Kolari Vision Hot Mirror Filter (UV/IR cut) vs S8612

[Andrea B.]

This is the Schott download page.

Look for Advanced Optics Filter Glass Calculation Program and Tutorial

https://www.us.schot...load/index.html

 

You need Excel to run it.

 

I think for a U-360 x 2.00 you only need S8612 x 1.50 or 1.75

[bsas]

Got it, thanks! Also, I've just responded too fast and I didn't saw that you pasted the graphs, sorry.

 

So, because of fairy dust science magic on refraction or material transmission, even if the UG11 transmits more UV then U-360, in theory when it is stacked with the S8612 that changes and some UV pass filters "stack better"?

Interesting, and I am really curious to understand why :D

 

Also, one very straight forward question: if BaaderU has about 78% transmission. Is there any stack that offers similar (or better) transmission or doesn't matter what I do the best transmission will always be the BaaderU?

[bsas]

This is the Schott download page.

Look for Advanced Optics Filter Glass Calculation Program and Tutorial

https://www.us.schot...load/index.html

 

You need Excel to run it.

 

I think for a U-360 x 2.00 you only need S8612 x 1.50 or 1.75

 

Awesome Andrea, thanks.

 

But, this Excel is from Schott, so, I cannot find the U-360 (Hoya) or the U-340 (Hoya) there so I can compare with theirs UG11 :(

Do you know how can I manually input the Hoya's data to it?

[Andy Perrin]

So, because of fairy dust science magic on refraction or material transmission, even if the UG11 transmits more UV then U-360, in theory when it is stacked with the S8612 that changes and some UV pass filters "stack better"?

Interesting, and I am really curious to understand why :D

It is because the location of the peak for UG11 and U-360 are in different places. UG11 peak is at 330nm, while U-360 is at 360nm. When combined with the S8612, the UG11 peak "bumps into" the left wall of the S8612 cut-off.

[bsas]

It is because the location of the peak for UG11 and U-360 are in different places. UG11 peak is at 330nm, while U-360 is at 360nm. When combined with the S8612, the UG11 peak "bumps into" the left wall of the S8612 cut-off.

 

Aha! That makes total sense. Thanks Andy :D

[Andy Perrin]

I think you CAN put the Hoya data in there somehow. I haven't used that program so I can't tell you the details, but Cadmium must have done it to make the plot I put up above there.

 

Also, one very straight forward question: if BaaderU has about 78% transmission. Is there any stack that offers similar (or better) transmission or doesn't matter what I do the best transmission will always be the BaaderU?

Baader U will always win. However, it doesn't matter much because it's only a tiny bit better than the stacks for most uses. And the stacks don't have the dreaded dichroic color shift issue, so are actually better in that respect.

 

Keep in mind that a few percent difference in transmission is only a fraction of a stop. A 50% difference is only 1 stop on your camera.

[dabateman]

Yes you can download the Hoya data sheets and enter it manually. I think the last tab is user data. Sadly there is no Baader data sheet. I should ask Ulf one day for his data. I also like to directly compare in the program.

If you search the forum, there is a Cadmium post about how to use this software. Not too long ago.

 

This is the thread I was thinking about:

https://www.ultravioletphotography.com/content/index.php/topic/3357-schott-2017-filter-program-graphs-compared/

 

[bsas]

I think you CAN put the Hoya data in there somehow. I haven't used that program so I can't tell you the details, but Cadmium must have done it to make the plot I put up above there.

 

 

Baader U will always win. However, it doesn't matter much because it's only a tiny bit better than the stacks for most uses. And the stacks don't have the dreaded dichroic color shift issue, so are actually better in that respect.

 

Keep in mind that a few percent difference in transmission is only a fraction of a stop. A 50% difference is only 1 stop on your camera.

 

Cool, thanks!

Yea, I am probably overthinking it. Basically, if BaaderU has 78%, the U360 stack has around 60% and the UG11 stack has around 50%, can I basically think that the difference between those is even less then an 1/3 of stop of light (around 18-28% diff)?

 

If so, because of cost, maybe the UG11 stack is the cheapest for me to go since I found this filter that looks like it has a reasonable price:

https://www.ebay.com...ee/153462684525

 

By the way, did anyone ever bought from this eBay vendor (photonics.center)?

 

Thanks all, learning a lot from all! :D

[Andy Perrin]

I don’t know that vendor. I do know that the market is full of counterfeit glass that is mislabeled as Schott (but is really Schitt if you get me).

[Cadmium]

OK, wow...

