Irix 15mm f/2.4

[Harald]

Sorry, German autocorrection...

Harald

[bjornthun]

Being able to calibrate the infinity stop is very good news, since I would be using the lens with an adapter to Sony E mount. Now I wonder, if the lens uses floating elements, since that will require in theory a calibration of the adapter. This since a floating element construction relies on a properly calibrated flange.

[Tristin]

I really like some of the design detils such as the engraved and fluorescent markings, hopefully the lens is serviceable.

[Harald]

Hi Bjorn,

the adapter needs to be able to control the electronic aperture!

Harald

[bjornthun]

Hi Bjorn,

the adapter needs to be able to control the electronic aperture!

Harald

Yes, for the Canon EF version. I assume that the Nikon version is Ai-S or Ai-P, in which case a mechanical adapter will do, but EXIF and full exposure automation of the Canon version is nice. There are many Canon EF to Sony E adapters to choose from.

I will wait for further tests.

Note that Cyberphoto.se is a Swedish internet shop, when you read their test.

[stenrasmussen]

I am very keen to learn more about the Irix. Currently on my 2nd copy og the latest generation Sammy Fourteen and the problem with decentering and focus seem persistent. Will give it one more go before I order the Irix...I think.

[bjornthun]

The price in was just under 7000 SEK, so still quite favourably priced.

I wonder if an f/2.4 lens stopped down to f/2.8 will vignette less than a lens with a max aperture of f/2.8 at f/2.8. Any thoughts on this, regarding Sammy/Irix 14mm?

[Tristin]

I wonder if an f/2.4 lens stopped down to f/2.8 will vignette less than a lens with a max aperture of f/2.8 at f/2.8.

Entirely dependent on the lens. 

[Roland Vink]

With many (most) lenses, closing down half a stop from wide open makes no difference to the corners - the corners are already stopped well down due to mechanical vignetting. The aperture blades don't start to intrude into the corners until stopping further, and then they only do so by trimming the extreme points of the "cats eyes". At these settings the aperture blades tend to stop down the central region only, so that it starts to "catch up" with the corners, resulting in more even illumination, and vignetting is reduced. Most lenses require stopping down at least 2 stops before the aperture blades are the only thing affecting the aperture (mechanical vignetting is eliminated), and some zooms and extreme fast lenses may need 3 stops or more.

This is also why the corners of many lenses do not improve until the lens is stopped well down.

[MFloyd]

Already 3 pages and no one single image. Looks nice at least:






And a small video clip https://youtu.be/EJBu7BTeCu8

[Hugh_3170]

The rear view of the lens has me intrigued:  is it showing the rear most lens element or is it showing a filter or the like that is covering the rear element?  As shown, there appears to be one side slightly shaved off?  Anyone know?

[Tristin]

Hugh, it is a gel filter.

As for the comments on why all the fast ultra-wides, Irix has an 11mm f/4 coming.

[MFloyd]

The rear view of the lens has me intrigued:  is it showing the rear most lens element or is it showing a filter or the like that is covering the rear element?  As shown, there appears to be one side slightly shaved off?  Anyone know?

Here you see the gelatin filter:

[Bjørn Rørslett]

A gel filter has lost much of its raison d'etre in the digital era, with an exception for IR and false-colour IR photography in which gels are an attractive alternative to huge front-mounted filters.

The official Irix 'Mountains & Milky Way' image intended to show the quality of the lens instead highlights uneven sharpness over the frame and clear signs of decentering. Image centre and upper left corner appear OK, but elsewhere there is frankly a lot of mush. Little chromatic nasties though. Thus, QC or lack thereof apparently is something these third-party products are troubled with.

[bjornthun]

Have a look at the street lights in the lower left section. They are elongated and become short stripes rather than point sources. The stars also show this, particularly toward the right edge. I first wondered if the exposure was too long, so it caused a beginning star trail, but the shape of the street lights have me wondering.