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SMC Pentax-A* 300mm F4 Review RSS Feed

SMC Pentax-A* 300mm F4

Sharpness 
 9.6
Aberrations 
 8.4
Bokeh 
 8.4
Handling 
 8.9
Value 
 9.4
Reviews Views Date of last review
18 116,088 Thu October 1, 2020
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Recommended By Average Price Average User Rating
100% of reviewers $482.57 9.06
SMC Pentax-A* 300mm F4
supersize


Description:
This lens is one stop slower than its faster A* counterpart, but it's also much more compact, only weighing 850g.



SMC Pentax-A* 300mm F4
© www.pentaxforums.com, sharable with attribution
Image Format
Full-frame / 35mm film
Lens Mount
Pentax K
Aperture Ring
Yes (A setting)
Diaphragm
Automatic, 8 blades
Optics
8 elements, 7 groups
Mount Variant
KA
Check camera compatibility
Max. Aperture
F4
Min. Aperture
F32
Focusing
Manual
Min. Focus
400 cm
Max. Magnification
0.09x
Filter Size
77 mm
Internal Focus
No
Field of View (Diag. / Horiz.)

APS-C: 5.5 ° / 4.6 °
Full frame: 8.2 ° / 6.9 °
Hood
Built-in, slide out
Case
Hard case HE-189
Lens Cap
Plastic clip-on
Coating
SMC
Weather Sealing
No
Other Features
Diam x Length
84 x 132 mm
Weight
850 g
Production Years
1984 to 1989
Engraved Name
smc PENTAX-A* 1:4 300mm
Product Code
24390
Reviews
User reviews
Notes
A separate, dedicated screw-in hood was available for use in connection with a 77mm circular polarizing filter since the filter would prevent the built-in hood from being pulled out
Features:
Manual FocusBuilt-in HoodAperture RingAutomatic ApertureFull-Frame SupportDiscontinued
Price History:



Add Review of SMC Pentax-A* 300mm F4
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Site Supporter

Registered: July, 2020
Posts: 131

1 user found this helpful
Review Date: October 1, 2020 Recommended | Price: $571.00 | Rating: 9 

 
Pros: solid build and design; relatively light; sharp optics; built-in lens hood; aperture priority
Cons: some CA (color fringing)
Sharpness: 10    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 10    Camera Used: K10D, K-3 II, K-1 II   

I was happily surprised to see how sharp this lens is after doing my astrophotography tests; this will definitely be in my arsenal of lunar/solar-eclipse lenses and will be used for long-exposure, faint-object astrophotography, as well. The chromatic aberration is not too bad -- much improved over my other, older-production Pentax telephoto lenses (smc 200-mm f/2.5, smc-A 400-mm f/5.6, smc 500-mm f/4.5). As with my A* 200-mm f/2.8 lens (see my review of that lens), the focus and aperture rings are superb in terms of feel and movement. (My only gripe with the aperture ring is in common with many Pentax lenses, in which the ring is really too close to the camera for easiest access. But this issue is largely negated in all modern Pentax cameras because you can use aperture priority with the ring set to "A".) The focus ring turns about 270 degrees between infinity and closest focus (about 13 feet = 4 meters), which gives the opportunity for really fine focusing. While not really close focusing, I have gotten nice flower photos (hand-held) with good bokeh near minimum distance, but I'll increase the ISO to get more acceptable fast-exposure photos that are sharper when hand-held. To really take advantage of the fastness (f/4, f/5.6) without degrading images with higher ISOs, a tripod is really recommended. Because the lens' optics are very sharp to begin with, I can get pretty good results with my Pentax Rear Converter-A 2X-S (which also works well with aperture priority), but that's only with a tripod.

Sure, I'd love this lens to be faster, but the f/4 means you get a smaller, lighter 300-mm lens with still very good optics. For my purposes (mostly with tripod), it's plenty fast. I bought my lens from Japan via Ebay, and the stated price was the total cost to me, including shipping and taxes (as always in my reviews), and it really is in mint condition as advertised. One of my photos below shows a size-comparison of this lens with two other similar-but-heavier Pentax telephotos lenses in my collection. Below are photos showing this 300-mm f/4 lens with and without the lens hood extended -- the built-in lens hood being a practical and great-design feature that I really like a lot in every one of my seven older K-mount prime Pentax smc A, M, [K], and Takumar telephoto lenses ranging from 120mm to 500mm focal length. As the table above says, the outside tube diameter is about 83-84 mm (for purposes of place a solar filter over the end tube), and the unobstructed objective aperture glass is around 72 mm in diameter.




