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UltravioletPhotography

Caution....Zeiss IR lens on eBay


Shane

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The image posted is a stock image and it is not the IR version. Anyone owning this lens can spot this immediately. It is unclear if the seller actually has the IR version or not. I sent them a message suggesting they use an actual image of the IR lens. The description doesn't mention it being the IR version, only the title....... so be cautious. I suggest you contact the seller directly and ask for more info and photos.

 

In addition, it is listed as a Nikon lens but lower down it states it is a ZF-IR ZS lens. This is a contradiction in nomenclature as it indicates both Nikon mount and M42 mount. In fact, the M42 mount version of this lens actually is engraved with ZF-IR but is fitted with an M42 mount, so this is not a Nikon lens mount version.

 

I notified the seller and he has now corrected the listing. Itappears he does have an IR lens but most likely M42 mount.

 

Further Update: It was clear when corresponding with the seller that he has no idea about this lens and he also admitted this. Further discussion with him indicated that it does not have a threaded mount and therefore appears to be a ZF-IR Nikon mount lens. I suggested he remove the ZS designation from within his title and posting since this is used for M42 mount.

 

This is a really good price since the lens cost about $1400 when new and was a very limited production lens and now discontinued.

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Not sure I know whats special about this IR lens. Does it see into SWIR. That would make it more special. As that is rare for lenses.

 

But, 700nm to 1000nm, what our typically silicon sensor sees isn't too hard for many lenses. I think my Canon 40mm f2.8 STM lens is good even into that range.

Just avoid Sigma lenses. Since the Foveon sensors are very IR sensitive, Sigma typically uses a coating thats not good for IR.

I tested the Sigma 18-35mm f1.8 lens, which was reported as good for IR and its not. You can't go to f8 with a 830nm filter. Horrible hot spots and very low contrast. Was okish at f2, but thats it.

 

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Not sure I know whats special about this IR lens. Does it see into SWIR. That would make it more special. As that is rare for lenses.

Not true! Unless you mean very far into SWIR, the majority of ordinary (uncoated) lenses only lose a couple of stops in the 1100-1700nm range characteristic of InGaAs and germanium. Beyond that probably a specialist lens would be good.

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I define NIR as 700-1100 nm and SWIR as 1100-3000 nm.

 

I think most lenses can easily reach the far NIR/early SWIR region, like 1000-1200 nm. Maybe some can reach 1450 nm, but they wouldn't be very useful I guess. Andy Perrin has some experience in SWIR, maybe he tried some lenses (let me/us know if you are reading this). It seems in SWIR lenses behave just like in UV, they start to absorb and you can't use them after a certain cut-off. After 2-3 µm normal glass is useless. Probably there are no common lenses that can reach 2 µm.

 

That's also why I love SWIR. Things start to get messy again, like in UV. They are more interesting and stimulating. NIR is like a blank sheet of paper, like if you stripped all colors away from things, like in a colorbook.

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Not true! Unless you mean very far into SWIR, the majority of ordinary (uncoated) lenses only lose a couple of stops in the 1100-1700nm range characteristic of InGaAs and germanium. Beyond that probably a specialist lens would be good.

I wrote my post without refreshing the page, so you already answered me.
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All our usual "accidental UV" lenses seem to do fine in the range of my TriWave, which cuts at 1600nm. I have tried my Edixa Auto-Cassaron, the KSS lens (quartz), and the Wollensak 25mm/1.5 and they all seem ok. I do prefer the ThorLabs lenses, but that's because they have the AR coating designed for SWIR, which makes a substantial image quality improvement.
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The Z*-IR Zeiss lenses have a coating optimized for IR which give it about an extra stop of IR in the NIR range when fitted to a silicon based imager. There is no other optical or mechanical difference between the standard Zeiss Z* lenses and the Z*-IR lenses. That said, the Zeiss IR 25/2.8 is a beautiful lens for wide angle work and better than any other standard (non-designed IR) lens I have tested. I am fortunate to have both Nikon mount and M42 mount in that focal length. The same cannot be said about the Zeiss IR 50mm.
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from above: There is no other optical or mechanical difference between the standard Zeiss Z* lenses and the Z*-IR lenses.

 

But wouldn't there be an adjustment for focusing in the IR range? The Zeiss IR lens would have to have a slight difference in its flange focal length to enable proper convergence of the IR wavelengths on the plane of focus??

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from above: There is no other optical or mechanical difference between the standard Zeiss Z* lenses and the Z*-IR lenses.

 

But wouldn't there be an adjustment for focusing in the IR range? The Zeiss IR lens would have to have a slight difference in its flange focal length to enable proper convergence of the IR wavelengths on the plane of focus??

 

Well, if the lens had been designed from scratch then that would probably be true. However, Zeiss used the exact same design as their standard visible lenses but placed IR friendly coatings on the optics instead. So yes, the lens requires IR focus correction when being used.

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A Stranger In The Wind

The winner got an excellent deal.

 

The Zeiss IR weren't available for that long and near their end of run their prices skyrocketed almost doubled in price on the bay.

 

Thankfully I got my set 25,50 and 85 when prices were reasonable. The 50 is my favorite.

 

Several years ago I shot the both the ZF's and ZF-IRs on a normal camera to see how they differed on a normal camera. I found the ZF-IRs had a very slight red tinge easily corrected in post and the ZF-IRs were not quite as sharp as normal ZFs. I used live view for focusing.

 

At the time I was thinking of selling off my normal ZFs if the ZF-IRs were close enough in results to the ZF-IRs. In the end I kept both ZF and ZF-IRs.

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I also found the ZF-IR used for regular visible photography often produced a slight blue hotspot. However when caught without a macro lens, in overcast low early morning light my ZF-IR 28/2.8 captured a great close up shot of a moth which the ZF 35/2 failed to do.
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