Viewfinder off... mirror or screen?

[imaginator]

I have a K1000 and the viewfinder is off, mostly in the longer

dimension (left/right in landscape orientation) Is it the mirror or

the screen (or both)? How can I fix this (I'm very good with tools)?

[richard_oleson]

Are you sure? If the mirror were tilted (the only way it could cause a left/right error, I'd think), your focusing problems would be much worse than the lateral position error. There should not be a whole lot of room in the focusing screen area for it to be shifted out of place, maybe a millimeter. How far is it off, between the screen and a groundglass in the film plane?

 

To fiddle with the screen, you have to remove the top cover and take the prism out. This Spotmatic sketch will give you an idea of the degree of difficulty, though there are some differences between the Spotmatic and the K1000: http://rick_oleson.tripod.com/index-113.html

[imaginator]

Am I sure it's off? The images on the film are off compared to what I saw in the viewfinder... about 3/16 inch (out of 1.5 inch width of the frame on the film) It's also very slightly off in the shorter dimension, but not enough to be a problem. I first noticed this when my verticals of waterfalls kept chopping the top of the frame... also when I did some lens test shots using a topo map as a target. The map was centered in the viewfinder, but off-centered on the film. Actually, I've been mentally compensating when composing, but just recently became concerned about focus issues (since I usually stop down to f/11 or f/16 it might not have showed up with so much depth of field) I'll shoot some test shots with the lens wide open and "bracket" focusing just to be sure. Could it just be the prism is out of whack? I have another camera (Minolta) so the K1000 is going to be used mosly for long exposures (night, astro) I'm considering altering the setup so I can view the screen directly from above the camera, using a loupe for critical focussing (the prism won't be needed) In fact, I'd also like to replace the original screen with a solid matte screen (no center focusing spot... I don't use them and they are just in the way) Looking down at the screen from above will also help when I have the camera pointed up at steep angles... hard on the neck with the standard viewfinder. Any tips?

[richard_oleson]

This is a really extreme error, I can't think at the moment what would cause it. If the prism is crooked (raised at one side) that could do it, but you would see the center focus aid as being 3/16" off center in the finder, it would be very obvious. The location of the focus spot in this case would still correspond to the center of the image on film.

 

A crooked mirror sufficient to cause this much error, I'd think, would be visibly crooked as you look in the lensmount from the front. There is not generally any adjustment for "crookedness", it would only be caused by damage or something seriously falling apart.

 

Other than that, I don't know: it's not physically possible for the finder to be displaced laterally 3/16 of an inch, you'd have to remove half of the mirror operating mechanism to make room before that could happen.

 

For your waist-level finder project, it is possible to remove the top cover and the prism; I don't recall in the Pentax if the screen is secure with the prism removed or if you'd have to make some special accommodation to retain it. You couldn't put the top cover back on, of course, so you'd have a lot of mechanical stuff exposed to the dew at night. For your astro work, are you using a T-mount telescope? If so, then you could use any lens mount, and there are some cameras with waist level finders that would be easier than customizing a K1000 for the purpose: Just about all Mirandas had removable prisms, and they're available pretty cheap; Nikon F's can occasionally be found for under $100 without a prism (and you don't want the prism anyway); Ricoh made an interesting (Pentax screw-mount) camera called the TLS401, which had a second eyepiece on top, giving the effect of an eye level finder but viewed from above. These are all mechanically controlled cameras equivalent to the K1000 in performance. There are also older cameras, like Exaktas, Exas and Prakticas, which had waist level finders, but the age of these may introduce some reliability questions that you might not want to deal with (still, not likely to require more work than it sounds like you're facing with your Pentax).

 

rick :)=

[ron c sunshine coast,qld,a]

Hi Jeff.

<BR>Not sure all K1000's are the same but the one i have right now is the type where the focus screen can be taken out through the mirror box and front.I've seen these screens loose before so it can happen<BR>If yours is a removable type it should have a little screw partly covered by the mirror bump foam plus two others further in down each side.

<BR>I'm not sure if it's easy to see if it's out, but judging by the one here,you should be able to see by looking in the mirror box if it's way out.<BR>If it's the prism that's loose then you have more work to do.....the top has to come off.It's not very hard,just be aware that the main center screws that hold the winder/counter parts may be reverse thread.

<BR>Hope it goes well

[imaginator]

This is rather embarrasing... I belive this whole time it was my ball-head letting the camera slip on the mounting threads when I use the film wind lever. The ball head has some felt or similar material that I'm going to replace with something that grips better. Thanks for the tips on possible removal of the screen... I wanted to replace it anyway with a plain ground glass (no center spot focus helper... never use them anyway)