Puntofocale

While this filter should work on different filter systems as long as they have a rear CPL filter, it was specifically designed to be used with Haida’s own M10 filter kit which comes with a drop in CPL filter while a 0.9ND CPL and 1.8ND CPL are also available to offer even more flexibility.

And now a series of crops with the CPL and Insert Variable ND at various different exposure settings. I’m going from one to four stops, and even going past the maximum settings to nine stops. See, there’s nothing to limit how far you can rotate the CPL filter. It’s a shame since this is a standard feature with most circle variable ND’s.

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Distanza focalefotocamera

To do this I grabbed the Sigma fp and the new 24-70 f2.8  DG DN Art and set the camera to 24mm and pointed the camera the sky.

As you can see, there’s not really much in it at all. Using the filters adds a slight warming effect of around +14 temp and -3 tint to the image. The critical element – sharpness – remains almost unaffected. Pushing way past the recommended limit to nice stops does add a bit more color cast with a slight purple hue and a little less contrast. Sharpness is still good though!

The Insert Variable ND filter, like Haidas other filters, also comes with a scratch and waterproof coating. While I’m not going to test the scratch part, I did want to play around with some splash photography. It was fun to see the water just slide off the filter.  It makes it much easier to keep the filter clean too, which is a nice bonus.

Lastly, I wanted to look for the dreaded X pattern that variable ND filters can cause. This is why recent circular variable ND’s come with limiters  – to stop you from rotating the filter after a certain point. Although this combination has no such feature so you can easily go past the recommended amount.

Lunghezzafocalee zoom

Inside the box, Haida treats you to a lovely metal filter box. It does a great job of keeping the filter safe. Inside that box, you’ll find the Insert Variable ND.

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Unlike a traditional Variable ND filter, the new Haida Insert Variable ND is a single 100mm square polarizing filter. It’s kinda obvious fro the photo above. You use it with “other” CPL filters to create the variable ND effect.

To test the sharpness of the filters, I wanted to use a long focal length. In the past, I’ve had filters that were great on the wide side, but got soft past 100mm. I grabbed my Sigma sdQ which uses the 19.8mp Foveon 1.5x crop chip that can at time resolve more than a 36mp FF Bayer and the 70-200 f2.8 Sport.

Having separate control over exposure and reflections adds more creative options. Combine that with the extra flexibility a square holder kit provides, and you’ll give photographers/videographers incredible control over the final output.

The whole point in this Insert Variable ND filter is to easily adjust the exposure between a few stop-ranges. Let me quickly go over just what you get with each drop in CPL combination.

For anyone wondering, yes! You could use the Insert Variable ND with other holders with rear adjustable CPL filters if that’s what you have.  Although I do find using the filter with Haida’s own M10 holder with its quick-change CPL makes for an enjoyable photographic experience.

Changing the CPL filter in the M10 kit is also rather easy. You just grab the red clips at the top, push them in and pull the filter out. Then you drop in the new filter in, making it simple to go from one strength of Variable ND to another. Here is a quick demo for that:

Focalesinonimo

At 24mm (full-frame) with four stops of ND, we start getting some vignetting at the top left and bottom right corners. You can rotate that pattern by moving the front filter. If you go way past the recommended maximum exposure you can clearly see the X shape appear at seven stops.  The effect will vary from lens to lens and there are two ways to avoid the pattern: Using longer focal lengths and using a stronger drop in CPL to reach that ND level.

In real-life use, though, when shooting landscapes, I don’t feel that X is going to be much of an issue if at all. I shot this photo with the same combination as the tests above. While I don’t know the exact strength of the ND effect (there’s no way to tell without having a base exposure), I was a good bit past the maximum setting.

For this test, I took my Sigma sdQ-H and did three shots: One without any filters; One with the Insert Variable ND and CPL; and another with the internal IR-cut filter (Hot-Mirror) removed. I used a special filter from Kolari Vision to show what parts of the scene would be most affected by IR light, so we know where to check for the infrared pollution.

