[Filter Test] Blocking UV for Visible, Full-Spectrum Photos: Part #3 SUMMARY

[Andrea B.]

The filters I tested all blocked UV so well that I really don't think I need to make any more tests!

So I want to restate the summary here to wrap this up.

 

The following 4 options are the best for blocking UV and IR.

They are listed in order of increasing quality, IMHO. The possible quality issues have nothing to do with blocking UV or IR. I'm referring to potential problems with reflections and maintenance needs which might occur with uncoated, stacked filters. 

 

I also added these to Best Basic Gear:  Goggles, BG Filters, Torches

 

1. Stack: Schott BG38 + Schott GG400 (or GG 420), no coating, uncemented.

• Both filters are reusable in other stack types or separately.
• Uncemented stack slightly more prone to reflections.
• No anti-reflective coating.
• Uncoated BG glass needs routine maintenance.
• ADDED 20 Dec 2021: Very prone to flare & ghosting when facing sun or when illumination is angled into the lens.
  But you do know not to shoot facing the sun, don't you?
   

2.(tie) Stack: Schott BG38 + Schott GG400 (or GG420), at least one filter AR-coated.

• AR coating adds to the expense, but cutting reflections in a stack is good
• A cemented version of this stack is better.
• If not cemented, then the filters are reusable in other stack types or separately.
• I have not been able to test a stack like this having one (or both) filters coated.
   

2. (tie) Stack: Schott BG38 + Zeiss T* UV Filter (UV-Cut)

• Zeiss T* Price: (US)$67.00 for 52 mm.
• The well-made Zeiss T* is coated.
• Both filters are reusable in other stacks or separately.
• ADDED 20 Dec 2021: Although the Zeiss T* is coated, this stack is also very prone to flare & ghosting
  when facing sun or when illumination is angled into the lens. So don't do that.

 

3. NEW Singleton: Kolari Vision Hot Mirror Pro2  (UV/IR-Cut) BEST!

• Price: (US)$119 for 52 mm.
• CORRECTED 20 Dec 2021: The new Kolari hot mirror is a well-made, blue-green filter
  having a UV/IR-blocking interference coating.
• The Kolari hot mirror transmission chart matches many internal filtration transmission charts
  as shown by Kolari Vision's extensive measurements of internal filters.
• Make sure you get the NEW version. 
• ADDED 20 Dec 2021: When facing the sun, you can still get flare/ghosts.
  But the Kolari was better under this kind of extreme stress, than were the preceding stacks.

 

 

IMPORTANT VIS COLOR OBSERVATION:  Any minor deviations in the converted camera's original Visible color when used with one of these UV/IR-blocking options can be remedied by creating a color correction profile for the particular combination of camera & lens being used with the UV/IR-blocker.

 

Not particularly recommended:  Baader UV/IR-Cut alone.

This dichroic filter cuts UV/IR very well. However, it has that square right-hand shoulder which can cause a bit of red cast in some subjects. A color correction profile cleans up most, but not all, such color deviations. If you already have this filter, then add BG38 to soften the red shoulder.

 

Maybe, maybe not:  Schott BG38 + Schott GG395

There is such a narrow 5 nm band of possible UV "leakage", that I would say go ahead and use this stack as UV/IR-blocking in Visible photos if you already have it available and don't want to spend more money. I have not really been able to see differences in the tests I made with this stack.

 

 

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Please let me know of any corrections, additions or other suggestions.

 

[Andy Perrin]

I still want to know how they do at rejecting flare and ghosting when bright lights are in the frame.

[dancingcat]

A plain vanilla visible shot I took while fooling around yesterday: KolariVision Hot Mirror Pro2 - on Sigma 30mm dn, body Olympus EM1mk2 (Kolari conversion).  Ambient room light, f/8, iso 200, Zyrene 8 image stack.

 

[Flower is Rosa 'Home Run' from my front yard, a very hardy offspring of 'Knock Out'.  It survived temps well below zero F last winter, as well as Texas summer heat.]

 

[aphalo]

17 hours ago, Andy Perrin said:

I still want to know how they do at rejecting flare and ghosting when bright lights are in the frame.

Andy, I do not have the same filters as Andrea, but I do have some to play with. I am also interested in flare and ghosting so I will do some tests during the weekend (most likely using LEDs).

[Andrea B.]

Sue, glad that Kolari Hot MIrror is going to work for you.

I have some Knock Out cousins which are doubles. They also seem hardy here in northern NM.

 

*****

 

Andy, I did forget about checking flare/ghosting. So I will work on that.

[lukaszgryglicki]

I've just bought Hoya IR/UV cut 52mm - I already have Kolari hot mirror, but 77mm - and now because almost all new lenses I've bought are 52mm thread - I would prefer this one... cost was 249 PLN which is about 60 USD.

