Wide Angle Lens Compatibility Issue


ziggles

Link Posted 24/09/2007 - 11:36
Can anyone help me? My uncle has a old Pentax Wide Angle lens which fits on to my new K10D with no problems but it does seem to give a wide angle view. Its actually narrower than my standard 18-55mm lens. Can anyone explain to me if theirs something I need to adjust or is it just the lens is not compatible with my camera. Your help is much appreciated.[/b]

Tyr

Link Posted 24/09/2007 - 11:42
What focal length is it? Remember that the K10D has a 1.5x crop factor which means all lenses have a field of view narrower than usual.

18mm becomes 27.54mm equivalent FoV

28mm becomes 42.82mm equivalent FoV

So you need a really wide lens to actually get a wide shot.
Regards,
Dan

https://www.flickr.com/photos/honourabletyr/

MattMatic

Link Posted 24/09/2007 - 11:43
Ziggles,
The sensor on the digital SLR cameras is smaller than 35mm film.
Consequently, the digital will give a centre crop. For example, a 100mm lens on digital will behave like a 150mm did on film.

That's why for digital Pentax have developed lenses like the SMC-DA 12-24
Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

Tyr

Link Posted 24/09/2007 - 11:45
MattMatic wrote:

That's why for digital Pentax have developed lenses like the SMC-DA 12-24

LOL

I was going to give the 10-17 as an example but decided against it.
Regards,
Dan

https://www.flickr.com/photos/honourabletyr/

George Lazarette

Link Posted 24/09/2007 - 11:45
ziggles wrote:
Can anyone help me? My uncle has a old Pentax Wide Angle lens which fits on to my new K10D with no problems but it does seem to give a wide angle view. Its actually narrower than my standard 18-55mm lens. Can anyone explain to me if theirs something I need to adjust or is it just the lens is not compatible with my camera. Your help is much appreciated.[/b]

If it's old, it is very unlikely to be wider than the 18-55. In the days of film, the widest Pentax lens was the 15mm, and it was very expensive and correspondingly rare. Most wide-angles were 28mm or 35mm. The smaller the number, the wider the angle.

But to know the answer, just look at what it says on the front of the lens. My guess is that it is an SMC Pentax-M 1:2.8 28mm. The 28mm is the bit that governs the angle of view, and whilst 28mm was quite wide on film, it's not much more than a standard lens on digital.

This is because the digital sensor is smaller than a 25mm film frame, so it only captures the central portion of the image.

G
Keywords: Charming, polite, and generally agreeable.

Daniel Bridge

Link Posted 24/09/2007 - 16:18
ziggles wrote:
Can anyone explain to me if theirs something I need to adjust or is it just the lens is not compatible with my camera.

There's nothing you need to adjust, but the lens is compatible, just that the field of view is narrower than you expected, as described by everyone else above.

Dan
K-3, a macro lens and a DA*300mm...
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