Web Analytics RiceHigh's Pentax Blog: K-5D Mark III: DA 18-55 II Converted to a 24-80 FULL FRAME Lens!

Monday, June 18, 2012

K-5D Mark III: DA 18-55 II Converted to a 24-80 FULL FRAME Lens!

As we all knew, the DA18-55 lens (whatever version) does not cover 135 full frame image circle (and actually so do all other DA zoom lenses). Here is what we see when the lens is attached on a FF DSLR at 18mm:-


(See original post here)

Those DA zoom lenses, in 11 nos, are actually NOT compatible with 135 FF. Well, is there any technical solution and work around? Note that these days after I have posted about the new Pentax FF rumour, I've seen around in the Pentax land Pentaxians have been discussing crazily about it and one thing that is commonly raised is about the lack of Pentax FF lenses in the current lens lineup!

Now, let me announce my latest invention, the Riceh. K-5D Mk III, with built-in 1.4X magnifying glass on image circle! ;-D


(Click to Enlarge)

Then just mounted a DA18-55II onto it!


(Click to Enlarge)

Project succeeded! Now, a DFA 24-80mm F4.9-7.8 Full Frame lens is easily obtained! ;-D Look at the large samples of mine below to see is the IQ is good enough (lens was stopped down).

At the Wide Side:-

(Click to Enlarge)

At the Tele Side:-

(Click to Enlarge)

After all, I believe Pentax will market the DA 1.4 SDM Tele-Convertor very soon, so as to make all the old DA zoom lenses usable as if they were designed on the cropped sensor, and actually now can be a little bit wider, too. For example, in the above case, the original APS-C film equivalent 28mm field has become nearly a 24mm after the conversion.

People will then say now the lenses are too slow then. No problem, we all have recently learnt that Pentax is going to go down this route no matter how! :-o


Related:-

DA 18-55 on Full Frame

Compatibility of DA Lenses on Full Frame

The "Canon" 40mm FF Pancake is Here! :-D

Sample Photos of Full Frame Fisheye and 43 Limited on 5D

Comments (23)

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:-O

This is awesome =D
Not bad for JPEG
Nice one! :)
Did you make the tele-converter yourself or does it exist already ? (I can see Tamron written =)
Thanks.
6 replies · active 664 weeks ago
The TC was not made by Tamron neither, its OEM was Kenko.
Michael A.'s avatar

Michael A. · 664 weeks ago

Nice job RH, now you have to update FW on 5D Mk3 to get compatible with EF 40mm. How stupid is that? Glad PK world doesn't have that...
I haven't got my EF40 yet. :-(
Michael A.'s avatar

Michael A. · 664 weeks ago

You might, it's not pricy and looks nice. But still 40g heavier than silver DA40, attached to silver K-5 (the first one with chubby grip). "Strangely", I didn't need to update FW on K-5 to make it compatible.. :o) Should work fine with Pk D-FF too, it that happens in my lifetime...that is.
I guess it might be that the control algorithms are somehow different between the new stepping motor and the SDM, thus the update.
Michael A.'s avatar

Michael A. · 664 weeks ago

That makes sense, EF40 is so new. There is some buzz about 645D Mk2. To make a difference, P could implement FF (downsize crop) for FF glass on it (& new 645-K adapter with contacts), instead of main stream FF. That would be very useful....2 bugs squashed with one shot...
Did you used a canon-to-k-mount converter in-between the camera body and the k-mount teleconverter? If so, then can it operate zoom lenses automatically or you use it manually.
3 replies · active 664 weeks ago
Yes. The lens can expose automatically but exposure compensation is a must on the Mk III. The amount of EV compensation depends on the adaptor in use. Mine is a programmable one, so as to key-in the most accurate settings.
Nice! I might try this route if I decided to get a Canon body in the future so that I may still use all my Pentax lenses.
You need to get a better 1.4X convertor anyway. My results were not that good with the lens wide to near wide opened. Or, actually a faster and better DA lens should be used.
looks very usable. ok so is it a tamron or a kenko TC?
Thanks for the usual blend of humour and seriousness, Ricehigh. Long may you continue...
1 reply · active 664 weeks ago
You're welcome! More to come. :-)
Is the image circle big enough, that if a Pentax full-frame camera used their typical Sensor shift, that the image wouldn't be dark on one side? Such as when the sensor shifts with the Pentax GPS during astronomy tracking mode.
2 replies · active 664 weeks ago
Sony was able to do sensor-shift full frame sensor with their A900/850. So, it should be technically feasible. I guess the image circle of the old film lenses was not so tight and there is still margin.
The image circle of film lenses couldn't afford to be anywhere near as tight back in the days before easy post processing, which now leads to lens makers treating vignetting as being one of the easily correctable parameters they can afford to "let go" in favour of other parameters you can't correct for.

I don't remember seeing examples of image circles before, and I'm amazed at how tight the circle is in your example at the wide end of the 18-55, how it stops so abruptly, as if it's been engineered, as it surely has, to maintain brightness until the very edge of the circle. I'd have expected a much more gradual fall-off.
18-55 isn't that good anyway so why bother? It's not bad at the wide part but not so good past 35mm
Looking at the list of lens compatibility on FF, I would rather say that there are some DA zooms that are more to say usable than not. For example, DA 12-24/4 is usable straight from 16 and on, which is just its own view angle when mounted onto an APS-C body. Same goes to DA 16-45/4 which has even better potential (20mm on FF would be 13-14mm on APS-C).
István SZalatnyai's avatar

István SZalatnyai · 525 weeks ago

Awesome toy, really awesome and really a toy :) but none of the Pentax FF user will use the 18-55 with converter on FF body.
1 reply · active 525 weeks ago
It is just an experiment for the proof of concept, with no practical meaning of course.

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