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05-12-2018, 02:40 AM   #61
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QuoteOriginally posted by madbrain Quote
Bracketing in Tv mode with fixed ISO would change just aperture as function of shutter speed. I'm actually going to try that now.
Actually not bracketing - just set fixed ISO, Tv mode, and switch shutter speed with a dial to let the camera choose aperture.
Just did these tests. Shot at ISO 3200, shutter speeds between 1/40 and 1s (could not go to 2s because I reached F22 at 1s, which is the smallest aperture on D FA 28-105).
I did only a single shot for each aperture.
My two best shots were at 1/13 and f/7.1, and 1/10 and f/8 . These were the sharpest. There is no blur visible in any shot faster than 1/8 f/9.
Blur only shows up at 100% at 1/5 and f/11 . Gets progressively worse until 1s / f/22.
The widest apertures, wider than f/7.1, actually have significant vignetting in the corners. Probably something that can be easily corrected in post.
For the most usable image, that needs no NR in post, no vignette correction, the ISO3200 1/13 f/7.1 or 1/10 f/8 are the best. Both could be printed large, cropped and enlarged.

Incidently, when I first started my tests, I had set shutter at 1/20 and was surprised to get a blurred image. Actually, my trigger was set to "remote control", which disabled SR in the camera. As soon as I switched it to "single shot", SR came back.
Very obvious the K-1 II SR has a massive effect for this shooter.

Here is the best image at 1/13s :


Or pixel-peep all 36MP from
https://i.imgur.com/EQz0xla.jpg



---------- Post added 05-12-18 at 02:45 AM ----------

QuoteOriginally posted by biz-engineer Quote
Visibly sharp at 2 sec. exposure with the 15-30. That also my experience with the 15-30, in shadows, handheld, and it impressed me.
The 15-30 is big $$$ though . Wide range seems to be the most expensive to get for Pentax FF.
To that effect, I bought a Tamron 1.4x Pz-AF FF teleconverter on ebay a week ago. I tested it outdoors with my Sigma 10-20 f4-f5.6 DC . It vignettes at 10mm (15mm equivalent), but is usable at 11mm (16.5 equivalent).
That Sigma was the most expensive lens I ever bought, $500 on Amazon ten years ago. The TC was $150 last week. Poor man's wide lens solution. But hey, it's not $1200.
Time to try it indoors now. Will be interesting to see what I can handhold. I wonder if the stabilizer will get confused since it gets the focal length from the electronic contacts, and doesn't know there is a TC in the mix ... That may be a downside of having a TC. Time to find out.


Last edited by madbrain; 05-12-2018 at 02:50 AM.
05-12-2018, 12:19 PM - 1 Like   #62
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QuoteOriginally posted by madbrain Quote
So, no one has any comments on this ?

I guess it's the last time I post drunk stabilizer tests to Pentax Forums.
And that is a promise?

---------- Post added 05-12-18 at 22:25 ----------

The thing is that Pentax SR as also those IBIS thingies, work best and with OEM lenses on right body(Dual IBIS won't work with Oly, when non Oly lens is mouted). I'v found out that also Pentax SR works best with modern lenses, and Pentax labeled aswell. I suppose that it can compute things better with more accurate info between lens and camera.

This especially when working with lenses where you have to manually put SR focal info.(Samyang 14/2.8 for example).

Also Olympus is restricting some things to work for premium glass only.
05-12-2018, 01:30 PM   #63
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QuoteOriginally posted by madbrain Quote
Actually not bracketing - just set fixed ISO, Tv mode, and switch shutter speed with a dial to let the camera choose aperture.
Just did these tests. Shot at ISO 3200, shutter speeds between 1/40 and 1s (could not go to 2s because I reached F22 at 1s, which is the smallest aperture on D FA 28-105).
I did only a single shot for each aperture.
My two best shots were at 1/13 and f/7.1, and 1/10 and f/8 . These were the sharpest. There is no blur visible in any shot faster than 1/8 f/9.
Blur only shows up at 100% at 1/5 and f/11 . Gets progressively worse until 1s / f/22.
The widest apertures, wider than f/7.1, actually have significant vignetting in the corners. Probably something that can be easily corrected in post.
For the most usable image, that needs no NR in post, no vignette correction, the ISO3200 1/13 f/7.1 or 1/10 f/8 are the best. Both could be printed large, cropped and enlarged.

Incidently, when I first started my tests, I had set shutter at 1/20 and was surprised to get a blurred image. Actually, my trigger was set to "remote control", which disabled SR in the camera. As soon as I switched it to "single shot", SR came back.
Very obvious the K-1 II SR has a massive effect for this shooter.

