The New Skywatcher F5 Coma Corrector Review

[Deneb]

Hi

I originally was not going to write a review about the Skywatcher Coma Corrector, but after speaking to Steve @ FLO today, he encouraged to post up a pic of an image used with the coma corrector.

Well as some might know the Skywatcher Coma Correctors are optimised for the F5 range of Reflectors, they come with an adaptor for visual use also. If you want to use the corrector with a DSLR you will have to buy an M-48 adaptor for your camera otherwise you do not need one if your using a dedicated ccd camera.

Well I was quite surprised by the performance of the corrector, so much so that I have included a pic used with a Baader MPCC when I used to have my Celestron C 8N for comparison. Between the two I thought the Skywatcher was the better performer, but I let you be judge of that ! For £100 all in you can't wrong with it at all compared to the Baader product. So here come the pics. Mods please accept my apologies if the resolution of the pics are too big.

Some pics of the gear

Now the pic below was taken with my old Celestron C 8N with a Baader MPCC, you can some Coma on top right of the image.

This shot was taken unguided 30x 2mins @ISO 800 using the Skywatcher Coma Corrector. Excuse the vignetting on this image as I had not made a lightbox for my 200P DS when I took this image of the M48 StarCluster in Hydra.

A closer crop from the right edge of the image:

Is there Difference ? I think so... A very nice match I say...

Cheers

Nadeem.

Edited February 4, 2010 by Deneb

[Coco]

interesting stuff, I wonder if it can be used on a 600mm f/6 frac?

[ollypenrice]

Convincing review, and by heck you did a good job on that cluster! Gorgeous. No really, it is fabulous, Nadeem.

Olly

[LukeSkywatcher]

I have sooo much to learn. I honestly can not see a difference between both images. I can see that the 1st image shows diffraction spikes (i really like that effect) but thats all i can see.

[Deneb]

Look to the top right of the original image, there are stars with comet like appearences, this is coma, a quick explaination of coma can be found here, coma usually represents it self in parabolic mirrors e.g. reflector telescopes.

Cheers

Nadeem.

[Tim]

Do you still have both correctors Nadeem?

I would be keen to see a single short exposure shot with plenty of bright stars in (iso 1600 fine for the test) taken through the same telescope on the same night.

Although the baader pic above seems to have some coma issues, in fact all the stars across the image are a little elongated in that direction. I would expect in a well collimated setup for the coma to be apparent on all corners and edges of the field, and for the effect to amplify from the centre outwards, stretching the stars toward each corner. Is the shot a crop, or full frame?

As you only need to see the shape of the stars, and they will be stretched anyway with coma, a short exposure would help to get rid of any slight trailing traces, and a single shot rather than stacked is better.

That said, the skywatcher pic above has good stars to the corners, which shows that the corrector does a good job and is a fine recommendation for the product, but it doesnt seem fair to use it against the Baader unless the comparison is like for like.

With this new corrector, and the new updates to the newts from skywatcher, they seem to be an ideal way into astrophotgraphy with a DSLR. Let's hope many more take up this fascinating hobby of ours

Cheers Nadeem.

Tim

[MartinB]

Thanks for the review Nadeem. Are there a variety of adaptors for the different spacing required by different EPs for visual work?

[room16]

I have the Maxdslr adapter from flo which i use with my moonlite focuser on my 250px which is f5 i believe. Would i need to buy another adapter to use this with my 1000d?

[Beyond_Vision]

I would have to agree with Tim plus there looks to be some chromatic abberation with the Skywatcher compared to the Baader

[Deneb]

Do you still have both correctors Nadeem?

I would be keen to see a single short exposure shot with plenty of bright stars in (iso 1600 fine for the test) taken through the same telescope on the same night.

Although the baader pic above seems to have some coma issues, in fact all the stars across the image are a little elongated in that direction. I would expect in a well collimated setup for the coma to be apparent on all corners and edges of the field, and for the effect to amplify from the centre outwards, stretching the stars toward each corner. Is the shot a crop, or full frame?

As you only need to see the shape of the stars, and they will be stretched anyway with coma, a short exposure would help to get rid of any slight trailing traces, and a single shot rather than stacked is better.

That said, the skywatcher pic above has good stars to the corners, which shows that the corrector does a good job and is a fine recommendation for the product, but it doesnt seem fair to use it against the Baader unless the comparison is like for like.

With this new corrector, and the new updates to the newts from skywatcher, they seem to be an ideal way into astrophotgraphy with a DSLR. Let's hope many more take up this fascinating hobby of ours

Cheers Nadeem.

Tim

Sorry Tim, but I sold the Baader sometime back even before I sold the Celestron which was also a F5, so I can't give you an up to date comparison shot what you would have liked. The shot taken with the Baader is full frame, uncropped & stacked.

Even though you may not agree with some of the assumptions of my little review, don't get me wrong, the baader is a quality product, priced a little more which I would expect a better product, but from my own experience I never had stars looking that good in the baader, even with a very good collimation compared to the skywatcher when using a DSLR, I did think maybe it would have made a difference if i was using a Astro CCD camera & thats maybe where the Baader is more suited for.

