K10D for IR?


mattie

Link Posted 22/09/2016 - 21:06
Hi all

I appreciate IR conversions have been touched upon in other posts, but I've a couple of specific questions I'd appreciate any thoughts on.

I have an old K10D in pretty sorry state after my wife went a*** over t** in Brecon whilst carrying it round her neck a few years ago. Luckily, the damage is really just cosmetic (the camera, not the wife - if she's reading this she's lovelier every day) although the camera is scraped all over, the casing is split and the flash will never flash again.

Given there's nothing really left to lose, I was considering converting it to IR by replacing the filter in front of the sensor. One slight fly in my ointment is that the K10d doesn't have live view and hence no contrast focus either, and given wavelength differences the phase focus won't be effective. I can use some older lenses with separate IR focus lengths printed on the lens barrel, but I'd be keen to hear just how accurate this approach is. I'm unlikely to use this on anything other than still life and landscape, so I will be stepping down, but I'm anticipating difficulty with things I can't 'see'

I'm also not sure about the metering - I'm not sure how to adjust exposure to take into account the fact that the metering is set for visible light and standard filter, and IR light and the IR pass-through filter would have differing properties. Is this simply a case of 'suck-and-see', maybe iterating using the screen and histogram etc (I think K10D has histogram? Not used it in a while!) or is there a more reliable approach?

I'd also be interested to hear if anyone has done such a conversion with the K10/20 or, indeed, with any other Pentax DSLR. I'm not inclined to send it for professional modification given that it's damaged goods and that other contrast-based cameras would be a better bet.

As an aside, I also have a K5 that has a damaged AF board that is beyond economic repair, I did intend to keep this to use with my manual macro lens (hence it's not a write-off like the K10D) but I'd not be against tinkering with this if it's likely to be a better convert to IR.
Last Edited by mattie on 22/09/2016 - 21:17

johnriley

Link Posted 22/09/2016 - 22:48
The metering is complicated by the fact that the amount of IR light varies and, as you say, the meter measures visible wavelengths by and large. Live View would be helpful.

The technique is to meter without the IR filer, then fit the filter and adjust for the IR focusing mark and simply adjust the exposure by the filter factor. From memory this might be three stops, but full instructions will no doubt be available via a Google search.

It can be a bit hit and miss, but when it's right it can be really spectacular.
Best regards, John

derek897

Link Posted 22/09/2016 - 23:51
Hi Mattie, that's a pretty good use to put it to.
I'm afraid I can't really help with the metering question, as I shoot manual and at this stage I can pretty well get it close enough and if not it's easy enough to tweak after looking at preview, as you would be mostly shooting landscapes this shouldn't present any problems, like you might have shooting action shots where you might miss a crucial moment.
There is a huge difference in shooting a converted camera as opposed to a non converted, in regards to exp times.


IMGP7708edsm by dr.shutter, on Flickr

This was shot with converted K01 shutter speed 160th, iso 200, f8


IMGP3591edbwsm by dr.shutter, on Flickr

This one was taken with non converted k3, iso 100, f8 and exp 64 seconds

From what I have heard the K10D has a weak IR blocker compared to K5, k3, so you could put an IR filter on your lens without converting the camera and play about with settings to see what you'll get. Use a tripod
The older lenses with the IR markings are fantastic. Just line them up and work away.

It's good fun and some spectacular images can be caught.
After a little while you will start to see what would look good in IR.

Good luck with it.
Derek
I know what i like, If not always why.

mattie

Link Posted 23/09/2016 - 08:49
Great, many thanks John and Derek both - I'll look to get a screw-in IR filter and give it a go! Some great images there Derek, btw.

I've only got older K series 50mm lenses but I'll be shooting full manual, so can easily manually stop down - I might keep an eye for an a-series 28mm in the upcoming camera fairs.

I'll see what it's like with the in-camera filter in place, I'm thinking of replacing it with a visible light filter at some point - I gather I can take the sensor mount out the back so I don't need to touch the mirror assembly etc, it'll be an interesting DIY project if nothing else!
Last Edited by mattie on 23/09/2016 - 08:50

derek897

Link Posted 23/09/2016 - 10:25
If you are using the older lenses the best resulst i got were generally iso 400 max and adjust shutter speed as needed so it was usually between 30-60 second exp times.
I have a hoya R72 72mm IR filter here
I have taped a 49 mm ring to the back so it can be used with lens with 49 mm thread. Or if you have step up rings it would work with them either.
Drop me a pm with address and I'll post it on to you.
I dont use it anymore.
Derek
I know what i like, If not always why.

petrochemist

Link Posted 23/09/2016 - 13:25
johnriley wrote:
The metering is complicated by the fact that the amount of IR light varies and, as you say, the meter measures visible wavelengths by and large. Live View would be helpful.

