[bdery]

I wonder if the folks at Pentax have ever looked at how the 20-40's baffle affects performance on the K-1...

I met the North American reps at a photo expo some years ago. I showed them my modified 60-250mm. One of the two was enthusiastic, happy to see one in the flesh. The other one had no idea what was going on, that it was even possible to modify the lens for FF.

The one who actually had a clue said that when Pentax released the K-1, they (in Japan) had evaluated the 60-250 and decided it was not worthy of being a FF Star lens (I disagree, by the way). So I'd say the Japanese engineers probably have looked into it.

[mbukal]

and decided it was not worthy of being a FF Star lens (I disagree, by the way).

probably only due to the impossibility of easily combining new "SDM" with the existing focus lens layout, ie due to the impossibility of replacing the unreliable and slow focus original SDM motor on the existing focus lens cross-section / arrangement,
and we wanted to have a new lens with internal zoom and 60-250 / 4 it definitely isn't, most likely the announced 70-300 / 4,5 -.... will not have internal zoom and it will be a significant difference in construction (not optical quality) because the optics will be Pentax's recipe which again perhaps better than Tamron’s with constant aperture and internal zoom

[bdery]

probably only due to the impossibility of easily combining new "SDM" with the existing focus lens layout, ie due to the impossibility of replacing the unreliable and slow focus original SDM motor on the existing focus lens cross-section / arrangement,
and we wanted to have a new lens with internal zoom and 60-250 / 4 it definitely isn't, most likely the announced 70-300 / 4,5 -.... will not have internal zoom and it will be a significant difference in construction (not optical quality) because the optics will be Pentax's recipe which again perhaps better than Tamron’s with constant aperture and internal zoom

Not sure about internal zooms, but certainly they might have felt that the focus performance wasn't up to DFA Star standards. Optically I'd say it is.

They COULD have created a DFA 60-250 "not Star" but that's not how the people at Pentax think, apparently, they preferred to release the rebadged Tamron 70-210 instead of simply changing the AF engine in the 60-250.

[Fronta2]

Not sure about internal zooms, but certainly they might have felt that the focus performance wasn't up to DFA Star standards. Optically I'd say it is.

They COULD have created a DFA 60-250 "not Star" but that's not how the people at Pentax think, apparently, they preferred to release the rebadged Tamron 70-210 instead of simply changing the AF engine in the 60-250.

Hi,
me too
I had the same idea :-D a year ago.
I am satisfied with the result from 23mm.
and at 40 mm I have a vignetting from the side. I suspect that it is a reflection of the light of the cut part. You have a similar
thank you

[Bertrand3000]

Wow. You're brave. Congratulations for your result. I suppose 20mm leads to black corners?

[Fronta2]

Yes, 20mm has black corners. Its good from 23 mm.

[newmikey]

I'm truly sorry for bringing what seems to be the only dissenting voice to this thread. I wonder why anyone would go through the expense of buying a FF camera to then mate it with a lens guaranteed not to bring out the quality the camera body and sensor are capable of. I can understand the scientific satisfaction and DIY excitement to prove it can be done but why anyone would want to put up with the mechanical and optical limitations on a daily basis is beyond me.

Really similar to buying a top-of-the-line APS-C body and mating it with a less than mediocre superzoom lens. If one would have wanted a single lens superzoom camera, why buy a DSLR in the first place?

If you want top-level resolution and sharpness, why put an adapted APS-C lens on a FF body instead of actually getting an APS-C body or FF lens in the first place? I'm truly sorry if this sounds obtuse, snotty or just plain grumpy but I really, REALLY don't get it.

[Alex Zhang]

Hi,
me too
I had the same idea :-D a year ago.
I am satisfied with the result from 23mm.
and at 40 mm I have a vignetting from the side. I suspect that it is a reflection of the light of the cut part. You have a similar
thank you

Thanks for sharing the success story. I also got a little vegnetting on the sides after initial modification. It turned out to be caused by my initial cut not wide enough. After I widened the openning a little bit, the vegnetting at 40mm was completely gone. You could take the baffle completely off and shoot some 40mm samples to verify if this is your case too.

[Kjbecker79]

Definitely notice the improvement.

