The filter in this review is a little different from the usual run of the mill filters you see around – it is a Cine Mist and Circular Polarising filter in one.

STC very kindly sent me this filter to review before it was officially anounced in the UK, hence I have been busy out and about using the filter under different conditions before writing this review.

What does a STC Cine Mist filter do?

To quote from STC direct – the filter delicately handles highlights, providing a natural and subtle softness without excessive effects. There is a gentle brightening in the shadow areas yet still maintaining contrast and producing naturally soft and clear images of cinematic quality without the overly sharp harsh effect that some high resolution digital devices produce.

As is standard for STC, the Cine Mist CPL filter is supplied in high quality square plastic case fitted with foam inserts, included is the STC lens cleaning cloth, UV test card plus a guarantee booklet that is signed by the technician who quality tested the filter. Like all STC filters the Cine Mist CPL filter is double sided anti smudge, anti-static and anti-reflection nano coating, it is also serial numbered to enable the user to register the one year guarantee. Worth noting is that all 3 STC filters use German made Schott B270 Crown glass.

To see how the STC Cine Mist CPL filter performs I tested it against 2 other STC CPL filters, – these being STC Hybrid CPL and STC Hybrid Pure CPL, plus a relatively unknown brand – this being a Zomei CPL. – The Zomei filter is multi coated and uses Japanese made AGC optical glass.

Test Equipment and Proceedure

For test purposes I have standardised by using a Nikon D800 equipped with Nikkor 24-85mm f3.5-4.5G ED  mounted on Manfrotto 190 tripod fitted with 115 head. All exposures made using a remote release cable and the camera eyepiece cover in place.

Camera settings were: Standard colour, Adobe RGB Colour Space, Daylight balance, Contrast Normal, 0 exposure adjustment, Aperture Priority, Matrix Metering. All images were saved as RAW files.

The first 2 frames of each focal length test were made without a filter, then 2 exposures were made with each filter in place.

The first test involved photographing a gray target in bright early afternoon sunlight with each filter in turn – the purpose of this test was to check for any significant colour shift any of the filters. The camera was set at 400 ISO using an aperture of f8 and the focal length was set at 85mm. Exposures were made in aperture priority mode.

 

Without filter

STC Hybrid CPL

STC Hybrid Pure CPL

STC Cine Mist CPL

Zomei CPL

For the second test the photographs were taken late morning in direct sunlight, this time the ISO was set at 100 and the aperture set at f11 with a focal length of 50mm. This time 2 frames were taken at minimum polarisation of the sky and 2 frames at maximum polarisation.

Filters set to Minimum

Without filter                                STC Hybrid CPL                       STC Hybrid Pure CPL                   STC Cine Mist CPL                                  Zomei CPL

Filters set to Maximum

Without filter                                STC Hybrid CPL                        STC Hybrid Pure CPL                      STC Cine Mist CPL                                  Zomei CPL

Using a colour balanced monitor all the images taken were viewed in Adobe Camera Raw where the image and histogram of each file were examined for signs of colour shift and then the RAW files for each exposure were viewed at 100% in Adobe Photoshop – an image without a filter used was the baseline upon which all the filters were judged. At the same time I examined the Cine Mist files for its advertised effects characteristics.

Conclusions

Examining all the images side by side for colour variations it can be seen that the STC Hybrid Pure CPL filter produces a clean slightly cool image whilst the three remaining filters display a slight yellow/green shift, this is highlighted when the filters are used at maximum polarisation with the Zomei filter showing a stronger shift than the STC Hybrid CPL and the STC Cine Mist CPL. In practice and in isolation the  colour shift is nowhere as obvious as the side to side comparisons.

The STC Hybrid CPL and STC Hybrid Pure reduce light transmission by half a stop, whilst the STC Cine Mist reduces light transmission by a full stop and the Zomei CPL reduced transmission by a stop and a quarter. Both STC Cine Mist and Zomei filters are full strength polarising filters whilst STC Hybrid and Hybrid Pure filters are 70% strength polarising filters. The 3 STC filters polarised light smoothly and evenly, the adjustment ring in all cases rotated smoothly with just the right amount of resistance, the Zomei filter made a good job of polarising – but the adjustment ring had a very obvious rough spots when rotated.  All the filters maintain good sharpness when compared against the control image, the STC Cine Mist CPL filter give a very gentle softening, but it takes a very close examination to see – I would call it a very slight rounding of the image rather than softening, (this filter is listed as being 1/4 strength diffusion) STC also indicate that shadows are slightly brightened – again a very subtle effect and born out by my own trial images. I certainly like the results this filter produces.

