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Forum: Pentax Q
10-16-2021, 06:28 AM
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That's a rather good result, although I wonder how much more noticeable the longitudinal CA would be with a higher-contrast subject. But looks good here, and quite sharp. What f-stop did you use?
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Forum: Pentax Q
11-24-2015, 12:35 PM
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You don't have to. Some users won't click the link, but it's up to you to present your images how you want.
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Forum: Pentax Q
02-01-2015, 02:59 PM
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The Yashinon seems to have a glow very suitable for portraiture. The Lytar has especially pleasing color. But each of these lenses looks great.
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Forum: Pentax Q
08-26-2014, 04:23 AM
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Wow -- fantastic performer on the Q.
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Forum: Pentax Q
08-23-2014, 03:50 AM
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There's no such thing as too extreme of a macro! :D Not easy to work with because of diffraction, extremely low depth of field, small working distances, camera shake, and finding suitable subjects, but they're out there.
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Forum: Pentax Q
08-03-2014, 04:39 AM
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Looks very promising indeed.
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Forum: Pentax Q
07-19-2014, 05:01 AM
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Forum: Pentax Q
07-12-2014, 09:58 AM
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Nicely done -- some good glass and it shows well on the Q, even wide open.
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Forum: Pentax Q
04-03-2014, 08:03 AM
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Look at that beautiful red shoulder. :)
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Forum: Pentax Q
02-18-2014, 06:53 AM
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Looks excellent. Do you know the magnification for that shot?
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Forum: Pentax Q
02-16-2014, 05:51 AM
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Wow, amazing detail for such reach. I dare say there's a bit of motion blur in the head and wings; never a surprise with birds at 1/30s. What aperture setting on the adapter?
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Forum: Pentax Q
10-25-2013, 03:45 AM
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And the last shot of the set shows it is a good all around performer.
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Forum: Pentax Q
10-02-2013, 05:16 AM
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I think it makes the most sense to keep a single index.
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Forum: Pentax Q
07-21-2013, 05:31 AM
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Use a very stable base. Most tripods aren't very stable. Make sure the lens isn't fogging -- this often happens on a summer night. Use a fast shutter -- the moon moves surprisingly fast. Don't stop down too much -- try f/5.6 to avoid excessive diffraction softening. Check your histogram -- all too easy to overexpose the moon.
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Forum: Pentax Q
04-15-2013, 06:26 AM
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Pentax Adapter Q. All shots handheld (the macro shots were on a table and I was able to use that for support), available light. I didn't make note of the aperture settings, but from memory the first two would have been at setting 1.5 or 2 (i.e., f/4.5 or f/5.6) and the macro shots at setting 0.5 (i.e., f/3.5).
50% crop
Moderate crop
1:1 macro, 4 shots stacked in Zerene Stacker (PMax retouched from individual shots), uncropped
The pale yellow spot on the spider's head is an individual grain of pine pollen
Conclusions: certainly a good performer on the Q both as a telephoto and an extreme macro lens. Some CA but I have done no correction for it in the shots here, and it isn't bad. It's a fairly large and heavy lens for handheld use on the Q. For macro keep in mind that at high magnifications the effective f-number goes up; a good approximation is f(effective) = f(nominal) * (1+magnification), so at 1:1 the f-number is effectively doubled. Which is to say, for shots above 1:2 or so, use a smaller f-number.
Edit: Some testing in a studio setup (tripod, SR off) shows f/4 (setting 1.0 on the Pentax Adapter Q) as the best aperture at 1:1 magnification.
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Forum: Pentax Q
03-30-2013, 07:14 AM
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Um, the latter. :D 1 stop from f/4.5 is either f/6.3 or f/6.7. I say either because of Pentax's strange use of 4.5 to signify both the 1/3 stop past 4.0, and the 1/2 stop past 4.0. So 1.5 stops from f/4.5 is either f/8 or a 1/6 of a stop up from that. That's pretty small for the Q, which is why I asked.
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Forum: Pentax Q
03-29-2013, 06:44 PM
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1.5 on the Pentax adapter should be one and a half stops down. With the Sigma 500/4.5 I'm not sure if 4.5 is a third stop or half stop down from 4.0, but at any rate another stop and a half would be somewhere in the range of 7.1 to 8. Have you found the 1.5 setting to give the best results with this lens?
