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Pentax 150mm f/3.5 (Discontinued about 2000)
© 2009 KenRockwell.com. All rights reserved.

Intro   Specs   Performance   Recommendations

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Pentax 645 150mm f/3.5

SMC Pentax-A 150mm f/3.5. enlarge. You can find these used at these direct product links to Adorama and eBay. It helps me keep adding reviews of this old stuff when you use these links to get yours, Thanks! Ken.

 

January 2009        more Pentax reviews

 

Introduction          top

Intro   Specs   Performance   Recommendations

This is a manual focus short tele lens for the Pentax 645, 645N and 645NII medium-format cameras.

It works in all the automatic and manual exposure modes of the Pentax 645, 645N and 645NII.

These lenses are bargains today. They sell for between $75 and $200 in January 2009. Back in December 1997, B&H got $580 for this lens new (that's almost $800 with inflation in 2009), and in April 2001, they got $560. It was replaced by the autofocus f/2.8 version in about 2001, which sold for $1,050.

Pentax 645 150mm f/3.5

Pentax 645 150 3.5. enlarge.

 

Specifications          top

Intro   Specs   Performance   Recommendations

 

Optics

4 elements in 4 groups. Multicoated.

 

Focal Length

150mm.

35mm equivalent: It sees a similar angle of view on 645 film as a 90mm lens sees on 35mm film.

See also my 35mm Equivalent Focal Length Chart for other 645 lenses.

 

Diaphragm

8 blades stopping down to f/32. Arbitrary half and full-stop clicks.

 

Close Focus

4.6 feet (1.4m).

 

Filter Thread

58mm, metal.

Does not rotate with focus.

 

Size

2.91" diameter x 2.81" long (74 x 71.5mm).

 

Weight

15.409 oz. (436.8g) measured, naked.

Pentax specifies 15.3 oz. (635g).

 

Hood

Built in, telescoping metal, with rubber bumper. Excellent!

 

Teleconverters

Pentax suggests the A645 2X converter, but not the 1.4x.

Pentax 645 150mm f/3.5

Pentax 645 150mm f3.5 with hood pulled out. enlarge.

 

Performance          top

Intro   Specs   Performance   Recommendations

The Pentax 645 150/3.5 is excellent. It's sharp right out to the edges even wide-open at f/3.5.

It's the sharpest lens I've used of Pentax' manual focus 645 35mm, 75mm, 120mm macro and 150mm lenses.

It's also super easy and fast to use. I can flick focus with a light touch of one fingertip.

The weirdest thing about it, as cautioned in the Pentax 645N manual, is that in aperture-priority mode it reads, and film-edge-imprints, as f/19 when set to f/22 and f/27 when set to f/32. Weird, but nothing that even a geek like me would worry about. Pentax mentioned this in the manual so we wouldn't freak out.

 

Distortion

The Pentax 150mm f/3.5 has no visible distortion.

For very critical use, plug -0.2 into Photoshop CS2's lens distortion filter to correct the invisible pincushion distortion at infinity.

 

Ergonomics

I love it! I wish all my lenses were this good.

The focus ring feels fantastic; you can flick it with a single finger. It's smooth and slick, with no play. It's perfect.

The hood is the best built-in I've ever used. It's sturdy metal, it erects and retracts easily, and it has a tough rubber bumper around its outside.

Also better than other built-in hoods, it retracts inside the lens! When retracted, it doesn't leave a big blank area on the barrel; it just goes away.

 

Falloff (darker corners)

The 150mm has moderate to minor falloff at f/3.5.

It's gone by f/5.6.

You won't see it unless you deliberately make comparison shots at different apertures and flick though them.

 

Filters

The 58mm filter thread is generous. You easily can stack a few filters with no vignetting.

Don't worry about using extra-thin filters; you don't need them.

The metal filter threads don't rotate when focused.

 

Focus

This is one of the best parts: focus is a dream. One fingertip can flick it around. It's slick, smooth and perfect.

 

Mechanics and Construction

The Pentax 645 150mm is made as it should be.

Barrel: Enameled, anodized aluminum.

Focus Ring: Metal, rubber covered.

Depth-of-Field Scale: Yes.

Infra-Red Focus Index: Yes.

Aperture Ring: Metal.

Finish: Black enamel over black anodize.

Mount: Metal with some plastic nubbins.

Internals: Metal.

Markings: Engraved and filled with paint.

 

Sharpness

This 150mm f/3.5 is the sharpest lens I've used on Pentax 645, sharper than the 35mm, 75mm and 120mm manual focus lenses.

It's sharp even in the corners at f/3.5. Enjoy!

 

Sunstars

The 150/3.5's 8-bladed diaphragm leads to 8-pointed sunstars. The results will look similar to most Canon teles.

Pentax 645 150mm f/3.5

Pentax 645 150 3.5. enlarge.

 

Recommendations          top

Intro   Specs   Performance   Recommendations

The optics of this lens are superb. Originally I was considering using the 120mm macro as a general purpose tele, but this 150mm is sharper at normal distances.

This 150mm is small, light, works great, and sometimes can be bought for less than $100. It's a no-brainer for any Pentax 645.

I have not tried the 150mm f/2.8 AF. The AF lens is bigger and heavier, uses 67mm filters and only stops down to f/22, not f/32 like this manual focus lens. f/32 is sometimes especially useful with longer lenses to get depth-of-field in many common situations.

 

PLUG

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Thanks for reading!

Ken

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