Since I take a lot of landscape photographs I have tended to have either a STC Hybrid or STC Hybrid Pure CPL filter on my lenses almost permanantly, I have a feeling that they may have to take second place being replaced with the STC Cine Mist CPL filter. I thoroughly recommend the STC Cine Mist filter.

Sample Images

STC Cine Mist CPL Polarising effect

Being a long term user and supporter of STC filters, I am always interested when a new STC filter is announced.

However before I get to the review,  I must first extend my thanks to Ashley at STC for very kindly sending me the filter in question for me to test, along with several other equally interesting filters to review.

What is the filter and what makes it special?

It is a new generation UV Protector filter. According to STC’s website the filter is a world first and world thinnest 0.8mm filter glass.

The filter is made from new generation world thinnest chemical-strengthened 0.8mm single-crystal glass. The super slim lens is tough enough to withstand 700MPa, to prove this a 45g golf ball dropped on the filter from a height of 2.5mtrs, the filter was undamaged- impressive! In addition to this the STC Aura filter has lowest the Optical Path Difference in the industry – minimizing diffraction within the glass, thus enhancing edge detail restoration capabilities which is a must when shooting at 120 megapixels and 8k video. The filter is double sided anti smudge and anti-static nano coated. The filter ring itself is a rather fetching gunmetal coloured aluminium and is designed to be shockproof.

The STC Aura filter is supplied in high quality square plastic case fitted with foam inserts, also included in the package is a STC lens cleaning cloth, a UV test card plus a guarantee booklet that is signed by the technician who quality tested the filter. Also worth mentioning is the fact that all STC filters have a serial number on them, which is needed when registering the one year guarantee.

To get an idea of how well the STC filter performs I tested it against 3 other UV protection filters – these were: Hoya Pro 1 Digital UV, Kenko UV and STC Ultra Layer SMRC UV.

Filter Specifications:

Filter                                      Thread size             Coating                Weight

Hoya Pro 1 Digital UV                77mm                 Multi Coated               35g

Kenko UV                                     77mm                      None                       20g

STC Ultra Layer UV                    77mm                 Multi Coated               17g

STC Aura UV                               77mm                 Multi Coated               14g

 

Test Equipment and Proceedure

For test purposes I used a Nikon D800 equipped with Nikkor 50mm f1.8 D, Nikkor 24-85mm f3.5-4.5G ED and Nikkor 80-200mm f2.8 ED mounted on Manfrotto 190 tripod fitted with 115 head. All exposures were made using a remote release cable and the camera eyepiece cover in place.

Camera settings were: Standard colour, Adobe RGB Colour Space, Daylight balance, Contrast Normal, 0 exposure adjustment, ISO 100, Aperture Priority, Matrix Metering. All images were saved as RAW files.

The first 2 frames of each focal length test were made without a filter, then 2 exposures were made with each filter in place. Tests were made at 24mm with 24-85mm lens, 80mm and 200mm with 80-200mm lens.

All the filters were tested for their UV blocking capability using STC UV testing patches in bright sunlight.

Results

The first test performed was the UV blocking test – For this I used STC UV testing patches in bright sunlight.

The Hoya filter allowed a little UV through whilst the Kenko filter blocked very little UV and both STC filters blocked UV fully. The fact that the Kenko filter failed to block practically any UV light is to say the least a little worrying, admittedly the filter is the budget version offered by Kenko but still not an excuse.

 

                            Hoya Pro 1 Digital  UV                      Kenko UV                               STC Ultra Layer UV                         STC Aura UV

The second test involved photographing a gray target in diffused early morning light with each filter in turn – the purpose of this test was to check for any significant colour and density issues with the filters. The camera was equiped with a Nikkor 50mm f1.8 D lens, aperture was set at f8 and exposures were made in aperture priority mode. Subsequently the images taken were viewed in Adobe Camera Raw where the image and histogram of each file was examined for colour shifts.

The colour shift test was performed by overlaying each of the histograms one at a time over the image taken without a filter.

All the filters darkened the blue mid-range very slightly – the Kenko filter additionally darkened the blue highlight range slightly, whilst the STC Ultra layer filter reduced the mid range blue peak slightly and also darkened red mid range by a slight amount, finally the STC Aura filter made a small reduction in the peak of the green mid range.

 

Without filter

Hoya Pro1 Digital UV filter

Kenko UV filter

STC Ultra Layer UV filter

STC Aura UV filter

 

The third and final test was the sharpness test, this envolved making a series of exposures of Eastbourne Pier at 3 different focal lenghts with all four filters, the RAW files for each exposure were viewed at 100% in Adobe Photoshop using a colour balanced monitor – an image without a filter used was the baseline upon which all the filters were judged.

