Hello Jonathan,

First of all thanks for the compliment regarding my flower.
I think very fortunate to be abled (and allowed by my department head) to use this energy spectrum for my photography hobby, not many are.

Regarding my Metz flash, it isn't PTTL-compatible, but I don't have to use it in full manual setting all of the time. The flash has a nice trick up it's sleeve to surcomvent the non-PTTL-compatibility. It is abled to get information from my K10 (and even more from my Z1, providing full TTL-compatibility when used) regarding used aperture (A-lenses and newer) and focal length if using an F-type or more recent ones. Combined with a built-in light sensor it is abled to produce the right flash power quite succesfull resulting in correct exposed images most of the time (I haven't used it much since buying it recently so this opinion isn't set in stone just yet).

The AF-assist on my Metz uses light in the visible spectrum as can be seen in the following two images:

1: The AF-light and the control part of the flash generating it.




If the image looks a bit strange, it's because I PhotoShopped 3 images into one.

2: AF-assist detail.




You can see the line pattern (not a true grid, but it does the trick very well) which helps with shooting low contrast objects.

No flash uses laser light (monochromatic light is a better term I think, because 'laser-leds' aren't lasers at all afaik). Laser is an abbreviation of Light Amplified by Stimulated Emission of Radiation, which defines the working priciple, not the output it produces. The reason is the inherent risk to someone's eyesight when struck by a energy rich lightsource, such as a laser or 'laser'-led. My caution was directed towards the DIY-plans in one of the replies.
I think infra- (beyond) red is the correct term as it starts directly following red, hence the name. Near or far just places it on one or the other side of the infra-red spectrum itself. An easy way to visualise infra-red light I sometimes use to see if a remote control is functioning properly, is to use a videocamera or webcam as can be seen in the next image featuring my main remote control (poor quality thanks to my crappy webcam):





I was a little comprehensive going off-topic regarding the grid used for reducing scattered radiation in my line of work, but I then realised you're the topic starter, so it won't be a problem. Here it goes:

You're in the right area but you haven't hit the nail 100% with your assumption. I'll elaborate with a figure I cobbled together to visualise the process:




In the figure you can see the primary bundle genarated by the device (blue). Part of it passes through the object, this is the part of the x-rays that exposes the detecting medium, either on film or when using a digital system using detector-arrays or imaging plates.

Ionising radiation has the ability to convert the silver crystals itself, but isn't very good at it. In order to reduce the exposure times, and of course the amount of radiation the patient is exposed to, an image intensifying screen is placed above the film. This sreen consists of rare earth materials, these having fluorescent properties in the energy spectrum used in radiology (by the way this is how Conrad Röntgen discovered x-rays in the first place. Using a vacuum tube which where invented recently he noticed a screen lighting up nearby, even when placing a piece of paper between the two, realising later this could be used in the medical profession, thus giving birth to the line of non-invasive diagnostic internal imaging called radiology).

Digital imaging systems can use other means for imaging, direct or indirect. Direct regards to 2 different principles which might be a little confusing. In one context it is used to explain the difference between detector arrays and image plates.
In the other context to explain the different working priciples used by detector-arrays.

Detector arrays use both ways of information conversion. (1 Reading the amount of ionising radiation directly with a sensor-array (direct, direct), or (2 with a step in between (direct, indirect), converting ioinising radiation into visible light and then reading the light levels with photodiodes for instance (fluorescent principle).

Image plates use another principle, always combined with image intensifying screens (so it's indirect, indirect). In stead of the agitated electrons falling back directly, these excited electrons residing in a higher valency band need to be persuaded to fall back to the original lower band with a little bit of extra energy to nudge it over the edge, so to speak, thereby releasing the stored information, then read out to produce the image. This is mostly done using a laser to provide the energy needed to release the electrons from it's agitated state (phosphorescent principle, also used for glow-in-the-dark paint).

Both have clear advantages and are used both in hospitals. Detector imaging is faster, also less cumbersome, for you don't have to carry around the image plates to and from the reading unit and will be used more and more in the future.
The image plate method requires a much lower initial investment, for one can use the original equipment, you just throw out the film based system and replace the cassetes with image plates and a reader for the plates so you can use the excisting equipment for it's full technical life span, which is almost always very long, 10 years+ in most cases.
This is important, because the radiology department is one of the most expensive departments of a hospital, if not the most expensive. This is caused by the budget needed for equipment, a conventional radiology room costs app. 500.000 euro's, a CAT-scanner depending on its features 1.500.000 up to 2.000.000 euro's, a MRI-scanner even more than that and needs liquid helium for maintaining the temperature of the super-conducting electromagnetic coils (not always used, but by far in the most cases) just a fraction above 0K. Add this to the cost of employing highly qualified employees, all the precautions to be taken regarding the radiation used. Added also are materials used such as contrast enhancing agents, catheters for angiography (allmost all hand-made, the most expensive ones cost 500+ euro's a piece), because all forementioned materials have to meet very strict standards, for they are inserted or injected into a human body) and can be used only once to name a few. And last but definately not least the electricity bill.
Image plates (up till now, I think this will also change in the future) also easier to use with mobile equipment, used for patients who for some reason aren't abled/allowed to leave their room (drains, monitoring and physical condition for instance).