The photo below shows a size-comparison between this smc-A* 300-mm f/4 lens (on the right) with the Pentax smc 200-mm f/2.5 lens (on the left) and the Pentax smc-A* 200-mm f/2.8 lens (center). The tube of the 300-mm lens is shorter than the tubes of both 200-mm lenses -- a good example of how aperture * f/-ratio = focal length, where the two 200-mm lenses have larger objective lenses and aperture openings than does the 300-mm lens.



The photo below was taken at f/8 and 1/125 second and ISO 100 with my 300-mm f/4 A* lens on a tripod with a K-3 II camera on 2020 Oct. 3 at around 2h30m UT, showing the red planet Mars to the upper left of the just-past-full moon. Uncropped JPEG image converted from original RAW image. Mars is prominent in the original (much is lost in the posting here), and the craters near top right of the moon in shadow relief are fairly sharp in the original frame (see blow-up of moon from this same image below).


Magnification via screen shot to new JPEG of above photo:
   
Forum Member

Registered: July, 2016
Location: Pennsylvania
Posts: 65
Review Date: December 10, 2019 Recommended | Price: $310.00 | Rating: 9 

 
Pros: Compact and easy handling
Cons: Axial chromatic aberrations, low contrast at wide aperture
Sharpness: 9    Aberrations: 7    Bokeh: 8    Handling: 8    Value: 10    Camera Used: K-3, K-1000   

I picked up a lightly-used copy of this lens a few years back, and it has done admirable duty for me ever since, shooting slow-moving wildlife and deep sky targets mostly. Lack of autofocus and long focus throw means this isn't a lens for trying to catch birds on the wing unless you do some clever pre-focusing and have a lucky shutter finger.

Cons:
  • Contrast is a lacking when you shoot this lens wide open, but improves rapidly until it is just about perfect at f5.6. Even at its worst, it is easy to fix in post.
  • Images also suffer from a fair amount of purple fringing in certain challenging lighting conditions or super high-contrast situations - occasionally bad enough to be hard to fix in post. Most of the time, it isn't an issue though, and I've never noticed any green/magenta aberrations of note.
  • The minimum focusing distance is also a bit on the long side, though I didn't pick it up expecting a macro lens.

Pros:
  • Quite sharp for its era.
  • The lens is quite compact and easy to handle for a manual lens with such a long reach. It's small enough that with a sturdy tripod, I don't miss a tripod collar.
  • Produces good images with pleasingly smooth bokeh even up to f8 (depending on distance). It would be nice if it got as wide as f2.8, but I'm not rating it on what I wish it was.
   
New Member

Registered: November, 2018
Posts: 1

1 user found this helpful
Review Date: November 25, 2018 Recommended | Price: $500.00 | Rating: 9 

 
Pros: compact size; sharpness; build quality
Cons: slight CA
Sharpness: 9    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 9    Camera Used: K-70   

(I withdraw my previous review of this lens because the initial conclusion was made on the lens+TC)

The best features are (1) compact size (2) sharpness. It is a little heavy but built like a tank. It is well balanced on the K-70. The small barrel makes manual focusing easy. The image is sharp, but not as sharp or contrasty as the modern DA 55-300mm for digital SLR. When I use this lens with the HD pentax DA 1.4 TC, there is no loss of quality and I get 420mm at f5.6 in a very compact size and good weight for handheld shots. The "A" lens allows aperture adjustment on the camera which is benefit.



(100% crop)




(100% crop)
   
New Member

Registered: February, 2017
Posts: 2
Review Date: February 9, 2017 Recommended | Rating: 10 

 
Pros: Sharp, Nice handling
Cons:
Sharpness: 10    Aberrations: 8    Bokeh: 8    Handling: 9    Value: 9    Camera Used: K-30   

A great handling lens. It is very sharp with little aberration.



