| Joined: | Thu Apr 19th, 2012 |
| Location: | United Kingdom |
| Posts: | 4428 |
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OK have taken some test images with the D1x normal body and the body with the LPF removed.
I have managed to reproduce the hot spot effect you describe but only at f16 it is just visible at f8 and gone altogether with wider apertures.
The hotspot is present on both bodies but not as distinct on the one with the LPF removed. I will take a set with the IR camera then put them up here after lunch.
Yes the small apertures (I think these boots were f16) do focus and intensify the effect. In fact I invariably keep the aperture I use for IR at between 5.6 an 8...which may be a subliminal recognition of your observation?
This step alone probably increases the range of lenses that are 'usable'.
Ironically and bizarrely, one of the current flagship lenses (24-70) has a horrid IR hotspot even at f5.6! Which contradicts previous thinking... as its not evident when shooting in colour even at small apertures?
So there is more to this than meets the eye.
:baffled::baffled:
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Eric