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Technical Question about using older lenses

Posted 01/09/2011 - 16:42 Link
Please excuse me if this is a familiar question but im after a bit of advice about fitting lenses.

I have a K-x and am toying with the idea of getting a 50mm lens from a popular auction site.

whats is the score with fitting an old lens to my camera? how functional will a lens be, i appreciate i will need to use manual focus but how will i adjust the apeture and will the camera be able to meter or will i have to learn how the lens behaves with certain shutter speeds and whatnot whilst ignoring the camera's metering?
wvbarnes
Posted 01/09/2011 - 16:51 Link
Hi,

your handbook will tell you the functionality for Pentax lenses. You can use them all with lesser or greater need to be manual in use.

If manual exposure due to lack of contacts then you can set the green button to optical preview and this will give you exposure for the selected manual aperture bottom right in the viewfinder. Again all in the book.
Edited by wvbarnes: 01/09/2011 - 16:51
matwhittington
Posted 01/09/2011 - 18:13 - Helpful Comment Link
As Bill says the manuals for Pentax DSLRs, I find, are pretty good. However, there are also plenty of useful websites out there... one of them is here:

link

Hope that helps

Cheers
Mat W

My Flickr: link
madmazda86
Posted 01/09/2011 - 19:42 Link
Okay, a couple of things to consider:

1) Make sure the lens has a Pentax K bayonet mount. If it's a M42 screw thread lens, or another type of mount, it may not fit. The K bit is the important bit - Olympus also do bayonet mount lenses of the OM type and those ones won't fit on your camera. Good names to look out for are Asahi Takumar (Pentax's own brand), Tokina, Contax and certain Hanimex, Vivitar, Tamron and Sigma ones. You can use M42 screw mount lenses with your Pentax but you need a proper adapter for it.

2) Look up reviews of the lens you're looking to buy online. One manual lens is not as good as the next, and by googling around you can find out which Ebay steal is actually a steal and not a waste of your money!

3) The lens should be fully functional on your camera provided you go into the customisation section of your camera menu (the spanner, I think) and set the 'Using aperture ring' to 'Permitted'. Once you've done this, when you have a manual lens mounted to your camera you'll notice that the aperture bit of the viewfinder will have -- on it instead of a number. It'll also ask you to input the focal length of the lens when you switch the camera on. I sometimes forget to do this and it's set to 28mm or summat when I've got a 40-80mm on, and it doesn't make much difference to the picture XD

To meter while you've got one of these lenses on, I set my k-m so that it would stop-down meter when I pressed the wee +/- button on top of my camera. I find it tends to set a much lower shutter speed than what I actually need (whiting out the shot) so I have to tweak it a little after it's metered it. I'm full manual for mine so I can't tell you much about which other modes you can use while you've got one of those lenses mounted on.

Hope that helps. My lens kit for my k-m is a 28mm Tokina and a 40-80mm Asahi Takumar. I also have a 70-210mm Takumar-A but the quality of that one turned out to be not so good (hence looking up reviews is important!), so I don't use it much. I also have an official Pentax M42 screw thread adapter and a few M42 lenses that I had from my old camera. So all up (including the adapter), my kit cost me £117.50.
Edited by madmazda86: 01/09/2011 - 19:42
ChrisR
Posted 01/09/2011 - 20:02 Link
matwhittington wrote:
As Bill says the manuals for Pentax DSLRs, I find, are pretty good. However, there are also plenty of useful websites out there... one of them is here:

link

Hope that helps

Cheers

A very good link, thanks Mat.

Take care.
Chris R.

I. El. (Eng). (Rtd).
davidstorm
Posted 01/09/2011 - 20:45 Link
I would recommend you buy some older primes without hesitation, even if they are manual. You don't need to program the 'green button', just use the Exposure Compensation button (+/-) and this will do the metering for you in manual mode.

It's more fun taking pictures in manual mode and focussing yourself!

