Adam J

I think for a mini obsy the hinged design is in fact optimal especially if using German hinges as Skipper Billy used. Once you are getting higher walls and heavier roof panels then you need to be using a roll off roof design.

I have been wanting to better understand this as I self modified my DSLR removing both filters to make it full spectrum. I have a clip filter after the coma corrector. I have been working on the assumption that if I have removed glass (overall) from between the CC and the sensor that this would result in the optimal spacing from CC to sensor reducing? As such I am considering moving my CC closer to the sensor using the spring loaded adjustment screws on my 550D DSLR. I have also been getting an effect that appears like squashed stars radially around the centre of the image, kind of the opposite to coma appearing squashed as opposed to stretched radially. I am lead to believe this is as a result of the CC being too far from the sensor and hence over compensating for the coma and going past round stars to stars that are squished in the opposite plane. This is again in line with my understanding that removing the filters will have reduced the effective focal length requiring that the distance to the sensor be reduced. Any opinions on this?

Most people on here use the Baader and are very happy with it so it works well with the 130PDS. Alacant: you are imaging at F4 so you may get different results compared to the 130PDS users at F5.

The elements the wrong way? Thats hard to imagine was it a MK1 or a MK3?

The point was not really to do with the KAF8300, more to do with the QSI having a price point that places it along side larger format sensors. I was merely pointing out to the OP that if you are willing to spend that kind of money then there are other options also worthy of consideration.

Huum I would not pay that for filters, I would probably get the 3.5nm Baader filters.... and ill stand by it, if your going to spend over 3k on a camera I would not be buying one with a KAF8300 in it.

I have 2inch filters anyway to it would definitely be the way to go for me.....if I was looking in the 3k price range at any rate. But in general I would say that if you are put off by 450pounds for the baader 2 inch filter set then I don't know why you would be considering such an expensive camera in the first place.

Erm it would have to be vastly better to make it worth 1200 more...in the end its the same chip I strongly suspect that its not that much better if at all. If i was going to pay that kinda money i would not be getting a KAF8300 i would be looking at the newer KAF16200 based cameras.

M101, 50 x 5mins ISO800, Over Two Nights, 130PDS, HEQ5pro, Orion + QHY5L II Mini Guider, Astronomik CLS Filter. Having trouble with color balance, let me know what you think guys I may add some longer exposures next to bring out the fainter trails of the spiral arms more and then combine them with this image.

Thanks, not sure if that is good or bad then, what color is it normally lol. Edit: Probably the CLS Filter clipping the green out.

My first full year of astro imaging. Not much compared to some of the crazy good images above, but not to bad considering I am using a very old DSLR.

No it was the adapter, this was a while back and its all great now with a better quality adapter. I only just thought to mention it on here because something in another thread prompted me.

I recently posted in another thread about a problem that I encountered with collimation of the 130PDS. I thought that it would be best to share here too as it may not just be me. When I first purchased my 130PDS it came with a 1.25" to 2" converter. I also purchased a 1.25" laser collimator. On first collimation following my purchase I placed the laser collimator into the 2" to 1.25" adaptor I noted that the laser was a long way off hitting the primary mirror centre spot. I adjusted the secondary to move the laser into the centre spot. I then rotated the laser collimator within the 2" to 1.25" adapter to see if the spot remained stationary and hence reassure myself that the laser itself was collimated. The spot did not move. I then adjusted the primary as normal. However, despite taking grate care with this procedure I found my results to be inconsistent, some sessions I would have apparently good collimation and in others collimation would appear very poor. As a newbie astronomer at the time it was only some months later that I worked out that if I rotated the entire assembly (collimator + 2" to 1.25" adapter) within the focusing tube then the laser spot moved in a 1 inch diameter circle as observed on the primary! My eventual conclusion was that the two sides of the Skywatcher 1.25" to 2" adapter supplied with the 130PDS are not parallel and by a long way. Like I have said I have no way of knowing it this is a general issue or if this is just a problem with my adapter but be warned!

