Infrared Hot Spots
Posted 12/06/2019 - 23:46 - Helpful Comment
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I've not noticed any effect from the filter used, but there are certainly a huge number of variables that affect hotspots:
I've had a lens cause them every time with one body, yet never at all with another.
Another lens only seems to give hotspots when focused close
Then we have aperture setting, Direction of lighting...
I wouldn't consider it surprising for a 850nm to be worse than a 720nm - it is after all working further from the wavelengths the lens is designed for!
I've had a lens cause them every time with one body, yet never at all with another.
Another lens only seems to give hotspots when focused close
Then we have aperture setting, Direction of lighting...
I wouldn't consider it surprising for a 850nm to be worse than a 720nm - it is after all working further from the wavelengths the lens is designed for!
Mike
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Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
Posted 13/06/2019 - 04:46
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Thanks Mike. I've heard similar experiences on other forums. It seems to call into question the usefulness of the tables of good and bad IR lenses.
Barrie - Too Old To Die Young
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
Posted 13/06/2019 - 09:16
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bforbes wrote:
Thanks Mike. I've heard similar experiences on other forums. It seems to call into question the usefulness of the tables of good and bad IR lenses.
They do need to be taken with more than a pinch of salt.Thanks Mike. I've heard similar experiences on other forums. It seems to call into question the usefulness of the tables of good and bad IR lenses.
If contemplating a new lens for IR they may have some benefit, but I've never bothered with them. I've got quite enough lenses in all reality!
Mike
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
Posted 13/06/2019 - 10:44
Link
I'm looking to replace a lens that came highly recommended, but did not work out for me. This time I'm taking all the kit to try using the lens as I'm going to.
Barrie - Too Old To Die Young
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/
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6913 posts
16 years
Co. Durham UK
Example IR720 filter no visible hot spots from f2.8 to f22. IR 850 filter hot spots from f11 to f22.
https://pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/