Good thing about the Skywatcher is that using it for ccd work, DSLR imaging or visual the price is £100-120 all in, with the baader retailing at £130 for photographic & for visual add another £40 on top, it is quite appealing to anyone who wants to buy a coma corrector & start imaging. In my perspective or experience I found the Skywatcher better then the baader which I have already stated. As they say "Whatever Floats your Boat" & the Skywatcher is floating it..

Cheers

Nadeem.

[Deneb]

Thanks for the review Nadeem. Are there a variety of adaptors for the different spacing required by different EPs for visual work?

Sorry Martin, whatever was supplied with the coma corrector is in 1st coma corrector pic apart from the M48 Adaptor on the right of the pic, which you have to buy seperatly if using DSLR. I really bought it for imaging purposes, im sure other adaptors would fit for visual purposes with the corrector apart from the ones supplied.

Cheers

Nadeem.

[MartinB]

Thanks Deneb. If that is the case you get more with the Baader for visual than you appear to with the SW. Different EPs need different spacing and the Baader comes with a range of spacers.

[LukeSkywatcher]

Look to the top right of the original image, there are stars with comet like appearences, this is coma, a quick explaination of coma can be found here, coma usually represents it self in parabolic mirrors e.g. reflector telescopes.

Cheers

Nadeem.

Thanks Deneb. I have a basic grasp of what coma is on images (strethching of stars/detail towards the outer edge of the EP?). I just cant see it in the original image.

I DO need new glasses though.

[ngc2403]

just back from an astro weekend with the uni

got this corrector on monday from FLO (wonderful people)

but i couldn't get the CCD in the right place!

it was way to far, from where i thought i should be (about 55mm) adn it don't fit the thread on the front of any CCD camera

I also don't seem to fit the threads on the filter wheel either????

which is that 2'' threaded M48 stuff i think as well

i think i might need to get an adapter made to fit it.

when it was in my 10'' f/4 it made the coma worse, and yes i know meant for f/5 and the distance was off too.

am sure i can get a few pics to show, but i am sure it needs an adapter for CCD's perhaps SW have one on the way?

alasdair

[Deneb]

mm, maybe I should have tried this out on a ccd camera as well - if i had one, the M48 adaptor is only meant for dslr's. From what I can understand they were specifically made for the F5 range of the skywatcher reflectors not for f/4 orion optics. You could try flo again to see if they have the right adaptors for your ccd.

cheers

Nadeem.

[Doc]

I have tried this coma corrector for purely visual and could not reach focus on any of my eyepieces.

The Skywatcher is unlike the Baader in that it doesn't connect to the eyepiece it connects to the focuser itself thus increasing the outward travel.

It placed my eyepieces to far out and I needed alot more inward travel which I could not achieve.

The Baader one connects to the bottom of your eyepiece so this would not be a problem.

[ngc2403]

am not so sure about this only for f/5 stuff seen as the baader MPCC corrects f/4 through f/6?

I don't see any adapters for CCD's and the only way to connect them seem to be through the 2'' barrel adapter for the corrector.

this look more and more like just a DSLR flattener

lucky then that it was the Uni's CCD and not mine. I only have a DSLR and i know it works with that

alasdair

[Deneb]

Sorry you guys are having problems with the Coma corrector, maybe skywatcher has to go back to the drawing board. But for certain - it is turning out to be a corrector for DSLR only. Well at least I know when I do move over to CCD stuff, either skywatcher updates their product or as I stated before the Baader maybe/will be more suited for the CCD imaging.

Cheers

Nadeem.

[Shibby]

Since you wrote this Nadeem, the MPCC is now priced at £99, whereas the Skywatcher + M48 adapter is £107.50. Not a big difference, I know, but does this now mean the Baader is a better buy than the SW?

Also, since I use a D70, which seems to have a big distance to the sensor (and I've no idea how to find out exactly), how important is it to get the spacing correct with these correctors?

[davew]

Just to let you know, the CCD register on the Nikon is 46.5mm and the Canon is 44.0mm.

As far as I know the 2.5mm is taken up in the adaptor. Check first though.

Dave

Edited September 8, 2010 by davew

[tooth_dr]

AFAIK the baader MPCC is optomised for F4.5, but works from F4.0-6.0. I've it on my F4.7 scope and it works effectively. I need to alter spacing by 1-2mm to get optimal results, but screwed directly on to the T-ring/adpater and placed in the focuser it works verywell

[Shibby]

Thanks for the advice guys, very useful I don't know where else I would get it!

Just to let you know, the CCD register on the Nikon is 46.5mm and the Canon is 44.0mm.

As far as I know the 2.5mm is taken up in the adaptor. Check first though.

Dave, does this mean the spacing will be at 49mm total as standard? And therefore 3mm from ideal positioning? Or is there some additional distance internal to the coma corrector itself?

I did find this extension that adds 5mm...

[davew]

Hi shibby,

As far as I know the adaptor is built with the register in mind. Check first before you spend your cash but I'm sure it fits ok.

Dave.

[Shibby]

Well, I finally got my shiny new coma corrector and an opportunity to test it so I though I'd post my results! I have to say, I'm very pleased with its performance, even though I've only managed a quick test!

The two images are of different subjects, but I looked for something with a similar(ish) field of stars. They're not great images, just quickies, but the purpose is to just test the field correction!

Before (full camera frame):

Before (corner crop):

After (full camera frame):

After (corner crop):

[Deneb]

Those are really excellent results Lewis, definitely perfects the image.

Nadeem