[Andy Perrin]

Lukas, exactly which Hoya UVIR cut did you buy? The one I have is this one:

https://hoyafilter.com/product/uv_ir_cut/

 

It's actually not that great because it has very square cutoffs like the Baader, so it is passing a lot more red than is ideal. If you are stacking it with the Kolari, it's still not that great because the UV cutoff is 390nm. Better would be to get one that cuts more towards 420nm. Because of these issues, I never use this filter anymore. I am using Tiffen Haze 2E 77mm for 420nm cut, and Zeiss T* 77mm when I want 400nm cut, stacked with BG38 (similar to Kolari hot mirror).

[Andrea B.]

Here is a flare/ghost stress test. I'm shooting directly towards the sun, but not at it, of course.

 

Filters:

stack Zeiss T* + BG38 x 2.0 mm (BG38 is not AR-coated)

stack GG400  + BG38 x 2.0 mm (neither is AR-coated)

singleton Baader UV/IR-Cut

singleton Kolari Hot Mirror Pro 2

 

Camera:  D610 full spectrum conversion.

(My D610 is wearing out. It has become an oil splattering mess. And I think either the metering is getting flakey or the back LCD is getting flakey.)

Lens:  Coastal Optics 60/4.0

 

Photos:  They are NOT presented in the filter list order.

I was focused on the small cactus at the edge of the driveway, which is covered in river rocks.

The sun is above the frame in the top middle.

 

Each of the four filters produced some flare/ghosts. That is not a surprise in such a direct stress test. The question becomes which of the four handled the flare/ghost the best?

• To my eye there are two "losers" in this test, one of which was particularly bad.
• And there are two "winners", both of which did a better job and one of which did the best job.

 

I think we probably should be careful about making final judgements about flare/ghosts on the basis of this one test??

 

The filters are identified in a later post:  LINKIE

 

 

 

 

 

 

 

 

[lukaszgryglicki]

30 minutes ago, Andy Perrin said:

Lukas, exactly which Hoya UVIR cut did you buy? The one I have is this one:

https://hoyafilter.com/product/uv_ir_cut/

 

It's actually not that great because it has very square cutoffs like the Baader, so it is passing a lot more red than is ideal. If you are stacking it with the Kolari, it's still not that great because the UV cutoff is 390nm. Better would be to get one that cuts more towards 420nm. Because of these issues, I never use this filter anymore. I am using Tiffen Haze 2E 77mm for 420nm cut, and Zeiss T* 77mm when I want 400nm cut, stacked with BG38 (similar to Kolari hot mirror).

I went lazy (as usual) I just need (non-ideal) UV/IR blocker for travelling - so I can just take one camera (Nikon D610 f UV/IR full spectrum with bayer) and UV/IR blocker (Hoya UV/IR cut), Infrared (Hoya R72), UV (Kolari UV-pass) full spectrum (no filter) and one lens (Atom-Nikkor 35 Nikkor-N f/1.4 Thorium).

I'll be travelling (around Norway coast) Hurtigruten Trondheim -> Kirkenes (new year celebration while on the ship). I don't want to take a ton of photographic stufff - I think I'll only bring additional Nikkor 28/1.4 AF-D - only for AF and possibility for asking other people to photograph me & my wife.

 

EDIT: its like one lens/camera challenge - Atom Nikkor is 52mm, all those filters are also 52mm ... I'm good :D (also, this is TOTALLY strange, but I love it - all gear is metal & glass, no plastic china staff). I need to convert Nikon Df too - then I'm really home with lenses and camera all old metal & glass (radioactive) school. I really don't know why I so much love Thorium glass - maybe because I'm a chemical elements collector? I have Uranium, Thorium, Thallium , Mercury, Beryllium and other 50+ elements...

 

 

 

[Andy Perrin]

Andrea, that first photo looks best to me of the four and the last two are the losers. I have a question though: did you put the coated filter on the part facing outward (towards the sun)? When coatings are involved, the order does matter in principle. 

[dabateman]

Well 1. is a totally loser, I can't make out any details of your ghost. 

Four is even worse,  low contrast in the tree home of your ghost and very little ghost details. 

Number two is the clear winner, I can see nice ghost details,  almost a face and the tree where it lives has good contrast.

Number three is close, the body of the ghost is more visible,  but its home has lost most contrast. 

[lukaszgryglicki]

Actually, the only thing I need from UV/IR cut is to remove IR (UV can stay there, I would even prefer UV to stay). I'm just speaking about normal photos while travelling with a converted camera as the only camera.

[Andy Perrin]

Lukas, just use the Kolari by itself then. It has a rounded shoulder and will do better than the Hoya by itself. 

[Andrea B.]

David, you are always making me laugh.