   
Pentaxian

Registered: March, 2008
Location: Quebec city, Canada
Posts: 9,352
Review Date: October 19, 2012 Recommended | Price: $400.00 | Rating: 9 

 
Pros: Sharpness, build quality, colours
Cons: Heavy, closest focus distance not that close, ackward shape
Sharpness: 10    Aberrations: 9    Bokeh: 8    Handling: 8    Value: 8    Camera Used: K20D   

This is a fine example of the Star series of lenses. The images it produces are excellent, sharp, with rich colours and beautiful contrast. Chromatic aberrations are very well controlled even at wide apertures. Sharpness does increase slightly when stopping down, but it's very good even at f4.

The build quality is fine, as fine as you'd expect for a lens in this class. It feels just as sturdy as the mose reliable MF lenses Pentax ever manufacture. The large front element is somewhat ackward to handle, but the lens still feels well-balanced on a DSLR body (it has a weigth-lifting dumple feeling...)

The only draw-back (for me) was the absence of AF. It's not a flaw of the lens but it meant no one in my household except me would use it, so I ended up selling it to a happy pentaxian.
   
New Member

Registered: November, 2011
Posts: 2

3 users found this helpful
Review Date: May 21, 2012 Recommended | Price: $400.00 | Rating: 9 

 
Pros: Sharp at usable apertures, price-performance
Cons: ( None really ) long minimum distance, its not a macro
Sharpness: 9    Aberrations: 9    Bokeh: 8    Handling: 10    Value: 10    Camera Used: K-5   

Here are some shots from my A* 300 f/4 on a K-5 body. Most are unprocessed from JPG.

http://public.fotki.com/boborama/smc-pentax-a-300mm-/

Pixel peeping examples of resolution & CA for near focus at various apertures:

http://blog.trafficshaper.com/?p=524

This lens is rather unique in that it is fairly light weight, compact, and for mid-80's full frame optics, performs very well..

This lens does use an ED glass element, and has fairly well controlled CA, but is subject to PF and "color bokeh" when wide open. This resolves itself fairly well by f/5.6 and almost completely ( less than a pixel width ) by f/8. In the blog post you can see the pinwheel of 100% crops by aperture. There is certainly a high degree of PF and CA when wide open, and for near focus. Its not as good as modern APO equivalents. But if you can operate the lens in the f/6.3 to f/13 range, it certainly makes a good enough cost-performance argument.

The bokeh from the A* 300 / 4 is not "astounding" nor is it bad, with its 8-blade aperture. But with the long minimum focal distance ( 4 meters ) its really more of a true tele lens. Don't get me wrong, it certainly works for fairly close birds, giving very nice images with lots of detail. Again, with the qualification "for the price." It excels at far off landscapes where the optical quality of the lens far exceeds most atmospheric conditions - unless you reside on the Moon. Look at http://blog.trafficshaper.com/?p=569 for a comparison to a typical 80's mirror lens. Even resampling the A* 300's image to 2x, its still MUCH better than my 650mm cat.

Operationally, its easy to get precise focus. Its very easy to get good hand-held shots, even if you don't work out at the gym. Its small enough that it does not need a lens bracket, you can easily use K-5's tripod threads. Works well with SR. Works well for tele-candids, and even with the integrated flash. Works well for video and will do a fairly decent job indoors or at the kids school concerts. With video, the CA and so on wide open are largely unnoticed because video has such low resolution. The biggest problem is sound when using any tele for video. You need a shotgun and then post process out the audio delay, or get a line-in from the board.

Geometric distortion seems very minimal. In addition to the architectural details in the above gallery, look at http://public.fotki.com/boborama/egner-memorial-chap-1/ and the resulting panos at http://public.fotki.com/boborama/egner-memorial-chap-2/ which are 100-150 MP stitches made from this lens. Its not a macro lens and does not lens itself to that sort of work. I've used auto-extension tubes, with rather unimpressive results. If you want a macro lens, this isn't it. Images from the A* 300 f/4 tend to withstand significant sharpening and post processing, and most of the wider aperture optical issues can be concealed in post.

Summary: its not the "best lens ever" but certainly a usable and useful lens for the price. A keeper.
   
Veteran Member

Registered: May, 2010
Location: Hong Kong / Irvine, CA
Posts: 636

2 users found this helpful
Review Date: July 24, 2011 Recommended | Rating: 10 

 
Pros: very sharp
Cons:

I got it for cheap because of a rock chip on the front element.
I think this is a very sharp lens wide open compare to my DAL55-300.
It is very light and I can easily use it with my K1000.