All images were saved as jpeg files in Photoshop without any corrections made.

From left to right images are: Without filter, Hoya Pro1 Digital, Kenko, STC Ultra Layer, STC Aura

Nikkor 24-85mm at 24mm

Nikkor 80-200mm at 80mm

Nikkor 80-200mm at 200mm

Under critical examination the Hoya Pro1 Digital showed a very slight increase in contrast, Kenko filter was a little warmer, the STC Ultra Layer filter displayed a slight increase in contrast and a slight increase in edge sharpness, the STC Aura filter was similar to the STC Ultra Layer filter in contrast whilst giving a slightly better edge sharpness.

Conclusions

None of the filters tested displayed a huge colour shift, which is not unexpected. Formulation of the glass and coatings used to enhance light transmission will always make extremely slight differences, but only close comparison of the histograms reveal this.

Coating of the filters also play an important part in maintaining image sharpness and contrast, however the thickness of the glass also has a part to play in this – thicker glass will diffract light more than thinner glass. This is where the STC Aura filter comes into it’s own, being a world first thinnest single crystal optical glass filter- allied to state of the art coatings. It helps to produce very sharp images with excellent contrast.

Surprisingly when comparing weight between the four UV filters, I was half expecting the Kenko filter to be the heaviest, how wrong I was -it weighed 20g a full 15g less than the Hoya Pro1 Digital. The STC Ultra Layer filter tipped the scales at 17g and the STC Aura filter came in at only 14g.

More worrying was how little UV light Kenko’s budget filter blocked (according to the test- none). To be fair to Kenko, there are other multicoated UV filters in their range which probably make a better job of blocking UV light but for the purposes of this test I wanted to test a recognised budget filter from a known brand (Kenko are part of the Tokina group) rather than one of the  ‘No Name’ brands that are on offer at various outlets.

What you expect from your UV filter and how much you want to spend will certainly dictate which filter you opt for.

If you want an inexpensive piece of glass to put in front of your lens then the Kenko filter is for you, just remember that it does not effectively block UV light. A better but obviously more expensive filter would be the Hoya Pro1 Digital, this filter made a better job of blocking UV light. The ‘Digital’ in it’s description aludes to the fact that the multicoating have been optimised for digital camera sensors. Top marks go to the STC filters, with the Aura filter making it to the top spot due to the better edge sharpness it produced. I tested all the filters with a 36.3mp camera, so imagine the image quality the STC Aura filter will produce at twice and four times that!

Further evidence to how robust the STC Aura filter is can be born out by personal experience – I accidentally dropped my filter onto concrete from at least a metre high, the filter was completely unscathed.

Prices of all four filters are subject to change, but as a rough guide for a 77mm filter : The basic Kenko UV filter costs on average £6.00, whilst a Hoya Pro1 Digital UV filter (now superceeded) or equivelant costs in the region of £73.00, STC Ultra Layer UV filter costs approximately £65.00* and STC Aura UV filter approximately £85.00*

* Prices converted from USD – Please contact UK suppliers for exact prices.

The final question is: What UV filter would I choose? Easy answer – the STC Aura UV filter, in fact I am already using one, it’s top quality!

 

Sample Photographs

STC recently announced the release of a revision of their well known Hybrid CPL (Circular Polarising) Filter.

What is the difference between the ‘New’ Pure CPL Hybrid filter and its predecessor? According to STC the new filter has a more neutral colour balance.

I have used the original STC Hybrid CPL filter for some years now, so was interested to see the difference between the two filters for myself. As a result I obtained a STC Pure Hybrid CPL filter and put it to the test.

What makes the STC Pure Hybrid CPL filter special?

Made with Schott B270 super tough glass, has a double sided anti reflection, antistatic, oil and waterproof coating, the filter edge is black rimmed to reduce reflection from the edges of the filter, the filter rings are Teflon coated to ensure smooth rotation in addition to this a special polarising film is used . All in all this makes for an ultra light and ultra slim polarising filter which also cuts UV light.

Being a Hybrid filter it cuts light transmission by only 1/2 a stop whilst giving a 70% polarising effect.

The filter is supplied in a square hard plastic padded case, also included are a high quality lens cleaning cloth, a UV test card (to prove how much UV light the filter blocks) and a certificate of accreditation– STC filters are individually numbered, this identifies the filter when registering to activate the guarantee.

How the filter was tested.

