Canon 70-200 F4 L - CCD Inspector Results

[ashworthacca]

I'm having major problems with distortion and vignetting on some test images I've taken with my Canon 70-200 Lens. Here is the CCD Inspector curvature screen shot

CCD Inspector Result by ashworthacca, on Flickr

What should I be checking out?

I'm sure it's not my camera as when it's attached to my ED80 I don't get any vignetting issues?

Any pointers would be appreciated.

Regards

[brianb]

You've got a sample with badly centred optics (or maybe an issue with the image stabilizing lens module if your lens is the IS version). It needs servicng. If recently purchased, return it for repair / replacement.

[ashworthacca]

You've got a sample with badly centred optics (or maybe an issue with the image stabilizing lens module if your lens is the IS version). It needs servicng. If recently purchased, return it for repair / replacement.

Thanks Brian, I'll get in touch with Canon to arrange a service as I bought it second hand.

[ashworthacca]

I sent the lens off to Colchester Camera Repairs and have just had a call back. The guy said he had checked everything and the optics are aligned perfectly and he can't find anything wrong.

He knew a little about astrophotography and said he had carried out DSLR mods and we discussed my problem in detail.

The upshot is he is going to do some more tests before he returns the lens to me but is confident that the lens is working as it should and the optics are perfectly aligned.

Right......what should I do now other than take some more images at different aperture/zoom to see what happens??

I'm stumped.

[Psychobilly]

I can upload a raw sub from mine if you want to run it through CCD Inspector... the guiding wasn't brilliant though

Definitely needs flats...

[ashworthacca]

I can upload a raw sub from mine if you want to run it through CCD Inspector... the guiding wasn't brilliant though

Definitely needs flats...

Please Peter, I'd be very interested in comparing it to mine.

[Psychobilly]

Uploading i'll pm you a link when its finished...

It is a canon raw file from the 1000D withthe 70-200 f4l @ 172mm

[Psychobilly]

I Have taken some more test images tonight..

The vignetting pops out starightaway in the Stack and is centered on the short axis but offset to one side on the long one...

I have uploaded a new tiff is you want to run it through CCD inspector again...

Looks like a 200mm f2.8L might be called for...

Billy...

[MG1]

Billy, how did this turn out? is the image in your profile?

Michael

[ashworthacca]

I'll have a look later and let you know the results:)

[ashworthacca]

Peter, is it the same link as before or do I need a new link?

[Psychobilly]

Martin - need a new link... i forgot to send it lastnight

I will do it when I get home...

Mike the flats sorted it ok... didnt manage a deep image last night as it started to rain cleared a lot later judging by the frost this morning...

Only got 12x60s at ISO200... unguided on the EQ3-Pro... with just a Polar Scope PA... and Sidereal Tracking enabled (no 3 star alignment) basically usign the mount in syntrek mode which is how I tend to use it in the "field"...

The lens was stopped down to f4.5 will try it again wide open... tis is full frame no crop...

Peter...