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Forum: Pentax Medium Format 5 Hours Ago  
I have this itch (for a 645)
Posted By kaseki
Replies: 3
Views: 176
It is quite "handleable," like a 35mm on steroids. However, because the camera components are larger, you may find that most camera bags are a better fit for 35mm, and generally nowadays 35mm DLSR. So how a candidate bag can be reconfigured will be worth considering when you find you want to take the camera somewhere.

For pricing, observe similar units on eBay. In my experience, in addition to NA sellers, those in Japan with high scores ship excellent condition lenses and miscellaneous Pentax 645 devices. The postal system set up between Japan and the USA leads to very quick delivery.

Read Ken Rockwell's review (www.kenrockwell.com) to gain some insight of the differences between the 645, 645N, and 645NII film camera bodies. There are reviews on this site also. Consider the merit of any Pentax improvements vs. cost relationships among the bodies.

Delve into the lens reviews here to determine which are best for your purposes.

So far I haven't had any problems, so I can't advise on what to look out for. More experienced users here may be able to fill in this aspect. Bodies with low exterior wear may just have low interior wear. Of course, always check the battery compartment for signs of corrosion.
Forum: Pentax Medium Format 1 Day Ago  
Pentax 645Z replacement?
Posted By kaseki
Replies: 88
Views: 4,851
This message was very difficult to follow because there appears to me to be confusion between energy (or charge) and wavelength. Suggest reading a bit of the RCA EO Handbook, (republished by Burle.com), copies of which may still be found on the www, or a more formal text on electro-optics.

The link here Rca Electro Optics Handbook. Download free pdf or Buy Books doesn't generate the expected results, but this may be due to script filtering.

Edit: This version is intact other than missing the cover. http://www.ok1rr.com/tubes/burle/Electro-Optics-Handbook.pdf
Edit2: The Burle paperback version is available from Amazon for a measly $9 (used, I think). Original cost from RCA x inflation factor would get one into the $40s at a minimum.
Forum: Flashes, Lighting, and Studio 3 Days Ago  
Lighting Control for Flowers
Posted By kaseki
Replies: 23
Views: 644
+1 for that support structure. :lol:
Forum: Pentax Medium Format 4 Days Ago  
The real 645!
Posted By kaseki
Replies: 76
Views: 2,399
For his 14 September "News" article comparing three mirrorless cameras, Ken Rockwell links to a commentary of his ( https://kenrockwell.com/tech/mirrorless-vs-dslr.htm ) that makes a series of assertions about the superiority of the mirrorless camera architecture. While his arguments aren't going to get me to put my cameras up for sale, I believe that in the long run DLSR has to have merits that dominate those of mirrorless; else future DSLR camera sales will depend on preference inertia from an ever decreasing number of DSLR photographers.
Forum: Pentax Medium Format 6 Days Ago  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
Fascinating!
Forum: Pentax Medium Format 09-13-2018, 08:24 AM  
Pentax 645Z replacement?
Posted By kaseki
Replies: 88
Views: 4,851
Many devices conceived over several decades have "lusted" for some type of electronic shutter. Most of these depend on electrostatic (ex: liquid crystal) or magnetic effects, and tend to have spectral band-pass and/or angular acceptance issues. Electro-mechanically-driven (piezoelectric, say) clacking prisms (Pechan or right-angle pair) can make use of closing or opening the internal reflection surface and have good spectral characteristics, but angular acceptance is still limited, and in any case one has a seriously large mass for anything approaching a MF focal plane in size.
Forum: Pentax Medium Format 09-11-2018, 08:01 AM  
Pentax 645Z replacement?
Posted By kaseki
Replies: 88
Views: 4,851
Once upon a time, RCA as I recall had a sensor architecture with which the image array could be simultaneously flushed, a new image taken, and then the pixel storage capacitors' charges transferred all at once to a secondary storage array under them. This second array could then be read out "leisurely." This architecture should be flash compatible, but not necessarily compatible with the technology that is being used for present-day sensors.
Forum: Pentax Medium Format 09-11-2018, 07:47 AM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
I am at a loss for a sufficient superlative.
Forum: Flashes, Lighting, and Studio 09-08-2018, 06:44 PM  
changes in flash protocol
Posted By kaseki
Replies: 31
Views: 769
It may be slightly relevant, protocol-wise, that the 645Z Operating Manual page 66 notes that the AF assist light operates using the AF500FTZ, the high power flash "native" to the 645N, as will as the AF assist lights of the AF540FGZII and AF540FGZ as expected.

I am hoping that this coming week I can test out my recently acquired Cactus V6II and RF60X system with the 645Z, so if there is some specific test that can be defined using a 645N, I will be happy to try it. (In other words, I skimmed the previous messages so it might be said that my understanding of exactly what needs to be tested is a tad under assimilated.) I have several AF500FTZs, but no AF540s of either flavor, and only one V6II. My Cactus units are running Pentax compatible software.