The technique is to meter without the IR filer, then fit the filter and adjust for the IR focusing mark and simply adjust the exposure by the filter factor. From memory this might be three stops, but full instructions will no doubt be available via a Google search.

It can be a bit hit and miss, but when it's right it can be really spectacular.

John you missed out one important step - Bracketing exposures with this approach is very important!
As you say the ratio of IR & visible varies significantly (rather like trying to measure the red light by looking at the green) I've known the ratio of the two to vary by more than 2 stops in sunlight.

IIRC I just used Av with the filter mounted for my shots with an unconverted K100d, and adjusted the EC to give improved exposures, though these days my IR is nearly all on a converted mirrorless camera.
Mike
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.

.[size=11:].Flickr WPF Panoramio
Last Edited by petrochemist on 23/09/2016 - 13:26

bforbes

Link Posted 23/09/2016 - 13:31
@ petrochemist are there advantages in using a mirrorless camera for conversion?
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/

petrochemist

Link Posted 23/09/2016 - 14:47
bforbes wrote:
@ petrochemist are there advantages in using a mirrorless camera for conversion?

Yes, several.

With a filter fitted to the lens the viewfinder still shows the scene - my camera is full spectrum converted, so I usually have a filter fitted many of which you can't see through.

AF works from the picture taking sensor so is automatically the same wavelengths as used in the shot. (No focus shift needed)

Exposure readings are also taken from the main sensor & so are relevant for the filtered image.

There's no chance of stray light leaking in via the viewfinder - a real issue on non-converted DSLRs doing long exposures...

IMO these aspects make using a DSLR considerably more awkward than mirrorless. For visual action shooting I still find a DSLR preferable, but when you can't see through the viewfinder, or focus accurately any advantage they had is gone.

I got mine pre-converted with some cosmetic body damage, for less than any conversion charges I've seen.
In hind sight a different model would have been preferable for me. It turns out MFT has a very thick sensor stack which limits it's UV sensitivity drastically, I'd have liked to dabble in UV photography too...
Mike
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.

.[size=11:].Flickr WPF Panoramio

bforbes

Link Posted 23/09/2016 - 15:08
petrochemist wrote:
bforbes wrote:
@ petrochemist are there advantages in using a mirrorless camera for conversion?

Yes, several.

With a filter fitted to the lens the viewfinder still shows the scene - my camera is full spectrum converted, so I usually have a filter fitted many of which you can't see through.
...

I've seen reference to the different types of conversion, so are your filters used to bring the full spectrum conversion into one of the other ranges?
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes
https://www.flickr.com/photos/189482630@N03/

petrochemist

Link Posted 23/09/2016 - 16:18
bforbes wrote:
I've seen reference to the different types of conversion, so are your filters used to bring the full spectrum conversion into one of the other ranges?

Exactly, with the exception of any UV influence, I can do any of the standard conversion types. UV might be relevant for the 'superblue' conversion, at least in some situations, but for landscapes my results seem broadly comparable.

I can also use a range of technical filters such as U330 (deep blue & some IR) , some less well known filters such as a 'variable wavelength IR' (actually a red filter stacked with crossed polarisers - standard polarisers typically transmit IR untouched. This allows the ratio of reds to IR to be changed with a twist, roughly 590 to 720nm in effect.) and even old photographic filters which mainly transmit IR... It gives me loads of options to play with!
Mike
.
Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.

.[size=11:].Flickr WPF Panoramio

redbusa99

Link Posted 25/09/2016 - 10:30
these were taken with an un converted K5 11s and Tamron adaptall lenses which have the IR focus points on. that means that if i buy a converted camera it can be any make that i can get an adaptall converter for so no need to buy more lenses. the downside to unconverted is the long exposure, you do need little or no wind for the vegetation but sometimes even that being a bit blurred can look ok
https://www.flickr.com/photos/haywagon200/albums/72157670934936870
odd lens or 2

Flickr
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