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11-21-2010, 12:23 AM   #1
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K-X with manual focus lenses

Hello everyone,

I am a current Pentax MX 35mm user and soon to be a new Pentax K-X owner. I have a decent selection of good quality manual focus lenses that I hope to use on my new K-X until I can afford newer lenses.

I am just wondering if anyone else has done this, and what I should expect. Will my results be as good as they are on 35mm format? Will I be able to shoot decent quality video with the older lenses? Do the focal lengths translate differently onto a DSLR?

Thank you very much,

Brent

11-21-2010, 12:34 AM   #2
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I can answer some of the questions.

1) Focal lengths - the 35mm camera is 'full frame' but the K-X has a smaller sensor. Mutliply the focal length by the 'crop factor' which I believe is 1.5 to get how the lens will work on the K-X. Useful if you like long lenses, a pain if you are into wide-angle.

2) Quality should be fine though my own experience is that manual focus without a split image focusing screen isn't that easy. Hopefully the lenses have an 'A' setting on the aperture dial.
11-21-2010, 01:11 AM   #3
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Your focal length on digital doesn't change, but the field of view does (it's cropped).

Think of a 35mm on digital providing about the same field of view as a 50mm on film. The crop factor is 1.5x, so basically you'll need a wider lens on digital to accomplish the same effect on film.

The good thing about this is that when you mount full-frame lenses on your DSLR, it won't be using the edges of the image circle where the image quality isn't that great. Most of the older lenses work wonders on film. I myself still use lots of FA* lenses for everyday purposes. Don't use MF lenses that much simply because there are AF alternatives, but that doesn't discredit their stellar IQ!

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11-21-2010, 01:30 AM   #4
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Great, sounds like I can get away with using my old lenses for a while.

My Vivitar 17-28mm and Tokina AT-X 28-85mm both have an A function...which I have never used because I currently shoot on an MX.

I am a little disappointed to hear that I won't get as much bang out of my wide angle lenses. I love shooting wide angle shots. I guess it's ok though because I will still use the MX on occasion.

Thank you for the info, I appreciate it.

Brent

11-21-2010, 02:21 AM   #5
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QuoteOriginally posted by BrentPDX Quote
I am just wondering if anyone else has done this
As a MX owner, I can say yes, others have indeed been down this path before.

You'll have fun with the K-x and your old glass. If your eyes aren't as good as they used to be though, for manual focussing in low light (daylight is less of a problem) I'd suggest picking up a magnifying eyepiece like the Pentax O-ME53 to make the K-x focus screen easier to work with.

Even though you have access to some great old glass, I'd still recommend getting the K-x kit with the 18-55 and the 55-300. They are both excellent lenses and make a great value kit, and you may find yourself using the old glass less and less.

One solution for the 'loss' of wide angle as a result of shooting on a crop body is an excellent stitching/panorama tool like Microsoft Image Composite Editor that you might like to download and explore:
Microsoft Research Image Composite Editor (ICE)

I've used it several times to stitch together multiple images from my K-x using my M28 f2.8 to produce really vast, seamless panoramas. It is very easy to use too, so I haven't felt the need so much to invest in specific wide-angle glass (yet).
11-21-2010, 10:51 AM   #6
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Manual focusing without a split prism requires practice. Yes there is a focus conformation beep, but its not 100% accurate.
11-21-2010, 01:11 PM   #7
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QuoteOriginally posted by rawr Quote
If your eyes aren't as good as they used to be though, for manual focussing in low light (daylight is less of a problem) I'd suggest picking up a magnifying eyepiece like the Pentax O-ME53 to make the K-x focus screen easier to work with.
I just turned 27 on Monday, and I feel old...but I think my eyes will be ok for a few more years.

QuoteOriginally posted by rawr Quote
One solution for the 'loss' of wide angle as a result of shooting on a crop body is an excellent stitching/panorama tool like Microsoft Image Composite Editor that you might like to download and explore:
Microsoft Research Image Composite Editor (ICE)

I've used it several times to stitch together multiple images from my K-x using my M28 f2.8 to produce really vast, seamless panoramas. It is very easy to use too, so I haven't felt the need so much to invest in specific wide-angle glass (yet).
Thank you for the suggestion. I will definitely look into this.
11-21-2010, 09:21 PM   #8
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QuoteOriginally posted by BrentPDX Quote
I just turned 27 on Monday, and I feel old...but I think my eyes will be ok for a few more years.
Let's just say, without getting into specifics, in two years, I will have exactly an age of 27 .... but I am dyslexic.

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