I'm still debating whether there is real difference between the Irix on APS-C and my Sigma 8-16mm set to approximately the same zoom setting and I think I can see better corner detail, less smearing and better contrast but unsure. Anyway, the fact I can use the Irix on my full-frame K-1 where I don't have anything close to that angle of view on FF means I won't be sending it back. It is now my preciousss!
Actually never had to use it but now that I have an Irix 11mm/f4.0 Blackstone it’s starting to make a lot of sense! Have a look at these crops, first with lenscorrection module enabled but without TCA override and the second with. Huge difference! I did do some straightening and sharpening which normally accentuates any color fringing issues but this is amazing output!
First image is 400px crops from the corners, sides and center without TCA-override, second with and the last is the final image which was also corrected in the rotate and perspective module.
So the good news is that this lens is an absolute stunner in terms of optical performance both on my full-frame K-1 Mark II as well as on my full-spectrum converted K-3 with an STC 720nm clip-in filter.
Found a Pentax LCP correction profile for it on the Irix website which ChatGPT converted to a Lensfun Calibration file. I shot some stupid testshots right after getting this lens which was a steal as it was a demo model at my favorite camera store (CameraNu in the Netherlands).
Sharpness for such a wide lens across the frame is quite amazing and the lack of any noticeable hot spot in infrared is a relief. Even in IR, edges and corners don't degrade into mush nor does stuff in the background like with the Sigma 8-16mm.
So...what's the bummer? Sticky aperture lever causes wrong exposures. I noticed in while shooting, initially though it was an incompatibility with the latest Pentax firmware corrected by Irix in late 2024 but when I unmounted the lens and moved the aperture actuator to it's wide open position it either returned slow or not at all to minimum aperture. The store is decent though so I receive a free drop-off label with 15 minutes of me calling them. I ordered a new one which will be delivered tomorrow so my only problem now is impatience. The difference in price was unbelievably low; I paid €279 for the demo version but they were on sale now so only €404 for a new, sealed, lens.
Apologies for the sorely lacking test shots but the lens is on its way back via PostNL already. I thought of some tests I could run such as setting the Sigma between its 10mm and 12mm markings and shoot an aperture series on the tripod, minimally processed, as the control. Then, careful lifting the camera off without moving the tripod and then replacing the Sigma with the Irix. Can't change lenses while still on tripod because of the clip-in filter.
To be continued...
"𝘏𝘰𝘸 𝘢𝘳𝘦 𝘺𝘰𝘶 𝘨𝘶𝘺𝘴 𝘥𝘰𝘪𝘯𝘨?" someone asks when I’m walking the dog in the park, with my camera of course (many people in the village know me as "that guy with the old English sheepdog and the camera"). What a horrible question, why such a horrible question, such a meaningless, evasive, neutral question where it seems obvious whoever asked it isn't actually interested in the answer to begin with - just being polite.
I often answer along the lines of "𝘞𝘦𝘭𝘭, 𝘲𝘶𝘪𝘵𝘦 𝘖𝘒. 𝘈𝘯𝘥 𝘺𝘰𝘶?". I am perfectly aware that this person knows very well that our son took his own life 7 years ago but cannot cope with the fact, is actually startled to run into me. Mistake, wasn't in the plan, I just appeared around a bend and there wasn't a side path for him to slip in to, so no chance to avoid me. Cowards, both of us.
But am I really that much better than with my "𝘸𝘦𝘭𝘭, 𝘲𝘶𝘪𝘵𝘦 𝘖𝘒"? Am I actually coping with it then? Do I dare to say "𝘳𝘦𝘢𝘭𝘭𝘺 𝘣𝘢𝘥 𝘢𝘤𝘵𝘶𝘢𝘭𝘭𝘺" on days when it feels that way, which is quite often? No, I am just the same. A coward. I don't dare do anything else, not even challenging "𝙝𝙤𝙬 𝙙𝙞𝙙 𝙮𝙤𝙪 𝙖𝙘𝙩𝙪𝙖𝙡𝙡𝙮 𝙚𝙭𝙥𝙚𝙘𝙩 𝙄'𝙢 𝙙𝙤𝙞𝙣𝙜" when I'm having a rebellious day.
It is a winding path that we walk. One day things go a little better, and the next day you hit rock bottom again. The Arabs have a saying for it: "yom asal, yom basal," which means something like "one day tastes like sweet yogurt, the next like sharp onion" (roughly translated, that is).
