Got the Adapter..Good to go..But..

Throndor · Joined: 15 Sep 2008 Posts: 157 Location: Ankara / TURKEY

I've just got my M42 adapter (flush fit - roxen) at last and god it took long (no infinity-focusers in Turkey) and i have a few MF lenses now (thanx to you guys) but..

1- When set to AV mode, the cam seems to be underexposing.. Any k100D guys experiencing the same thing?.. Any way to overcome this without the EV compansation?

And more interestingly, the underexposure seems to be more apparent with some lenses while less with others..Is this the case or is it a consistent underexposure on all lenses and my untrained eyes are fooling me?

Note : Read about it after i posted this.. This seems like a serious issue on Pentax cams.. The exposure miscalculations vary with the lens and between aperture values on the same lens.. Bad news..

2- Some M42's i have do not have an A/M switch.. So the little aperture pin on the back stays out and i can not set the aperture.. Anyone tried a lens modification for this?

3-Sometimes the focus confirm just works fine.. sometimes i fell i got to press the shutter half-way to activate it though i am not sure if its true.. What is the way it works?.. Should i really activate it by pressing (or pressing and holding?) the shutter half-way?

4- Have you realised that manual focusing on a dSLR without the aid of a "katz eye" is harder than one expects?.. I really would think again about the MFs if a focus confirm was not available.. Or is it just me?

Note : This is a partial cross-post with pentaxforums..

luisalegria · Expire: 2018-01-18

I have a K100D and I've got the same problems.

I use the EV compensation. Some lenses take more than +2 EV. It also seems to vary with lighting conditions. I usually do an exposure check when changing lenses, or if I'm switching classes of subjects from those that need small vs large aperture.

I've done all the fixes on the A/M problem. I've disassembled lenses and modified them, used rubber bands on stop-down buttons, bits of brass and screws, etc. I've never succeeded in gluing the pins though. But out of 80+ M42 lenses I just have three I haven't fixed - all Mamiya SX.

Focus confirm is necessary on these because of the lousy viewfinder. Its not as accurate as I would like though. There are several strategies to deal with this, such as focusing at maximum aperture and focus bracketing. I do all of these. I never figured out the logic of when focus confirm kicks in. I look at holding down the button as a kick in the pants to a lazy worker.

Poolhall · Joined: 25 Feb 2008 Posts: 1296

Had the same probs myself, I use a cheap Ebay diagonal split focusing screen from China that helps a lot. Seems to me that the focus confirm stops working as you close the lens down, ie no joy at f16, but works fine wide open. So I keep the button down as suggested. I use the 'q-tip' method of fixing the pins, by taking the bottom of the lens off and placing a sleeve over the pin so it can't stick out, either a section of q-tip or some thick wire insulation, its in the forum somewhere, but on the K100d I tend to use M42 and Pentax m lenses purely in manual mode, rather than AV. On my Samsung GX-10 (same as K10d) I fitted a Pentax screen from the istD, the LL-60, that seems to sort out all of the above problems to me, and they work fine in AV mode.

piticu · Joined: 04 Aug 2008 Posts: 591 Location: Romania

Throndor · Joined: 15 Sep 2008 Posts: 157 Location: Ankara / TURKEY

What I figured out with some further fiddling with the AF conf. is that it stays on only while the info leds in the viewfinder are lit up.. And thats about a few seconds after shutter is half pressed.. You have to press it again if you can not focus within those seconds..

orly_andico · Joined: 02 Jul 2008 Posts: 253 Location: Philippines

In general this is what I've seen....

at f/2 and f/2.8 you have to dial in +2 EV
at f/4 around +1 EV
at f/5.6 it's spot on
at f/8 and f/11 you have to put in -2 EV

but the above is inexact at best, so I always chimp the histogram. Shocked

soikka · Joined: 11 Jun 2008 Posts: 534 Location: Finland

Try to short circuit the mount contact with ie. aluminium foil. This should help the exposure problems with M42 lenses in Pentax DSLRs.

montecarlo · Joined: 04 Apr 2007 Posts: 1865 Location: Romania

I follow these when using M42 on Pentax dSLR (K100D):
-Using RAW is not a problem correcting the exposure together with EV at +0.5/+1.
-I do not buy lenses without A/M swich or A only.
-The AF/MF which from the camera must be set to MF.
-Must be changed a setting in the camera allowing the use of aperture ring lenses.
I think that's it. I don't use but the original focusing screen.
Good luck

rayatphonix · Joined: 24 Mar 2008 Posts: 28

Although I'm an EOS shooter, I have some of the same issues. In general, I've found that most of my MF lenses that need EC are predictable. In my case, all my Oly wide angle lenses overexpose 1-2 stops when wide open or nearly wide open. As another poster said, by about F8, things get back to normal. It's now second nature to dial in some EC as soon as I look through the viewfinder with certain lenses. In general, the longer the lens, the more accurate the metering in my EOS cameras seems to be. I still check the histogram with just about every shot, just to be sure.

I've got an aftermarket focusing screen on one of my cameras and it's made a world of difference. I would guess that my percentage of OOF shots dropped 90% when I installed my KatzEye screen. I have one adapter with focus confirmation and 5 or 6 others without. I obviously didn't have much luck with the focus confirmation. In my case, it wasn't a substitute for the aftermarket screen. My KatzEye was one of the best investments I've made since I started using MF lenses again.