Now there is no hard stop with this combination, so you can actually go past the recommended maximum. You start to degrade image quality doing so, by how much depends on the scene or lens used.

Overall I’m really happy with the results and wish I could actually go travel around to get some better landscape images but sadly Scotland still has restrictions on travel at the moment.

To use the filter you simply place it in the front of the M10 kit. A CPL filter is in the back; and to change exposure, you rotate the little CPL dial to achieve the desired results.

La sequenza degli Stop o dei valori dei numeri f viene standardizzata al congresso di Liegi nel 1905 ed è rappresentata da una progressione geometrica di ragione 2 {\displaystyle {\sqrt {2}}} (circa 1,4), in quanto considera il diametro equivalente dell'apertura relativa, invece della superficie, e comprende i seguenti intervalli:

I’m very pleased with the Insert Variable ND filter. Particularly the image quality and for around $85 it offers great value over buying several standard ND filters. If your main focus is using wide angles with a strong ND effect then a fixed ND filter would offer better image quality. You should not be surprised by this, and its the tradeoff you get when you need a more versatile tool.

Un alto rapporto focale, come ad esempio f/12 o superiori, determina un obiettivo poco luminoso, detto anche lento (per il motivo opposto a quello precedentemente illustrato).

But what if you wanted both the convenience of a Variable ND filter AND the ability to use graduated or other filters. This would give you far more control over the scene that you are going to capture?

Valori come f/0,95 o f/1,4, con basso rapporto focale, indicano un obiettivo fotografico o un telescopio particolarmente luminoso, anche detto veloce (in quanto per la stessa quantità di luce può essere utilizzato un tempo di posa più corto, più veloce appunto), adatto a tempi di esposizione brevi anche nel caso di condizioni di scarsa luminosità, nel caso dell'ambito fotografico, o a una maggiore capacità di raccogliere luce, a parità di diametro, nel caso di un telescopio.

Il rapporto viene espresso graficamente come “ 1:n ”, “ ƒ/n ” o “ f/n ”, dove “ n ” è il numero risultante dal rapporto: ad esempio, se la lunghezza focale ƒ di una lente è 10 mm e il suo diametro di apertura è di 5 mm, il rapporto focale può essere espresso come 1:2, ƒ/2 o f/2, ovvero, 10 : 5 = 2 (a volte si trova anche f2, ma è una forma non propriamente corretta).

Aperturafocaleobiettivo

I set the lens to 135mm at f6.3, this should let me focus purely on any changes the filters are having to the images. I then took a shot without the filter and here is the overall scene.

Il rapporto focale o numero ƒ di un qualsiasi obiettivo, è il rapporto matematico tra la lunghezza focale (ƒ) e il diametro (D) della lente sottile equivalente, dalla quale entra la luce, o del diametro effettivo del diaframma del sistema, detta anche «apertura» o «pupilla d'ingresso». Ciò vale anche per gli obiettivi a specchio riflettore.[1]

From my testing turning the CPL dial no longer has any effect on the reflections on the image. It simply darkens the exposure. You can rotate the front filter to control reflection, as you can see in this demonstration.

Lunghezzafocaleedistanzadal soggetto

The filter looks great between its recommended minimum and maximum settings. Honestly, at 135mm, the image starts to degrade only at nine stops of ND. Wider lenses will degrade quicker though. But even then, results can be in a pinch, as you can see with this quick edit.

Un basso rapporto focale determina anche alcuni problemi di natura ottica come quelli della coma e di altre aberrazioni; in questo caso è necessaria l'applicazione di costose tecniche di correzione che fanno aumentare il valore commerciale dell'ottica in questione.

