Using lenses with no aperture-control ring on a Pentax LX, Part 2

**reuvens** · 08-23-2019, 06:48 PM - **1 Like**

So after the info I got from the forum members here last time, I decided not to get a 100mm F2.8 WR. But I was still curious about using said lenses and whether I could rig a solution to allow me to use those lenses on my LX. So I installed a spring on the aperture control lever of a Promaster Spectrum 7 2x teleconverter and attached my HD 20-40mm DA Ltd WR. The metering stopped working completely because the indicator lever to the camera was swinging free, but the DoF lever showed I had a full open aperture when the mechanism was actuated. I was a bit worried that the lens wouldn't cover the entire image frame, but thought the teleconversion might fix that. I shot a roll of ektachrome 100 in it, after a friend advised me that a slide film would be more forgiving to underexposure (he was wrong). The results were not terrible though! The image circle does a decent job of frame coverage and the bokeh is pretty nice in some portrait shots. I will probably try this again with something with a wider aperture just to see how they come out. I have the plastic 50mm f1.8 DA and it has been gathering dust for a while waiting for something interesting.

Attached Images

nickthetasmaniac · 08-23-2019, 09:12 PM

Really interesting, thanks for sharing!

Originally posted by reuvens

I shot a roll of ektachrome 100 in it, after a friend advised me that a slide film would be more forgiving to underexposure (he was wrong).

Lol that is genuinely terrible advice

Wasp · 08-25-2019, 12:59 AM

Originally posted by nickthetasmaniac

Lol that is genuinely terrible advice

I concur. Slight underexposure on chromes gives you more color saturation - about half a stop, one stop maximum. More than that and you are in uncharted territory. Color negative film, on the other hand, can be abused a lot as far as underexposure goes. Point and shoot owners did it all the time and left it to Kodak to save the day. Actually, the technician at the lab. A friend was in the business and he related quite a few tales of how he had to rescue extremely 'thin' negatives.

08-23-2019, 06:48 PM - 1 Like	#1
reuvens Site Supporter Join Date: Aug 2018 Photos: Gallery Posts: 145	Using lenses with no aperture-control ring on a Pentax LX, Part 2 So after the info I got from the forum members here last time, I decided not to get a 100mm F2.8 WR. But I was still curious about using said lenses and whether I could rig a solution to allow me to use those lenses on my LX. So I installed a spring on the aperture control lever of a Promaster Spectrum 7 2x teleconverter and attached my HD 20-40mm DA Ltd WR. The metering stopped working completely because the indicator lever to the camera was swinging free, but the DoF lever showed I had a full open aperture when the mechanism was actuated. I was a bit worried that the lens wouldn't cover the entire image frame, but thought the teleconversion might fix that. I shot a roll of ektachrome 100 in it, after a friend advised me that a slide film would be more forgiving to underexposure (he was wrong). The results were not terrible though! The image circle does a decent job of frame coverage and the bokeh is pretty nice in some portrait shots. I will probably try this again with something with a wider aperture just to see how they come out. I have the plastic 50mm f1.8 DA and it has been gathering dust for a while waiting for something interesting. Attached Images

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08-23-2019, 09:12 PM	#2
nickthetasmaniac Pentaxian Join Date: Dec 2008 Posts: 2,361	Really interesting, thanks for sharing! Originally posted by reuvens I shot a roll of ektachrome 100 in it, after a friend advised me that a slide film would be more forgiving to underexposure (he was wrong). Lol that is genuinely terrible advice

08-25-2019, 12:59 AM	#3
Wasp Pentaxian Join Date: Mar 2017 Location: Pretoria Photos: Gallery Posts: 4,660	Originally posted by nickthetasmaniac Lol that is genuinely terrible advice I concur. Slight underexposure on chromes gives you more color saturation - about half a stop, one stop maximum. More than that and you are in uncharted territory. Color negative film, on the other hand, can be abused a lot as far as underexposure goes. Point and shoot owners did it all the time and left it to Kodak to save the day. Actually, the technician at the lab. A friend was in the business and he related quite a few tales of how he had to rescue extremely 'thin' negatives.