Go Back   Steve's Digicams Forums > Digicam Help > Newbie Help

Reply
 
Thread Tools Search this Thread
Old Mar 29, 2007, 4:20 PM   #1
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

i recently bought some old used lenses with manual focus and i would be quite happy with them if it wasn't for the fact that they don't offer DOF preview. whenever i use the aperture ring, the iris is immediately changed.

is this always the case with older fixed focal length lenses that use MF only or is there something i can watch out for when looking around on ebay?
also - is dof preview standard with all AF lenses or could i encounter the same problems with those as well?

thanks a lot in advance
sh4dow is offline   Reply With Quote
Sponsored Links
Old Mar 29, 2007, 4:57 PM   #2
Senior Member
 
Bob Nichol's Avatar
 
Join Date: Apr 2003
Location: Eastern Ontario Canada
Posts: 822
Default

The Minolta and Nikon cameras I've used had the DOF preview as a button on the camera that allowed the iris to close to the aperture setting rather than as a function of the lens.

My Nikon D70s must have the aperture ring set to the smallest setting (largest number) and the camera holds the iris open until you press the shutter. I'm not sure about other brands however.

What camera model and what brand and type of lens are you using?
Bob Nichol is offline   Reply With Quote
Old Mar 29, 2007, 4:57 PM   #3
Senior Member
 
Join Date: Dec 2006
Location: Davenport, IA
Posts: 2,093
Default

What your seeing is a mechanical incompatibility between the old lenses and the body you're trying to use them on. The old lenses depended on the camera body either applying mechanical motion to stop the lens down when the shutter was tripped OR alternately hold the aperture wide open until the shutter was pressed. A spring in the lens closed the aperture in that case. In either case the DOF preview function was on the camera body.

Going back even further there was a class of lenses known as "presets". On these the photog manually set a stop ring on the lens to the desire aperture, manually opened the lens for focusing and then closed it until it hit the preset stop for exposure.

Again in the relatively early days of SLRs some were mount compatible with that manufacturers interchange lens rangefinders and those rangefinder lenses had no auto open/close capability at all.
ac.smith is offline   Reply With Quote
Old Mar 29, 2007, 5:23 PM   #4
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

i use a pentax k10d in combination with lenses which might well be from some time in the 80ies... made byporst (28mm), ricoh (50mm) and osawa (135mm) (+ one by cosina but the iris is a little stuck, i know that i could probably clean it rather easily but half of the screws are simply too tight... i did manage to unscrew the "upmost" part though, which is also why i already knew about that spring inside the lens )

as far as i have seen, if i activate the DOF preview on the camera, there's actually a little lever moving on one side of the lens mount. i'm not sure though if that thing is supposed to work with such old lenses or if it's just designed for new ones. since the support for older lenses by the k10d is supposed to be good i felt like i either simply have the wrong kind of lenses or i just haven't discovered some feature yet.

@ ac.smith

this presetfunctionality actually reminds me a lot about how these lenses work. after all since the iris is immediately closed, i have to focus with open iris first, then stop down. and this is exactly why i would like to find an alternative (or figure out if there is a way to use those lenses properly with my cam).i really don't want to have to go back and forth all the time... i can already picture myself throwing those lenses into some river
sh4dow is offline   Reply With Quote
Old Mar 29, 2007, 6:00 PM   #5
Senior Member
 
Corpsy's Avatar
 
Join Date: Dec 2005
Posts: 879
Default

This question should probably have been posted in the Pentax DSLR forum. You'd get a lot more first-hand knowledge there since not everyone likes to stray from their favorite sections.

Any K-mount lens should support DOF preview on the K10d unless the lever on the lens has been broken off. Of course, when the lens isn't on the camera the aperture will change when the dial is turned. Once the lens is attached to the camera mount, the lever is set into position and the aperture is opened all the way, only to be closed back down again when the DOF preview button is pressed, or when a photo is taken.
Corpsy is offline   Reply With Quote
Old Mar 29, 2007, 6:18 PM   #6
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

hm well i thought that this would be a general "problem"with older lenses.

but now that you say that it actually should work... i really don't know how to figure out what's wrong. after all the lever is there on all three lenses...

and i'm not talking about turning the dial while the lens isn't on the camera, i actually mean that the iris immediately closes when it's mounted and i turn the dial...

strange enough, i have the feeling that this used to work. because at first i thought that it was just a certain lens which was incompatible. afterwards i discovered that it's like that with all other lenses as well. damn... could it be that that one incompatible lens broke something in the camera? now that would really be ... words probably couldn't describe how mad i'd be (i just got the camera 5 days ago...)
sh4dow is offline   Reply With Quote
Old Mar 29, 2007, 6:39 PM   #7
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

oh damn... i think i've discovered it... right where the lever of the lens is when it's mounted there is this part that gets pushed back and forth if one uses the DOF preview. or at least i suppose it should be pushed back and forth. well in my camera just the cogs and the lever that move this part are actually moving, this plastic part that's probably supposed to move rests in the same position all the time.

now it's the question - did i get the camera this way or was it that one lens... i honestly couldn't tell. and more importantly - i really don't want to send it to pentax to fix it
sh4dow is offline   Reply With Quote
Old Mar 29, 2007, 7:24 PM   #8
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

looking closely at the lever i can't even figure out how it got where it is in the first place! the gap between the case and that plastic thingy isn't even wide enough so the lever could get through there. i really wonder how it got on the wrong side... and i'm starting to think that it couldn't have been one of the lenses. i just can't see how.
sh4dow is offline   Reply With Quote
Old Mar 29, 2007, 7:53 PM   #9
Junior Member
 
Join Date: Jul 2002
Posts: 12
Default

alright... you guys won't believe it but... i just managed to fix this myself. i found out how the lever could've gotten on the wrong side of that nose. i knew that the gap between the nose and the case wasn't big enough, that i had to "switch it over" somehow on the inside.

since i couldn't have done any more damage anyways (if pentax would have to fix the dof mechanism or they had to fix the dof mechanism - what's the difference...), i decided to give it a try.i switched to dof-preview with my right hand, pushed the lever with a tweezer towards the case with my left hand and THEN... took a screwdriver in my mouth and tried to push that whole sliding plastic thing past the lever. i must've blacked out somewhere because i just remember a snapping sound and the plastic thing sliding back and forth while using the dof-preview like nothing ever happened.

might not sound healthy but as i said... the would've had to fix the dof mechanism anyways and it's not like i tried to open up the case. now that would be rather... risky, i suppose

so if anyone who ever used a wrongold lens with the k10d - you could try this before paying pentax probably the same amount of money to fix it.



now that i took a closer look i wonder how i managed to fit that one lens on my camera in the first place, since the mount isn't correct. i just assumed that it was because i bought a ricoh camera together with 3 lenses which according to the seller should've all been pentax compatible. guess it is possible that a lens can both fit AND cause damage nevertheless... if i just would've known that before...
sh4dow is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 3:48 AM.