SMC K (fully manual) lenses on K20D

This has probably been dealt with elsewhere but I am not sure where so here goes.

I have had an LX and K2 since 1981 and only ever used manual lenses - K and M lenses. I only have one with an A setting so they all predate autofocus - in fact anything 'auto' at all pretty much apart from a new digital lens I received with my K20D.

I just want to make sure I set the camera up right for correct metering with old SMC K and M lenses without an A setting.

I have changed the setting near the lens mount to MF for manual focus and set the custom setting to PERMITTED. I entered the focal length where asked, although this is rather arbitrary if you are using a 80-200mm zoom - which focal length do you input? Or if you are on a tripod and just using one focal length of the zoom, do you just input that length?

Although I still get the flashing F, yet it lets me take shots.

I gather I can then shoot in either AV or MANUAL modes (and USER presumably since that is just a preset you ccreate?) and manually focus my lens and still get focus confirmation. Of course the LX has the brilliant OTF metering so it measures the exact amount of light energy reaching the film plane and adjusts accordingly.

What do I need to look out for in the K20D metering with manual lenses? Is it likely to underexpose? Should I set it up to bracket automatically, or should I increase the EV on all pictures by a stop to make sure? I am not clear on how to set it up correctly (and then save the settings presumably as a USER profile) so that I can use the old lenses without screwing up shots.

If this has all been answered elsewhere please direct me to the thread.

thanks in advance

PS Interestingly I once I was shown, I found the K7 very easy to use with an old lens. Maybe the K20D is the same, but I just need to make sure I am doing it all correctly

Focal length input: Yes, tricky with a zoom. Try and input the length you're going to use (for example 80, 135 or 200) as this value will be fixed as long as the lens is attached to the camera. Although I've got quite a few old lenses they're all primes - zoom technology is one area where things have come on a long way in the last 30 years so I don't tend to bother with old ones.

Metering: This will usually be pretty accurate with lenses set somewhere around f/4 - f/5.6. With a wider aperture you'll often find the camera will underexpose, with a smaller aperture the opposite will happen. I tend to take a picture at my chosen aperture, check the histogram to see how far under/over it is, then apply the appropriate amount of exposure compensation - works pretty well if you're taking a series of shots at the same aperture (which I often do) as the under/over exposure is usually fairly constant.

Flashing F--: There's no communication between camera and lens so you'll always have this on the body and in your EXIF data when using a non-A lens.

You'll get the hang of it all pretty quick.

You have setup the camera correctly already.

Av mode with this lens only works with the largest aperture*.

You need M mode to use the smaller apertures. Select the desired aperture via the ring on the lens. Use the Depth-of-field Preview to get a meter reading, or press the Green button to get a reading and automatically set the shutter speed according to that reading. This will sometimes/often result result in incorrect exposure due to inadequate design from Pentax. It's often over-exposure, in my experience.

Take a test shot then use Ev Compensation or manual adjustment as required. Ev Compensation on the K20D (unlike K10D) affects the result of the Green button in Manual mode.

* Unless selotape is stuck over the part of the lens where the electrical contacts would be if there were any. There still would be metering errors for smaller apertures anyway.

Regarding the Shake Reduction for an old zoom lens: Ideally the focal length value should be changed everytime you zoom - which can be done via the menu or after turning the camera off and on.

But you may wish to use a compromise value sometimes for the sake of convenience. I suppose this should be half way between the range you most use.

Pete - does the compromise really work? Given that we are told to turn SR off when using tripods, that tends to imply "wrong" SR can be as bad as no SR? I've been put off buying manual zooms because of this.

As regards SR, old lenses can be set to an approximation quite happily, but if preferred simply turn SR off.

STEVE, BRILLIANTLY CLEAR AND UNDERSTANDABLE!

So setting the focal length is only needed for the SR function, and no other reason? i.e. irrelevant on a tripod with SR switched off

So, if I have got this right:

A lenses are fine with AV mode but K and M lenses are probably better suited to MANUAL mode.

Can the manual settings be stored somehow as a USER profile or I guess each one is different depending on the lens?


many thanks everyone

Thanks Steve/John. Advice appreciated.

'A' series lenses are fine in any mode, as long as the aperture ring iss is set to the 'A' position. You will still need to tell the camera the focal length if you want to use SR.

As for storing settings, you can I believe only store a generic profile, as the camera would have no way of identifying a lens without electrical contacts.

Steve

I've yet to see evidence of it yet, but yes in theory "wrong" SR can be as bad or worse than no SR. You could turn it off altogether when in doubt, and that won't matter when you can use a fast-enough shutter speed.

There are other reasons for avoiding manual zooms, though. They tend to be larger and heavier than more modern zooms, and the optical quality is rarely better. This is not so much the case with primes. The best value-for-money combination I reckon is old primes and modern zooms.

Correct. Irrelevant when SR is switched off, whether on a tripod or not.

ps. Actually I think the focal length is recorded in the Exif info, so you might like it set correctly for the sake of your records.

Yes, except when you want to use the largest aperture, then Av mode is most convenient - although Manual mode can be used for that too if you like.

I have just tried a very rough and ready test using a 28mm M series lens. Shutter speed was 1/4 of a second. I set the focal length for SR purposes at 15, 28 and 70.

At normal viwing magnification, I could see no discernible difference between the 15 and 28 settings, however at 70 there was very noticeable blurring.

I occasionally use 35-70, 35-105 and 70-210 'A' series zooms, which I would usually set at thre mid ponit and have never noticed this effect before.

Steve

I only have one 'classic' zoom which is the 80-200mm and although slower than modern zooms and maybe heavier construction I got a lot of use out of it back in the day and there's nothing wrong with it optically. I have always had a steady hand and except in low light very rarely had problems handholding all but the largest lenses at slow speeds - it's just practice I suppose, but SR makes it even easier.

The other zoom is Vivitar Series 1 A lens which I bought in Hawaii in 1989 as a walkaround lens since it covered most lengths I felt I would need and it is a very clear sharp lens and is a very good dogsbody. Like all my kit it's been in snow and on beaches and deserts...never had any issues and of course the LX was weatherproofed before they invented the term I expect - gasket city!

Thanks Steve. I think I will follow the general advice and stick to primes for older lenses! (Now let's take a look at ebay....)