Lensbaby Studio Forums

 

Latest Post

20 hours ago by TG-J

Re: Fisheye Star Trails

view post

Mysterious spots using pinhole/zoneplate optic

Newer Topic | Older Topic

Mysterious spots using pinhole/zoneplate optic posted by jankapoor January 29, 2009 06:11AM reply | quote
posted by jankapoor

I ran a complete set of test on all my new optics and the aperture rings(of course, the zone plate/pinhole optic does not use aperture rings).

I noticed dark spots and a hairlike object in both the zone plate and pinhole settings, in exactly the same locations.

This defect does not occur when using the various glass/plastic optics.

Is this something to do with the pinhole/zoneplate optic, or do I need to get my DSLR cleaned?

Thanks--

Jan

Landscape, nature and still life using pinhole, zoneplate, Lensbaby DSLR and toy cameras; alternative printing processes including cyanotype, VDB and platinum/palladium. My website: [www.jankapoor.net]
Re: Mysterious spots using pinhole/zoneplate optic posted by Jack Howard January 29, 2009 06:42AM reply | quote
posted by Jack Howard

Jan--odds are it is your sensor. Due to optical physics, dust and particles are more noticable and hard-edged at smaller apertures.

Try this to confirm:

Put your non-lensbaby lens on the camera.

Shoot a blank white wall at widest aperture, then again at smallest aperture, then with the pinhole aperture of your 'baby.

Stack all three images into Layers in Photoshop and if the specks line up, it's the sensor, and not the lenses...

~~~~~
~~~~~~
~~~~~~



Check out my new book! (2nd Edition now Available!)
Re: Mysterious spots using pinhole/zoneplate optic posted by jankapoor January 29, 2009 10:51AM reply | quote
posted by jankapoor

Hi Jack--

I will definitely try this procedure. I think you're probably right, as the spots seem to be much less focused with the zone plate, which is a much larger aperture than the pinhole.
Thanks!

Jan

Landscape, nature and still life using pinhole, zoneplate, Lensbaby DSLR and toy cameras; alternative printing processes including cyanotype, VDB and platinum/palladium. My website: [www.jankapoor.net]
Re: Mysterious spots using pinhole/zoneplate optic posted by jankapoor January 30, 2009 05:29AM reply | quote
posted by jankapoor

I went through the sensor cleaning process using a blower brush, then made some more test images. There are still a couple of very faint, blurry smudges towards the bottom of the frames, but I'm hoping that when I do "real" images, they will hardly show at all. If they do, I'll get the camera thoroughly cleaned.

Thanks for your help.

Jan

Landscape, nature and still life using pinhole, zoneplate, Lensbaby DSLR and toy cameras; alternative printing processes including cyanotype, VDB and platinum/palladium. My website: [www.jankapoor.net]

Newer Topic | Older Topic

Sorry, only registered users may post in this forum.

Click here to login

Lensbaby Newsletter - Signup Today