Pentax MX Idea

Logan Becker · Aug 25, 2017

This is going to sound slightly crazy perhaps, a longshot at best.

I want to MODIFY my MX to have a DoF preview.

I may in the near future have access to metal parts fabrication and other associated tooling. I have a bum camera body (also an MX) which can be used to test any prototype design I come up with, but I am limited in understanding on what mechanisms are involved in triggering the diaphragm to close independent of the shutter, having access to only the service manual for the MX. Has anyone ever had such a crazy thought? Any insight and advice is welcome, I hereby place my idea on the table for all to offer their $0.02

Todd Barlow · Aug 25, 2017

I will check my Pentax MX, but I am very sure it already has a DoF preview by pushing the self timer towards the lens.

Logan Becker · Aug 25, 2017

Well then. That simplifies things. In all the material I've read on the body I can't recall ever seeing that. I thought it was an innovation that was added to the LX after the MX's production run had ended.

AgX · Aug 25, 2017

I'm ignorant on the MX. What is the idea of the self-timer lever actuating also the automatic diaphragm. It does not hurt, but I do not see the benefit or a technical reason.

faberryman · Aug 25, 2017

From the MX manual:

voceumana · Aug 25, 2017

AgX said:
I'm ignorant on the MX. What is the idea of the self-timer lever actuating also the automatic diaphragm. It does not hurt, but I do not see the benefit or a technical reason.

It saves having a separate lever on the camera--less manufacturing cost. Has nothing to do with a benefit to the photographer or any technical reason.

vsyrek1945 · Aug 25, 2017

Logan Becker said:
This is going to sound slightly crazy perhaps, a longshot at best.

I want to MODIFY my MX to have a DoF preview.

I may in the near future have access to metal parts fabrication and other associated tooling. I have a bum camera body (also an MX) which can be used to test any prototype design I come up with, but I am limited in understanding on what mechanisms are involved in triggering the diaphragm to close independent of the shutter, having access to only the service manual for the MX. Has anyone ever had such a crazy thought? Any insight and advice is welcome, I hereby place my idea on the table for all to offer their $0.02

A long while back I wondered about the possibility of adding DoF preview to an ME Super using either Super Program parts or by cannibalizing a junker P3 or P30 [In the early 00s, there were numerous non-working samples of the latter two on eBay for parts/repair]. With the Super P Pentax added the feature with a lever through the mirror box side pivoting just above the camera body iris actuator that would push it and the lens mount lever to stop down the lens, and continued the same design in the P series; both the A and P series appeared to have identical mirror box front designs and dimensions as the ME series. At the time, I felt that would have made it a near-perfect camera . . . . .

Chan Tran · Aug 25, 2017

Logan Becker said:
Well then. That simplifies things. In all the material I've read on the body I can't recall ever seeing that. I thought it was an innovation that was added to the LX after the MX's production run had ended.

Innovation? Older cameras are more likely to have DOF preview than newer ones. Not an innovation but a necessity on some older cameras that can only meter stopped down. Worse some require you have to manually stop the lens down before you take the shot.

Bill Burk · Aug 26, 2017

I think it's brilliant. Right where I would want the DOF preview lever to be.

E. von Hoegh · Aug 26, 2017

My Canon FTb QL has the same arrangement. gotta get a lens for that....

vsyrek1945 · Aug 26, 2017

Chan Tran said:
Innovation? Older cameras are more likely to have DOF preview than newer ones. Not an innovation but a necessity on some older cameras that can only meter stopped down. Worse some require you have to manually stop the lens down before you take the shot.

Maybe not an innovation, but definitely a feature.

As I see it, once manufacturers moved away from stop-down metering systems, DoF preview was eliminated from low-end, entry-level and non-enthusiast-oriented models [Nikon's EM, FG, N2020, N6006, N70; Canon's AV-1, AL-1, T50, various EOS Rebels; most, if not all of Minolta's XG- line and X-370; Pentax's forever-classic K1000, MV-, MG- and ME- lines, for example], but continued to be offered on mid-level as well as high-end units right up to the present [like the F100's little brother N80, the EOS 600/620/630 and 10S, the later Elan II and Elan 7 variants and Rebels 2000 and Ti].

The practice continued into the DSLR era: Nikon's D70, D80, D90 and D7000-up series included the feature, while D60, D40, D3000- and D5000-series models didn't; the original Canon D-Rebel I once used, as well as Canon's intermediate-level EOS 20D through 80D all include DoF preview in their feature sets.

Maris · Aug 26, 2017

This is how I do depth of field preview with my Pentax ME-Super camera:
Press and hold the lens release button.
Turn the lens as if to take it off the camera but stop before it comes off.
The lens stops down to the selected aperture and the result may be seen in the viewfinder.
Turn the lens back so it mounts securely on the camera with a little "click".....shoot!

480sparky · Aug 27, 2017

Maris said:
This is how I do depth of field preview with my Pentax ME-Super camera:
Press and hold the lens release button.
Turn the lens as if to take it off the camera but stop before it comes off.
The lens stops down to the selected aperture and the result may be seen in the viewfinder.
Turn the lens back so it mounts securely on the camera with a little "click".....shoot!

That's what I've always done with non-DOFP bodies.

Pentax MX Idea

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