100mm lens?

[MisterTransistor]

Can anyone tell me the difference between a 100mm 'portrait' lens like this
Pentacon auto,

and a 100mm macro lens like this
http://www.kenrockwell.com/pentax/35...m-f4-smc-m.htm

I know the fit is different ... Can't believe the price on eBay - I have one of those...

Thanks
Andrew

[Benchista]

Yeah, one's a macro lens that's designed for close focusing and will reproduce up to half life size, the other is a fairly uncommon portrait lens that won't focus that close.

[MisterTransistor]

Thanks but I was hoping for a bit more information than the utterly obvious.

Perhaps I should have been more specific:

1. does this lens have two modes - normal and macro - like macro zoom lenses?
2. if not, presumably it cannot focus to infinity?
3. how does it compare with say a Vivitar Series 1 zoom 70-210mm macro lens?

Thanks
Andrew

[Manofolympus]

The pentax lens has an extended focussing range allowing a closer than normal approach to the subject-it doesn't appear to have a macro mode as such. I presume it focusses to infinity as pentax have put an infinity mark on the focussing scale! I would think the image quality of such a prime would be far better than a zoom-remember the vivitar series one 70-210's varied considerably depending on who made them.
The pentacon lens is a normal 100mm lens of no special merit-it is being offered at a silly price by a Polish dealer with seriously dodgy feedback.
The term "portrait lens" simply means a lens which falls in the focal length range traditionally considered suitable for head and shoulder portraits-85 to 100mm in 35mm cameras-giving a more natural perspective than a 50mm lens but the photographer is not so far away they need to shout instructions at the sitter. Though the Pentacon lens may have the other attribute of the original portrait lenses-a rather soft image!

[Learning]

The 100mm (or 105 from other manufacturers)f4 or f2.8 macro is from the likes of Nikon, Pentax, Canon, and Minolta is a lens type of modest aperture capable of close focusing high resolution and very accurate drawing. Faster lenses make compromises in these areas that this class of lenses excel. They are excellent for copying and for macro. They are also suitable for portraiture by reason of the focal length. For portraiture with film you may need to stretch a a bit of nylon stocking over the enlarger lens to soften facial blemishes. Of course in digital manipulation you can soften far more selectively.
My present example of this type of lens is the Nikon 105 VR macro which adds a very good implimentation of VR to spec. I have also used a very much older Pentax which optically was practically as good. Be aware that there is also an M42 bellows Takumar which I should have bought in my SP2 days when I bought the bellows. It will only focus on the bellows, and it does not have modern coating or even old SMC. It is not auto, auto in the old sense that the aperture is not auto. It still commands high prices but I suspect that is because of its rarity rather than quality.