[mayoapo]

Hello......im new to the forum,so hi everybody...I actually own a Pentax K100D,..i have also the Kit lens..the 18-55 DA...An ok lens ,i would say....somehow matches the performance of average prosumer compact digital cameras in the market).The DSLR concept is a total change and departing point from point and shoot digital ,i am enjoying SOOOO much my Super-Multi -Coated takumar 50mm 1.4(yesss thorium rules!!!)...Excellent lens...to get such large aperture and play with those extreme field of views is what i like about taking pics...anyway..i have a couple screw mount lenses,and recently i bought a couple M lenses to compare..i bought the 135,3.5 (havent received yet)and a 50mm 1.7 ....the 50mm arrived in bad shape ,with fungus inside...i got my money back and i was able to keep the lens as well,so no harm here....i went to the web and look for instructions ,to see if i could clean the lens...and i did!!!!! it wasn't to difficult to open and clean(white vinegar) the (small amount of) fungus....so far no problems...but since the lens was now clean i wanted to try it...but i cant!!! when mounted on the camera,the aperture is frozen...the ring moves but with no effect whatsoever on the aperture...it seems like if the design of the lens doesnt match the camera!!!!!i want to get the 135mm to see if i have the same problem with all "M" lenses...anyone knows what is going on??????thanks...WAIT AS I AM FINISHING THIS MESSAGE I HAD THE 135MM DELIVERED....IT DOESNT WORK EITHER!!!!!!!!!!!!!THE APERTURE IS FROZEN ..WHY?????????????IS MY CAMERA DEFFECTIVE?

[bc_the_path]

I assume you already know that the aperture of those lenses cannot be set by the camera; don't you?
If they are "frozen" outside the camera when you turn the aperture ring; then they need a repair. I have a couple of M lenses and they behave normally.
Good luck.

[Finn]

Before you have a heart attack...relax. It's probably that you are trying to use an "M" lens in P, Av, etc, which you can't actually do. Look in the FAQ on this forum for instructions on how to use an M lens on a K100D. It takes a couple of extra steps to do, but fear not! It is totally worth it.

[mayoapo]

ALAS!!!! i see.....since my old takumars work without a problem i assumed that the "M" lenses would be as forgiving.......im looking right now...! thanks a lot....keep you posted...

[mayoapo]

I am anxious...but i cant find any info!!!!!plus...what would prevent the aperture to manually work,anyway?....i dont see any menu option,and with camera set to "M",no changes in performance appear....the hopes went high after your message...but i think something is wrong!!!!

[mayoapo]

Now Pressing The Ae-l Button In M Mode Actually Closes The Diafragm!!!!!!!!!!!!!!!!!!but The Shutter Is Now Frozen.....help!!!!!!!

[mayoapo]

Ok...i Thnk I Am Figuring The Way.....m Mode,manual Focus.....the Ae-l Shows Measures....oh Boy...stop-down Metering With The Takumars Is Very Easy...!!!!!!!!!!!

[mayoapo]

HEY...i think i figured it out!!!! and all by myself....my am i sharp!but not as sharp as the 135 3.5...im thrilled....and i love the camera!!!!!is so cool the way the M lenses work!!!!So you set the aperture,press AE_L,the camera measures and then shuts the diafragma..isn't it?..that is the way "A" lenses worked in my K1000,right...anyway...thanks Finn for the info....i still have to get this completely figured ,but i think im in the way.....it would be cool if some sort of meter gave you kind advice,but i guess i would need a K10 for that......

[Finn]

Happy shooting.

[Arjay Bee]

Camera doesn't close the diaphragm - there is no communication between body and M lenses. You have some of the steps below under control but some have not been mentioned although Mo does have this all listed in the FAQ section and it is all stated in the manual.

In custom setting menu "Using Aperture Ring" is set to position 2 'permitted' to enable use of physical aperture ring lenses.

You make a decision and select what aperture you would like to use, focus, half press the shutter button and simultaneously press ae-l button and the camera chooses a shutter speed to match and then you fully press to take the image. Depending on the aperture and metering mode selected it is possible to reframe the picture without badly upsetting the metering selected up to that point.

If after checking the outcome in the LCD you think the image is under or overexposed you can then force your choice of shutterspeed for the image by holding down the exposure comp button on the top of the body and rotate the rear thumb wheel.

[mayoapo]

Well...THERE IS COMMUNICATION....Simple mechanic contact on the aperture lever ,but through that lever ,the camera DOES closes the diaphragm...at least my camera does(k100D)...Is actually closing the diaphragm how the camera is able to read the light and set exposure....i set the aperture based in my preferences,then focus...after focusing and get focus confirmation,if i press AE-L ,the camera CLOSES the diaphragm and meters ,giving me a exposure reading....then i can change the exposure to what i decide or stay with the auto exposure,...then shot ,AND THE CAMERA WOULD CLOSE THE DIAPHRAGM AUTOMATICALLY AT THIS POINT
THE DIAPHRAGM STAYED OPEN ALL THE TIME THROUGH THIS PROCES UNTIL AE-L GETS PRESSED,AND THEN CLOSES TO THE APERTURE I HAVE CHOSEN AND METERS,..IS VERY GOOD BECAUSE I HAVE THE EXPOSURE SET AT THIS POINT,BUT I CAN REFOCUS OR CHANGE THE APERTURE AT WILL IF I WANT AT THIS POINT...THIS IS THE WAY THE CAMERA IS WORKING FOR ME.I WAS EXPECTING A STOP DOWN METERING ,WHERE I ACTUALLY CLOSE THE DIAPHRAGM MANUALLY,BUT I ONLY SET THE APERTURE RING,AND THE CAMERA CLOSES THE DIAPHRAGM....IS NICE!

[Mike Cash]

Not a very excitable fellow, are you?

[Arjay Bee]

You're talking K mount still - I'm talking M42 SCREWMOUNT - sorry misunderstood.

[mayoapo]

YEs,Arjay Bee,,as a matter of fact i dont think any of the steps you explain in your previous post have anything to do with M42,.I use M42 lenses,but use AV mode and stop-down meter......no AE-L apply..........As for the Manual,there is a compatibility table,but not much about operation of the camera with anything else but AF lenses..i will reread it though...thanks again...

[Arjay Bee]

To Mo's FAQ thread:
https://www.pentaxforums.com/forums/pentax-dslr-faq/3800-can-i-use-m42-screwm...unt-d-slr.html

Not exactly nothing to do with the process as Mo also describes the technique in the same way I do...... I guess we all develop our favourite techniques as there is a follow up post to his describing the use of the AV mode in the same way you do (I think).