Coma corrector recommendation

[rnobleeddy]

Thanks all - sounds like the 0.9x is fine as long as you don't mind taking a little length off the focus tube.

As best I can tell, the 1x's are a little more expensive, but I'll probably see what comes up second hand until the 130PDS is back in stock.

[Uranium235]

The SW 0.9x will be problematic when you point it at anything bright. Try taking an image of M45 with it and you will soon find out

Remember, the review posted earlier is based on using an F4 newt - which will always be next to impossible to get flat over a 22mm diagonal for your average imager. However when you apply something like the Baader to an f5 130pds, the results are much more consistent. Its entirely possible to (just about) get round stars over a KAF8300 using the Baader MkIII (example below)

 

[Tommohawk]

I think the OP got more than he bargained for with this post!

Interesting that you mentioned reflections with the skywatcher 0.9 coma corrector. I think I noticed something similar on bright stars when setting up for my Bahtinov. 

In the link I mentioned earlier the baader coma corrector doesn't come out best but it does do quite well and at 40 mm is shortest so less intrusion into light path. Probably the way to go so long as not faster than F5.

BTW There is an interesting comment at the bottom of that thread from a user of the Baader with 130pds. 

[Anthony1979]

Yes i regret buying the 130pds now i will probably send it back... Not impressed especially when it suppose to be an imaging scope and need to buy a corrector which cost more than the scope itself or need to cut up the focus tube.. Not happy

[Anthony1979]

It arrives tomorrow and not that excited now

[spillage]

@Anthony1979 These little scopes are such good bang for your buck. I can only highly recommend it. I Think at the end of the day they are a newt and so do need some form of housekeeping. Yes the focus can seem a little extreme but worth it. I would also recommend flocking the tube, baffling the primary mirror and making (or using a thick black shower cap) a cover for the end of the scope.

[Anthony1979]

18 minutes ago, spillage said:

@Anthony1979 These little scopes are such good bang for your buck. I can only highly recommend it. I Think at the end of the day they are a newt and so do need some form of housekeeping. Yes the focus can seem a little extreme but worth it. I would also recommend flocking the tube, baffling the primary mirror and making (or using a thick black shower cap) a cover for the end of the scope.

Whats baffles the primary mirror 

[bottletopburly]

Don’t be so disappointed you only need to look at the 130pds thread it performs well above its weight , people adapt the scope to make it better just mind you don’t cut too much off which is determined by the second set of rollers the focus tube rides on , in the fully out position the tube needs to rest on the rollers without slipping off , if you do mind that can be overcome by fitting a small grub screw on the focus tube flat to act as a stop .

Edited May 31, 2020 by bottletopburly

[rnobleeddy]

1 hour ago, Anthony1979 said:

It arrives tomorrow and not that excited now

I'm jealous you found stock! 

Let me know if you find a viable alternative - it might not be perfect, but if you want to image there doesn't seem like there's anything else that comes close at the price.

[Anthony1979]

2 hours ago, rnobleeddy said:

I'm jealous you found stock! 

Let me know if you find a viable alternative - it might not be perfect, but if you want to image there doesn't seem like there's anything else that comes close at the price.

Had 1 left at rvo so snapped it up hoping i would have a good imaging scope

[Tommohawk]

21 hours ago, Anthony1979 said:

Yes i regret buying the 130pds now i will probably send it back... Not impressed especially when it suppose to be an imaging scope and need to buy a corrector which cost more than the scope itself or need to cut up the focus tube.. Not happy

I haven't owned a 130PDS but as others have said they are excellent and great value. Remember any Newtonian will require a coma corrector if you want perfect stars in the corners - but you dont have to have one. I imaged for about a year quite happily before I bought one. Often the object of interest is central so you end up cropping the periphery anyway. 

Also, bear in mind the alternative to a newtonian is a small refractor -  and that would need a field flattener and possibly reducer which will also cost extra, probably more than a coma corrector.