Another reason to use AF with a fully-manual lens is Catch In Focus.

The problem with DOF tables is that they assume a certain viewing size and distance of the final image, such that the out-of-focus areas are lost below the level of detail the eye can resolve at that range. If that image is blown up to 100% on the computer then the DOF will be considerably less since the image is now viewed at the pixel level. This reveals all sorts of errors in focussing.

On my GX10 I calibrated the AF until the focus agreed with the results from 100% images on the computer. However, I had to shim the focussing screen to make that agree, since otherwise MF gave results that were noticeably out (with the dioptre adjustment as correct as I could make it). Three tiny strips of Post-It note each side of the screen made it spot-on with the Samyang 85mm/1.4. That's about 0.25mm.

See this old thread.

Looking at the 'exploded parts diagram' there isn't a separate ball-bearing, but it might be part of the switch and got dislodged by the breakage.

Contrast AF works by doing more or less what you do as a human - it changes the focus by analysing the contrast of the image on the sensor. It doesn't know how far to change focus, but it keeps refining it until it is as sharp as it can get it.

Phase AF is an entirely different kettle of fish. It uses a separate sensor mechanism: Two micro-lenses capture the light rays coming from the opposite sides of the lens and divert it to the AF sensor, creating a simple rangefinder with a base within the lens's diameter. The two images are then analysed for similar light intensity patterns (peaks and valleys) and the separation error is calculated in order to find if the object is in front focus or back focus position. This instantly gives the exact direction of focusing and amount of focus ring's movement.
It is that final part which can give the error - although it can work out how much to move the lens (so it is fast) it doesn't really know whether the image is in focus - it only knows what the analysis of the split image told it.

Different lenses have different optical characteristics and some tolerance in the focussing mechanism, so telling the lens to go to focus distance X as computed from the phase AF analysis is not as good as it could be.

Hence the provision of an adjustment mechanism in the software.

I would have had that - but I missed it!

I'm still on the lookout for dead bodies, or faulty bodies. I'm particularly interested in a dead or faulty K-7 since I haven't taken one of those to bits yet.

Now sold.

There's one person definitely interested - any more?

There's no reason in principle why you couldn't convert a GX10/K10D/GX20/K20D yourself. After all, I had to learn how to do it from a few bits of information gleaned from the internet. Years ago I did a Sony F707, then recently I did a GX1L twice, this DL twice, and 3 different K20D's. Sadly a K-m didn't survive the operation and that's the risk. I think I'm better at it now than I was when that one failed

In good sunlight the DL can be used with a filter on the lens to give worthwhile IR shots, but exposures are borderline hand-held and you can't see through it without removing the filter. You'd need to invest in a filter suitable for whatever your main lens is.

I've decided to sell my own DL since I'm now using a modified K20D. Thread in For Sale is here.

This is a modified Pentax *ist DL with shutter count 7198.

I have replaced the original IR-blocking filter with a new Schott RG830 optical filter, so it is effectively an IR camera without requiring a filter on the lens.

You can use the viewfinder normally - the filter is after the mirror and before the sensor.
AF works normally, but for optimum results should be calibrated for different lenses. It is set for the kit 18-55 at the moment, it is easy to set up for different lenses as long as you don't mind taking some test shots. I have left the camera in debug mode so that altering the AF is easy, full instructions will be provided. For my Sigma 10-20mm I just pre-focus manually on 1m and that covers everything.

This is not a camera to be purchased casually - IR photography needs some thought. You should be familiar with the concepts, if you are a Plus member then please look at the two articles I've written, part 1 and part 2.

You can also see examples taken on modified Pentax/Samsung bodies in my Flickr stream, this camera is modified in exactly the same way.

History: I converted it originally and it was used briefly by aliengrove to produce his shots of the Himalayas. He's now moved on to a converted K20D so I've now reworked this conversion to remove some dust spots and recalibrate the AF. There are still a few dust spots on the left of the frame that may become evident against some plain backgrounds or when contrast is enhanced - these respond well to the Photoshop healing brush or clone stamp.

Today I used this camera to take some shots at Portchester Castle to verify the AF calibration and to field test it. Not ideal weather, but it proves it works. The pictures in that thread are not converted to mono - that's the colour balance out of the camera.










It comes with the box, paper manual and strap. No mini-USB, no CD. It requires 4 AA batteries, I have been using some Duracell rechargeables but most people swear by Sanyo Eneloops.

The pop-up flash doesn't pop up due to a broken connection on the main board - external flashes work fine. To be honest I wouldn't expect you to need or use the pop-up flash in IR.

To fund my acquisition of cameras I'd like £250 plus shipping, which is probably about £7 for Royal Mail Special Delivery in the UK.

Since this is a specialised camera please ask any questions in this thread or via PM, I want to make sure the new owner understands what they are buying.

No, these don't have the effects that IR gives to foliage and grass in sunshine, since for the most part it was very gloomy indeed! It did serve to bring out the drama of the clouds though, used simply as a B&W camera for shapes and textures rather than the IR 'glow' that you get in sunshine.

An experiment if you like.

Taking the filter off the sensor is easy. Getting the sensor out is the fiddly bit - for some reason they put it deep inside the camera

This is a FrankenDL. I've removed the filter that normally stops IR from reaching the sensor, and replaced it with one that stops visible light from reaching the sensor. The sensor responds to IR just fine, so the end result is a camera that gives black and white pictures using the natural IR present in a scene. Have a look at my Flickr stream for more examples on other converted Pentaxes. Since you are a Plus member take a look at my two articles over on the right for more background. Part 1 and Part 2.