[Piotr]

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unless you set it up

amazing, great shot, congratulation

[rfortson]

Hey Mo,
I think I saw this on KEH but it mentioned a "manual diaphragm". What does that mean and how is it different from manual aperture?

[Adam]

"Manual diaphragm" simply means that there's no stop-down lever on the mount, and hence the aperture of the lens will always be what it is set to on the [huge] aperture ring. This is obviously because the aperture is situated very far away from the camera.

On DSLRs, this elimitantes the use of the green button, so it can be seen as good

[rfortson]

"Manual diaphragm" simply means that there's no stop-down lever on the mount, and hence the aperture of the lens will always be what it is set to on the [huge] aperture ring. This is obviously because the aperture is situated very far away from the camera.

On DSLRs, this elimitantes the use of the green button, so it can be seen as good

Thanks Mo. Then how do you set exposure if you can't stop down?

[Adam]

The aperture is permanently stopped down to whatever the ring is set to as opposed to being kept wide-open when mounted on the camera.

The fact that most M and K lenses have an auto diaphragm actually makes them harder to use. This is because you have to stop down first to measure the light, unlike on man.diaphragm lenses.

Basically, the point is that you can use P mode with man. diaphragm lenses.

[rfortson]

The aperture is permanently stopped down to whatever the ring is set to as opposed to being kept wide-open when mounted on the camera.

The fact that most M and K lenses have an auto diaphragm actually makes them harder to use. This is because you have to stop down first to measure the light, unlike on man.diaphragm lenses.

Basically, the point is that you can use P mode with man. diaphragm lenses.

Interesting. So I guess the down side would be that if you're shooting stopped down, the view in the viewfinder could be dim?

[Adam]

Yeah, that would be the only downside

Adam
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[roy]

Interesting. So I guess the down side would be that if you're shooting stopped down, the view in the viewfinder could be dim?

i just use Av mode. focus at f4.5 and close down to get the shot.
what's really weird to me is the aperture adj is further away from the camera than the focus adj. backwards from other lenses.. i'm still trying to focus with the aperture ring.. stopping down isn't all that necessary because these lenses are tack sharp at f4.5 and unbelievable at f8-16.

[shadowrulz3164]

im insanly jealous..you do know that right? :P

[lzzap]

Just picked up mine this winter, a 500mm Takumar M42, non SMC. So far a
wonder lens. If anyone is curious I had to do some repair work on this. The
work required partial dissasembly. I have some pointers if anyone else needs
help and some pix of the unit being disassembled.

I have seen notes on the web that these lenses are interchangeable with
the 645 system with their removable rear barrel, and that Pentax had a
terrestrial eyepiece for these also. So far I have found no details on this. Any
suggestions out there?

[Ole]

Just picked up mine this winter, a 500mm Takumar M42, non SMC. So far a
wonder lens. If anyone is curious I had to do some repair work on this. The
work required partial dissasembly. I have some pointers if anyone else needs
help and some pix of the unit being disassembled.

I have seen notes on the web that these lenses are interchangeable with
the 645 system with their removable rear barrel, and that Pentax had a
terrestrial eyepiece for these also. So far I have found no details on this. Any
suggestions out there?

We need to do some work on a Takumar, where the auto/manual aperture button is stuck.
Your disassembly instructions could come in handy.
Thanks in advance,

[d.bradley]

Any chance one could use a monopod with one of these bad boys? I'm half-looking at picking one up someday, but have yet to migrate to tripod-based shooting.

[Arjay Bee]

Ole - what Takumar are you working on?
This website is worth a read:
PENTAX MANUALS

For if you want to go the whole hog: (no connection to me)
eBay: Pentax Takumar & Super Takumar Lens Repair Manual (item 320076114552 end time Mar-27-07 02:40:51 PDT)

Another site:
Manual Focus Forum / Takumar 300mm problems
This forum has a heap of info on scores of other lenses as well.

This is my favourite site and I have spent hours here:
Topics - The Classic Camera Repair Forum
Almost leads you to think you can do everything yourself....

Are you sure there isn't a little pin that you need to actuate by mounting the camera on a body to get that button to slide. Or if the lens is mounted that the pin is not protruding far enough to be actuated?

[FotoPete]

Haha The biggest threat to average joe shutterbugs worldwide..

Lenses of Mass Dimensions.

Hey has anyone tried the Phoenix 500mm f8. The refractor one.

[Adam]

I have the Pentax 400-600mm mirror lens, and although it's compact and fairly sharp, it's very hard to keep steady (even on a tripod) and can therefore not replace a regular tele.