Pentax SMC A 50 mm Lens usage

Hello,

Help/advice please ... could someone please give me some tips or tutorials on using this 50 mm SMC Pentax-A Lens.

I used a 50 mm 1.8 lens on a cannon but that was automatic and the results was outstanding and therefor decided to buy the SMC Pentax - A lens.

I have a Pentax KM and have been experimenting with all the settings but the M and A are not giving me an image that I am satisfied with

I tried on Auto ... and the image is much better ... but I find it difficult to set the DOF.

Thanks in advance,

Karthik

The only way to "set" DOF is to set the aperture yourself. That means using Av mode, which is what many people prefer to use, most of the time.

What actually is wrong with your pictures? Just DOF, or something else too?

G

Hmm I will try more with the AV mode .... but i need some kind of a guide for the distance the F numbers relates to ... ?

I am not able to get a sharp well exposed image ... but I have been trying indoors and not with natural light.... I'll give it a go during the day while there is day light.

Thanks G .. I'll work on it

George has a good point.

If you are using an A lens, this will mean that the exposure will be done in camera, but the focus will be done by you. Are you relying on the focus beep in the camera to confirm the area is in focus? If you are only the centre point of the image will be in focus (unlike AF lenses which you can choose the focus point). There are various settings in the menus which can help here, like switching off the beeb, AF adjustment if they are out, etc etc.
Finally, make sure that your diopter is set correctly, as any slight inaccuracy will mean that the image will be out of focus, it needs to be spot on with what your eye sees with manual focus lenses.

Hope this helps.

You are aware of course that it's a manual-focus lens?

Pentax-A lenses have a DOF scale round the ring with the yellow blob. For any particular aperture, this shows what will be in focus.

I don't know why your exposures are not spot-on, but one possibility (as this is an old lens), is that the aperture blades may have become a bit gummed up through lack of use.

If that is the case, the lens will be stopping down too slowly, which will give over-exposed images with a shallow DOF.

Give it some exercise!

G

I have just been experimenting with the Av setting now .. and its getting better ....

I am aware that its a manual lens just needed some experts to tell me how to use it properly. Thanks Guys.

I'll check my diopter as well now. I'v just been taking some random pic that are getting better

Guess its just getting used to the lens.

The exposure is looking better now.. and you are right ..its a used lens.

With MF lenses, the only accurate indication you have that an object is in focus is the green hexagon in the viewfinder. Neither the beep or the presence of the red focus indicator in the viewfinder should be relied upon to indicate correct focus, because they don't.
The beep simply means that a part of the image at one of the sensor points has been found to be in focus, and that sensor point will be illuminated by a red square. That doesn't mean that it still is in focus.

If the green hexagon is illuminated in the viewfinder, it shows that the part of the image at the chosen focus point is in focus.

Thanks Pete, I think you might have helped me there too
I have never looked at the green box, now I will.
Cheers

Iain

Thanks Pete ...thats really good information ... Trying it out now...

Regards,

Karthik

Actually, there is another method.

If your dioptre is set correctly and the image in the viewfinder is bright enough and your trust your eyesight, use your own eyes to determine if the part of the image that you want to be in focus is, or not.

A magnifying eyecup is available to make this task easier.

Thanks Pete... I'll try it