Is Pentax 100mm Macro as sharp focused at infinity as up close?

*Rich · 11-01-2016, 10:07 AM

Thinking about purchasing the Pentax 100mm f/2.8 lens for macro work.

It would be great if this lens is also sharp focused at infinity, since this would give me an equivalent 150mm f/2.8 telephoto for my K5 & K70. Anyone know if this is the case? Thanks.

wibbly · 11-01-2016, 10:39 AM

i can mount the lens and go take one at infinity if you like. i'll see if i can find a subject nearby that would reflect sharpness.

will do it across a few apertures as well.

**bobbotron** · 11-01-2016, 11:15 AM

I have the DFA (previous gen) version, it's quite good at telephoto distances. I think the WR is very similar or identical to this lens, but WR and nicer coatings. I did the SIC challenge with it two months ago, there are two photos in my set at a real distance, looks sharp to me. F2.8 isn't really where this lens shines though.

Single in August 2016 SMC DA 100mm macro | Flickr

**savoche** · 11-01-2016, 11:19 AM

I find it very sharp at any distance. Found it prefect as a fast tele in the rain forest (well, didn't use it at infinity there, but definitely at longer distances than macro!). Not at home this week, and have only my phone with me, and slow Internet access, so can't post examples.

The main drawback for general use of those lenses is the slow auto focus. Not a huge problem for my use.

BrianR · 11-01-2016, 11:32 AM

I've found it to be pretty fine at all distances, I've posted a couple examples here (from the older non-WR version):

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/323992-pent...ml#post3695936

I've also said many times the AF at 'normal distances' is pretty zippy... unless it decides to go off hunting and spins all the way down to the minimum focusing distance which eats up valuable time and is obviously frustrating. How often this happens depends on camera body, light, and contrast of your subject. For example it was nearly unworkable with my k100d in all but the best conditions, but with a k5iis, I'll use AF in light I can hardly see in.

wibbly · 11-01-2016, 11:41 AM

here's some quick and dirty examples. just handheld in the back yard, pdaf, f2.8, f4, f8 and f11, iso 400, varying shutter speeds. shot in raw, zero processing, just a crop and resize. so these are SOOC with zero anything applied. you can see the PF pretty clearly wide open.

f2.8

f4

f8

f11

MJKoski · 11-01-2016, 11:52 AM

I have some stuff shot at infinity distance with K-1. Can post few crops when I get home. It (WR version) is sharp but very hard to focus correctly due to very short focusing throw towards infinity. Small bump to tripod is enough to knock it over/under infinity sometimes. I cannot recommend it in dim conditions for this purpose.

**BigMackCam** · 11-01-2016, 12:31 PM - **2 Likes**

Regarding the purple fringing at high contrast edges wide open, it's worth noting that the Tamron SP 90mm f/2.8 Di isn't immune to this either (I have the DFA100 for Pentax, and the Tamron on Sony A-mount).

As for the focus racking back and forth, the Tamron wins hands down here with the focus limiter... But, if you get into the habit of presetting the DFA100 to either infinity or MFD (depending on whether your subject is near or far) before auto-focusing, it will nail it every time without racking back and forth. It's a simple practice to get used to and it works (I use the same technique on the DA55-300 for the same reason)...

Na Horuk · 11-01-2016, 12:44 PM - **1 Like**

I posted many DFA 100mm landscape photos in this thread:
https://www.pentaxforums.com/forums/26-mini-challenges-games-photo-stories/32...dscapes-5.html
(and some more in my 500px gallery, in sig)

I find it very sharp at any focusing distance, any aperture. It beats pretty much all of my lenses, though I am not one of the "sharpness hunters."
The main downsides of this lens are lack of aperture ring, focus limiter. I read that purple fringing in general is connected to lens sharpness, sharper lenses tend to fringe more easily. Of course, lens producers are already starting to take precautions against this, but these Pentax lenses still have some fringing. With modern day Post Processing this isnt a big problem, though. CA, fringing don't always show up, and when they do, its just a couple clicks to get rid of them.

