experiments with niffty 50

[ako]

Ive had the adapters to mount the canon f1.2 50mm camera lense to my atik 324e ccd for a while but have never got round to it.

last night i thought id try it inbetween the rain showers

a quick m31 to give me a sense of fov, moon was really bright. 5 60sec subs, roughly processed. focus not the best- has to be very precise at this speed.

Picasa Web Albums - Matt Atkinson - Galaxies

i put my Ha filter in and took 3 shots of the viel before an extended shower and i packed in. 5min shots (should have been 10min subs or more i think)

Picasa Web Albums - Matt Atkinson - Nebula

there is a distinct softness to the bottom third of both images, any ideas? dew mayb? does it look undersampled?

looking forward to refining things a little and getting some proper time in on a subject?

any comments/suggestions welcome

cheers

matt

[vincentnm]

Matt,

The softness at the bottom is due to misalignment of your CCD and the focal plain of the lens. Stars at the bottom are not focussed as much as the stars in the top.

Regards,

Vincent.

[ako]

thanks very much for your reply vincent, i wonder why that would be, the canon lense is attached via a geoptik adaptor, which faces a t-thread, to a 10mm t-thread extender, to the t-thread of the ccd?? it all seems very secure and fit for purpose?

i shall look into it, if any1 else has any thoughts?

does any1 else use fast camera lenses attached to a ccd, anything else to watch for?

cheers matt

[Erwin Kats]

maybe its vigenetting cause by the fact your photographing on full aperture.

i got the same problem when using 70-200 2.8 is on 2.8 with my QSI.

nice FOV by the way !

[ako]

Did u manage 2solve the problem? Is it possible 2 stop a lense like that down when using a ccd??

[Erwin Kats]

Yes, i connected the lense to one of my canon bodys.

then i set the f number i want and make a exposure,then turn your lens of the body and your lens will maintain that aperture.

next time when you connect the lens to youre camera it will be back at the normal f number again.

[Photosbykev]

another way of setting the aperture is to press the DoF preview button (if you have one) and while it is pressed release the lens from the body. This trick is used a lot in time lapse photography to avoid flicker.

[Coco]

defo looks like a bit of tilt in there, it looks like its on a horizontal plain .. Not that I'm sure it was planned but it looks like 3D

.

[Shibby]

It looks 3D because it's a false depth of field effect. A bit like tilt photography. This means that the focal plane of the sensor is not perfectly perpendicular to the focal plane of the lens (it's "tilted"), as Vincent says.