I often choose the middle ground and am honest for just a moment: "𝘏𝘰𝘸 𝘬𝘪𝘯𝘥 𝘰𝘧 𝘺𝘰𝘶 𝘵𝘰 𝘢𝘴𝘬, 𝘐 𝘳𝘦𝘢𝘭𝘭𝘺 𝘢𝘱𝘱𝘳𝘦𝘤𝘪𝘢𝘵𝘦 𝘵𝘩𝘢𝘵. 𝘚𝘰𝘮𝘦𝘵𝘪𝘮𝘦𝘴 𝘵𝘩𝘪𝘯𝘨𝘴 𝘨𝘰 𝘢 𝘣𝘪𝘵 𝘣𝘦𝘵𝘵𝘦𝘳, 𝘴𝘰𝘮𝘦𝘵𝘪𝘮𝘦𝘴 𝘢 𝘣𝘪𝘵 𝘸𝘰𝘳𝘴𝘦. 𝘛𝘰𝘥𝘢𝘺 𝘐'𝘮 𝘩𝘢𝘷𝘪𝘯𝘨 𝘢 𝘨𝘰𝘰𝘥/𝘣𝘢𝘥 𝘥𝘢𝘺."
We won't be getting off that winding path anymore. The straight road has been broken up for good. That is the "injury time" we live in, as my wife describes it in her book. I have been walking this winding path daily for years now, both with my feelings - in a figurative sense - as well as with my dog - in a literal sense.
This is the photo I shot this morning. I had to have "𝙩𝙝𝙚 𝙘𝙤𝙣𝙫𝙚𝙧𝙨𝙖𝙩𝙞𝙤𝙣" twice... luckily I had the camera with me as a diversion/distraction.
Full-spectrum K-3 with Sigma 8-16mm and 720nm filter
It's not the greatest of lenses for IR although I'm just teasing it a bit since I got the STC clip-in filter. These were mostly shot at the wide end (8mm) and at a reasonable aperture (f6.3) which avoids the worst effects of diffraction and is not wide-open. Results are a bit soft except for the centre of the image. I'm getting the Irix 11mm tomorrow and will see how it compares to the Sigma.
The STC 720nm clip-in filter was delivered this morning - 3 days after I ordered from TW to NL, that's in and by itself is quite amazing. I only had time for a few quick testshots through my bedroom window and that confirms my earlier assessment with the IR/UV cut clip-in filter: it pretty much works as advertised ... with caveats.
At F16 I get to see how dirty my sensor is, and then some. The bulbous front element wasn't too clean either and I shot through my bedroom window so all less than optimal I suppose. I'll give everything a good cleaning next time. Sharpness was pretty ok throughout the frame except for the amount of blur due to going way over the diffraction limit of course.
At F4.5 the images seemed fairly clean and reasonably sharp in the center but the corners were extremely fuzzy due to field curvature of this lens. It's crazy on a regular APS-C body and IR seems to aggravate the situation. I found F7.1 to be the right "compromise" without too much sensor filth showing, way less diffraction and decent sharpness in edges and corners.
I do note that the B&W shots were fairly straightforward but using a color LUT has quite a penalty as it accentuates a central hot spot it the red channel (at 720nm that should be no surprise to anyone). This was fairly manageable with a masked application of the [color contrast] module in DarkTable. The mask was a round mask centered in the image with a size of 75% of the image height and a 150pixel feathering radius around it (see example screenshot).
Preliminary conclusion: usable filter but with limitations when using an extreme UWA lens. Could be fun inside churches or with modern architecture, somewhat less for landscape.
I added this month's shots (and some reprocessed ones from earlier this year) so it it is back up to date now - I had neglected it for too long. It's just my photography site so feel free to take a look in this (or in any of the other albums for that matter).
A few shots which I got around to converting and processing only today. I used the deep pink LUT on these but then changed color impact in the [Color Contrast] and [Color zones] modules (see example) for conversion to jpeg. Post-processing consists of applying GMIC's illustration filter at low strength to enhance (micro)contrast and a run through Digikam's Showfoto editor for levels&curves.
A few shots which I got around to converting and processing only today. I used the deep pink LUT on these but then changed color impact in the [Color Contrast] and [Color zones] modules (see example) for conversion to jpeg. Post-processing consists of applying GMIC's illustration filter at low strength to enhance (micro)contrast and a run through Digikam's Showfoto editor for levels&curves.
Update:
I've taken my test shots (K-3 full-spectrum + sigma 8-16mm + UV/IR blocking clip-in filter in lens mount) and run them through a script that takes 400x400 pixel crops from corners, edges and center. As you may or may not know, when the EXIF for this lens shows 0mm that means you shot at a focal length below 10mm (for some reason no one contemplated a zoom lens could go that wide I suppose).