Hand carry and shaked a little bit (slow shutter)
Kx iso100 F4 1/125s
   
Pentaxian

Registered: August, 2007
Location: Apiary, Oregon
Posts: 1,181

4 users found this helpful
Review Date: May 16, 2011 Recommended | Price: $481.00 | Rating: 9 

 
Pros: Small, inexpensive, good optics
Cons: loose lenshood, not close focusing
Sharpness: 10    Aberrations: 10    Bokeh: 10    Handling: 8    Value: 9   

I just bought this lens off of EBAY. the small size and modest price attracted me. I've owned for years the big brother to it--- the F/ 2.8 model which comes in a suitcase and costs a fortune. It's small enough and light enough to be hand held and readily fits in a camera case designed to accommodate a zoom lens.

Indeed it is shorter than my DA* 50-135, and only modestly longer than my DA*16-50. Although not compatible with the Pentax-A 1.4x-L or 2x-L converters it works well with the Pentax F 1.7x AF adapter, and is fast enough to focus well and to provide sharp photos with that combination. It also provides excellent results with the Pentax Rear Converter 2x-S.

The builtin lens hood is sort of micky mouse. It needs to be remembered that this is a Pentax-A series lens which does not support auto focus. On your digital body you will need to manually input the focal length upon mounting to keep the shake reduction happy. While the lens is one of the smallest and shortest 300mm lenses around, the price of this is paid with a minimum focal distance of 4 meters. Although you can overcome this with extension tubes, you will have to look really hard to find a lens
that won't focus more closely than 4 meters. I have downgraded this lens because of this limitation. At f/4, the lens is still relatively fast, and its optically superior rated by Pentax as an A* lens. It tends to be fairly inexpensive on the second hand market and it's small enough and light enough (825g) to go hiking, and good enough to provide top quality photos, if you can live with the 4 meter minimum focus.

It usually is (and needs to be) priced as a substantial discount over its newer successors who have autofocus and much closer focusing.. This design was originally released by Pentax in 1981 at the Pentax-M* (and upgraded to a Pentax-A* in 1984 to suupport the mount change compelled by the introduction of the Program mode in the camera bodies of the day) when Pentax had a theme of trying to make their cameras and lenses smaller and lighter than anyone else in the industry. They accomplished that,but not without compromises on this lens.
   
Veteran Member

Registered: January, 2011
Location: Orlando, FL (USA)
Posts: 523

1 user found this helpful
Review Date: May 1, 2011 Recommended | Price: $600.00 | Rating: 9 

 
Pros: Long, Fast(ish), Small (for it's focal length)
Cons: Newer lenses are selling for about this price.

This is one solid hunk of glass and metal! 300mm Lets you really reach out and touch people. At this lens' (rather long) minimum focusing distance of 13 feet you can just barely squeeze most of someone's face into a 1.5x cropped frame. I must say, the first few months I had this lens I thought it was soft. I installed a split prism focusing screen when I got an old manual fast fifty and I realized that all of those soft pictures had been my fault.


(click image for larger sizes)

This was taken at f5.6 (my particular copies sweet spot!) and I must say, this lens is quite sharp at 25 years of age. It does show it's wrinkles in purple fringing at wider apertures, and there's almost always a tiny amount of CA that's easily corrected in post.

Disassembly is pretty easy, To get at the front element protector and the little felt strip that provides friction for the built in hood all that is needed is a twist of the body, no screw removal required! The same is true of accessing the middle of the lens and the aperture blade assembly. This could be seen as a plus for some, or a negative for others. Personally I just removed a rather large fiber from the middle of mine without so much as picking up a screwdriver! So you can color me happy.

This lens is becoming less and less of an attractive solution for a 300mm prime though. This is through no fault of it's own, it is mearly being undercut by It's youngest DA* sibling which is going used-mint for only three bills more. And it features: weather sealing, autofocus, almost no CA/purple fringing...
   
Senior Member

Registered: March, 2007
Location: Norrtälje
Posts: 220
Review Date: November 28, 2010 Recommended | Rating: 9 

 
Pros: Size, image quality, bulid quality
Cons: no tripod bracket

I´ve had mine for many years and actually, I had this lens in mind when switching from Contax back to Pentax again in the -90´s. This is the good stuff.

I often use it with the 1.7 AF-adapter and it works very well.
   
