Pentax A* 300mm f2.8 Review

This is A* lens and it has been one of my "walk around" lenses ever since it has arrived in my posession. Believe it or not. This lens is addictive... I bought it as a demo item from US.

Construction
This lens is definitely short, sturdy and compact. It weighs 3.2 kg (apparently same as Fa 600mm f4 - how come??) and is attached with a tripod mount. There is a built-in lens hood, sliding back and forth with a small screw to lock in. Apparently over-use of the lens hood sliding back and forth would produce inevitable scratch to contribute paint loss...
It accompanies a aluminium silver box that I left it at home most of the time. A UV filter of 49mm can be inserted into a drawer close to lens mount - I had not yet bothered that at all.

Specifications
Mount: Bayonet Lens Construction: 8 groups 8 elements Angle of View: 8.2 degrees Diaphragm: Fully Automatic Min Aperture: 32 Min Focus Distance: 9.8 ft. Filter Diameter: 49mm (rear) Size Max Diameter Length: 5.2 x 9.3" Weight: 104.8 oz. Filter Size: 49mm (rear) Lens Hood: Built-in Lens Case: Trunk Case

Image Quality
With this lens, I have been using it in very dark environment. Aperture wide open has such a narrow depth of field, the subject needs to have the whole plane exactly parallel to the camera sensor in order to have sharp image all over. Using this lens wide open really requires a lot of technique as many of you maye be aware of how poor lighting can really give you little details in an image.
The images are sharp at all apertures (if i could focus accurately with my clumpsy hands). Image is really sharp after f4.
The bokeh quality does vary! Sometimes it shows up sigma style tubular matrix type bokeh sometimes it shows up 31mm style bokeh. It does not have 77mm bokeh CA - luckily. I personally like its bokeh most of the time.
Here are a few examples of images: (Forgive my lack of talent)

1/1000s f/3.5 at 300.0mm iso400 full exif

1/1000s f/4.0 at 300.0mm iso400 full exif
1/350s f/6.7 at 300.0mm iso400 full exif

1/180s f/4.0 at 300.0mm iso400 full exif

Handibility
Thanks to k10d VR feature, I could use this lens just with a monopod attached (with the tripod head loosely tightened). This definitely improves my ability to maneuvre camera together with the lens for various angles at ease. While using this lens to track agile birds, the monopod can be easily adjusted with its height and move around easily locating spot for the monopod. I know using this lens is quite tough but this has been quite an addictive thing for me now. While I hike, I could use the monopod as a stick to frighten away the snakes. Tom Lusk might get annoyed with this as he wanted me to photograph these snakes if I saw them...
Tripod is a no no for this lens. It kills the whole purpose of getting this lens as the weight is just unbearable. Hard to go through the bushes up and down with branches coming out of everywhere. The height adjustment of the tripod would take decades to accomplish and miss million of shots altogether.

Conclusion
Great lens (too bad that I already bought it; I had to like it anyway). The only issue would be its weight and price. I think manual focus is not that bad once you got the hang of it. If you can find this lens, I would go and get it to do protraits and other low light environment shots.
I am getting my Pentax Rear converter 2X very soon and hopefully it would give me 600mm f5.6 to play around with. I will post my humble opinions regarding this combination later on.

James

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Leica 90mm f2 Summicron VS Canon 85mm f1.2 L

It is often an infallable trap for any photographers to entre the realm of measurebation. In other words, it refers to activities of pixel peeping exercises, looking at arbitary numbers of MTF, calculation of distorsion, so-called objective flare intensity and all other technical parameters that seem to be a great range of subjects to discuss regarding a lens.
As a photographer, I think it is helpful to get to know one's equipment. The knowledge I would like to acquire from my own gear needs to specific to myself. Hence, I would look at the matters differently. However, I do not need the objective method of testing to discern the unique properties of various lenses I own. The image quality usually speaks for itself when I am so fussy with my own images...

Here is a test comparison that I want to do upon the request of my friend Voe. There will be intermittent testings of other lenses according to my spare time.
Leica 90mm f2 summicron is a legendary lens as one of the trios (35mm f2, 50mm f2, 90mm f2). 90mm f2 is known to have most even graduated bokeh oosing in and out of focus plane. Smooth as cream. Smooth as butter. It is reputed to have the best centre and corner sharpness in its class.

Speaking of Canon 85mm f1.2L, there is an updated version as mark II where the contrast is quoted to improve wide open while the average autofocus speed is increased by about 1 second. It is the holy grail of many canon shooters and quoted as the best lens for protrait (Sigh ... Success of Canon Marketing)
Today, I will only show you the simple test chart comparison at f2 from both lenses. The background bokeh against cluttering leaves and branches from both lenses will be compared as well. (I have plenty of field experience to reveal at a later day). I use Canon 5D Body and mount a Leica R adaptor to allow Leica 90mm to be used in the test.

Canon 85mm Centre Crop

Leica 90mm Centre Crop

Centre sharpness looks identical to me. The leica shot is picked out of 10 images I took with split focus manual focusing.

Canon 85mm Corner Crop

Leica 90mm Corner Crop

The corner sharpness are not that much different from each other. However, more paper texture are observed from the Leica shot.
Sharpness is never really the concern for me but these two lenses really has little difference from each other.

Canon background bokeh

Leica background bokeh

Leica background bokeh against cluttering leaves seem to be more swirly. Now Canon shooters gonna hate me here.

Yet ...

I had done another test comparison regardomg flare and bokeh quality.

Canon at f2

Leica at f2

These two shots were all unprocessed and converted from Raw files as they are. Canon renders lower contrast in the background bokeh department and its specular highlights are of more harsh along individual edges. On the other hand, Leica renders more swirly and contrasty background blurr where specular highlights are equally harsh edged like canon counterparts.
What really stands out is the ability of Leica to take on the flare situation, rendering more shadow details and produce blurr a lot more effectively.

I will perform more testing regarding these two lenses in the future. Speaking of practicality, Leica has wowed me so much. I only owned this lens for 2 weeks so far and it has shown me what a "slow" lens could offer me comparing to Canon 85L. Leica renders texture and colours so well that even hidden details could be brought back by post processing.

Leica 90mm f2 summicron at Grampians with Joel

f2

Look at background swirly bokeh of 90mm f2 summicron

Then this amazing colour being sucked in by this Leica gem

Yes, I am subjective but I am not going to ditch my Canon 85L. I use it at f1.2 all the time. The autofocus is often accurate and spot on. The lens has been my work horse for some time and very reliable. When time is essence, Leica needs a lot more patience and trial + error to get focus right.

Here is my take on these two legendary lenses!

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