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Pentax SMC-A* 300mm F2.8

by Paal Jensen, 1998

The A* range of lenses are Pentax's best manual focus offering, with several (such as the lens reviewed here) still being offered for sale.


One of the main drawbacks of the A* 300/2.8 lens is related to its build quality - due to it's heavy duty construction it weighs all of 3kg, making it the heaviest manual focus lens of its type. Although the lens is heavy, it is quite compact - short and fat being a fitting description. It's all metal, including the supplied lens hood, which is of the slide type and locks with a small screw. A leather lens cap that fits the whole front part of the lens is also supplied, as is an aluminium trunk case that's completely useless for field work, but nice for transportation.

49mm filters can be used via a drawer close to the lens mount, and a tripod can be used on the sturdy, non-removable mounting which is fitted. The barrel of the lens is painted white and is more durable than the silver metallic finish of the Pentax auto focus lenses.


The lens is a 8 element 8 group construction featuring internal focusing (IF) and ED (extra-low dispersion) glass. It is very sharp at all apertures, but razor sharp from F4, although there is realy very little difference between the apertures. Slides are very contrasty - resolution and sharpness are absolutely first rate. Studying feather details of birds with a loupe on the light table is nothing short of a joy. I have aslo used the lens for low light landscape work where its performance is extremely impressive. Performance with the dedicated Pentax 1.4X-L and 2X-L convertors is also very good - particularily with the 1.4x where any performance dedication is so slight as to be insignificant. When using the 2X-L converter its recommended to stop down by at least one stop in order to achieve maximum optical quality.


Handling such a heavy lens is not easy so, due to its weight, this is a typical tripod lens. Its really too heavy for handholding although I have used mine for shooting birds from a Zodiac inflatable boat. The lens is a dream to focus because of its speed and nice internal focusing mechanism - the subject pops into focus and I d'not miss auto focus except when shooting from my boat.

The hood unlocked offers enough friction to leave it that way at all times, which is fortunate as the lock screw is a bit of a pain - it gets hooked up in everything. Mine eventually broke off! The inside of the lens hood is painted matte black, but this area often shows some wear with use due to the sliding motion of the lens hood.


The lens is 100% compatible with all Pentax K-mount bodies. The only thing you don't have when using it on auto focus bodies is auto focus!


Price The lens is very expensive and costs more than most 300/2.8 auto focus lenses, including Pentax's own. It is not a difficult to find on the used market, where it seems to have a slightly higher price than the more common Nikon and Canon 300/2.8 lenses.

In August 1998 some of the photo.net recommended retailers were listing this lens for around 5,150 USD, while the FA* 300mm F2.8 auto-focus alternative will set you back around 4,700 USD.


The lens is highly recommended if you can take the weight and cost (and AF isn't an issue for you). 300/2.8 lenses only make sense if you have use for the speed and/or want to use them a lot with converters. Remember, the Pentax FA* 300/4.5 cost less than 1/5 and weigths less than 1/3 of the A* 300/2.8 lens.

Editor's Note:

Where to Buy

The SMC 300 F2.8 is stocked by Adorama, a retailer that pays photo.net a referral fee for each customer, which helps keep this site in operation. For additional retailer information, see our recommended retailers page and the user recommendations section.

Article created 1998

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