My understanding is that the V6II cannot be used to control the AF500FTZ flash function, assuming that I had another V6II to attach to the flash. Perched on a 645N, whether the V6II can control the RF60X AF assist light function is unclear to me, but might shed light on whether the AF assist light protocol can be passed from the 645N via the V6II.
Forum: Pentax Medium Format 09-08-2018, 05:47 PM  
Pentax 645Z replacement?
Posted By kaseki
Replies: 88
Views: 4,851
Reducing specular reflection on the pixel surfaces might make them more film like in behavior, but that would preclude putting an interference filter onto the surface. Further, any pixel optical add-on technique, refractive or reflective, that enhances the angular acceptance of a pixel will of necessity reduce its effective collection area. This is due to the LaGrange Invariant that follows from the Laws of Thermodynamics. So one can in theory improve acceptance angle uniformity, but it will be at the cost of reducing the effective detector size of each pixel. The resulting reduced sensitivity may be of less importance than achieving uniformity if the detector technology provides enough S/N for the intended application.
Forum: Pentax Medium Format 08-31-2018, 08:36 AM  
645N wooden handle
Posted By kaseki
Replies: 2
Views: 279
This thread describes another approach. Vertical grip - PentaxForums.com
Forum: Pentax Medium Format 08-28-2018, 08:07 AM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
Nice.
Forum: Pentax Medium Format 08-27-2018, 04:56 PM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
As I very vaguely recall, in the ball park of $600. ca. 1970. I think I saw a used one on sale yesterday in a web link for $3k -- more than a used 600mm 645 lens costs, but significantly less technically complex. On the other hand, when industry needs a tripod that strong and there are few alternatives, they are a lot less expensive than having the corporate machine shop build a one-of version.
Forum: Pentax Medium Format 08-27-2018, 04:59 AM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
Forum: Pentax Medium Format 08-25-2018, 11:52 AM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
The compositional features in this one particularly attract my attention.
Forum: Pentax Medium Format 08-24-2018, 09:57 AM  
645N focusing screen with both splitscreen and microprism?
Posted By kaseki
Replies: 4
Views: 2,626
A very good observation. With the ground glass side 'up' the path length to focus will be about a third of the screen's thickness longer relative to the path length for the ground glass side 'down' (given a typical glass index of refraction).

On the 645N, I believe the Pentax supplied screens have a tab forcing the correct orientation. I haven't tried to change mine yet, do I could be mistaken in that regard. The aftermarket screen might not have such a tab.
Forum: Pentax Medium Format 08-23-2018, 11:20 AM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
Every time I see this photo I imagine it being augmented with an image of 'Nessie' floating on her back like a seal, with a grin and a bit of tartan hanging out of her mouth. :lol:
Forum: Flashes, Lighting, and Studio 08-18-2018, 07:35 AM  
Cactus V6II confusion
Posted By kaseki
Replies: 16
Views: 648
Having obtained a V6II and RF60X, I have delved a bit further into Linux compatibility.

  • First, the Cactus Firmware Updater V3.07 can be installed into older and newer builds of Crossover Linux running on Linux Mint using any of Win XP, 7, and 10 "bottles."

  • Second, Linux Mint itself can communicate with the V6II when it is in its firmware update mode. The V6II uses the Human Interface Device 1.11 spec USB compatibility mode. Linux can interrogate this device using such commands as "lsusb -v" and "udevadm (...)" for more V6II details than one might want.

  • Third, the Firmware Updater running under Crossover cannot (so far) see the interface with the USB device. This is likely due to the just-discovered-by-me position of Crossover to not support serial devices. To date their site suggestions for getting a connection haven't been successful. (Essentially, the V6II designated "/dev/hidraw3" by Linux Mint needs to be linked to "/dosdevices" in the Crossover windows part, but variously named links haven't been detected. I have asked Cactus by email what device name they are expecting to see.


Frankly, given the close parallelism between modern Mac OSes and Linux OSes, as well as the heavy Linux usage in China, I am surprised that a Linux based Cactus Firmware Updater is not available.
Forum: Pentax Medium Format 08-16-2018, 12:12 PM  
Post your medium format photos!
Posted By kaseki
Replies: 12,531
Views: 2,043,450
Here is an image of the female flower (group) of Catasetum "Dragonstooth" taken with the 645Z and FA 120-mm macro lens. Details are in the exif file.

It is notable that the male flowers vaguely resemble snap dragon flowers, but actually snap; an entering insect's back or an observer's finger will have a packet of pollen forcibly attached to it.

The image here is derived from the 645Z jpeg image. (The displayed image resolution is lower than the original by a factor of about 6.9 x 6.9.) The counterpart .pef file was readable by Darktable, but Darktable complained that it "failed to read camera white balance from" the file. Thus it wouldn't generate a brightness spectrum. Another investigation TBD.