I always recommend the DFA 100mm macro, as it is a great lens and comes at a pretty fair price.

old4570 · 11-01-2016, 10:00 PM

Hmmmm ,

DFA 100 is sharp enough ..
But if you want razor sharp , then perhaps on of the older Manual focus A lenses ..
Thing is , there is always some variance ( tolerance ) ...
So while one lens on a certain body maybe lethal , that same combo may be soft for some one else . ( Such is life )

pakinjapan · 11-01-2016, 10:31 PM - **1 Like**

Originally posted by *Rich

Thinking about purchasing the Pentax 100mm f/2.8 lens for macro work.

It would be great if this lens is also sharp focused at infinity, since this would give me an equivalent 150mm f/2.8 telephoto for my K5 & K70. Anyone know if this is the case? Thanks.

another confirmation, Yes, it is very sharp at infinity focus. I always use it as a landscape lens because of its sharpness at infinity. you just have to make sure you nail the focus.
below are link to a few of my photo on instagram taken with this lens at infinity.
001
001 large
002
002 large
003
003 large
004
004 large
005
005 large
006
006 large
007
007 large

all of them are taken via K5
the only prime in my collection can rival 100wr sharpness at infinity is the FA50 macro.

ciprian.craciun · 11-02-2016, 12:02 AM - **1 Like**

As it happens I just spent about two weeks photographing landscapes almost exclusively with the 100mm D-FA WR on a Pentax K-3, thus most of them were focused at infinity or long distances. At a first glance (I didn't get to process the raw images), I can say that the 100mm perspective gives the landscapes a unique perspective. (Perhaps it's just the novelty factor for me at this moment, but I enjoyed it more than with "shorter" focal lengths.)

Now about your question regarding sharpness: after a quick look I am not that sure that the images are as sharp as I would have expected for this lens (given how sharp it is at closer focus distances), but this might be perhaps due to the haze, hand shake (I didn't use a tripod), the shake-reduction system, mis-focus, or any other issue not pertaining to the lens. (As said the lens is sharp at close focus distances.)

However there is one serious drawback for the 100mm D-FA WR when it comes to landscapes: auto-focus is quite unreliable at infinity (even in bright day light, with the center-point and in single-focus mode), and I always had to resume to live-view and focus-peaking to manually adjust the focus. The problem wasn't the focus hunting (it happened only twice), the camera did catch focus quite instantly, but the focus wasn't quite "perfect". Thus my conclusion regarding focus was: always manual focus with live-view and focus-peaking. (Auto-focus in live-view is equally unreliable.)

As a side-note regarding focus, just as someone else said, it is so easy to de-focus the lens by even the slightest touch, and sometimes I had the impression that even pointing the camera downwards (to look at the LCD), would de-focus the lens (perhaps a form of "focus-creep"). Thus before any image taking: switch to live-view, enable focus-peaking, tweak manually the focus, exit live-view, compose, take image.

Regarding chromatic aberrations, it does indeed has purple-fringing, visible even in the viewfinder, but this does seem to disappear by F/5.6, thus I wouldn't say this is a problem.

Summarizing: nice perspective for landscapes, sharp enough especially for web-shared images, but almost exclusively manual-focus (with live-view focus-peaking) at infinity. Searching for an non-macro alternative.

Sandy Hancock · 11-02-2016, 12:28 AM

I reckon it's sharp enough.

MJKoski · 11-02-2016, 07:01 AM

The problem with screw drive focusing to infinity may be that the adjustment needed to get exact focus to infinity may be impossible to achieve with screw motor. it is PITA enough to do manually due to small movements required to get it just right.

DeadJohn · 11-02-2016, 09:34 AM

The current-model 100 WR macro, as well as older non-WR and the FA versions of the macro, are sharp at all ranges from macro to infinity. It can be used for macro, portrait, landscape, and any scene where you need 100mm.

As wibbly's samples above show, wide open f2.8 you'll get some purple fringing in high contrast areas. That's a normal limitation with many lenses. That cleans up starting at f4.0.

11-01-2016, 10:07 AM	#1
*Rich Junior Member Join Date: Dec 2011 Location: Silver City, New Mexico, USA Posts: 31	Is Pentax 100mm Macro as sharp focused at infinity as up close? Thinking about purchasing the Pentax 100mm f/2.8 lens for macro work. It would be great if this lens is also sharp focused at infinity, since this would give me an equivalent 150mm f/2.8 telephoto for my K5 & K70. Anyone know if this is the case? Thanks.

