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At the recent Photokina there was a company (STC) offering all kind of filters and as a special “clip filters” and these also for Nikon cameras. They had some examples to show, especially some IR-filters but no Nikon cameras do demonstrate. :-( So I came back the next day with my D810 to test. :-) They showed me, how to insert it, I took some quick pictures (and it seemed modern lighting has little IR), then they showed how to take it out again, but they could not sell it during the fair. :-(

Convinced the filter would be nice to have, especially for wide angle lenses, I tried to order one, but failed a couple of times. Though their main page worked fine, I had difficulties to reach their order site (I think, they have to work on their links. They seem to work a lot with facebook, but I do not). Eventually I could place an order and I got my sample (the 720nm version) shipped. Due to taxes etc. the price almost doubled.

Today I flipped into the camera and went out for first testing with my D810 and AFS 8-15/3.5-4.5. It seems to work fine, the lens is not optimal, it shows a slight bluish flare in the centre, but which can be handled.

At the booth, they also had a very nice little spectrometer they had built, but that was not for sale. You could place a filter or a lens in the optical pass and you got your filter curve on the little laptop screen. Unfortunately it only started at around 400nm and went into the IR, as that is the range, they build filters. I was told, they intend to build a smaller more affordable version of that spectrometer, but had no time frame. And no intention to extend the range into UV. As I had a UV-pass-filters with me (the SUV Version II, going slightly beyond 400nm), I put this into the optical pass of that spectrometer and the owner was quite impressed about the suppression of visual and IR light :-)

Here are some pictures of today (off course edited).

post-21-0-73612800-1541954881.jpg

post-21-0-24824500-1541954901.jpg

post-21-0-00657500-1541954927.jpg

post-21-0-24614900-1541954957.jpg

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Lovely photos especially the last one. Clearly those clip filters have their place, when putting a filter in front is not easy or possible.
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Today I flipped into the camera and went out for first testing with my D810 and AFS 8-15/3.5-4.5. It seems to work fine, the lens is not optimal, it shows a slight bluish flare in the centre, but which can be handled.

 

nice set of shots.. i do love the circular fisheyes.. i was wondering if the new 8-15/3.5 was IR capable.. it seems that it has a hotspot based on your statement although i can't find any problems with the images you posted.

 

just noticed what could be a hotspot in the first..

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So many interesting points in your post, Werner.

 

First, your photos are excellent. That last one is way cool as we look "down the tracks" with the slightly off-center curve of the track walkway adding its little bit of "compositional tension". I don't mean to go all art critique-y on you here, but that works really well.

 

And next - very interesting about this company STC and its clip-on filters AND its spectrometer for filters. I surely do wish I had one of those. It's nice to read that our practical observations about the SEU-Gen2 are borne out by another actual measurement.

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Added: Can the filter glass in the clip-on filter be removed and replaced by the owner? Or is the glass fixed permanently?
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Thanks for all the comments!

 

Bob, in the first picture (the only one not BW), you can still see a hint of the bluish flare around the bottom of the tree.

 

Andrea, the glass is kind of "clipped in". It is a steel frame and the glass is fixed with a frame and some bent "noses". Around the steel frame it has some soft plastic glued to the frame, which is used to hold it in place in the camera. So all in all I assume it has to be handed with care, because the soft plastic seems a bit delicate. And yes, I think the filter could be changed, it should not be too thick, then the noses would not work, or, something else would be needed (glue?), to keep a thicker filter in place.

 

Here is a quick picture (not very sharp):

post-21-0-76459900-1541971870.jpg

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Bob, in the first picture (the only one not BW), you can still see a hint of the bluish flare around the bottom of the tree.

 

 

yes.. that is why i edited my response. i don't get any hotspots with the 8/2.8 AiS fisheyes

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Astronomik.de has similar clip filters for various camera brands.

https://www.astronom...lip-filter.html

Click on the Clip-filter in the gray area to the left on the page.

 

A few of the filter-types are suitable for non astronomy photography.

 

Astronomik was very early with their Clip filters.

They started with Canon EOS APS version.

 

I have three types for my Canon 60D (OWB, ProPlanet 642 BP and ProPlanet 807).

They were the first filters I got together with the glass for replacement of the sensor filters.

Now I use the filters seldomly, due to sensor contamination risk when changing filters.

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Alaun, Thanks, I have been wondering for a while now how the new Nikon fish/zoom would work with IR.

Do you have a pic that shows the extent of the hot spot?

I really like that last shot a lot, by the way, #4, great shot!

 

It looks like a lot of telescope/astronomy places sell the clip in filters for different camera brands/models,

so the empty clip in frames are out there somewhere. If anyone knows, let me know.