One little thing, you point out UG11 stack = 50%, and U-360 stack = 60%, those two graphs are not the same, one if Transmittance, and the other is Internal Transmittance (T and Ti), so Ti graphs always show a higher % because they disregard the surface reflection factor.

 

The Baader U is a dichroic coated filter, I think it uses UG11 1mm thick substrate, and that is dichroic coated on both sides, which takes the place of the BG glass without cutting off as much of the lower UV reach.

However, again, the LENS transmission will cut off the lower Baader reach, and some of the Baader peak amplitude also, so not much of anything will be gained with the Baader U suing most lenses, unless of course you have a UV-Nikkor or such lens, and then I am guessing you will still not see much difference.

 

Personally, If I leave the house with one stack, it would be U-360 2mm + S8612 1.5mm to 2mm. It is my favorite, and using the same white balance looks identical to Baader U on my Kuribayashi 35mm.

So that should answer all your questions. Maybe.

BG39 works for S8612 in a pinch.

 

Once again, here is that graph showing how even the Kuribayashi 35mm lens will truncate the transmission of a Baader and other filters.

I consider the Kuri 35mm to be the best UV friendly lens other than those special lenses that cost thousands.

Many UV friend lenses will have a faster plot taper, even if they still reach down and land on 320nm (say), the plot taper or shoulder can be more rounded and thus cut off peak transmission more,

so the Kuri really does an excellent job of transmitting UV for an 'accidental UV lens.

Just remember, your filter will only be as good as your lens.

Note on the graph below, all plots are using Ti.

 

[Andy Perrin]

Oops, I missed that the second graph was actual transmittance, my bad.

[bsas]

Thanks Cadmium, that helps A LOT!

 

So, if I get the S8612 2mm your suggestion would be always the H-360 2mm to go with it?

 

In theory, giving all other variables being "perfect" (lens, etc), how much "better" is the transmittance of the BaaderU compared to a S8612 2mm + H-360 2mm?

 

Also, do you have any H-360 2mm in 58mm available? :D

[dabateman]

Read these threads:

 

https://www.ultravioletphotography.com/content/index.php/topic/1941-filter-test-straightedgeu-od5-od6-wins-ir-forcing-shootout/page__hl__seu__fromsearch__1

 

https://www.ultravioletphotography.com/content/index.php/topic/1977-filter-test-andreau-mk-ii-with-bu-seu-u-360-bouquet-in-raw-false-colours-and-in-wb/page__hl__seu__fromsearch__1

 

https://www.ultravioletphotography.com/content/index.php/topic/1943-filter-test-seu-bu-u360-stack-and-the-standards/page__hl__seu__fromsearch__1

 

https://www.ultravioletphotography.com/content/index.php/topic/1940-filter-test-scarecrow-garden-scene-straightedgeu-versus-the-others/page__p__13612__hl__seu__fromsearch__1#entry13612

[Andy Perrin]

Huge diameter filters are not a good idea unless you are personally very wealthy. It’s better to standardize around 49 or 52mm in my opinion. Get step rings for the rest.

 

I am personally not a fan of the StraightEdge because it’s too blue for my tastes. Everything tends to want to look blue-violet in UV anyway, so why get a filter that pushes things in that direction even more? The counter argument is that the exposure time will be a bit faster.

[dabateman]

I am not making an argument for the SEU, which you can't get any way. The SEU mk2 is very different and actually did cause an argument on whether its a UV filter as it lets in a lot at 405nm. This changes the UV character of a photo.

 

The difference between the Baader venus filter and U360 2mm with S8612 2mm seems to be at most half a stop. But the Baader will not be as good at IR suppression as the S8612 stack. You can force IR through it. I have with the super IR sensitive Sigma SD14.

[Cadmium]

Did I type H-360? Correction I meant U-360.

The main thing you will see is a slight exposure difference between most stacks and the Baader U.

If you stack U-360 1mm + S8612 2mm you will get a faster-than-Baader-U, but it has it's little toe over the edge of 400nm, about 405nm,

but it shortens exposure time and looks almost the same as the U-360 2mm + S8612 1.5mm to 2mm stack.

The S8612 2mm is pretty versatile, because it can be used with U-340 2mm, UG11 2mm, UG1 2mm, UG2A 2mm (and 1mm), and also for the UV+Blue+Green stacks like UG5 1.5mm, U-330 1.5mm, BG3 1.5mm,

The S8612 2mm is rather strong for the U-360 2mm stack, because that is OD 6 suppression, more than is really needed, OD 5 is solid.

