies too. Cheers.