| Author: | | New Member Registered: July, 2023 Posts: 1 | | Review Date: July 11, 2023 | Recommended | Price: $20.00
| Rating: 7 |
| Pros: | Size, Build Quality, Speed, Price | | Cons: | Focussing Difficulty, CAs, Low Contrast | | Sharpness: 8
Aberrations: 4
Bokeh: 7
Handling: 9
Value: 9
Camera Used: Sony A7 with Voigtlander PK Adapter
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Purchased in 2023 for very little. Mine is a Cosina Petri.
Build :
Surprisingly good build quality with full metal construction, I think in this regard Cosina primes get an unfair rep based on the shoddy plasti-zooms produced en-mass in the 90s. No complaints here, handles very well and mates to my Cosina Voigtlander adapter and Pentax K7 perfectly.
Handling
Handles very well, around the same size as my Pentax K 28mm f3.5, but it is an f2 lens. No real complaints here other than the focus direction being the 'wrong way' for a Pentax lens.
Good, positive whole stop clicks on the aperture ring - honestly the aperture ring feels better constructed and more solid than the aperture rings found on the K and M series Pentax primes.
Image Quality :
The thing with fast wide primes of this era is that the actual plane of 'perfect sharpness/contrast' is absolutely, critically razor thin. You will not be able to focus this accurately through an unmagnifed OVF, you must use LV or an EVF to get the most from it and achieve perfect sharpness wide open. When you do, it's just as sharp as my Pentax K 30mm f2.8 wide open. Sharp, but not amazing or anything.
Stopped down it behaves as it should, good for landscapes at around f11 but there is a fair bit of CA that never really goes away but can be corrected.
If misfocussed it will glow a lot.
Pretty low contrast wide open but that's par for the course on a fast lens of this era. Not punchy/contrasty like the K 28mm f3.5, but if I'm only able to take one lens I'm bringing the Cosina Petri due to the speed.
Focusses under 30cm which is pretty essential for wide angles.
Conclusion
It's the lens I leave on my camera as a default. I like it, but I wouldn't pay more than $50 for a mint example.
| | | | | | | New Member Registered: June, 2018 Posts: 1 | | Review Date: June 8, 2018 | Recommended | Price: $150.00
| Rating: 10 |
| Pros: | sharp | | Cons: | expensive | | Sharpness: 10
Aberrations: 9
Bokeh: 10
Handling: 9
Value: 9
Camera Used: pentax k3
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this lens is great.
my favorite lens.
There are also very good results in filmed cameras
| | | | | New Member Registered: January, 2018 Location: Paris Posts: 8 | | Review Date: February 23, 2018 | Not Recommended | Price: $140.00
| Rating: 6 |
| Pros: | Sharp above f4, nice colors | | Cons: | Blurry until F4, very far from a very good 28mm to my taste | | Sharpness: 6
Aberrations: 7
Bokeh: 7
Handling: 7
Value: 5
Camera Used: K1
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Got a mint copy
Maybe a lemon (but not sure...) mine was not sharp until reach F4
F5,6 to F8 are very good except the corners
Nice Colors.
The problem is at this aperture I already have a tak 35/3.5 and a k28mm/3.5 which are far ahead of this one...
Overrated lens for me. It’s not the fast lens i hope. Poor result until F4. Not usable to my taste
Very good lens for 50/60€ If you have not the choice....
Much better choice in Pentax SMC for IQ and build
Nota : don,t think monkey pic behind has been taken at f2 at speed 1/400(+nervous bokeh) ...f4 maybe or more
maybe this lens becomes a stellar one in apsc ....
| | | | | New Member Registered: October, 2016 Posts: 2 | | Review Date: October 20, 2016 | Recommended | Price: $90.00
| Rating: 9 |
| Pros: | Great bokeh, very sharp, pretty small | | Cons: | CAs and Flares in a few situations | | Sharpness: 10
Aberrations: 7
Bokeh: 10
Handling: 10
Value: 10
Camera Used: MX, Canon 550d
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I really love this lens. It is small, fast and sharp. Colors are no pro and no con for me, mine doesn't produce pictures with much contrast, but it doesn't look bad either. The only thing that is not so good about this lens is its behavior in situations where you shoot against the light.
By the way, I have the "MC COSINON-W" version of this lens, not the petri one. I don't know if there is much difference.
On crop this was the lens i used for everything. On film its pretty wide but you still are able to get some nice Bokeh. Anyway, the pictures may be better at showing you why I like the lens  (All shot on a Canon 550d with minor postprocessing)
@2.8 (I think)
@5.6
@2
@5.6
 | | | | | | | Veteran Member Registered: May, 2015 Location: Black Isle, Scotland Posts: 405 | | Review Date: September 26, 2015 | Recommended | Price: $70.00
| Rating: 8 |
| Pros: | Cheap, vibrancy, decent sharpness when used right, wild OoF effect | | Cons: | Whole stop aperture ring, build, difficult sharpness, wild OoF effect, CA | |
You may have noticed that I've given this lens a high overall rating, but lower for everything else; this is because the lens is more than the sum of its parts.
