[rp_dxn]

If you were to buy a dedicatd macro lens, which one should you choose and why?
The old
Pentax M 100mm f4 macro

The new
Tamron 90mm f2.8 macro

Obviously, tammy is way more expensive but is there really a significant difference between the both of them?
Please let me know your thoughts.

PS. Pls dnt suggest ext tubes or reverse lens

[Adam]

I'd go for the Tamron for the AF and faster aperture, and doesn't the Pentax only focus to 1:2?

[Swift1]

If you were to buy a dedicatd macro lens, which one should you choose and why?
The old
Pentax M 100mm f4 macro

The new
Tamron 90mm f2.8 macro

Obviously, tammy is way more expensive but is there really a significant difference between the both of them?
Please let me know your thoughts.

PS. Pls dnt suggest ext tubes or reverse lens

I would definitely get the Tamron for these reasons,

f/2.8 = brighter viewfinder/easier focusing.

AF = can be very handy

Auto Exposure ="A" position on aperture ring allows for use of all exposure modes.

1:1 Macro

It's a superb lens

The M100/4 is a great lens and if you don't mind the limitations it comes with, then you can definitely save some money that way.

[Na Horuk]

Keep in mind, there are many macro lenses available for Pentax. Sigma 70mm, Sigma 105mm, Tamron 90mm, Pentax M, A F, FA ,DFA (older version), and the latest aluminium WR DFA 100mm. There are some differences between them, but they all have great IQ - most macro lenses do. The difference is in features. WR, AF, focus limiter, focus clamp, etc.
Between the two you listed, Tamron is better because it is true 1:1 macro and it has AF. But you can still take great closeups with the 100mm f4 (even get 1:1 macro with extension tubes). But no AF, and no automatic metering.

[EarlVonTapia]

The Tamron 90 Macro is quite a spiffy lens. I owned one for a few months, but macro is not really my thing so I sold it. However, it performed extremely well, and I would have no hesitation recommending it to anyone who is looking for a macro lens.

[rp_dxn]

Thank you for the responses! It really helps me decide which lens to buy. So far, most have suggested the tamron. I know there are other brands that offer macro, but i find the tamron 90mm and M100 f4 to be cheaper than others. Sigma? Cant even touch the price.

[Col]

I'm happy with the IQ of both but found the Tamron edged it. Mechanically they are very different.

Personally I would look at the A version of the 100 f/4 for body control of aperture.

The main problem I have with the Tamron is its switch from AF to MF. This is not a true switch but a sliding of the focus barrel to engage or disengage it. It does not communicate with the camera nor disengage the drive screw. So turning the focus in MF on the lens will turn the focus motor (until you also select MF on the body). It also means that if you don't select MF on the body the camera will still refocus the lens. This has one other major drawback (for me) in that there is not a MF/AF combination that can be set to give a user Catch in focus. Which is a technique I use all the time in the field for insects etc.