For comparison purposes both the STC Hybrid CPL and STC Pure Hybrid CPL were fitted to a Nikkor 24-85mm f4.5 – f5.6 AFG lens on a Nikon D800 camera body. The combination was mounted on a tripod, using a remote shutter release. Exposures were made in Aperture Priority, using an aperture of f11, metering was set to Matrix, 100 ISO, Neutral saturation and Daylight balance, files were saved as NEF and converted to Jpeg for website use in Adobe Camera Raw without adjustment.

The NEF files were examined at 100% in Photoshop on a colour calibrated monitor.

Making the test images

Exposures were made without filter and at full polarisation. The filter ring was rotated several times on both filters to ensure that the full polarisation effect was used..The Teflon coated filter rings made rotation smooth with just the right amount of resistance.

When using full polarisation underexposing by 1/2 a stop sometimes helps compensate for the darker blue sky causing the camera to overexpose.

All photographs were taken in full sun from between 11.00 and 4.00

Test Images

                                                                                                                       Colour saturation

Without filter                                                 Original Hybrid CPL filter                                       Pure Hybrid CPL filter

 

Notice the difference in the RGB channels in the example screen shots below

                                                                                                                              Without filter

Original Hybrid CPL filter

Pure Hybrid CPL filter

Without filter                                           Original Hybrid CPL filter                                       Pure Hybrid CPL filter

 

                                                                                                                              Polarisation

Without filter                                             Original Hybrid CPL filter                                       Pure Hybrid CPL filter

 

Without polarisation                                                                                                      Polarised with Pure Hybrid CPL Filter

 

Without polarisation                                                                                                      Polarised with Pure Hybrid CPL Filter

 

Colour difference between filters

 Left –  Original Hybrid CPL filter colour balance                                                          Right – Pure Hybrid CPL filter colour balance

 

Results

As can be seen by the above screen shots the colour rendition between ‘Without filter and Pure Hybrid CPL filter’ are quite evenly matched and more neutral, whereas the original Hybrid CPL filter shows a slight cyan cast. Sharpness with or without  either of the two Hybrid CPL filters is unaffected, nor is there any  evidence of fringing thanks to the ultra slim high quality Schott glass and multi coating used. The Pure filter also makes a very good job of blocking UV light – see the examples below for further proof.

 

                                                                                            STC Ultra layer UV filter                 STC Pure Hybrid CPL filter

 

STC Ultra layer UV filter                 STC Pure Hybrid CPL filter

Conclusions

When viewed on screen photographs taken using the Pure Hybrid CPL filter are clearly neutral, combined with only a 1/2 a stop light loss, excellent polarisation properties and being ultra slim profile and light in weight, add to this the fact that the filter is excellent at blocking UV light – this new version of Hybrid CPL filter ticks all the boxes.

I keep a STC Hybrid CPL filter on my camera lens most of the time, the minimal light loss is hardly worth bothering about, plus it has the advantage that I have instant access to a polarising filter should the need arise.

This filter is a premium product so expect to pay around £138 for a 77mm Pure Hybrid CPL filter.

Would I recommend the Pure Hybrid CPL Filter?

Short answer -Yes!  The STC Pure Hybrid CPL filter will be my main filter from now on.

Extra Sample Images

STC Pure Hybrid CPL filter

 

Combination of STC Pure Hybrid CPL filter and STC ND 1000 clip filter

 

Thanks go to STC and their UK distributor InfinityX for supplying the new Pure Hybrid CPL filter for the purposes of this review.

As an extra incentive to purchase a Pure Hybrid CPL filter (or any other STC filter) there is a special 10% discount to be had when you add the discount code: 2023tpfp10off at the checkout through the link below.

https://www.stcoptics.com/discount/2023tpfp10off

The sun has now started to appear on a near daily basis now. That can mean only one thing!

Time to break out the Infra Red filters!

I should start by thanking our good friends William and Ashley at STC Optics for kindly providing the filters used in this review and  Protech Repairs for converting the Fuji X-E1 to a full spectrum pass filter.

In this review I will be testing 4 STC clip filters – 3 Infra Red pass filters consisting of: 590nm, 720nm and 850nm, in addition to this I will be testing a 650nm UV/IR cut filter.

The frames of  STC clip filters are made from black anodised 304 stainless steel which is virtually non magnetic, the glass itself is a mere 0.5mm thick and has a special nano coating to prevent dust from sticking to it.

First the basics – Infra Red pass filters allow the transmission of infra red light at varying wave lengths – the higher the number the less visible light is allowed through. A UV/IR cut filter on the other hand cuts out both UV and Infra red wave lengths – in the case of the STC clip filter, it absorbs UV light from 650nm. When fitted to a full spectrum pass converted camera and set to daylight balance it effectively becomes a regular camera suitable for general photography once more. (I used this particular set up when on holiday this year to reduce the number of cameras carried.)