Part of the primary bundle is absorbed by the object it passes through either producing heat, or secundary radiation, mostly through the so called Compton effect. A photon sometimes crashes into an electron in one of the outer shells of an atom, thereby freeing up an electron in the outer shell, or putting one in a higher shell. This energy transfer results in changing the angle and of course the energy level of the original photon and dependent on the binding energy of the stricken electron in secondary radiation when it (or another electron in the same shell replacing it) releases the energy required for the original stricken electron to get it in an higher shell when falling back to the lower shell (btw, these are discrete levels, adhering to the laws of quantum physics). Both secundary radiation and the original deviated photons from the primary bundle are omnidirectional, with some preference to certain directions, something every radiological imager is required to know about for reducing exposure to scattered radiation when being in the room during some procedures, angiographe for instance.


The scattered radiation in the figure is red.

The strips of lead in the grid (green, in detail at bottom) are positioned parallel to the primary beams inherent divergance angle. This is why a grid always has a distancemarked on it where it's apllcable. One can diverge from this distance only so much, thereby increasing the absorbtion level incrementally when not using it at the indicated distance.
There is also always a ratio, specified for instance 1:12. This is the ratio lead strip height : radiolucent material width (taken up in this assumption is that the width of both lead strip and radiolucent material are equal. The higher the ratio the more absorbtion takes place, the forementioned ratio of 1:12 is used most, for children 1:8 max. is preferred. You can imagine the longer the lead lamelles (hope this is proper english) get the more the beam to be abled to pass through has to be parrallel to the angle used in the grid.

I hope this explanes the working of the grid somewhat further. I also hope you din't find it to be too elaborate an explanation, I sometimes get carried away writing about subjects I'm interested in.

Greetings, John.

Hello everybody,

I've also been pondering about this, because I find the AF-assist (AFa) incorporated in my K10 to be at least annoying because of the potenial distraction generated by the strobe flashing and on top of that cumbersome when having to use it when needing AFa, but not wanting to use the flash for the exposure (pop up, AFa, close, shoot picture).
I found out by using the AFa incorporated in my Metz 50 MZ5 flash that it's really beneficial to the built-in AF.

Although not absolutely necessary, a grid placed in front of the AF-a has it's merits. When trying to focus on a surface that's lacking in contrast the grid makes life easier for the AF by introducing the contrast needed for the AF to function properly. The easiest way to make a grid is is to give the grid some depth prividing a tunnel like structure to break up the beam (stacked black drinking straws come to mind after remembering reading about a DIY snoot 'instructable'), filtering out the light not parallel to the aiming direction, reducing diffusion of the AFa light which will diminish the needed contrast for your AF when photographing objects with inherent low contrast.

[job deformation (and geek) mode]

A grid with some depth is a solution also used in my line of work (I'm a X-ray imager (hope this is a correct term, English is not my native language, but I think you catch my drift)). When taking a X-ray we only want to use radiation that comes from the direct X-ray beam. The problem is that X-rays from the primary bundle also excites secondary radiation eminating from the bodypart one is taking the X-ray of. This scattered radiation contributes to the exposure in a negative way, incremental to the thickness of the bodypart. Above 14cm thickness of the body-part, this scattered radiation, being omnidirectional by nature, reduces the contrast of the image to a point that the diagnostic value of the X-ray image is compromised, failing to show small but sometimes oh so important information. A grid constructed from sandwiched lead strips alternated by strips of a radiolucent material, parallel to the primary beam filters out most of the scattered radiation, greatly increasing contrast (and diagnostic value of the X-ray image) as with the grid on an AF-assist in a camera.

Work and hobby combined, as a bridge for getting back on-topic :



(image is much nicer on original analog print, flower exposed with a Siemens mammography device, print (somewhat poorly) digitized using my K10)

[/job deformation (and geek) mode]

I'm not really an expert on laser LED's, but it might be important to consider the light intensity its generating when using such a construction for portrait photography. You wouldn't want to use it when there's the possibility to harm someone's eyesight by shining direct into the eyes of your subject be it man or animal. Maybe it isn't a problem or it's already been taken into consideration, but I thought a word of caution would be prudent, one can't be to carefull regarding one's eyesight.