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Filter solutions for fish-eyes are always a major problem, but great shots Alaun! I especially like contrast of leaves scattered the road in #2.
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This is also an interesting version of the photo. I like those false colours.

So here we have a hot spot put to good use for artistic purposes, yes? :D

 

Now I use the filters seldomly, due to sensor contamination risk when changing filters.

 

Definitely could be a problem. But I still am interested in this clip for long-term but temporary conversions. FOr example, to shoot for a month or a season in IR without making a permanent IR conversion.

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Alaun, Thanks for the unprocessed version.

Like Bob says, the 8/2.8 Ai(S) fisheyes don't have a hot spot, but they are large and heavy, and not something you would much want to go back packing with,

they require a lot more care in keeping the front element safe from bumping into something, and they come with a lens cap that screws on, and you keep that cap on it all the time, between shots, because the front element is right out in front of the lens, and you can run it into something even by getting close, which is what you end up doing a lot with the fisheye (get close to things).

The 8/2.8 Ai(S) has a filter carousel which has yellow (for EIR), red (for 590nm false color IR), and a few other longpass filters between those two, and of course a clear filter for regular visual (on a stock camera),

but no UV/IR-cut or BG type filter for visual using full spectrum cameras, and no IR only filter (such as 720nm to 850nm+ range).

I don't like the hot spot of the out of camera shot, a little hard to tell with the non white balanced raw version.

The false color doesn't seem to be limited to the center, because the foliage on the edges is also blue, which is a result of the 720nm filter, but a little hard to say how uneven that is with this shot.

and the photo has a kind of natural hot spot in the sky which makes it hard to tell how much of that brightness is from the lens and how much is just the brighter sky area.

In most cases I remove the outer edge ring, which is also present with the 8/2.8 Ai(S) fisheye,

but maybe not quite as prevalent or thick as the AFS 8-15/3.5-4.5 above.

Thanks again for posting these. You are the first I have seen personally who has posted IR examples using this lens.

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Thanks. Just wondered because the thinner the glass it can shift the center and thus the false color a bit. So perhaps a bit stronger false color than the thicker 720nm filter. Not much though.
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Thanks. Just wondered because the thinner the glass it can shift the center and thus the false color a bit. So perhaps a bit stronger false color than the thicker 720nm filter. Not much though.

These types of filters very often are dichroic designs with rathe thin glass, just as the Baader U.

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Oh yes, well, a lot of the clip-in astronomy type filters are dichroic, but sounds like this one may be a longpass with simple coatings, if that...

Alaun will know.

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Both sides dichroic. Thats why I wrote about the lens, it seems to have a hot spot. Another explanation could be these coatings. On the site of STC optics, I have found a kind of warning, that these filters should not be used beyond 15mm. So 8mmmight be wide out of the recommended spec.
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I have this glue stick thing, not sure what to call it, but the glue is fairly removable, they even make another form of it for attaching labels to walls in galleries and such,

but I think it can be used fairly safely on the back of a lens, because it can be removed cleanly.

Anyway, when I get a full frame conversion, I plan to use it to stick a Wratten on the back on my fish for testing.

Here is what I have written down on my wall, may want to double check this:

720nm, Schott RG9, Hoya RT-830, Wratten 89B (57.6% @720nm), "Standard IR".

750nm, Wratten 88A (54% @750nm).

So, it looks like from that list that the Wratten 89B is closest to 720nm, but 88A is good too.

That could be wrong though, I will look it up, because I had it in my mind the other way around.

 

Here is what the Wiki says:

87 opaque Passes infrared but not visible frequencies. blocks wavelengths below 740 nm

87A opaque Passes infrared but not visible frequencies. blocks wavelengths below 880 nm

87B opaque Passes infrared, blocks visible frequencies. blocks wavelengths below 820 nm

87C opaque Passes infrared, blocks visible frequencies. blocks wavelengths below 790 nm

88 opaque Passes infrared, blocks visible wavelengths below 700 nm.

88A opaque Passes infrared, blocks visible frequencies. below 720 nm.

89B near-opaque red R72 Passes infrared, longpass filter blocking visible wavelengths below 690 nm (very deep red). Aerial photography is one use.

 

Compared to Schott/Hoya, I show the approximate 50% of the Wratten.

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Good News:

Just got a Wratten 88A

Looked how to fasten it to the lens: Surprise! The lens has a holder for this type of gel filters.

Cut a piece of 30x28mm, rounded the corners and ready.

Its dark outside, so here just a picture for prove of concept (WB and Auto in PSCC):

 

Looks like some flare (there is a halogen bulb in the top) but no real hot spot.

post-21-0-15452600-1542992214.jpg

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