The script labels each crop in a 9x9 grid with the filename at the top - said filename includes the ISO, aperture and focal length (either replaced when zero or the real focal length above that).
This should allow me to critically assess acceptable parameters such as minimum focal length and aperture combinations. Mind you, this is not on a regular Pentax body but one with the hot mirror filter over the sensor removed and a UV/IR blocking clip-in filter inserted in the lens mount. So these results should be indicative of expected sharpness with the 720nm filter I'm about to receive but are probably far from the critical sharpness when used on for instance an unmodified APS-C body such as my KP. I could not discern any hotspots anywhere so that gives me some hop the body will perform the same under 720nm.
It is no secret that on any rectilinear UWA the corners will be petty smeared out due to distortion - they are "pulled and stretched" so to speak. Initially I'm quite surprised that it takes closing the aperture all the way to F16 to get this under control at 8mm. This carries a penalty of higher ISO and more noise but still I would have expected the correction to kick in closer to F8-F11.
At the slightly longer focal lengths of 13mm and 16mm F8 seems to do the trick just fine where at 13mm even F4.5 is almost acceptable. I see a tiny bit of de-centering in the top-right image which lags in sharpness compared to the other corners.
I had tested one of STC Optics's clip-in filters (UV/IR cut or "hot mirror") for my full spectrum K-3 (legacy model) to see if it would make my camera equally usable for infrared as well as normal shooting. The outcome is that it does and it doesn't - more details on my blog about that which I've shared a couple of times on Reddit.
But last week I took my underused Sigma 8-16mm out with the K-3 to see how a true UWA lens would fare with the clip-in filter as I've heard the oblique angle of light might play havoc with sharpness and internal reflections. I'd had a taste of that with my DA16-85 at its widest when I tested it for my blog (totally unscientific so don't get excited).
To my surprise, the combo full-spectrum K-3 + STC clip-in hot-mirror filter + Sigma 8-16mm actually gave some pretty decent results, apart from the widest setting at 8mm. Shots I took at 10mm and beyond and at various apertures actually looked as sharp as they do on my regular KP.
So I dit the unthinkable and ordered STC's 720nm clip-in filter. My plans are to try and go for some spectacular interior architecture shots in B&W if everything works out and maybe goof around a bit in color as well. I'll keep you posted when it arrives - Taiwan to Europe may take a while I'm afraid...
I shot this scene on a full-spectrum converted Pentax K-3 with the SMC-F 28mm/f2.8 lens and a Hoya 720nm filter.
For the first, the PEF file was converted twice in Darktable, once with the IR LUT deep gold, once with deep pink and the images were opened as layers in Gimp for some selective masking to reveal the various colors. The other two were converted with the deep gold LUT. All images were corrected for levels & curves in Digikam's editor (Showfoto) and subjected to GMIC illustration filter at reduced strength.
De maand mei is de maand van de mentale gezondheid
https://psycholoog.nl/.../mental-health-awareness-month.../
In mei mogen we stilstaan, maar ook actie ondernemen en begrip creëren voor de mentale gezondheid. Er heersen veel stigma’s rond psychische aandoeningen en mentale problemen. Vooral het doorbreken van taboes is iedere dag belangrijk.
Veel mensen kampen met stress, zorgen, verdriet, depressies, angsten of andere mentale uitdagingen. Hier wordt vaak niet openlijk over gesproken waardoor het vaak als een eenzame strijd voelt.
Ken je familie of vrienden die hier mee worstelen? De zorg is vaak moeilijk bereikbaar en op het werk of in de studie krijgen mensen weinig begrip. Herkenbaar? Laten we dan wat meer empathie voor elkaar hebben en het onderwerp mentale gezondheid niet mijden. We kunnen samen verzachten en verbinden.
Lees boeken, luister podcasts of bekijk documentaires over de mentale gezondheid en breng het gesprek op gang. Stuur mensen een lief berichtje of kaartje en zeg niet veel, maar zeg net genoeg. Soms is een (virtuele) knuffel genoeg of soms kan je iemand aan de hand nemen.
These ferns in my garden are unfurling themselves and reminded me of some kind of insect alien rearing up...I tried to emphasize this a bit in post.
PEFs converted with Darktable, some post-processing with GMIC, Gimp and Showfoto
The first one is with the Pentax SMC-F 28mm/f2.8 lens, the others with the DA16mm/f4 Ltd lens