28-105 vs 24-70

[MightyMike]

He's not wrong, you are. The old FA had 1 Aspherical Lens element, the D FA has 2 Aspherical Lens elements, an Extra-low Dispersion Glass element and an Anomalous Dispersion Glass element. Even more, the old FA aspherical was positioned differently than any of the D FA's asphericals.

And, as I said before, the middle and rear groups are different.

Please stop ignoring these facts.

Alex

Even if the groups look similar or have similar looking curvatures they can have vastly different glass formulations... the general layout of the design has similarities but so does the vast majority of 28-105 style lenses regardless of the company making them. there are certain design philosophies that just work and don't cost a lot and therefore lenses are designed in similar ways. the quality can be vastly different between lenses depending on what aberrations were a priority to compensate for and what weren't.

 

[Alex Sarbu]

He's not wrong, you are. The old FA had 1 Aspherical Lens element, the D FA has 2 Aspherical Lens elements, an Extra-low Dispersion Glass element and an Anomalous Dispersion Glass element. Even more, the old FA aspherical was positioned differently than any of the D FA's asphericals.

And, as I said before, the middle and rear groups are different.

Please stop ignoring these facts.

Alex

Even if the groups look similar or have similar looking curvatures they can have vastly different glass formulations... the general layout of the design has similarities but so does the vast majority of 28-105 style lenses regardless of the company making them. there are certain design philosophies that just work and don't cost a lot and therefore lenses are designed in similar ways. the quality can be vastly different between lenses depending on what aberrations were a priority to compensate for and what weren't.

 

[desertbat]

Hi All, I have been looking at getting a walk around lens I have main primes and wide and long however for this trip my husband doesn't want me to plus we will be so busy, I have this old lens I wonder if I should just use this one Tamron AF 18-250mm F/3.5-6.3 Di II LD Aspherical (IF) Macro Len vs Pentax HD PENTAX-D FA 28-105mm f/3.5-5.6 ED DC WR Lens since the one I have is made from a crop would this be the most beneficial? I wondered if someone could shed some light on which lens will get the clearest picture for a walk around lens.