In genere il diaframma è progettato per variare la quantità della luce in ingresso, almeno di 4 o 5 stop (di norma 7 stop), ma alcuni modelli possono raggiungere anche una possibilità di scelta di 10 stop. Queste selezioni avvengono tramite regolazione meccanica, manuale o automatica, oppure controllata elettronicamente: alcuni obiettivi non hanno la ghiera manuale dei diaframmi e in alcuni modelli gli intervalli possono avere sub divisioni di 1/2 stop o addirittura fino a 1/3 di stop.

All this ease of use wouldn’t really be worth it, though, if the image quality wasn’t up to scratch. I did a few tests to try and stress the filters.

Even going two stops past the recommended limit for the Insert Variable ND + CPL combo at 35mm (45mm equivalent) the image has an even light reduction. With a corrected white balance any Infrared pollution is minimum.

Normally when we think of Variable ND filters, we think about a circular filter. One that gives us the ability to change the exposure simply by rotating the front element. Something like this K&F concept one I  recently reviewed here.

Next up I wanted to test for Infrared pollution. Lots of ND filters these days also block infrared light. It’s not something that’s normally part of Variable ND filters and some people recommend not using them on cameras with weak hot mirrors and use regular ND’s instead. The reason for this is that blacks can start to turn slightly red when you reduce only the visible light.

Paul Monaghan is a creative photographer based in Scotland. Paul is on of the leading landscape photographers in the UK and is an authority on ND filters in the industry. Among others, Paul is a Sigma UK Ambassador.

Nei sistemi ottici dotati di un diaframma regolabile, che consente di variare il rapporto focale, è possibile ricercare un compromesso tra qualità dell'immagine (in particolare la sua risoluzione) e luminosità dell'ottica. Entrambe queste qualità sono desiderabili, ma mentre la luminosità aumenta al diminuire del rapporto focale, la qualità dell'immagine migliora al suo crescere. Questo però è vero solo fino ad un certo limite: quando il diametro di apertura scende al di sotto del millimetro, diventano significativi i fenomeni di diffrazione della luce, che causano un veloce deterioramento della qualità dell'immagine al crescere del rapporto focale.

All'aumentare del rapporto focale (es: f/4 o f/5,6), diminuisce l'apertura dell'obiettivo e dunque anche la luminosità dell'immagine ottica formata.

Sistema utilizzato per unificare gli stop delle ghiere di tutte le ottiche, indipendentemente dalla loro lunghezza focale e dove ad ogni stop corrisponde una sezione del "foro" con un'area raddoppiata rispetto al valore precedente e pari alla metà di quello successivo. La modalità degli stop deriva presumibilmente dalla camera oscura e serviva per facilitare la regolazione accurata dell'apertura sull'ottica del riproduttore, agendo al "buio" (o alla cieca): utilizzando dei blocchi o dei fermi a scatto, sulla corsa della ghiera, viene segnalato al tatto uno spostamento di apertura pre-calcolata. La stessa "procedura" degli stop sulla ghiera del diaframma, può essere estesa anche ai tempi, alla sensibilità e alla correzione esposimetrica; per cui, quando si dice un f/stop o uno stop, è comunemente intesa una qualsiasi regolazione che provoca il doppio o la metà di luce sul sensore o sulla pellicola.

Paul Monaghan is a creative photographer based in Scotland. Paul is on of the leading landscape photographers in the UK and is an authority on ND filters in the industry. Among others, Paul is a Sigma UK Ambassador.

Lunghezzafocaletelescopio

As you can see this combo gives almost identical results to the normal CPL filter supplied with the Haida M10 kit. This is great news and a good sign of the filter quality.  I have had filters before that had different color casts with different strengths of ND effect, even when they were part of the same line.

One drawback I did find is that it’s hard to tell how much ND effect you are actually using. Without any physical markings or rotation limitations, it’s easy to go past the recommended maximum ND effect. Still, photography isn’t about camera settings, it’s about capturing light. The control and freedom to shape the scene are worth more than knowing exactly how much ND you apply.