******

 

Andy writes:  Did you put the coated filter on the part facing outward (towards the sun)? When coatings are involved, the order does matter in principle. 

 

Andy, I had the BG38 on the outside with the coated Zeiss T* underneath. I did think about the order, but couldn't decide which way to go. I will definitely run this again because the Zeiss T* + BG38 combo didn't look so good the first time.

*****

 

 

OK, here's the filter names.

 

Remember that this was a head-on face-the-sun stress test. No filter/stack completely cut the artifacts. However, the flare/ghosting was lessened in #1 and #2 while in #3 and #4 there was very little control of it.

 

But I probably made an error in stacking order for #4, so I'm going to shoot another round. I like to leave (possible) errors in place because it is a good lesson for us all to learn from. I've never tested for flare/ghosting before, so there's that also.

 

 

1. Baader UV/IR-Cut
    Did well and by far was the fastest filter.

    But then there's that red cast problem. The sky never looks quite right with the Baader UV/IR-Cut even after corrections. As previously mentioned, if you already have one, then stack it with some BG38 to soften its square shoulder. I used BG38 x 2.0 mm, but I think that might be a bit thick? I don't have any thinner BG38 with which to test.

 

2. Kolari Hot Mirror Pro 2, the newest version

    Did well and no color problem.
    I am wondering if exposure differences and white balancing made the ghosting a bit more prominent in this photo as compared to #1? I cannot say just yet. I need to shoot another round. At this point I would definitely choose this KHM Pro 2 over the BaaderU for Visible work with a full-spectrum camera. Much easier to get the correct colors.

 

3. BG38 x 2.0(outer) + GG400 x 2.0(inner)

    Ghosting and aperture reflection both.

 

4. BG38 x 2.0(outer) + Zeiss T* UV-Cut(inner)

    Ghosting and also strange streaks in the upper right corner.

    As Andy has pointed out, this could be my error because I had the Zeiss T* under the BG38. I need to shoot another round with the filter order reversed.

 

[Andrea B.]

OK, get ready for some amazing flare. 

 

And let's note that I do not think I've proven much of anything with these shoot-facing-the sun-tests?

Of course that will cause ghosts & flare. 

 

Photos are presented already labeled this time.

Nothing fancy during conversion. I used Luminar and its canned Daylight white balance.

I lightened the backlit Juniper bushes the same amount in each photo.

 

The Baader UV/IR-Cut and the Kolari Hot Mirror Pro 2 are the best, relatively speaking.

You could probably say the Baader UV/IR-Cut has slightly less reflection between the tree and the sun

than does the Kolari, but the Baader has that red cast (as has been mentioned many times).

 

 

 

 

 

 

 

With both the Zeiss T* stack and the GG400 stacks, the flare increases.

Air-gapped stacking does increase such problems a bit.

 

 

 

 

This next uncoated stack is a "whole 'nother level of bad". (American slang.)

There are long rays off the sun.

There seems to be an entirely new flying saucer near the big Juniper along with two new round blobs.

Whenever you want to make a high-drama flare photo, you now know what to use and which part of the sky to aim at!! 

 

 

 

 

 

[Andy Perrin]

Quote

OK, get ready for some amazing flare. 

YAY, tell me a flare-y tale! (goes to read)

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ETA: okay, first conclusion is that we can't compare test 1 to test 2 because the flare itself isn't replicable. So no comparing Zess T* outer to inner. 

 

Second conclusion is that GG400 photo needs some dramatic Zarathustra music for the 2001: New Mexico Odyssey reboot.

 

Third is that you are correct about the Kolari Hot Mirror Pro 2 being the best of that lot, but the differences are pretty modest, with the exception of that last GG400 pic.

 

Fourth is that I'm still waiting for my internal clip-in filter, but I'm quite anxious to do my own matchup whenever that should arrive.

[Andrea B.]

But srsly folks, don't shoot facing the sun !! I don't know of any camera/lens/filter combo which would be flareless under such stress as I put them with these last two series of photos.

 

Andy, I'll run a Zeiss T* inner and Zeiss T* outer test tomorrow. I don't really expect much difference when the poor Zeiss T* is used in a stack. Seems kind of unfair to Zeiss T*-dom.

 

I'm pleased with the new Kolari Hot Mirror Pro 2, all things considered. It really beats the Baader UV/IR-Cut I've used for so long. I do think it fills the need for an external UV/IR-blocker on converted cameras.

 

UPDATE:  The new Kolari Hot Mirror Pro 2 is a blue-green substrate having a UV/IR-blocking interference coating.

I have added this information to previous comments about the construction of the filter.

(I had initially thought it was a laminate, but is is not a laminate.)

 

 

[Bill De Jager]

Thanks for your work on this, Andrea! I just put in my order for the Kolari v2.