11-01-2016, 12:31 PM - 2 Likes	#8
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,657	Regarding the purple fringing at high contrast edges wide open, it's worth noting that the Tamron SP 90mm f/2.8 Di isn't immune to this either (I have the DFA100 for Pentax, and the Tamron on Sony A-mount). As for the focus racking back and forth, the Tamron wins hands down here with the focus limiter... But, if you get into the habit of presetting the DFA100 to either infinity or MFD (depending on whether your subject is near or far) before auto-focusing, it will nail it every time without racking back and forth. It's a simple practice to get used to and it works (I use the same technique on the DA55-300 for the same reason)... Last edited by BigMackCam; 11-01-2016 at 12:45 PM.

11-02-2016, 12:28 AM	#13
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	I reckon it's sharp enough. Last edited by Sandy Hancock; 11-02-2016 at 12:33 AM.

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11-01-2016, 10:39 AM	#2
wibbly Veteran Member Join Date: Nov 2014 Location: Edmonton Posts: 600	i can mount the lens and go take one at infinity if you like. i'll see if i can find a subject nearby that would reflect sharpness. will do it across a few apertures as well.

11-01-2016, 11:15 AM	#3
bobbotron Site Supporter Join Date: Jan 2015 Location: Ottawa, ON Photos: Gallery Posts: 3,349	I have the DFA (previous gen) version, it's quite good at telephoto distances. I think the WR is very similar or identical to this lens, but WR and nicer coatings. I did the SIC challenge with it two months ago, there are two photos in my set at a real distance, looks sharp to me. F2.8 isn't really where this lens shines though. Single in August 2016 SMC DA 100mm macro \| Flickr

11-01-2016, 11:19 AM	#4
savoche Master of the obvious Join Date: Jun 2011 Location: Lowlands of Norway Posts: 18,311	I find it very sharp at any distance. Found it prefect as a fast tele in the rain forest (well, didn't use it at infinity there, but definitely at longer distances than macro!). Not at home this week, and have only my phone with me, and slow Internet access, so can't post examples. The main drawback for general use of those lenses is the slow auto focus. Not a huge problem for my use.

11-01-2016, 11:32 AM	#5
BrianR Veteran Member Join Date: Dec 2010 Location: Ontario Photos: Gallery Posts: 3,332	I've found it to be pretty fine at all distances, I've posted a couple examples here (from the older non-WR version): https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/323992-pent...ml#post3695936 I've also said many times the AF at 'normal distances' is pretty zippy... unless it decides to go off hunting and spins all the way down to the minimum focusing distance which eats up valuable time and is obviously frustrating. How often this happens depends on camera body, light, and contrast of your subject. For example it was nearly unworkable with my k100d in all but the best conditions, but with a k5iis, I'll use AF in light I can hardly see in.

11-01-2016, 11:41 AM	#6
wibbly Veteran Member Join Date: Nov 2014 Location: Edmonton Posts: 600	here's some quick and dirty examples. just handheld in the back yard, pdaf, f2.8, f4, f8 and f11, iso 400, varying shutter speeds. shot in raw, zero processing, just a crop and resize. so these are SOOC with zero anything applied. you can see the PF pretty clearly wide open. f2.8 f4 f8 f11

11-01-2016, 11:52 AM	#7
MJKoski Veteran Member Join Date: Aug 2016 Posts: 1,784	I have some stuff shot at infinity distance with K-1. Can post few crops when I get home. It (WR version) is sharp but very hard to focus correctly due to very short focusing throw towards infinity. Small bump to tripod is enough to knock it over/under infinity sometimes. I cannot recommend it in dim conditions for this purpose.

11-01-2016, 12:44 PM - 1 Like	#9
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	I posted many DFA 100mm landscape photos in this thread: https://www.pentaxforums.com/forums/26-mini-challenges-games-photo-stories/32...dscapes-5.html (and some more in my 500px gallery, in sig) I find it very sharp at any focusing distance, any aperture. It beats pretty much all of my lenses, though I am not one of the "sharpness hunters." The main downsides of this lens are lack of aperture ring, focus limiter. I read that purple fringing in general is connected to lens sharpness, sharper lenses tend to fringe more easily. Of course, lens producers are already starting to take precautions against this, but these Pentax lenses still have some fringing. With modern day Post Processing this isnt a big problem, though. CA, fringing don't always show up, and when they do, its just a couple clicks to get rid of them. I always recommend the DFA 100mm macro, as it is a great lens and comes at a pretty fair price.

