[Rickster]

Got my Irix Blackstone last week. I'd like to thank all the great photographers who have shared their photos and experience with this lens. Thank you all!

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Last edited by Rickster; 09-08-2017 at 05:44 AM.

[Rickster]

Finally got out today to try out my Blackstone. Today's test was to preset the focus for F/8.0 hyperfocal. I also tried a shot with the sun in frame to test flare. All shots handheld. Tested the lens for decentering and found none. Sharp in all corners. I'm very happy with this lens.

All images ISO 100 F/8.0 1/45, 1/250 & 1/30 respectively







(Also posted in 'Post your K1 Pictures)

[PaulRookes]

Made the jump and ordered the 15mm firefly, unfortunately it suffered from what I see is a common fault with the 15mm Irix lens, its significantly soft on the left hand side, so unfortunately it has been returned to the shop (posted)….who are apparently going to test it, and send me a good one if they also note the fault.

Initially the shop said it was my K3 lens mount(surmised from my phone conversation?) it’s not the mount, as all my lenses are ok on this camera, so I now have a two week wait, so not a pleasant experience so far.

However, other than the problem above, I’m still impressed with the overall build of the lens…hopefully if I get a good one soon, I will be able to be more positive, we will see.

Example of the problem below, 1/250sec@ f/5.6, ISO 100
problem is evident at all settings, you can see it with the usual test charts, brick wall...
second image is two combined shots showing the left and right, i.e. lens rotated left to right to show the same pylon at the edge....

[Jens Lyn IV]

Those metadata don't make a lot of sense; my K-1 certainly doesn't pretend my Irix is a Sigma zoom lens. I'm curious how this could have happened.

And if the edges are that bad on APS-C, you are right to demand a replacement, and the shop are full of BS blaming it on the lens mount. My copy looks impeccable on full frame, even with pixel shift enabled and the sensor shifted ouside the nominal image circle. Ideally you'd test the replacement with a full frame camera, but at least use Composition Adjustment to get as far into the corners as possible.

Good luck.

[PaulRookes]

Those metadata don't make a lot of sense; my K-1 certainly doesn't pretend my Irix is a Sigma zoom lens. I'm curious how this could have happened.

And if the edges are that bad on APS-C, you are right to demand a replacement, and the shop are full of BS blaming it on the lens mount. My copy looks impeccable on full frame, even with pixel shift enabled and the sensor shifted ouside the nominal image circle. Ideally you'd test the replacement with a full frame camera, but at least use Composition Adjustment to get as far into the corners as possible.

Good luck.

Sorry about that, first image was from my old Sigma 17-50 at 17mm, (now corrected) closest I could get to 15mm, I did a side by side test to confirm in the field what I already knew regarding the lens mount, before I sent the Irix back.....yes BS, I understand them checking to see if the lens has a problem, and they are going to check the next lens before they send it to me. Like you I got annoyed when they immediately blamed the lens mount!
I do now have an email from them confirming they will refund if I’m not happy, apparently they are not aware of the QC problem, I shouldn’t believe everything I read… and they will look at it next week…I suspect the first copy was a returned lens and the replacement delay is due to a lack of Pentax fit stock …..Always a problem with Pentax fit lenses here.
Thanks again for your input…..

[PiotrM]

Hopefully this is the right place to post this. I got my Irix a month ago. I'm not a pro photographer and have never owned a wide angle lens before and don't know what to expect. Here's a representation of a photo I took a few days ago. I placed three crops at the top. All 3 crops are from near the horizon at the middle of the photo.

IMO there is definitely softness at the left and right. I have a similar pixel shifted shot of this scene. Pixel shift does a good job of sharpening the middle, but it's hopeless at the left and right cropped areas.

Note that the red cross hairs show the middle of the photo, which means that horizontally it's close to the horizon. I cut the top 45% of the pic off because it's just blue sky.

What do people think? Should I send it back?

[PaulRookes]

Hopefully this is the right place to post this. I got my Irix a month ago. I'm not a pro photographer and have never owned a wide angle lens before and don't know what to expect. Here's a representation of a photo I took a few days ago. I placed three crops at the top. All 3 crops are from near the horizon at the middle of the photo.

IMO there is definitely softness at the left and right. I have a similar pixel shifted shot of this scene. Pixel shift does a good job of sharpening the middle, but it's hopeless at the left and right cropped areas.

Note that the red cross hairs show the middle of the photo, which means that horizontally it's close to the horizon. I cut the top 45% of the pic off because it's just blue sky.

What do people think? Should I send it back?