PEG Moderator

Registered: August, 2008
Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake
Posts: 57,760
Review Date: July 4, 2010 Recommended | Price: $545.00 | Rating: 10 

 
Pros: A fine usable 300mm
Cons: None, that I've found
Sharpness: 10    Aberrations: 8    Bokeh: 9    Handling: 10    Value: 10   

Again for me not an everyday lens, so much so for my work it's not even carried all the time. That having been said when extra reach is needed it works just fine. It is well built, compact and well balanced in use, so it can be hand held without too much drama.

For me it's about results and this lens delivers when asked.
   
Pentaxian
Moderator Emeritus

Registered: May, 2007
Location: Edmonton Alberta, Canada
Posts: 10,643

4 users found this helpful
Review Date: June 8, 2010 Recommended | Rating: 6 

 
Pros: Size and Build
Cons: Optical quality

I'm going to review this lens directly in opposition to the rest. The only reason I'm even posting this is because I know another PF member that bought one recently and found theirs to fail as well.

The one I bought was in perfect condition. Cosmetics, glass etc was in great shape. That's the good stuff. Optically this lens was a disappointment.

I had a Takumar M42 SMC 300mm f4 at the time and was interested in the smaller size. The A* was about the same as the Tak optically, maybe a touch worse. There was a small amount of PF that could be easily corrected but the main issue was contrast and resolution. The lens scored low on both. Fine details just weren't there and it lacked contrast. I certainly did not feel it lived up to the A* designation.

I followed the sale of this lens with an FA*300mm f4.5 and hands down, without any doubt, that lens is superior in every way. Not much bigger, a better hood, just as well built and optically 3x better. Plus the bonus of AF.

So my review is a caution that IMO this is not the lens to hunt for and possibly there are quality control issues with it or as the lens ages, it does not hold up. I'm not sure why mine didn't perform as expected but since my friends was similar, I think it was worth posting this review. He compared his to a DA*300mm and felt the same way I do vs the FA*.
   
Inactive Account

Registered: November, 2009
Location: Winnipeg
Posts: 38

1 user found this helpful
Review Date: March 3, 2010 Recommended | Price: $570.00 | Rating: 9 

 
Pros: Small size, sharpness, contrast
Cons: None

As other reviewers have noted, this lens is unbelievably small for a 300mm, especially one that covers full frame. It takes up less space in the camera bag than the DA 50-135. The narrow barrel provides a natural grip; you can hold onto the camera dumbbell-style and it's very comfortable to walk with it that way. It's great for hiking or birding because of the light weight and compactness. The images it takes are extremely sharp and contrasty with very good separation of subject from background. The built-in lens hood is a bit awkward to operate and it doesn't extend very far, but I haven't had any problems with flare.

Occasionally I miss having AF but I suspect I wouldn't haul around a big AF 300mm lens as often as I take this one along. It's a perfect combination of portability and optical excellence. I would rate it 9.5 if that was available... can't quite give it a 10 but it is close.
   
Junior Member

Registered: May, 2009
Location: North Wales UK
Posts: 35
Review Date: October 16, 2009 Recommended | Price: $799.00 | Rating: 9 

 
Pros: Superb quality of image.Nice size to hand hold
Cons: None

After reading the reviews on here for this lens I felt I had to find one, I finaly have and I am delighted with it.
I think I had to pay top dollar for it at 799.00 (US Dollars) but it was the first one I have seen on offer so I don't think there are many around.
The built in lens hood is a little loose, but no problem.
I have only taken a few shots with it at the moment, but I am really pleased with the results and the feel of it.
http://farm3.static.flickr.com/2722/4017623666_db867b2f44_b.jpg
   
Junior Member

Registered: November, 2008
Location: South Florida, USA
Posts: 39
Review Date: July 5, 2009 Recommended | Price: $600.00 | Rating: 9 

 
Pros: small, light, great image quality
Cons: none

This is a remarkable lens in that it is the smallest and lightest 300mm F4 lens you
will ever find. I dont know why the tiny size is such a secret but its unbelievably compact. More like a typical 200mm than a typical 300mm. Image quality is excellent, nearly zero CA and no distortion. Contrast and resolution are top notch.
If you dont want to carry a big honkin' 300/2.8 lens, this is the way to go for sure
Add Review of SMC Pentax-A* 300mm F4



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