Advice Welcomed

[Stephen]

This isn't a complete, or properly processed image - it's just a single 120s sub from my 450D on the Meg72 with the SW field flattener plus a butt ugly channel align / stretch

Could I get comments on the (fully expected) misshapen stars? Is the flattener not working, or working as well as it can? Is this field rotation?

Guiding was pretty poor (I have another thread on that) as I had to keep dismissing a PHD dialog in order to get it to continue guiding - but the central stars are reasonably straight (I think?)

Thanks in advance!

[Jannis]

I've never had any corrector for my scope, so i can't share any experience, but it looks to me like the flattener didn't take it all away. But it's absolutely better then what i get with my 200PSD Without any corrector.

Doesn't look like rotation lookign at the stars as they're all shaped to they point towards the center of the pic (exept maybe the top right corner as far as i can see?). With rotation i would expect the stars to be all shaped in the same direction?

[Stephen]

Thanks for the input

I agree it doesn't look like rotation either.

NickH and rocketandroll have both helped me via PM and we reckon it's the SW flattener not being compatible (despite others managing to make this combination work) - something rocketandroll has direct experience of (same issues.)

It's gone to a new home via ABS and I'm now getting the "proper" reducer/flattener (WO 0.8 Reducer III 2011) from the wonderful chaps at FLO

[Star Gazer]

Hi Stephen,

You may remember PM'ing me, asking me for first refusal on my SW FF as a result of the comment I made about giving up on this flattener in this thread.

http://stargazerslounge.com/discussions-cameras/159086-field-flatteners-wo-megrez-72-a.html#post1996008

I believe you are seeing exactly what I see every time with this flattener. I am also using a Megrez 72

If you look closely you will see the stars in the corners appear to radiate outwards from the centre image. This "spoke" like pattern has nothing to do with poor PA or field rotation. It is unfortunately a weakness of this FF in that it does not flatten the image all the way to the corners on a Canon 1.6 crop sensor.

oops didn't see your last post!

What is slightly annoying is that certain internet retailers advertise the SW flattener as being a perfect match for a Magrez 72; clearly it is not.

Let me know if the new flattener is the business and I might place an order with FLO

[Stephen]

I can't say I've seen a retailer advertise it for the 72, but I took the chance on it as it fit the criteria.

Live and learn!

The new flattener arrived today, but I'm not going to get out with it unless the ground miraculously dries up as I've got a mini flood in the garden.

The one detriment about it is the lack of finess on the top cap. A weak plastic cap on a t-thread?1? It's got a little chewed up just removing the cap once

Time for "another" threaded cap from FLO

Comparison sub will be posted ASAP!

[Star Gazer]

Cheers Kh3ldar! I'll be chasing you for that comparison sub. I hope its the business.

[Stephen]

Well stubborn-ness dragged me and the kit out anyways!

The reducer comes with two t-thread attachments, I think they are of slightly different sizes so you can interchange them (three grub screws) or use them in conjunction.

This is with the default one. Single sub, same everything as last time, but with the new reducer.

I think it looks an awful lot better. Not sure what's going off with the random colouration, but I've not processed bar align and tweak the levels a bit.

Next test will be with the alternate t-thread attachment (there are no instructions so I'm working blind here!)

[rocketandroll]

That's looking a lot better.

As has been said... someone really needs to stop retailers from recomending the SW flattener for the Meg... it just isn't suitable.

Here's a couple of crops of the same corner of full frame images using the Megrez72 and my Eos 500D to show the difference I got...

This is with the SW flattener:

This is taken from the center (bottom left) all the way out to the edge of the frame... barely 25% of the image area has round stars. I haven't checked but I actually think this is worse than the scope by itself with no flattener at all.

This is when I switched to the WO FFII flattener/reducer:

The stars are round all the way to the corners... well, apart from a tiny amount of field rotation at the very edge :-)

The difference is chalk and cheese.

I'm glad to see WO have now released another flattener/reducer that is actually suitable for the great little scopes... though, to be fair, they really should sell it with the scope all the time because I can't see much practical use for the scope without it?

Looking forward to seeing your results now this is sorted Stephen :-)

Though I have no idea what that orange artefact is in the M42 image? Looks like stray light getting into the optical train somewhere to me?

Ben