An elegant solution to switching the DIY-AFa on and off at the right time might be using the 2.5mm remote connector and introducing a third switching step for controlling the external DIY-AFa. Preferably switching on before the AF-switch is triggered, and switching of prior to shooting the pic. The only drawback I can think of is the somewhat decreased hand-holdability of the body due to the open lid at the left side to acommodate the connector and to a lesser degree the mechanics to realise it (maybe 2 swithces for the AFa, one for making and one for breaking connected serially).

My 2 cents, hopefully usefull to someone in the context of this topic, greetings, John.

I.m.o. this is not true. I don't think it's wise to let everybody get hold of a weapon (I know there are the obvious exemptions from this).
Firstly it's far more likely you or someone close to you gets hurt by it. Be it an accident or misuse during highly emotional episodes or under the influence of alcohol or any other substance.
Secondly if I were a robber in a handgun friendly area I'd make damn shure you wouldn't be abled to use it against me by incapacitating you at forehand, most likely by (grievous) bodily harm.

Violent solutions beget violent results, (hope this is proper English).

1: Duely noted and corrected, thanks.

2: True in every situation, think twice about replying you have the law behind you regarding what you can photograph when someone for whatever reason doesn't want you to, possibly accompanied with the offer to make acquaintance with the end of one of his/hers extremities.

First of all why would you create evidence of you having been in Amsterdam (A'dam) by taking pictures? (Just kidding, I'm from Rotterdam and there's always (regarding football 'supporters' sadly sometimes not so) friendly rivalry between the two cities ).

I have read info on restrictions regarding photography, partly because I like to roam around the vast industrial landscape that is the harbour of Rotterdam, mostly with some Pentax equipment at hands reach.

The law in The Netherlands (thanks for noting my oversight John R.) is quite clear regarding photography.

Above all counts:

If you take a picture with someone clearly recognisable in the frame and you want to publish it in any form, you have te get a written consent from that person(-s). Mediacoverage for news purposes does't have to adhere to this (and some others, which illude me at the moment).

Public spaces are subject only to above stated restriction. And not really relevant: photo's of objects essential to state security whilst the objects function is blatantly obvious to you. I personally don't know of any except maybe military installations. Even those mostly aren't a problem, remembering my time as a conscript and visits to open days. I even bought my first slr (Pentax Z20 with FA-28-80 kitlens the start of my 'relationship' with the brand) in a dutyfree shop situated on an armybase where my assigned unit resided (Seedorf Germany).

Any private property that can be seen whilst standing on public terrain (I'm not sure what the law states about utensils like ladders and other height extenders you take with you, but luckily this blurry spot memorywise isn't relevant to your situation) can be freely photographed. If there's anything on a private property one doesn't want photographed it should be taken out of sight or covered!
The exclamation mark is there for the following reason: This is not out of personal experience, but there are reports of conflicts regarding this. For instance other people sharing my interest in industrial/architectural photography have had encounters with overzealous securitypeople which more often than not patrol these industrial and petrochemical areas. They were stated to stop photographing while standing on public terrain (and if I recollect correctly sometimes demands were made to delete the photo's) under the context of 11/9 (or 9/11 depending on where you live) and the subsequent paranoia regarding potential target scouting and terrorism (maybe not so very out of place in the Rotterdam harbour area I might add, a larger collection of volatile liquids concentrated in one area can't be found elsewhere on earth). They can only ask you to stop photographing, but in no way you have to conform to the request.
I personally find the paranoia regarding terrorism silly. Whilst contemplating the silliness of the thought of an 'Al Qaeda' operative chuffing along on an 20 year old Puch Maxi (50cc moped) held together by spit and ducttape with 5 kg of photographic equipment, including a tripod strapped to the handlebars spotting for targets (I'm describing my own situation when I'm on a shoot further from home, if you haven't guessed already) I thought of several easuer ways to collect information on possible targets. Which I won't state, things preventing come to mind like 'giving someone ideas' and 'Echelon-like projects' + 'possible trip to the U.S in the future' can result in 'an intimate encounter with the friendly customs officer and his gloved finger' (regarding the latter 3 I'm a bit paranoia myself )

Train stations can be photographed from the inside and outside. With exception of compositions featuring personell or counters or waiting rooms. It's also not allowed to use tripods or artificial lighting.

Photography on private terrain is subject to the restrictions set by the legal responsible party (user/owner and the likes).

Regarding criminality, common sense is the key word here. What I have done regarding this is the purchase of a Crumpler bag, a bag that, besides being practical and comfortable i.m.o., doesn't scream: 'valuable camera equipment inside' which was already stated in another reply in this topic and I keep it more or less within reach/eyesight depending on surcomstances.