Post processing by Darktable was limited to pulling in the white edge a bit and turning on the Pentax curve. Darktable may do other things on its own that I don't know about yet. I expect using it to be a real discovery process.
Forum: Flashes, Lighting, and Studio 08-14-2018, 06:52 AM  
Cactus V6II confusion
Posted By kaseki
Replies: 16
Views: 648
Thank you, thank you, thank you. The rabbit hole excavation was sufficient to not only see the light, but also the Cheshire cat's smile.

kas
Forum: Flashes, Lighting, and Studio 08-13-2018, 05:03 PM  
Cactus V6II confusion
Posted By kaseki
Replies: 16
Views: 648
Thanks. My extended response was just eaten by the site somehow, so it will take a while to reconstruct.

---------- Post added 13th Aug 2018 at 20:39 ----------



Thank you. I think it will be helpful if I excavate the rabbit hole a smidgen further, if you are game. I have taken the liberty of rearranging your text.



I would expect to be using A06 and PEN.A.001 firmwares. These are the XTTL relevant ones?

By "controlled" do you mean merely that the V6II must be directed via its user interface to allow the pass-through, or that the V6II meddles with the data being passed through?



I fear that I meant something entirely different expecting multiple P-TTL pre-flashes, but which upon reflection could imply a control process too Byzentine in operation to possibly work. So let me ask a simplified question: With one Pentax P-TTL flash mounted on the V6II operating in passthrough mode, and one or more R60X under RF control of the V6II, how many flash heads generate a pre-flash when the camera thinks it is in P-TTL mode and all the flashes think that they are in P-TTL mode?



I think the answer to the additional No. 2 question applies here also.



But let me ask another simplified question: With no Pentax P-TTL flash mounted on the V6II, but with one or more R60X being under control of the V6II, how many flash heads generate a pre-flash when the camera thinks it is in P-TTL mode and the R60X flashes think that they are in P-TTL mode?



Depending on the new answers, it would seem that one can operate with one V6II and one or more off camera (and connected by RF only) R60X flashes, avoiding the need for an AF-540FGZ, even when only a single P-TTL flash is needed.
Forum: Flashes, Lighting, and Studio 08-13-2018, 08:43 AM  
Cactus V6II confusion
Posted By kaseki
Replies: 16
Views: 648
In a BruceBanner initiated thread centered around brackets, mcgregni wrote: "Just to clarify, the TTL passthrough applies to a P-TTL dedicated system flash, not the RF60x. The RF60x can only provide TTL when operating as a radio slave, controlled from the V6II, both with X-TTL firmware."
Read more at: Do you even need a Flash Bracket if using a flash modifier such as Mogmod sphere? - Page 2 - PentaxForums.com
This statement really cuts to the core of the thousands of seemingly conflicting words I have recently read trying to make sense of what does and doesn't work, so please let me drop the original AF-500FTZ aspect of this thread and try to ensure I understand Nigel's message.
Using a 645Z, K3, or similar operating Pentax digital P-TTL camera, which of the following statements are true?
  1. An AF-540FGZII mounted on a Cactus V6II set into pass-through mode will operate as a P-TTL flash as if the V6II is not there (from the camera's point of view)

  2. In this mode, the V6II can "tap" the camera's flash control signals and thereby also control remote R60X flashes as additional P-TTL flashes

  3. In P-TTL mode, the additional R60X flashes operate such that each flash generates a pre-pulse and each flash's pre-pulse in some way adds to the camera's detected pre-pulse light level, just as if additional optically-communicating AF-540FGZII were present (assuming that is how they work)

  4. With the V6II mounted on the camera, but no flash mounted on the V6II and one or more R60X flashes used remotely (even if remotely means within inches) the R60X flashes can all operate in P-TTL mode as defined above, thereby eliminating any need for the AF-540FGZII's presence

Thanks!
Forum: Pentax DSLR Discussion 08-11-2018, 07:44 AM  
Sticky: Pentax Proud Owner Signature Banners : K-3, K-5 II, K-30, and many more!
Posted By kaseki
Replies: 285
Views: 200,594
Thanks, Adam, for the 645NII banner copy to the first page. There is also a 645N banner on page 18, post 269.
Forum: Pentax DSLR Discussion 08-10-2018, 07:49 PM  
Sticky: Pentax Proud Owner Signature Banners : K-3, K-5 II, K-30, and many more!
Posted By kaseki
Replies: 285
Views: 200,594
How about consolidating the 645N and 645NII banners to the first page too, unless there is something defective about them.
Forum: Flashes, Lighting, and Studio 08-10-2018, 06:19 PM  
F5P connectors
Posted By kaseki
Replies: 5
Views: 263
Thanks from me too for confirmation of what I suspected -- a proprietary connector that we are unlikely to find unless it is listed in some Japanese (or Philippine?) connector company's catalog. My plan is to extend existing 5P 3-m cables if and when I find I need to do so. And this only has merit for me when applied to old style analogue TTL paralleling of AF-500FTZ flashes for use with the 645N. 645Z-appropriate P-TTL flashes (some anyway) can be RF controlled using Cactus gear (see recent experiments reported in this forum), significantly reducing cable clutter.
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