How to use the clip filters with a Fuji mirrorless camera.

When using infra red filters of any kind the camera must first be adapted for use with infra red filters – this usually involves having the hot filter (this blocks infra red light) removed and replaced with a full spectrum glass. Warning – do not attempt do do this yourself, if something goes wrong you could be left with a very expensive paperweight! Contact a reputable company to undertake the process. – See link at bottom for my personal recommendation.

Installing the filter

When using the clip filters for a Fuji mirrorless system for the first time, be aware that on the reverse side of the filter the two outer edges have a sticky layer, this is revealed by removing the clear cover layer.

Remove the camera lens and place the filter into the throat of the camera, ensuring the lettering on the filter is facing outwards –  most of the STC clip filters will only fit one way up with the exception of the Fuji filter , this will fit upside down, but with lettering outward. Very gently press the outer edges of the filter to ensure the sticky layer make contact, replace the lens.

 

Inserting clip filter                                                                                                          Clip filter in position

 

Before taking a photograph a custom white balance must be made. This is done by first setting the camera to ‘Custom White Balance’, (the exact method of making a custom white balance vary with each camera model, consult your camera manual for further guidance.) Typically a 590nm balance is created using a white sheet of paper, for 720nm and upwards the white balance is done using green foliage as the neutral point.

The setup

For this review I used a full spectrum converted Fuji X-E1 plus a conventional Fuji X-T1 as a bench mark for daylight colour balance. Two lenses were used – the lake images were taken using a Meike 12mm f2.8 manual focus lens, the broken wall images were taken with a Andoer 35mm f1.8 manual focus lens. Custom white balances were made and set prior to taking the photographs, lenses were stopped down to f8, shutter speed set to Auto and sensitivity was 200 ISO. In both sets of tests the camera used was fitted to a tripod. All images were saved as Jpeg fine, large and 3:2 ratio. Focus confirmed prior to exposure. Lighting conditions were bright and sunny. It is worth remembering that Infra red light focuses at a different point to the visible spectrum, so ignore the fact that when focusing the point at which infinity is sharp will not align with the infinity mark on your camera.

 

Test images

The Lake photographs are shown in ACR (Adobe Camera Raw) to illustrate the wavelengths of light each filter passes.

 

590nm pass filter

720nm pass filter

850nm pass filter

Converted Camera set to Daylight balance – No filter

UV/IR Cut Filter – Camera set to Daylight balance

Unconverted Camera set to Daylight balance – No filter

 

Wall and doorway

590nm pass filter

720nm pass filter

850nm pass filter

UV/IR Cut Filter – Camera set to Daylight balance

Unconverted Camera set to Daylight balance – No filter

 

Additional Sample Images

                                   850nm Pass filter – Image converted to Black and White                                                 850nm filter – No Adjustment

 

UV/IR Cut filter in converted camera – Daylight Balance                                             UV/IR Cut filter in converted camera – Daylight Balance

 

Conclusions

All the photographs were opened and examined at 100% in Adobe CC on a colour profiled monitor, no alterations were made, the images are just as they came from the camera. The images were observed to be sharp from edge to edge and free from distortion and fringing.

The photographs taken with display more detail in the shadow areas compared with the full colour images, it is worth noting that there is a colour balance difference between the images taken with the UV/IR Cut filter and the unconverted camera, this could be down to the amount of UV/IR being blocked by the clip filter compared with a lens without a UV filter and also the variance between the sensor arrangement of the two cameras used, in saying that either of the colour images is perfectly acceptable when viewed on its own.

The all important question is. Do the STC clip filters offer value for money? For a Fuji X series APS-C  prices range from £96.99 for a single STC clip filter infra red filter (including case) to £111.99 for the UV IR Cut filter.

Whilst this might appear expensive at first glance, consider the cost of purchasing a filter for each lens you wished to use and in the case of ultra wide angle lenses that have a protruding front element fitting a filter is not possible.

Taking all this into account, the STC clip filter range offer excellent quality and great value for money. I own a number of STC clip and screw-in filters and would not be without them.

STC are unique in the range of clip filters that they offer, fitting cameras from Nikon Z series to Pentax APS-C and most cameras in between.

 

Update : STC Optics are offering readers of this blog a special discount on all their filters. Use the link below and add the discount code: 2023tpfp10off at the checkout.
Filters can be purchased direct from STC Optics

For further information on Infra Red conversions contact Protech Repairs