Also you won't attract any attention, positive or negative these days when you pull out a (d-)slr (fair is fair we have to thank Canon for that), because more and more people prefer it above a compact and they are becoming more affordable every day.

Places and/or times to avoid with a camera strapped around your neck I can't tell as I don't live in A'dam. Except the only obvious one, the infamous Red Light district.

Hope this is any help!

I've also replaced the original screen with the LL-80 version helping me keeping my horizon level.

I replaced it myself and it's quite straightforward to do with the included tool whilst following the instructions in the manual.

Also a tip, try to replace it in a place that's as dustfree as possible, it's quite annoying to find specks of dust that settled on top of the screen during replacement (as I found out the hard way, even though I'd met previously mentioned condition, or thought I did). An airblower I use for my negatives in my darkroom came to the rescue. A simple method for keeping dust levels as low as possible often used in (DIY-) constructionwork is hanging up damp sheets or other pieces of cloth. Dust particles will adhere to the wet cloth thus removing it from your work area.

I also used surgical gloves, not really essential, but I always do this when my fingerprints have the (even remotest like in this case) potential to ruin something delicate, for instance my negatives or like here the screen by leaving a mark.

From initial posting:

I know it can be done in Photoshop, among a plethora of other features. I use PS quite often. I am used to doing it 'live' because I started making this kind of shots with my analog Z1. And I also like the challenge of getting it right in one or a couple of shots, this makes my hobby on the analog side less costly. My shooting rate per subject will undoubtedly rise whilst using my K10d.

Thanks for the explanation and the quick reply.

I don't think it's a great loss Pentax abandoned the power-zoom option, as I notice I'm using this function progressively less since I started taking even more attention to composition.

First of all, hello to everyone as this is my first post. I've been looking through this forum for a while and got some usefull information during the browsing.

I've been using Pentax equipment since my interest grew in photography during the early nineties. I started with a Z20, followed by the Z1 and last thursday I took a step into the digital world with my latest addition, the K10d.

I'm still figuring out how to use my dSlr at its best and I'm enjoying it more and more. But a couple of questions arose during use. I'm using the lenses I used on my analog camera's (see signature for details).

First of all the additional features (zoom clip etc.) don't seem to work in combination with my K10d (not that I use these features frequently, but still).

Secondly when I used to turn off my Z1 and Z20, with AF and power-zoom activated, the lenses would return to it's shortest state automatically.
The K10d still returns the power-zoom to its shortest point, but the lengthening caused by the focussing isn't taken care of automatically.

Am I doing something wrong (menu setting for instance)?

Regarding the multiple exposure feature: I sometimes like to use this to produce abstract images, example below. I find it slightly annoying that after every time I complete an image this feature shuts off and the menu has to be opened to reactivate it. Also I can't see how many exposures are left to complete the image. My Z1 shows this in stead of the normal exposure counter. Is this something I have to live with (not a real problem but more a slight annoyance) or can this be adjusted somewhere in the settings (I haven't found anything pointing in that direction). I know this feature can be replaced by using Photoshop to superimpose images, but that's not my style.





Thanks at forehand for thinking with me.
(regarding grammar and spelling, English isn't my native language)

I'm glad to find out I'm not the only one foolish enough to open up lenses, trying to repair them yourself.

The score:

Failure: 28-80/3.5-4.7 powerzoom, bent electric slidecontacts during reassembly. I bought a 28-70/4 (lightning fast focus compared to the forementioned 28-80) to replace this kitlens along with my next repair subject featured next.
Btw. the kitlens came with my first Pentax, the Z-20.

Succes (a couple of days ago): a 28/2.8 , something was rattling inside, turned out to be a loose screw, used for fixating a slideguide for the focus.


I was laughing out loud whilst reading the diy repair stories here, especially concerning the Jesus spring and the A confirmation contact, both combined prolonging my 'enjoyment' of the repair a couple of hours during the 28mm fix. Actually one of the springs of the 28-80 contacts is now being used as a replacement.

I actually also found back the original one, via another, in my opinion even easier method. I took a piece of cloth, inserted a bit of it in the nozzle of my vacuum cleaner, it forming a small 'dustbag'. To fix it on the nozzle I tied an elastic band around it. Vacuumed my workarea and surrounding floor and emptied my pouch in a bowl and sifted through the collected rubbish, and low and behold, there was my 'Jesus spring'.

I would not hesitate to open one up again for repair, although hopefully not soon . I learned what (and especially what not!) to do next time. The solution for the 'A-contact' was bending a piece of thin electrical solid core wire to hold the two pieces (not the spring as I learned the hard way, promoting its name to 'Jesus spring' instantly). I shaped it so that it could hold the two pieces in place during as long as possible, while I put the rest on top. At the last possible moment, I removed the wire holding both parts together, which did the trick.