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs
womble
Posted 01/09/2011 - 20:59 Link
I don't know what the K-x is like for metering with older manual lenses but with my K10D/K20D the standard "green button" method is often way off. Provided your image preview is set to show the histogram, it isn't really a problem. More often than not I'll not even bother with the green button but will shoot a picture of the grass (or anything else mid-toned) and adjust the exposure until I get a good looking histogram. From there on it is just a matter of increasing or decreasing the exposure a little bit as I go along.

As always, the histogram is your friend. No wonder someone said it was the greatest help to photographers since the invention of the light meter...

K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

My website
davidstorm
Posted 01/09/2011 - 21:14 Link
Kris, my K-x seems pretty good at metering with the manual lenses, most exposures come out spot-on. I always use the Exposure Compensation button as pressing this carries out the metering and sets the Shutter Speed.

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs
Posted 01/09/2011 - 21:55 Link
Thanks so much for all of the help, you guys are ace and the help is exactly what i am looking for.

the lens i am looking at is an "smc Pentax - M 50mm f1.7"

as suggested above, i have read some reviews of it which make it sound like a great lens and at 30 quid it seems like a bit of a bargain

At the moment i am only using my camera in "M" mode (and sometimes in full auto (please dont burn me!)) Bearing this in mind, to use a "m" lens, would i be able to leave the camera in "M" mode, adjust the apeture with the ring on the lens and adjust the shutter speed using the thumbwheel on the body as normal?
davidstorm
Posted 01/09/2011 - 22:05 Link
Buy it!!!!!!!!!!!!!!!

I have the 28mm f3.5 Pentax-M and it is a great little lens. I don't have the 50mm f1.7 but I've read good things. Most Pentax lenses are really good.

Your comments on how to set the shutter / aperture are correct, but also as mentioned earlier, you can get the camera to set your shutter speed by pressing the +/- Exposure Compensation button (then adjusting it from there with the thumbwheel if you wish).

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs
Posted 01/09/2011 - 22:21 Link
thanks again.

Im a bit confused about the pressing +/- button.

in "M" mode, when i press that button, it changes the operation of the thumb wheel. Does this mean that when in "M" with a manual lense fitted, the +/- button changes role?

or am i missing the point? (highly likely i might add)

sorry for the massive list of bone questions, thanks in advance for everyones patience.
davidstorm
Posted 01/09/2011 - 22:34 - Helpful Comment Link
The +/- button allows you to set exposure compensation via the thumbwheel with an automatic lens fitted, but with a fully manual one it makes the camera perform stopped-down metering and sets the shutter speed based on the aperture you have selected.

Regards
David
Flickr

Nicola's Apartments, Kassiopi, Corfu

Some cameras, some lenses, some bits 'n' bobs
Dangermouse
Posted 01/09/2011 - 22:47 Link
The 50/1.7 is an excellent first prime. Very sharp and compact.

I'd stay clear of the manual zooms though. Some of them are excellent lenses but the SR business is a pain, so I tend to keep them on my film cameras. I haven't used most of my manual primes on digital since buying the DA 35/2.4 and DA* 50-135mm to be fair.
Matt

Shooting the Welsh Wilderness with K-m, KX, MX, ME Super and assorted lenses.
JamieT
Posted 01/09/2011 - 22:52 Link
Have a read about the 'catch in focus' mode on the KX, worth playing with if you are nervous about accurate focusing.
K5, LTD 15 SIG 30, SIG 105.
Posted 01/09/2011 - 22:58 Link
superb

thanks so much for the help.

The main reasons i chose a pentax were the tactile feel of the camera (i dont how much that is worth to other people but the camera physically feels good to me) and the opportunity to make use of a vast array of older yet highly rated lenses for very little money.

now i understand the techniques required to make use of a "legacy" lens, i cant wait for my first to arrive.

Thanks to everyone for their help, no doubt i will be back once the lens arrives!

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