Cant help with a comparison but may people including myself use the MPCC MKIII with great results even on APS-C sized sensors and the KAF8300 is sub APS-C so you will be good. Worked great on my 1000D, having some teething problems with my 550D but am sure ill get it working well with some tweaking. The F4 will most likely work well too...its just that the optimal spacing changes with F-number.

Nice one, my only worry would be how do you fit a dew shield?

My new DIY dew shield, the classical camping mat design.

It looks like you have poor focus to me, its possible that the focus shifted after removing the mask, maybe combined with something else, maybe mirror pinch. I have not seen anyone report an issue with triangular stars with the 130PDS before.

What edition was it?

I could see this being an issue with older hand ground mirrors, not so sure I would expect the mirror to have been ground off centre with modern automated equipment. I'll have a read about Cheshire colimators, my issue it is currently that the laser spot moves as I rotate the collimator on my current bargain basement model.

Very nice, so will you be using both scopes at the same time to get place detailed objects within a wider field? I am starting to wonder if my centre spot is actually central....its just such a pain to remove the primary. How far out was it? Either way I need to get shot of my terrible laser collimator as the laser is not parallel to the focuser before I do anything else. Anyone got a suggestion for a quality collimator....preferably still costing less than the scope?

It gives bloated stars because of chromatic aberration in a refractor, OP lists a 150PDS which is a reflector and so chromatic aberration is not a problem UV and IR will still be brought to focus. Also unless he has removed both the filters from his astro-mod 500D then the front filter (also the sensor cleaning element) already acts as a UV IR cut filter, its not quite as harsh as a Baader replacement filter but it will work perfectly well with a 150PDS even if he is using a coma corrector. Having modified my own cameras I can 100% grantee you that an additional UV/IR cut filter is totally redundant in a reflector / coma corrector combination. The only exception to this is if both the filters where removed from the 500D as opposed to just the rear filter, this is called a full spectrum modification, in this case chromatic aberration would result due to the lens elements in the coma corrector as IR would be passed and detected way out to 950nm rather than just 720nm with the front filter intact. However, the OP states that his 500D is merely an IR mod in his signature.

I am very confused, what makes you think that you need a UV / IR filter for use with a IR modified 500D perticually when used with a reflector? You only really need a UV/IR at all on a DSLR if you have had a full spectrum mod done on the camera, but even at that point unless you are also using a coma corrector on the 150PDS you still dont need a IR/IR filter....

Yep it definitely worth remembering that a EOS clip filter is just a 1.25 inch filter in a different mount that allows it to be held very very close to the sensor. A fact that I find deeply annoying given that the Clip filters cost so much more than the 1.25 inch equivalents for no real reason. Problem with the approach you linked though is what do you do if you are using a coma corrector? Also a slight warning, some filters (normally narrow band filters) are actually directional. So threading them on in the way shown in your link may have unknown consequences to their performance.

Yeah but they want more than the combined cost of my narrow band filters for the filter Wheel......

I was in this position I bought 2 inch filters with the intent to use them with my DSLR now and a Larger format CCD in the future...though I may also be tempted by a pro cooled full frame CMOS camera if and when they come to the market. But I went with 2 inch filters because I run my DSLR in a cool box and the t-ring is within the box, as such its not possible to change a clip in filter without removing the camera from the box. I don't like doing that as it lets moist air into the camera and means that you have to re-start the cooling process every time you change the filter. A 2 inch filter just screws onto my coma corrector and it gives me more options in the future. I currently own a 2" CLS, a 8.5nm OIII and a 7nm H-a filter; all work very nicely with my 550D. To be honest when I get a CCD i may not even buy a SII, only a few targets respond to it strangely and a am not a fan of the Hubble pallet anyhow. The only issue I see with using 2" filters later on is that you can only get 5 filter wheels. Unless someone knows of a larger one available that I have not seen. It means you cant fit your LRGB and narrow band filters into a single wheel.