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01-28-2016, 08:54 AM   #16
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01-28-2016, 09:08 AM   #17
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QuoteOriginally posted by Imp Quote

They do say it's got ASTROTRACER! Not a big surprise, but good to know!
Interesting, the astrotracer function should have blurred the trees on the foreground for a 30 second exposure, but they look sharp to me ... or is 24mm wide enough so the sensor does not have to move noticably for a 30 sec exposure?
01-28-2016, 09:38 AM   #18
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QuoteOriginally posted by W.j.christy Quote
how does pentax cripple the Kmount?
All but the last of the film bodies had a mechanical linkage by which the lens reported how many stops from wide open it was set, so the camera could meter with the lens wide open (e.g. aperture set to f/8 on an f/4 lens; the mechanical arm will tell the camera it's going to be two stops closed down when the shutter fires and the camera can meter and set/recommend shutter speed accordingly). In Pentax-A lenses and subsequent, this information is passed also through electrical contacts but the film-era lenses kept the reporting arm to maintain backwards compatibility with older bodies.

The last of the film-era bodies and all the digital bodies so far do not have the equipment in the mirror box to match up with the mechanism in the lens. This is referred to as the "crippled" K mount.

In addition, the DA lenses do not have the reporting arm - they pass their aperture data solely through the contacts. For this reason, non-program Pentax film cameras (K and M series, and I think the LX too) cannot read the aperture or actuate the diaphragm; to them, the lens is permanently stuck on the smallest aperture, while later manual focus program cameras (Program A, Super A, P series etc) default automatically to shutter priority or full auto depending on what's in the body. I think the autofocus cameras all have the electronics required to manually select and report the aperture.
01-28-2016, 10:27 AM   #19
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QuoteOriginally posted by npc Quote
Interesting, the astrotracer function should have blurred the trees on the foreground for a 30 second exposure, but they look sharp to me ... or is 24mm wide enough so the sensor does not have to move noticably for a 30 sec exposure?
I think the rule of thumb is you can expose for 600 / focal length (some people use 500). So there wouldn't be a lot of blurring even without astrotracer, especially with the image scaled down drastically.

---------- Post added 01-28-16 at 12:30 PM ----------

What really caught my eye about the astrotracer picture is that it was shot at ISO12800. I'd love to check out the full-size image to see how much noise there is (or isn't)!

01-28-2016, 11:17 AM   #20
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QuoteOriginally posted by DougieD Quote
What really caught my eye about the astrotracer picture is that it was shot at ISO12800. I'd love to check out the full-size image to see how much noise there is (or isn't)!
About the noise at iso12800, you see all those "stars" that are supposed to be the Milky way? Are you sure it's the Milky way?
01-28-2016, 11:23 AM   #21
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I am hesitant to enter the fray but...

QuoteOriginally posted by pathdoc Quote
I'm still trying to work out if we can read anything specific into "All K mount lenses are compatible". At worst we have what we've already got (green button). At best... well, you know what us K and M fans are all hoping for.
I am cautiously optimistic that the FF will be de-crippled. Although, nothing they have officially said so far indicates either way. The reason I am optimistic is that the teasers so far do seem to indicate an interest in attracting users with old glass, which makes sense at a point when the majority of FF glass is old. Of course, not all old FF glass exclusively uses the de-crippled mount for AE (A, FA)...

Having said that, it is hard for me to gauge whether they might de-cripple or not because I am not sure I understand why they did it in the first place. It started with low-end film bodies and spread to all bodies in the DSLR era. This seems like it started as a cost-cutting effort, but how much could be saved by omitting the aperture-coupler and related parts? Why the spread to all bodies in the DSLR era? What are the obstacles to re-adding it? How much has changed in the K-mount from the MZ-S (the last body to not be crippled, I think) to the K-3II that would make it hard to re-add? I don't see any major disadvantages to de-crippling besides engineering costs to add it back into the design of the mount. It doesn't seem likely that the manufacturing costs of a de-crippled mount could be significantly higher. The main reason I can come-up with for not re-adding it in the DSLR era is lack of interest due to people primarily using crop lenses designed for DSLRs. Hopefully this equation will change with the FF.

