[Dlanor Sekao]

I recently found myself acquiring two SMC-K Pentax 105mm f2.8 lenses and briefly tried one for a few images before packing them up and sending both for Cleaning. I paid $50 for one and $115 for the other in a lot with several other camera lenses included and both are exc/mint condition overall minus a little too much internal dust for my taste.
My initial impressions were quite good as I have never got to try a 85mm prime before on APS-C. Can anyone vouch its true that the 105mm is what is considered a poor mans 85mm at half the cost ? I read that somewhere and it stuck in my mind. Looking forward to playing more when I get them back and trying to decide if I should keep both or sell one for a SMC-K Pentax 85mm or maybe a SMC-K Pentax Macro..... I read in the reviews on here that they go for about $300 for a half way decent copy and both these are for sure and seem to have really good possibilities if a FF ever arrives in my future.......Thanks.

[LennyBloke]

The K105 is often under-rated but it is still a more-than-competent performer. The problem it has when comparing it to the K85 is that the K85 is a real top-end K lens and has the advantage of being more than a stop faster, you'd probably need to be shooting at f4 on the K105 to get the sharpness and IQ whereas on the K85 you'll get it even before f2.8 (plus the better Out of Focus effect).

The other comparison could be against the M or A 100/2.8, and here the K loses out (IMHO) - my A100/2.8 is absolutely top notch (all copies I've owned have been), it's excellent at maximum aperture plus it's compact and lightweight.

So, the answer to your question is "Yes" and "No"

[Adam]

I wouldn't consider it a bad lens, but any 85mm that isn't F1.4 is a poor man's 85mm

Check out the Samyang 85mm...it's well worth the money at just $260 ish.

[Barabas]

Maybe this link might help:

http://www.takinami.com/yoshihiko/photo/lens_test/pentax_tele.html

As you can see Yoshihiko has done some serious testing and the K105mm scores much better than the M100mm. At f2.8 it is sharper then the M100 at f8.

It is very close to the K85 in sharpness in fact, the bigger differences are the focal length and speed. I like to have clear differences in focal length and enjoy using the K105 f2.8 next to the K55 f1.8 and a K30 f2.8. Now if I could get the K85mm for a reasonable price I would not hesitate to buy it, but these speedy 85mm lenses -all brands- are a bit overhyped at the moment. I wouldn't regard the K105 to be a cheap alternative, it is so rare that the value is about double of that of the more common 100mm lenses (such as the M100). It's just another lens than the K85 and calling it the poor mans version doesn't do it any justice. But if I had two I would certainly sell one of them

Talking about a poor mans K85 I would say the M85 fits the bill.

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Last edited by Barabas; 06-22-2015 at 04:06 AM.

[hoopsontoast]

I love my K85, beautiful bokeh, amazing build and sharp enough wide open and sharp as anything f2.8 and above. I prefer it to the Voigtlander 90mm APO I had previously..
It really is worth saving up for, its also quite small for a fast 85mm, I lust after the FA* 85mm f1.4 but they are getting rare and expensive!
My dream is that Pentax release a similar D-FA 85mm f1.8

A cheaper option, is the K55 f1.8, I have this lens and it makes a nice portrait lens on APS-C, although you have to get a bit closer.

With the MZ-S

[Wild Mark]

Another advantage offered by the extra speed in the 85mm (1.4 in particular) is the extremely thin DoF, not necessarily for OOF, but for improved focus accuracy. By comparison, a f2.8 lens will be a little less 'accurate' on average. This advantage really only has relevance in near range photography (portraits) which the 85-135mm focal range is all about (FF of course). Hence the reason why there is a Pentax A 135mm f1.8 and the Pentax A* and FA* 85 f1.4 lenses.

Some say the F and FA 100/2.8 macro makes a good portrait lens too (and I tend to agree). What they lack in 'speed' they make up for in sharpness. So, I guess it is not a clear cut rule

Anyway, I must say that all the lenses mentioned are very good, although I must say that I would probably get the M85/2 last.

[Kerrowdown]

but any 85mm that isn't F1.4 is a poor man's 85mm

Well said that man.

[Dlanor Sekao]

I do have a couple of various 55mm 1.8 Pentax lenses and impressive they are ! Didn't realize this 105mm lens is as rare as it obviously is as there is only 2 copies on Ebay at the moment and both are at $300+
Think that maybe I will keep the nicest one for a while and save for the 85mm and give it a try for a while....... then decide what stays and what goes.
Has been a BIG gap in my lens lineup from the 55mm to 135mm for a very long time.

---------- Post added 06-22-15 at 09:51 PM ----------

I wouldn't consider it a bad lens, but any 85mm that isn't F1.4 is a poor man's 85mm

Check out the Samyang 85mm...it's well worth the money at just $260 ish.

Thanks Adam for throwing Sammy into the mix ! You do have a very valid point though as I own a couple Samyangs and they perform great. Only problem with Samyang I can find at all is they don't say Pentax or Takumar on the forward facing end......lol.
Decisions...decisions....decisions.......

[noelpolar]

And then there is the really rare silver K85


k85.JPG by Noel Leahy, on Flickr

[Dlanor Sekao]

Maybe this link might help:

http://www.takinami.com/yoshihiko/photo/lens_test/pentax_tele.html

As you can see Yoshihiko has done some serious testing and the K105mm scores much better than the M100mm. At f2.8 it is sharper then the M100 at f8.

It is very close to the K85 in sharpness .

Thanks for the Link....I had that saved and couldn't find it.

[hoopsontoast]

Don't know if its allowed to post links externally, but there is a nice looking K85 here with free US Shipping:

Pentax K 85mm F1.8 and Pentax K 135mm F2.5

Good price too.

[Dlanor Sekao]

And then there is the really rare silver K85

Please.....Don't do this to me....lol.

---------- Post added 06-22-15 at 10:03 PM ----------

Don't know if its allowed to post links externally, but there is a nice looking K85 here with free US Shipping:

Pentax K 85mm F1.8 and Pentax K 135mm F2.5

Good price too.

I just picked up the K 135mm 2.5 and it too went for a good servicing at Eric Hendricksons. Thanks...but by the time I get them back and sell one it will be long gone.

[formercanuck]

I wouldn't consider it a bad lens, but any 85mm that isn't F1.4 is a poor man's 85mm

Check out the Samyang 85mm...it's well worth the money at just $260 ish.

I agree. I have the Rokinon 85mm f/1.4 (optics by Samyang). Manual focus lens.. quite sharp, somewhat hefty.
I will say that a 50-55mm on APS-C ~= 85mm on FF.
You can pick up a Pentax M 50mm f/1.4 for ~$70. They are sharp!.
https://www.flickr.com/photos/formercanuck/16204649124/

[gofour3]

SMC-K 105mm......is it really a poor mans 85mm alternative lens ?

I have the K85/1.8 and K105/2.8.

Both are equally sharp, the K85/1.8 is just faster so hence the higher price. Both are excellent as a portrait lens and easy to focus.

Phil.

[fwcetus]

I used to briefly have a K 105/2.8, way back in "Ye Olde Film Days of Yore" (probably in the late 1980s or early 1990s). I say "briefly" because I didn't care a whole lot for its bokeh, as compared to the K 85/1.8 and the K 135/2.5. It was reasonably sharp, and its build quality was (not at all surprisingly) superb. However, the background bokeh (sometimes a bit harsh or "busy") in the images taken through the lens seemed to be more sensitive to the nature of the background objects and to the nature of the lighting than with the K 85/1.8 and the K 135/2.5. (Obviously, YMMV...)