11-01-2016, 10:00 PM	#10
old4570 Veteran Member Join Date: Feb 2013 Location: Melbourne Photos: Albums Posts: 2,551	Hmmmm , DFA 100 is sharp enough .. But if you want razor sharp , then perhaps on of the older Manual focus A lenses .. Thing is , there is always some variance ( tolerance ) ... So while one lens on a certain body maybe lethal , that same combo may be soft for some one else . ( Such is life )

11-01-2016, 10:31 PM - 1 Like	#11
pakinjapan Veteran Member Join Date: Jun 2012 Location: Tokyo Photos: Gallery Posts: 1,041	Originally posted by *Rich Thinking about purchasing the Pentax 100mm f/2.8 lens for macro work. It would be great if this lens is also sharp focused at infinity, since this would give me an equivalent 150mm f/2.8 telephoto for my K5 & K70. Anyone know if this is the case? Thanks. another confirmation, Yes, it is very sharp at infinity focus. I always use it as a landscape lens because of its sharpness at infinity. you just have to make sure you nail the focus. below are link to a few of my photo on instagram taken with this lens at infinity. 001 001 large 002 002 large 003 003 large 004 004 large 005 005 large 006 006 large 007 007 large all of them are taken via K5 the only prime in my collection can rival 100wr sharpness at infinity is the FA50 macro.

11-02-2016, 12:02 AM - 1 Like	#12
ciprian.craciun New Member Join Date: Apr 2016 Posts: 1	As it happens I just spent about two weeks photographing landscapes almost exclusively with the 100mm D-FA WR on a Pentax K-3, thus most of them were focused at infinity or long distances. At a first glance (I didn't get to process the raw images), I can say that the 100mm perspective gives the landscapes a unique perspective. (Perhaps it's just the novelty factor for me at this moment, but I enjoyed it more than with "shorter" focal lengths.) Now about your question regarding sharpness: after a quick look I am not that sure that the images are as sharp as I would have expected for this lens (given how sharp it is at closer focus distances), but this might be perhaps due to the haze, hand shake (I didn't use a tripod), the shake-reduction system, mis-focus, or any other issue not pertaining to the lens. (As said the lens is sharp at close focus distances.) However there is one serious drawback for the 100mm D-FA WR when it comes to landscapes: auto-focus is quite unreliable at infinity (even in bright day light, with the center-point and in single-focus mode), and I always had to resume to live-view and focus-peaking to manually adjust the focus. The problem wasn't the focus hunting (it happened only twice), the camera did catch focus quite instantly, but the focus wasn't quite "perfect". Thus my conclusion regarding focus was: always manual focus with live-view and focus-peaking. (Auto-focus in live-view is equally unreliable.) As a side-note regarding focus, just as someone else said, it is so easy to de-focus the lens by even the slightest touch, and sometimes I had the impression that even pointing the camera downwards (to look at the LCD), would de-focus the lens (perhaps a form of "focus-creep"). Thus before any image taking: switch to live-view, enable focus-peaking, tweak manually the focus, exit live-view, compose, take image. Regarding chromatic aberrations, it does indeed has purple-fringing, visible even in the viewfinder, but this does seem to disappear by F/5.6, thus I wouldn't say this is a problem. Summarizing: nice perspective for landscapes, sharp enough especially for web-shared images, but almost exclusively manual-focus (with live-view focus-peaking) at infinity. Searching for an non-macro alternative.

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11-02-2016, 07:01 AM	#14
MJKoski Veteran Member Join Date: Aug 2016 Posts: 1,784	The problem with screw drive focusing to infinity may be that the adjustment needed to get exact focus to infinity may be impossible to achieve with screw motor. it is PITA enough to do manually due to small movements required to get it just right.

11-02-2016, 09:34 AM	#15
DeadJohn Pentaxian Join Date: Jan 2011 Location: New York Posts: 4,833	The current-model 100 WR macro, as well as older non-WR and the FA versions of the macro, are sharp at all ranges from macro to infinity. It can be used for macro, portrait, landscape, and any scene where you need 100mm. As wibbly's samples above show, wide open f2.8 you'll get some purple fringing in high contrast areas. That's a normal limitation with many lenses. That cleans up starting at f4.0.