First off, I've no idea why but when I got it the auto-aperture wouldn't function either side of F5.6-8. I took apart the mount and put it back together, not really having any idea what I was doing and losing a screw in the process. Now the aperture works, but as a preset. This doesn't really inspire confidence in the build quality, but hey-ho, I paid only £40 for a 28mm F2 so what can be expected? Like the other Petri lenses I own, the aperture ring also only does full stops.
Perhaps having something to do with my bungled mount job, the lens also judders when I take photos with it. I think this has occasionally thrown my focus off, and means it tends to work best in Live View, or with the 2s timer.
Edge sharpness is pretty dire until stopped down to F8, but then it's pretty fine - on the crop sensor at least. Centre sharpness is surprisingly good all the way from F2 until diffraction sets in. Though of course the centre is sharper at F5.6, you're splitting hairs unless trying to print larger than A4.
Flare resistance is minimal, so in most circumstances a hood is highly recommended. There is also noticeable chroma at high contrast edges, though we do have the modern advantage of software CA correction.
So why would I rate this lens 8/10? Sounds pretty crap, right? Yeah, but now we're coming to the good bits.
The standout quality of this lens is the colour. I was utterly astounded by how vibrant the colours, and particularly the reds, were. When flare is under control there is absolutely no requirement to boost saturation in RAW development. It's damn beautiful and satisfying to see.
The second aspect of this lens that I enjoy is perhaps a bit more of a divisive issue. Despite the standard aperture design (6 flat blades) meaning that bokeh has no character most of the time, when wide open the OoF effect is utterly wild. I have so much fun pointing this lens at different textures and seeing what comes out the rear end.
Without further ado, pictures!
Sharpness at F8
Colour
Out of focus
A flawed beast, to be sure, but a fun ride when tamed.
| | | | | Inactive Account Registered: February, 2012 Posts: 1 | | Review Date: August 5, 2014 | Recommended | Price: $145.00
| Rating: 9 |
| Pros: | Sharp from F2 on, good color rendering, best 28mm Ive had. | | Cons: | build is not so good as pentax k lenses. | |
When I noticed that someone was selling this lens earlier this months I decided to buy it, I already got the famous Pentax K 35mm F3.5 but I was just very curious about this nearly ultra rare lens. In terms of sharpness this is really an outstanding lens, much better than my other 28mm's (pentax a 28mm f2.8, pentax m 28mm f2.9, panagor 24mm f2.5, sigma mini wide, and the vivitar 28mm f2.8), colors are great too. If you see one, just buy it I'd say.
Some images: no longer active
| | | | | Senior Member Registered: March, 2011 Location: Ontario Posts: 115 | | Review Date: January 17, 2012 | Recommended | Price: $120.00
| Rating: 10 |
| Pros: | Sharp, great colours, smooth focus and bokeh | | Cons: | Manual - K or M like | |
I think this lens is well suited for darker situations, being f2, and at that opening, it is still quite sharp. The bokeh transitions smoothly without any unsightly bright rims on lights/specular reflections in the background. Colors are rendered vibrantly.
As stated in an earlier review, the screw head nearest the locking slot, had to be covered with aluminum tape in order to allow the green button to work properly on my Kx.
I did a bit of research beforehand and found that this lens was made for Petri by Cosina (Cosinon). There were a few other 28/2's available in a K mount in this price range by Vivitar (Kiron/Kino) but these were reviewed to be soft when wide open so I went after the Petri and I am not disappointed.
This lens will be used frequently and is highly recommended.
| | | | | Senior Member Registered: February, 2011 Location: Tallinn Posts: 162 | | Review Date: April 2, 2011 | Recommended | Price: $150.00
| Rating: 10 |
| Pros: | beautiful sharp at f2 with creamy bokeh | | Cons: | it may not mount properly on K-5 | |
So I got this lens out of curiosity and 'cos I got it cheap. I got it for 40EUR, but it sells on eBay sometimes around 150USD or more.
It really is exiting lens. Beautiful soft bokeh but pixel sharp in detail still.
Look at the pictures here
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/138944-petri-2...elievable.html
Initially I had difficulties to get the aperture lever to work on K-5. I could not understand what caused the aperture not close when mirror goes up. It works perfect on K10D.
When you look at the mount there is a screw close to the lock slot. It locates right under the contacts of the camera and one of contacts will "fall" right in the screw hole. Thus making no connection. When I placed a piece of aluminum tape over the screw hole it works as it should.
| | | | | | | | Review Date: November 23, 2010 | Recommended | Price: None indicated
| Rating: 10 |
| Pros: | sharp and high contrast at all apertures | | Cons: | none | |
 tiis is the best 28mm lens i have ever used i used it on my k. 20d in custom permitted mode, i t was a gift from a lady at our photo club, who had gone over to canon d.s.l.rs from film. i could not believe my luck when i ran some tests, on tripod and hand held, its equivelent to42 mm on my sensor so it would serve as a short normal lens, i will probably use it for architecture details, i remember the petri cameras from the late 60s and early 70s the lenses were always well rated in photo mags but i never actually used one, then the brand dissapeared.
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