U-360 2mm stacked with S8612 thicknesses below:

1.25mm = OD4

1.5mm = OD4.75

1.75mm = OD5

2mm = OD6

 

But if you want the all around most versatile S8612 thickness, then it would be 2mm.

[ulf]

Cadmium, that was a good summary.

 

I would go for a S8612, 2mm all the time, for the flexibility with many filters!

 

To get the fastest Baader U look with an ionic glass, I would, just as Cadmium say above, use a U-360, 2mm.

The thinner versions of U-360 is lacking in my filter collection.

The UG11 give a peak further into UV where the sensor is less sensitive. The colours are almost the same as with the U-360.

 

The colours you get are yellow for objects mainly reflecting around 365nm and dark purple for objects mainly reflecting closer to 400nm, with those UV-pass filters.

---

I disagree with Andy's statement above "If the peak of the combined stack is too close to 400nm, it will give you lots of light but not much color."

This is not what I have experienced.

On the contrary, at least with my camera and a good UV-transmitting EL-Nikkor 80/5.6 I get more colours with stacks having the peak closer to 400nm.

 

With a stack S8612, 2mm + UG2A, 2mm, I get significantly shorter exposure times and still maintain any black UV-signatures if present in flowers.

The S8612, 2mm + UG2A, 2mm give more rich yellows than the Baader U-style and instead of the deep purple you get a pastel blue, but more saturated than the SEU3.

 

The shift to blue is mainly because this stack passes more UV light just below 400nm with a tiny bit of light just above 400nm.

As those two components are very close neighbours and the UV part is dominant, the visual part is not important, and unlikely to contribute at all to the image.

 

For me the U-360 stack and UG2A-stack are complementing each other and are a good pair for exploring colours in different flowers.

For lanscape UV-photography most false UV colours are blue or purple and the tone is a matter of taste and need for speed.

 

Some define that the S8612, 2mm + UG2A, 2mm is not a strictly correct UV-stack as it passes more light on the 400nm border and do not give the same colours as the de facto reference Baader U.

In my mind it still is a proper UV-stack with an alternative colour palette.

It still maintain any black UV-signatures if present in flowers. I will not debate this any further.

---

I think the reason for what Andy said is comparisons with results from good and bad UV-lenses and a Baader U.

Then the lenses transmitting UV badly give less and less colour than the ones transmitting UV well.

The reason for this is that the combination of a Baader U and a bad UV lens transmit a much more narrow wavelength range.

[Andy Perrin]

In this test, it looks to me like the U360 stack was the nicest rendition:

https://www.ultravio...dpost__p__13824

[Cadmium]

Well, we can get pretty complex, but we want to answer Bsas' basic questions here.

I would answer him by saying U-360 2mm + S8612 1.5mm to 2mm.

And 1.75mm makes for a perfect OD 5 suppression which is bolted to a cement floor, so it would work fine, especially if that was all you want to use it for, like glued even...

But, if you want to use the S8612 for multiple uses, then 2mm is more versatile. The two most common uses might be UV only and UV+Blue+Green ("bee vision"). And S8612 2mm would work for UV+Blue+Green also.

I want to simplify the answer, because his question is pretty simple.

[ulf]

In this test, it looks to me like the U360 stack was the nicest rendition:

https://www.ultravio...dpost__p__13824

I agree, but the WB was not done on pure UV-white, only at the same part of a flower.

That can skew the colours some.

[ulf]

Well, we can get pretty complex, but we want to answer Bsas' basic questions here.

I would answer him by saying U-360 2mm + S8612 1.5mm to 2mm.

And 1.75mm makes for a perfect OD 5 suppression which is bolted to a cement floor, so it would work fine, especially if that was all you want to use it for, like glued even...

But, if you want to use the S8612 for multiple uses, then 2mm is more versatile. The two most common uses might be UV only and UV+Blue+Green ("bee vision"). And S8612 2mm would work for UV+Blue+Green also.

I want to simplify the answer, because his question is pretty simple.

Well done!

 

Sorry for expanding the topic too much above.

[Andy Perrin]

Ulf, she did both, the other way was in the post above. Either way the U-360 won in my view.

[Cadmium]

She did both? I don't understand.

[Andy Perrin]

Andrea did both white balances in the post I linked. One was on Spectralon, the other on the sunflower disc. I was talking to Ulf in post 45.

[ulf]

Ulf, she did both, the other way was in the post above. Either way the U-360 won in my view.

Sorry, I missed that.

I agree and like the U-360 best too.