DA* 60-250 Modification for Full Frame

Well, I've gone and ordered my K-1 today with some specific work related use in mind, so I won't have too many lenses for it, nor will I be able to buy the new ones at their current prices, so trawling the web recently I came across this mod for the DA* 60-250 which I have and would definitely be of interest. (To skip all the theory and go straight to the images of the job being done, click here)

Apparently, Pentax issued a patent for a FF 60-250 lens and the current one seems to have a baffle inserted that doesn't need to be there, which prevents full frame coverage. The theory at least is that the current APS-C lens is in fact that patented full frame version, just 'crippled' for crop cameras with this baffle. You should be able to see it in this image, linked from the thread mentioned above.




Just wondering if anyone here has actually done this and what your results were, as most of the results I've seen from the other side of the pond seem to be really good!

The ideal plan for me would be to see if the part is available to buy from the repairers and if it is, then I can take the dremel to one of them so I can easily (only 3 screws) put it back to original spec.

Would love to know your thoughts!

My thpughts are simple; if that works then I just sold the best zoom I have owned.

I replaced it with the 70-200 FF , which is optically as good and slightly faster but it is very big, very heavy, slightly shorter at the longend and very expensive.

In the field I would prefer the 60-250, which offers a wider zoom range and also is much easier to handle.

I hope this mod does the job because for sure, the patent information,which is downloadable, indicates FF capability and compatibilty in the original design.

A fact that has been posted on before ( fairly recently)

it would be curiouse to know if you could do it to other lenses

it would be cool if you could save a fortune

There is a precedent going back to the Spotmatic. The f/2 version of the Super Takumar 55mm lens was the same as the f/1.8 version, but with a baffle to restrict the aperture.

The DA 12-24 f4 also has a baffle...

I'm totally baffled😇

Update!

The part has been tracked down and ordered for less than £25 posted, should be with me within a month depending where it has to come from.

As soon as it's here, I'll get hacking and let you know the results!

I am interested to know if the mod was successful and what are the results on the K1 and on a cropped sensor body?
thanks
Paul

Hi Paul,
Have a look at the thread below - I have modified the lens and have posted 'before' and 'after' pictures. In practice, it works very well needing very little cropping.
https://www.pentaxuser.com/forum/topic/k1-and-da--60-250-56699
Here's a shot with it, albeit cropped:


Cheers.

Yes, the mod was very successful and the results on the K-1 were very good. As I was planning to only have this as a landscape lens, at F8 - F11 where I would normally shoot it at, it eliminated the vignetting.

On a cropped sensor, I can't answer as I've sold all my cropped bodies but it was great to start with and would only have the result of reducing any vignetting that was visible.

Can highly recommend doing this if you have a K-1 & 60-250. If you're thinking of buying one, then mine is up for sale in the classifieds with both baffles! Only selling as I got an unexpected great price on the 70-200 and couldn't help myself!