End of rant.
01-28-2016, 11:48 AM   #22
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QuoteOriginally posted by Gimbal Quote
About the noise at iso12800, you see all those "stars" that are supposed to be the Milky way? Are you sure it's the Milky way?
It is the Milky Way. The MW strip starts in Centaurus (RH side) and meanders it's way towards Canis Major (LH side).
Similar region at ISO52800. It was shot on a K-500, much better than my *ist DS@ ISO 3200. The Milky Way: Triangulum Australe To Carina Photo by pixelsaurus1 | Photobucket
01-28-2016, 11:53 AM   #23
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QuoteOriginally posted by Gimbal Quote
About the noise at iso12800, you see all those "stars" that are supposed to be the Milky way? Are you sure it's the Milky way?
I'm hopeful it is! I do some deep sky astrophotography once in a while and if you get reasonable performance at ISO12800, or even above ISO6400, I'd be much more likely to purchase this camera than I am now. I have to see it to believe it, though. Currently I don't shoot much above ISO800 with my K-50, although I've been planning to give 1600 a try. Problem is, I haven't had a clear sky at night for what seems like months!

01-28-2016, 11:56 AM   #24
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The reason given for removing the aperture coupling lever from the APSc bodies has been space inside the small body (size is a product differentiator). Perhaps there will be more space inside the FF body . . . .
01-28-2016, 11:59 AM   #25
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QuoteOriginally posted by JBox Quote
I don't see any major disadvantages to de-crippling besides engineering costs to add it back into the design of the mount.
Didn't someone from Pentax (in an interview) rule out de-crippling because of technical difficulties?
01-28-2016, 12:06 PM   #26
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QuoteOriginally posted by pathdoc Quote
In Pentax-A lenses and subsequent, this information is passed also through electrical contacts
I am such a stickler about the fine points. The contacts on the A-series and newer lenses do not transmit the set aperture and neither does the non-crippled mount.* What the contacts do is encode the maximum aperture and aperture range allowing the body to control the taking aperture via the aperture actuator rather than having it set by a ring on the lens. Body-based aperture control is required for Sv and Program exposure modes. The aperture ring was retained for A, F, and FA-series lenses for cross and backward compatibility to bodies where the aperture ring is required for M and/or Av modes. This would include the Super Program, LX, and many other bodies up through AF era.


Steve

* The aperture "follower" mechanism in the non-crippled mount does not transmit the current aperture setting per se. What it does is to bias the meter based on the relative position of the aperture ring to allow open-aperture metering. The system is fully passive and at no time is the actual set aperture available to the body. A full textual description of how this works would be tedious, though it is probably enough to say that there is a spring-loaded ring in the body side of a non-crippled mount that is coupled to the aperture ring and moves whenever the aperture ring moves.

Last edited by stevebrot; 01-28-2016 at 12:21 PM.
01-28-2016, 12:13 PM   #27
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QuoteOriginally posted by monochrome Quote
The reason given for removing the aperture coupling lever from the APSc bodies has been space inside the small body (size is a product differentiator). Perhaps there will be more space inside the FF body . . . .
Ha! Ha! I guess that begs the question of how the quite tiny MX could accommodate the thin ring that drives the non-crippled mount. It is my opinion that the true reason the mount was crippled was the effort needed to assemble and calibrate this second access path to the meter system.

I don't remember, was the *ist (film) body the first to feature the crippled mount? Nope...Dimitrov gives the full list...

Summary of the K-Mount Evolution, Names, and Features


Steve

Last edited by stevebrot; 01-28-2016 at 12:22 PM.
01-28-2016, 12:28 PM   #28
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QuoteOriginally posted by Imp Quote
EDIT: It's just my firefox that has weird formatting, looks fine on Safari - it looks like its because they've got a slideshow going! Upping the ante... but with poor browser compatibility
QuoteOriginally posted by boriscleto Quote
Just a poor browser choice
Looks great with Firefox on Windows.


Steve
01-28-2016, 12:32 PM   #29
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You can't say much about those photos but certainly that star photo doesn't look that impressive - that's just for my eyes. Yes, not noise can be seen from that size but neither much of details aka stars - it looks a bit soft in some way. Compare it to for example this:


Taken with K-5, ISO 12800. I didn't remove any noise and look those stars.
Bigger version: http://laurikoo.kuvat.fi/kuvat/Maisemat+ja+yksityiskohdat/IMGP0007.jpg/_full.jpg

What do you think?
01-28-2016, 12:42 PM   #30
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Different exposure. Different composition. Different processing. But yes, yours is nicer.
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