Uranium235

Yes I do use a FR (of sorts), its just the Skywater coma corrector. As well as fixing the coma (but not as good as the Baader in that aspect), it has the odd side effect of being a 0.9x reducer. And that reduction factor is tuneable (ie: more distance = more reduction, but more coma). Ive managed to get mine running about 0.87x(ish), which translates to f4.4. Though its great for NB, its not really apochromatic - so you need to refocus between filters (something you dont need to do with the Baader). If I were to do some RGB work, id probably switch to the other corrector.

Yarrr.... it be another blast from the 130 Fullsize with info can be found in the deepsky subforum.

I just need to add, the velcro isnt actually stuck to the scope, I used it to extend the leg strap of the ankle weight so it fits the circumference of the OTA.... a bit like having a really big leg...lol.

My leg weights are held on with a combination of velcro straps (to hold it roughly in place), then backed up with a load of elastic bands to make it a snug fit. That makes it easier to remove if you need to... tape would be a bit of a one-way process (and leaves residue on you nice new shiny OTA if left for too long).

Blimey, got a few people jumping on the bandwagon now Just be prepared to find a way of balancing out the primary (I used 0.5kg leg weights), these little newts hardly weigh anything so they end up going camera heavy.

You can use that figure to work out how much time you need for each sub, I find that 600s binned @ f4.4 gives a signal three times cleaner than 600s on my 80ED. So, I can get away with using less - ie: 2 hours binned is normally enough for a clean(ish) pic, and to do it unbinned would take roughly double the time (4 hours). Im not sure whether the binning gain is chip or camera electronics based (probably both), and will more than likely differ from camera to camera. Thats why you need to check it out for yourself, but theres probably someone better qualified than me to give stats on the internal gubbins of CCD cameras. I just go on real-world observations (which dont always follow whats on paper).

2.97" p/p aint bad! I usually reserve binning for mosaics, as it allows me to quickly build something under tricky conditions - albeit at the price of resolution. Think of it this way, its like transforming your 750mm of focal length into 375mm, except without the increase in FOV. Which is only 25mm less than Espirit 80 (2.78" p/p), and 25 more than the Star71 (3.18" p/p) - but im just comparing resolution here nothing else. Its probably worth measuring your gain between 1x1 and 2x2 first. Take some flats at 2x2 (using a Ha filter) and achieve a target ADU of something like 24000 - make a note of the time, now switch to 1x1 and see how long it takes to get the same level, then divide one by the other to get your (rough) gain.

Thanks for confirming that, I thought it might not work.

Im not sure if a DSLR will come to focus on the 130/900, the only images i've found are taken with a modified webcam (google search).... but type "skywatcher 130pds" into google, and you get a torrent of images

Oh dear.... ive found my first image, taken Jan 2010:

Welcome to the club! Good news is that you have the MPCC, which maintains the parfocal nature of the 130. So no need to refocus between Ha and OIII (done it for myself). It will require more cooldown time than your frac, about 30min until its settled down enough to get good feedback from the b-mask. If you do it hot, the pattern jumps about all over the place making it difficult to judge. Two things you need, the spacing for the MPCC: From bottom of T2 thread: 55 (quoted), 57 (actual) From bottom of M48 thread: 57.5 (quoted), 59.5 (actual) The numbers marked as actual are what I needed to do in order for it to cover the 8300 chip.

I can definitely echo the above statement in that lasers by themselves (unless its a glatter with attachments) are pretty useless. But when used in combination with a cheshire/sight tube, they do start to prove their worth. Cheshire first, laser second (then repeat if need be). But it is still possible to get a (very) duff laser. I was given a Seben laser with one of my telescopes and bloomin' awful it was. It couldnt hit the side of a bus, never mind my primary spot!

It will be slightly faster than the WO, but with more focal length. And with your cameras pixel size, the resolution will be 1.44" p/p (2.88 binned) - anything below 3.5" p/p is useable, its down to personal preference really. It would help if you knew your camera's gain between 1x1 and 2x2, mine was measured at x2.23 (however I suspect the Sony chip will be a little lower). Easy way to do that is take some flats at 2x2 and achieve a target ADU (something like 24000), then switch to 1x1 and then see how long it takes to achieve the same ADU level - divide one by the other, and there you go! Another way is to do it under starlight using a non saturated star. If im working on just 1-2 panes I usually go 1x1, but for more than that I opt to take a hit on the resolution but halve the time it takes for each pane - so its pretty easy to rack up a large scale image quickly. I'd like to figure out a way to combine both types of data in a sort of "halfway house" of signal and resolution.

Ok, the 130.... its not as difficult as you might think. Firstly, collimation. No, you will not need to collimate it every time - in fact, months can elapse between collimation - and even then its only out by a small amount. Mine normally gets done when I take the imaging train apart for cleaning. But getting it right first time does matter, you need as little tilt in the secondary as poss (preferably none), that will ensure your field is corrected properly by the coma corrector. Secondly, focuser. It helps to know the combined weight of your imaging train (camera, FW, corrector), anything up to 1kg is fine - but you may need to tweak the tension grub screws a little to get it "just so" (this is normal on any scope ive owned). You will also need to drill and tap a third thumbscrew hole in the 2" EP holder, that improves the rigidity considerably. Unfortunately, there is no replacement focuser for this telescope so you have to work with what you are given (makes it more fun!!). My imaging train is ~1.6kg, the 383, 2" FW, tilt adaptor and corrector make for a fair old lump - but it copes alright. However, to cope with the weight (and cos I hate push-fit) I did have to convert my focuser to a threaded connection (custom built adaptor). Third, corrected field. Your CCD chip is smaller than the 8300 right? Then either the Baader or SW corrector will suffice (both have pros and cons), your corners should be pretty good with that sized chip. Fourth, performance. Again your CCD has small pixels? Going 2x2 bin at that FL with those sized pixels you could pretty much tear strips out of the sky with it and still get a good image. F5 (or F4.5 with the SWCC) @ 2x2 totally wipes the floor with f6 1x1 (in terms of signal to noise). Going from a frac to a newt may be a bit of a shock and you may think it looks a little "softer" or less contrast than a frac - but what you have is speed and depth of signal..... and if you have lots of signal then sharpness and constrast can be won back at the processing stage. Other stuff: 1) Bottom end, make a cover for it or you will get light leaks 2) Flats, can be a pain in the rear end at times. So once you have a good set, dont touch the camera!!! 3) Sweet spot: If you have a slightly dodgy corner, slew to a bright star then place it toward the affected corner (about 2/3 way out) - refocus (using the B-mask), then that should balance the field out. But its unlikely you may need to do that given your chip size. Hope that helps Oh, forgot to add... the 5" primary isnt what you would call heavy, so there is a good chance you will be camera heavy. I strapped x2 0.5kg leg weights to the bottom of mine so it balances out without me having to slide it all the way back in the mount saddle.

Cheers Heh, neither can I!!! Ive been hankering after an mosaic of this area ever since I started AP - and now that tree is going down next door, I can get a full night on it rather than having to wait until it crosses the meridian.

A quick run out for the 130 at f4.5 last night, it hoovered this lot up in just 2.5 hours - easy to see where this one is going