[vagabond79]

I've been wondering something as of late -- I've been hoping I can kind of combine a walkaround lens with something that is capable of macro.

If I have a 35mm, 50mm, and 100mm macro lens each capable of 1:1 magnification, can I get the same image using each one? I am guessing that I can, as long as I am closest to the subject with the 35mm, further away with the 50mm, and furthest with the 100mm.

Is this accurate? I realize each focal length has its advantages and disadvantages, but it would be cool to have a 35mm walk-around lens that allows me to bust out a still-life macro shot should I come across something of interest.

I hope this makes sense. Thanks!

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Last edited by vagabond79; 08-25-2014 at 08:22 PM.

[baro-nite]

No, or at least not exactly. Each of these lenses has a different angle of view, so that even if you get the subject the same size with each lens, any elements closer or further will be differently scaled. If you're shooting flat objects, say stamps or coins, then you could indeed get very similar images with each lens, but for anything with depth each image will produce a different look. And working distance can also be a factor, especially regarding lighting. 1:1 with a 35mm lens is almost zero working distance and it is all too easy to block the light with the lens and/or camera.

However, the 35 Limited is certainly well regarded as both a walk-around and a macro lens, so it might well do just what you want.

[Na Horuk]

Not the same.
You can get the same magnification, for example. But the field of view and depth of field will be different, as well as perspective and space compression. With a 35mm macro, you focus only a few centimetres in front of the lens for 1:1 magnification. It is difficult to get so close to certain subjects, like skittish animals. Another problem is with a lens so close, it might cast shadow over the subject or cause reflections. It also limits flash use. This is why 100mm macro is preferred. For most tasks it is easier. On crop sensor, 50mm is also okay. 35mm can do some great dramatic perspectives, though, that might not be possible with a 100mm macro. I see that baro-nice already explained this pretty well. The example of stamps is a good one - with some subjects, the difference between the lenses (or rather, their usage) will be negligible. With other subjects, it can be very important.
The DA 35mm f2.8 macro limited is a very beloved lens btw. Some say its the best Pentax lens, because it is so sharp, contrasty, and has such a wide range of applications - from macro to landscapes, group photos, low light, etc. The current HD version is a little more expensive, look for the previous SMC version. Especially used, you can get a great bargain for an "everything" prime
Also, all of the Pentax macro lenses are really high quality and deliver amazing performance for a (in my opinion) quite reasonable price. Sigma and Tamron also make macro lenses that are pretty good and will not disappoint you.

[dms]

Depth of field is only a function of magnification; however, the near far relationships will change with FL.

[Mistlefoot]

Minimum focus distance for your 3 choices are:
35mm = 14 cm
50mm = 19.5 cm
100mm = 30 cm

Close one eye and look at, say a flower, but 14cm away and then look at it from 30cm away. You will easily see the perspective is different. You get more of a flatter view the further away you are.

[vagabond79]

I have been eyeing the 35 limited for its versatility. I already own a dine 100mm macro and the A 50 2.8 macro (1:2). I thought the A 50 would take care of my need for a walk-around/close-up lens but I was out today and it just wasn't wide enough. Alas...

---------- Post added 08-25-14 at 11:18 PM ----------

Minimum focus distance for your 3 choices are:
35mm = 14 cm
50mm = 19.5 cm
100mm = 30 cm

Close one eye and look at, say a flower, but 14cm away and then look at it from 30cm away. You will easily see the perspective is different. You get more of a flatter view the further away you are.

Thank you for that info. That is a good way to gain perspective on the different focal lengths.

[stevebrot]

There is no difference in FOV at various focal lengths at 1:1, 1:2, 1:3 or any other composition defined by magnification ratio. FOV in that case is determined, quite literally, by the frame size and the frame size alone.

What does affect the look of the photo is the working distance. 1:1 with a 100mm lens happens at a larger working distance than with a 50mm or a 35mm lens. The position of the front element determines perspective within the context of whatever FOV is available for a given magnification.

The matter of working distance is more important than it might sound. There is the obvious issue of having to simply be very close. There is the related issue of not being able to get light to the subject because the lens is in the way.



This is a little watch photography with my 50mm macro.


Steve

[baro-nite]

That is a good way to gain perspective on the different focal lengths.

Bear in mind that MFD is measured from the sensor to the subject. The distance from the front of the lens to the subject is called working distance. Steve shows an excellent example of this above (using the hood doesn't help, but even without the hood the working distance would be very small here).