No expert, but I would say yes.
It shows up very clear shooting a chart.....and shot at infinity with similar or the same subject to show.
Its also seems to be a trend that these lenses are soft on the left side?
check this out



Irix 15mm frustration - PentaxForums.com

[Jens Lyn IV]

Both edges look soft, the left perhaps more so. This might be field curvature failing to maintain infinity focus throughout the frame at f/4.5, combined with slight decentering. Have you tried different focus settings, comparing the centre and edges in live view? At f/4.5, you may need to use a compromise focus setting, rather than focusing for peak sharpness in the centre of the frame.

[Rickster]

Hopefully this is the right place to post this. I got my Irix a month ago. I'm not a pro photographer and have never owned a wide angle lens before and don't know what to expect. Here's a representation of a photo I took a few days ago. I placed three crops at the top. All 3 crops are from near the horizon at the middle of the photo.

IMO there is definitely softness at the left and right. I have a similar pixel shifted shot of this scene. Pixel shift does a good job of sharpening the middle, but it's hopeless at the left and right cropped areas.

Note that the red cross hairs show the middle of the photo, which means that horizontally it's close to the horizon. I cut the top 45% of the pic off because it's just blue sky.

What do people think? Should I send it back?

I wouldn't send it back just yet.

I'm not sure this technique is the right way to test this issue. (Decentering) I think it is best to do a critical focus on a distant object in the center of the lens field, lock the focus, then rotate & tilt the camera on your tripod (you are using a tripod, right?) to take 4 additional frames of that same object in the 4 corners of the image field. In your test above the towers on the left and right are not in the same image plane as the center focal point.

[PiotrM]

At f/4.5, you may need to use a compromise focus setting, rather than focusing for peak sharpness in the centre of the frame.

Not sure what you mean. It was all on infinity. That quarry is half a km away from where I was standing.

think it is best to do a critical focus on a distant object in the center of the lens field, lock the focus, then rotate & tilt the camera on your tripod (you are using a tripod, right?) to take 4 additional frames of that same object in the 4 corners of the image field.

I'll do that this weekend. It will serve as good evidence when emailing Irix. This particular shot wasn't from a tripod unless you count the fact that I was holding both the camera and tripod in the air to get above the grass.

[Patriot]

Singing Canyon from the inside,
Staircase-Escalante National Monument
Irix 15mm F2.4

[Rickster]

Not sure what you mean. It was all on infinity. That quarry is half a km away from where I was standing.



I'll do that this weekend. It will serve as good evidence when emailing Irix. This particular shot wasn't from a tripod unless you count the fact that I was holding both the camera and tripod in the air to get above the grass.

See this article for more in-depth info on testing for decentering.

PentaxForums Decentering Testing Article

[PaulRookes]

Made the jump and ordered the 15mm firefly, unfortunately it suffered from what I see is a common fault with the 15mm Irix lens, its significantly soft on the left hand side, so unfortunately it has been returned to the shop (posted)….who are apparently going to test it, and send me a good one if they also note the fault.

Initially the shop said it was my K3 lens mount(surmised from my phone conversation?) it’s not the mount, as all my lenses are ok on this camera, so I now have a two week wait, so not a pleasant experience so far.

However, other than the problem above, I’m still impressed with the overall build of the lens…hopefully if I get a good one soon, I will be able to be more positive, we will see.

Example of the problem below, 1/250sec@ f/5.6, ISO 100
problem is evident at all settings, you can see it with the usual test charts, brick wall...
second image is two combined shots showing the left and right, i.e. lens rotated left to right to show the same pylon at the edge....

Just an update, the shop (ukdigital) I purchased my 15mm firefly from has apparently tested the lens on a Sony with an adapter….and they say it’s as they said, my K3 lens mount. Apparently Sony cameras are renowned for their lens mount reliability, Pentax not so…..
So getting my money back and my experience with Irix is over.
Funny thing is all my current lenses are OK with the K3 and had the same characteristics on my K20D?

[Jens Lyn IV]

I'm no expert on bovine manure, but going by you account, "ukdigital" are full of it. If all your other lenses work on the K-3, there's no way its lens mount is defective. I think you should consider telling Irix about your experience with this company; I've seen a few posts about decentered lenses now, but it's difficult to judge the magnitude of the problem from anecdotes, and I get the impression Irix are less dismissive about grievances than this shop.

[Erd§]

and they say it’s as they said, my K3 lens mount. Apparently Sony cameras are renowned for their lens mount reliability, Pentax not so…..

That's laughable since they had to use a cheap adapter to test the lens, I wonder if the adapter manufacturer is also renowned for its lens mount reliability?
Also, did you see the images they shot when "testing" the lens? I'll bet they were not so generously provided.
A shame, really - good copies of the lens are...well, the evidence is here within this thread.