Here is the best image at 1/13s :


Or pixel-peep all 36MP from
https://i.imgur.com/EQz0xla.jpg



---------- Post added 05-12-18 at 02:45 AM ----------



The 15-30 is big $$$ though . Wide range seems to be the most expensive to get for Pentax FF.
To that effect, I bought a Tamron 1.4x Pz-AF FF teleconverter on ebay a week ago. I tested it outdoors with my Sigma 10-20 f4-f5.6 DC . It vignettes at 10mm (15mm equivalent), but is usable at 11mm (16.5 equivalent).
That Sigma was the most expensive lens I ever bought, $500 on Amazon ten years ago. The TC was $150 last week. Poor man's wide lens solution. But hey, it's not $1200.
Time to try it indoors now. Will be interesting to see what I can handhold. I wonder if the stabilizer will get confused since it gets the focal length from the electronic contacts, and doesn't know there is a TC in the mix ... That may be a downside of having a TC. Time to find out.
People talk about SR in terms of stops of benefit. So at 15mm it should be a stop easier to hand hold than at 28mm. Sandy's image is still really impressive -- by my count about 5 stops of benefit of stabilization over the rule of thumb 1/15 second that you should be able to hand hold it, but obviously the question is what you are comparing it to and my guess is that Sandy can probably hand hold a 15mm image for 1/8 second with SR.

If you are looking for cheaper wide angles, I would look seriously at the Samyang 14mm or Irix 15mm. Both are considerably cheaper and while they don't have auto focus, you really don't need to have auto focus in a lens this wide -- hyperfocal distance works remarkably well.
05-12-2018, 02:17 PM   #64
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Irix is fully compliant with K-mount automation features. It does not even have aperture ring and one needs to adjust it from camera body.

I recently purchased the 15mm lens and it transmits EXIF-data nicely including lens name.

05-12-2018, 05:19 PM   #65
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QuoteOriginally posted by Rondec Quote
People talk about SR in terms of stops of benefit. So at 15mm it should be a stop easier to hand hold than at 28mm. Sandy's image is still really impressive -- by my count about 5 stops of benefit of stabilization over the rule of thumb 1/15 second that you should be able to hand hold it, but obviously the question is what you are comparing it to and my guess is that Sandy can probably hand hold a 15mm image for 1/8 second with SR.
Oh, I agree Sandy's image is impressive, only saying that how impressive at 2MP or even 8MP isn't the same as impressive at 36MP.

QuoteQuote:
If you are looking for cheaper wide angles, I would look seriously at the Samyang 14mm or Irix 15mm. Both are considerably cheaper and while they don't have auto focus, you really don't need to have auto focus in a lens this wide -- hyperfocal distance works remarkably well.
I don't mind buying a prime lens - hardly ever used the 20mm end of my Sigma 10-20 . But lack of AF is really a big issue for me in general. Especially with the AF in K-1 II being so good.
I just don't like to take the time to MF, and I'm also not very good at it.

That said, the price for the Samyang 14mm certainly is right - $279 new right now on Amazon. IRIX is almost double that .
I would definitely buy the Samyang if it was AF, but they are not doing any AF for Pentax.

I tried my Sigma 10-20 last night at 12mm indoors, shooting a bookshelf. Both in crop mode, and in FF mode with a Tamron 1.4x AF TC.
The image just isn't sharp enough, even without the TC. The TC doesn't make the image worse, just makes the AF worse.
Maybe I need to repeat my tests under different conditions. I have never had any real issues with my outdoor landscape shots with that lens.
But it is most useful indoor in small spaces, IMO, when standard zoom isn't wide enough. That's the main reason I want a wide lens.
In recent years, I haven't used my Sigma 10-20 very much. It is a bit bulky. A wide prime lens makes more sense to me than a zoom, as it should be smaller and have better IQ. I just want one that is AF.
That doesn't seem to exist for Pentax FF, unless I'm mistaken.

Seems like Sigma has a 10mm/2.8 APS-C prime . Goes for around $600, though. Wonder how much it would vignette with the 1.4x TC, and whether IQ would be good enough. Never mind - it's a fisheye.
05-12-2018, 05:21 PM   #66
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I've done 1/8 of a second perfectly sharp on my K-01 with a 135mm lens. I think 2 seconds may be possible but man you'd have to be rock steady even with really advanced stabilization.

05-22-2018, 12:28 AM   #67
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OK, this isnt OLY compared to Pentax but its similar principle.M43(both brands) have very good stabilisation.
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