[Alex Zhang]

I'm truly sorry for bringing what seems to be the only dissenting voice to this thread. I wonder why anyone would go through the expense of buying a FF camera to then mate it with a lens guaranteed not to bring out the quality the camera body and sensor are capable of. I can understand the scientific satisfaction and DIY excitement to prove it can be done but why anyone would want to put up with the mechanical and optical limitations on a daily basis is beyond me.

Really similar to buying a top-of-the-line APS-C body and mating it with a less than mediocre superzoom lens. If one would have wanted a single lens superzoom camera, why buy a DSLR in the first place?

If you want top-level resolution and sharpness, why put an adapted APS-C lens on a FF body instead of actually getting an APS-C body or FF lens in the first place? I'm truly sorry if this sounds obtuse, snotty or just plain grumpy but I really, REALLY don't get it.

All valid points there and I respect the more simple way of dealing with camera gears. As to why someone like me would go through all the troubles of hacking an apsc lens for fullframe use, maybe the Buddha can shine some light into it. The buddha said that all physical and spiritual phenomenons arise out of desire (and ignorance), and my desire in this case is to have a lightweight wheather-sealed prime-like wide angle lens mainly for travels. Desire for scientific satisfication indeed is another one, a habit formed with years of engineering works in my earlier life. The buddha called all these ignorance because the desire for pleasure will lead to clinging and clinging to pain because all phenomenons are impermanent.

[bdery]

I'm truly sorry for bringing what seems to be the only dissenting voice to this thread. I wonder why anyone would go through the expense of buying a FF camera to then mate it with a lens guaranteed not to bring out the quality the camera body and sensor are capable of.

It makes some sense when the lenses were made before FF was a thing for Pentax, such as with the 60-250. That lens's patent definitely stated that it was at first intended for FFF, the baffle was the only reason it was not compatible right off the bat.

[Bertrand3000]

I'm truly sorry for bringing what seems to be the only dissenting voice to this thread. I wonder why anyone would go through the expense of buying a FF camera to then mate it with a lens guaranteed not to bring out the quality the camera body and sensor are capable of. I can understand the scientific satisfaction and DIY excitement to prove it can be done but why anyone would want to put up with the mechanical and optical limitations on a daily basis is beyond me.

Really similar to buying a top-of-the-line APS-C body and mating it with a less than mediocre superzoom lens. If one would have wanted a single lens superzoom camera, why buy a DSLR in the first place?

If you want top-level resolution and sharpness, why put an adapted APS-C lens on a FF body instead of actually getting an APS-C body or FF lens in the first place? I'm truly sorry if this sounds obtuse, snotty or just plain grumpy but I really, REALLY don't get it.

While I understand your point of view, reality is a bit different. Full frame are not always better than crop lens. Some crop lens are "almost" full frame, while some other crop lens are just unsuitable. Some crop lens have better resolution than full frame, and finally, there is no modern full frame wide angle prime, hence the temptation to use the 20-40 as one. Finally, someone can own both a full frame body and crop lens body. Pentax system allows us to use both lens type on both bodies, so I can see the point of trying to use almost full frame lenses for a better gear management.

[newmikey]

...and finally, there is no modern full frame wide angle prime, hence the temptation to use the 20-40 as one.

You lost me there. Using an APS-C zoom as a FF prime?

Wide FF zoom: HD D FA 15-30mm F2.8 (similar range to the 20-40), HD D FA 24-70mm F2.8 as well as various 3rd-party options
Wide FF prime: FA 31mm F1.8 Ltd.(same FOV as the 20-40mm at its widest) and countless 3rd-party options (both MF and AF)

Finally, someone can own both a full frame body and crop lens body. Pentax system allows us to use both lens type on both bodies, so I can see the point of trying to use almost full frame lenses for a better gear management.

You lost me again. Those baffles on APS-C lenses are not there for fun or looks alone. Removing or permanently altering them will alter or even diminish IQ when used on an APS-C body.

TANSTAAFL

[JPT]

I think the appeal is to use the range wider than 31mm on the K-1 in FF mode. The 15-30/2.8 weighs a ton, and until the 21 Limited comes out, there is no lighter wide-angle zoom or prime in the current lineup. The 20-40 is often said to have prime-like qualities.

I would not rule out Ricoh making a FF limited zoom at some point, because it seems to fit into their philosophy, and the DA zoom seems like one of the most popular lenses they have at the moment.

[hongman]

A very nice and valuable discovery for those who are fortunate to have a K-1 and a DA 20-40 Limited .. thanks for posting your findings