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Forum: Pentax Q
03-29-2013, 05:09 AM
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Wow those look good. So that would be somewhere around f/7.1?
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Forum: Pentax Q
03-16-2013, 05:00 AM
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Great comparison, Amy. Naturally I want to see more. :D Do you have any thoughts on how the Sigma 500/4.5 performs on the Q? Or on the Sigma TCs on the K-5?
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Forum: Pentax Q
02-19-2013, 07:51 AM
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Wow, it really does look like a winner -- would love to see this stacked up against the 01.
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Forum: Pentax Q
01-24-2013, 06:50 PM
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Given the high-contrast edges, that's really not too bad for longitudinal CA with an adapted lens. And the bokeh looks rather good.
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Forum: Pentax Q
01-22-2013, 10:31 AM
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It's been noted elsewhere that the aperture ring on the Pentax K->Q adapter turns past 0 on the scale, about half a step beyond. Does 0 really mean 0? I did a quick test, photographing a gray wall lit with off-camera flash. I then checked how much exposure compensation was required in RAW processing to get the same mean brightness level. My findings:
Reference point is turning the ring until it stops (at the N in OPEN). Compared to this, the 0 setting is a quarter-stop slower. The 1/2 setting is .9 stops slower. The 1 setting is 1.3 stops slower.
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Forum: Pentax Q
01-21-2013, 08:19 AM
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I wanted to see just how far I could push this lens, to see if it would be possible to capture any features of Jupiter, so I did some testing indoors before attempting the challenge of field photography with such a tiny angle of view. While I have the Pentax L-converters, neither one fits on the DA*300, so I used the cheap 4-element TCs I have available. I wasn't really expecting this to work, so I was surprised and pleased by the results. One key is of course the extraordinary resolution of the lens. The other, I think, is that even cheap TCs do well at the image center, and with the Q that's all we see.
My test subject is a printed box shot from about 6 meters away. I put the box at an angle so that I could then select the best-focused part in PP, and hence to take focusing variation out of the comparison. I used flash to also take motion blur out of the comparison, and didn't adjust the power, other than putting a diffuser on for shots where I was getting overexposure, so I've adjusted exposure (and white balance) in PP. I did sharpening subjectively, trying to maximize detail in each shot without creating sharpening artifacts. For each configuration I took one shot wide open and another down one stop; in each case the stopped-down shot was better. (I also did two stops down with the lens alone; it was no better than one stop down.)
All 100% crops.
1. Lens alone. In the thick gray lines I can see some texture, but not detail per se.
Attachment 156345
2. With 1.4x. Now the texture of the thick gray lines resolves into nearly vertical rows of dots, but it's hard to discern separation between the dots.
Attachment 156346
3. With 2x. Now I can clearly see the separation between the dots in the thick gray lines.
Attachment 156347
4. With stacked 1.4x and 2x. I see no loss of detail compared to the 2x alone.
Attachment 156348
To my eye, each addition in magnification adds additional detail, or at worst does not lose any detail, while making the image larger. I'm surprised for several reasons. One reason is that while the lens has proven itself on the Q, magnifying it by an additional 2.8x is asking a lot. Another reason is that these are cheap TCs, and while I knew that both perform well at the image center, at least on APS-C, again this is really pushing things. A third reason is diffraction. With both TCs and the lens at 5.6, this is effectively f/16.
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Forum: Pentax Q
01-17-2013, 06:41 PM
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Sounds frustrating! I won't say I have the answer, but here are some thoughts. Moderate CA that not particularly bothersome on the DSLR gets magnified to become shot-ruining when using that lens on the Q. I consider my A400/5.6 a fine lens, but it is basically unusable on the Q (the slow max aperture doesn't help). I've also been trying my macro lenses, both of which have sterling reputations, and so far I'm not convinced that either is up to the Q's resolution. Camera shake also becomes magnified; some tripods that are good enough for the DSLR just don't have the stability needed for the Q. Don't forget the issue of diffraction: f/5.6 is pushing the limits on the Q. Finally, a great many of the stunning shots we've seen from the Q have something in common -- the DA* 300. I've been doing some testing and am realizing just what an amazing lens this is -- resolution way beyond what is needed for its native format.
Also wondering about the issue of reflections inside the adapter, that others have discussed.
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Forum: Pentax Q
12-26-2012, 12:03 PM
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