An experimental Rosette with a 0.67x reducer and Atik 460

[swag72]

My new kit arrived - An Atik 460 mono and an AP 0.67x reducer (CCD67T). I know that this combo should not work at all, but I'd spoken with Nik Szymanek who has a Pentax 75SDHF and he'd used this combo to great effect. I thought that to get a 337mm and f4.5 on the Pentax it was worth a punt.

So here's the first result - The Rosette in Ha. 10 x1200s with no calibration at all. I've linked to Flickr so that you can look at the full size original and appreciate the awful corners!!

I have changed the spacing for the next clear night to the minimum possible (This was done at the recommended 85mm) and will see if this makes a difference. If I really can not live with it then it will be in classifieds soon!!! Of course if I was using it with my 314L+ the corners would probably be fine, but that would kind of defeat the object, I want a wider field!

The 460 is nice to use, so I have high hopes for that. I may have to bite the bullet and buy the 27TVPH instead. I think this would work better.

Rosette nebula in Ha by swag72, on Flickr

[sologuitarist61]

I think most people would be more than happy with a great image like that - excellent

[VigdisVZ]

Those dark streaks are really stunning, lovely detail. Going to add colors later?

[Stephen Green]

A great image the dust lanes are very clear

Stephen

[Velvet]

very nice detailed image, you should be very happy with this one

Velvet

[Earl]

Nice, getting those corners sorted will be even nicer

[Gina]

I totally agree - excellent - I would be delighted with that

[swag72]

Thanks all, but until these corners get sorted this image will be going nowhere! I am pleased with the detail, the 460 is a nice camera.

[Black Knight]

That looks a lovely image Sara, the corners notwithstanding.

[swag72]

..... the corners notwithstanding.

That's a real issue for me. If I can not sort them, then this reducer is useless for me. Olly has kindly shown me how to sort them in processing, but the results were not as good as getting it right first time! If I need to crop out the corners, then I've not gained anything with this combo and I may as well not bother with it ..... or try something different!

[Gina]

Maybe we could see something wrong if the image were magnified much much more than we see here but at this magnification I can't see anything wrong. What is wrong with the corners Sara?

[swag72]

If you click on the image link, it takes you to Flickr. Left click on the actual image in Flickr and you can view the original size.

[Gina]

Ah yes, full size and zooming in with Firefox I can see the elongated stars in the corners. But it did need high magnification to see it.

[Mark72]

Nice work,

I use the reducer with RC 10''. Did not see coma there.

Mark

[Tom OD]

Good pic with stand out contrast. I guess some trial and error with the spacing will fix it out.

[TakMan]

Yes, agree with Tom above, some lovely detail and contrast in the core - the Bok Globules are very nice.

I say 'core' as I feel that the issue is not just in the 'corners' but extends quite a bit further into the field when viewing the hi-res version.... that can't be anything related to the Pentax with it's super flat field...only the reducer/spacing/camera fixing.... sorry...

Clear skies,

Damian

[swag72]

Cheers Damien, spacing will either sort it or won't. In which case I'll try something else! It may have worked in which case I would have been over the moon!!

[TakMan]

Sara, yes, hopefully it'll be easy to resolve (without any more expenditure either!)...

I wasn't trying to be funny by the way and hope you didn't take it that way - I have had my own issues with spacings back to the Tak's reducer.... I'm still out by about 0.7mm and think I'm just about 'getting away with it' - although think there is some elongation in one corner....

Thankfully the 8300 chip is not particularly big, but I think if I was using a Kodak 11Mp 35mm sensor based camera - I'd really have problems!

All most annoying!

Damian

[swag72]

Nothing taken the wrong way at all Damien Just resigned to the fact that I don't think it will work out for me!

[RobH]

Fine result Sara. With the AP67 reducer you will inevitably run into some distortion on a larger chip due to it only being a reducer, not a flattener. It works best on scopes like RC's etc.

How do you find the sensitivity of the camera? Looks like a very quiet chip too.

Cheers

Rob

[Star Gazer]

Nice image Sara,

I've just noticed that the corners don't show even distortion of the stars; the bottom left is much worse than top right. Do you think this is a result of a flawed reducer, or maybe misalignment of the optical train?

Probably this is not significant when you want to remove all distortion, but at least if it was even cropping might be an option, while matting some of the original composition.

Just a thought.

[swag72]

I'd noticed that tilt as well!! Grr!!! Rob the 460 looks like it will be a very nice camera, I am looking forward to it's first proper light!!

[rfdesigner]

Lovely image.

Looks like with that camera, scope and reducer you're almost 2 arc seconds per pixel, with the very low readout noise of that camera it makes relatively short narrow band shots possible.. quite course but for nebula like this it's clearly bringing huge sensitivity and in turn excellent images.

food for thought....

Derek

[KevUU]

I know you're upset with some of the technicalities, but from where I stand as a 'consumer' rather than a critical imager that's a really stonking picture full of amazing details

Thank you for a 'wow' moment in my otherwise dull and frustrating day!

[swag72]

Thanks Derek and Kev. I think if I can get the reducer closer to the camera it may well be acceptable - watch this space!! I wish I didn't want everything perfect all the time. I did a quick Rosette the other night without the reducer and I was surprised at the extra data that the lower f number achieved. I am not absolutely done with this combo yet!