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08-17-2019, 09:09 AM   #1
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600mm f/4 67 on 645z

I want a cheap long zoom and this one has come up as an affordable and fast option but I'm not sure about IQ on the small sensor of the Z when compared to 6x7.

To me it's a bit like putting a full frame lens on a MFT camera, the image circle compared to the sensor size is so large I can only imagine CR and other problems are exaggerated.

Anyone know of a 6x7 to 645z speed booster? LOL, I've got a 300mm f/4 67 and it's okay but I never use it because it's just not sharp enough (compared to the 400mm f/5.6 645 lens I already own).

Thanks for reading!
Paul

08-17-2019, 10:03 AM   #2
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You can read the test on this lens by several users, including myself, within Pentax Forums. The 600 Takumar has some serious Longitudinal Chromatic but it is primarily at the wider stops. From f/13 to f/45 the CA is very small. There is differential color focus by lens zone (spherochromatism). Once you are stopped past the problem areas of the glass, you get really sharp images, unless you're at f/45 where diffraction softens the image a bit. This is a big, heavy lens.
08-18-2019, 05:02 AM   #3
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QuoteOriginally posted by desertscape Quote
You can read the test on this lens by several users, including myself, within Pentax Forums. The 600 Takumar has some serious Longitudinal Chromatic but it is primarily at the wider stops. From f/13 to f/45 the CA is very small. There is differential color focus by lens zone (spherochromatism). Once you are stopped past the problem areas of the glass, you get really sharp images, unless you're at f/45 where diffraction softens the image a bit. This is a big, heavy lens.
Thank you! This is all I needed to hear... Any other suggestions for a zoom with decent IQ?
08-18-2019, 07:11 PM - 1 Like   #4
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QuoteOriginally posted by safford1977 Quote
I want a cheap long zoom
At the risk of being pedantic, you know the 600 is not a “zoom”, right? It’s a tele fixed at 600mm, no zooming.

Regards,
Sterling

08-19-2019, 08:09 PM   #5
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QuoteOriginally posted by sbjornda Quote
At the risk of being pedantic, you know the 600 is not a “zoom”, right? It’s a tele fixed at 600mm, no zooming.

Regards,
Sterling
Yes, lol but thank you for double checking!
08-29-2019, 05:29 PM   #6
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QuoteOriginally posted by safford1977 Quote
Thank you! This is all I needed to hear... Any other suggestions for a zoom with decent IQ?
better than decent IQ and beautifully constructed...



SMC Pentax-M* 67 400mm F4 ED[IF]


or if you want to spend a lot less money, a true zoom lens for the 645 mount is the SMC Pentax-FA 645 150-300mm F5.6 ED [IF]

Let me know if either interest you as I have both of these available.
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