M 42

[snoid]

Ok, seems I've lost my fear of running full manual, until now.

I have an M42 lens that lacks an auto/manual switch, it still has the aperture pin on the mount, but I can only shoot with it wide open, as it won't stop down without the switch.

A web search found this solution, but I can't seem to find anyone else who's ever used one and I've heard too many horror stories about using nonpentax adapters.
Is this the only solution? 

[blackcloudbrew]

Can you be more specific on your question(s)? I'm not clear on what your problem is - non-Pentax M42, using that lens, that adapter, the pin, or what?

I went the Pentax M42 adapter route and have never had a problem with. I read all the horror stories too about non-Pentax flavors on the adapters. I recently saw a post that said, hey you are risking your $$$ camera and $$ lenses to a cheap mount, spend the $30 and get Pentax mount. It has occurred to me that you see many of the 'horror stories' because one wouldn't write about it when they (the cheap copies) work fine. Actually, getting the Pentax adapter off can be tricky too. I had a problem with my M42 bellows and my K10 as it went on fine but the flash holder make it very very difficult to get off. I digress.

Anyway, I may not know that answer to this but if you elaborate a bit more on your problem that might help.

[snoid]

The lens in question has the aperture pin on the mount, but lacks the A/M switch on the barrel.
No matter what F stop you choose the lens stays open until the pin on the mount is depressed.
I have the Pentax adapter and it works fine with lenses that have the A/M switch.
The adapter pictured has a flange on it that depresses the pin, allowing for use of the aperture ring on the lens.
The Pentax adapter lacks this flange to depress the pin, so the lens stays wide open.

I've seen other lenses like this on the flea, but have been hesitant to bid on them.

I may have found an adapter like this made by Kipon. Ever heard of them?

[spyglass]

Hi Snoid,

Try and buy a decent adapter. You want good threads, good machining, decent finish. My opinion is that it is best to buy one for each threaded lens you have and remove the locking mechanism from the adapter (general this is a little piece of spring steel that prevents the adapter from removing when you unthread your lens). This will allow you to change lenses quickly in the field, and switch between K mount lenses and older screw mount lenses on the fly. If you don't remove the locking mechanism you will have to use a key like tool to remover the adapter.

What lens do you have  Snoid?  Camera systems today allow the users to view their composition with the lenses opened up. This allows for maximum light to enter the lens and makes it easy to see. Modern systems offer communication between the camera body and lens. The camera knows what aperture setting is being used and can deliver the correct exposure.

If using an older full manual lens that does not allow automated aperture control from the camera body you will have to use stop down metering. This is where you turn the aperture ring to the desired setting, obtain an exposure reading, then open up the aperture to make your composition, then return the aperture ring to the desired setting and take the picture. I have a Pentax Shift lens that requires stop down metering and even offers an addition special ring for this task.

Nice to see people using some of the older glass. You can often pick them up for a steal. Lens made back to around 1971 (the year Pentax patented their famous Super Multi Coating) are worth buying. To showcase the new improvements to their lenses Pentax changes their lens name line from Takumar and Super Takumar to Super Multi Coated Takumar and SMC Takumar.

Spyglass

[blackcloudbrew]

The lens in question has the aperture pin on the mount, but lacks the A/M switch on the barrel.
No matter what F stop you choose the lens stays open until the pin on the mount is depressed.
I have the Pentax adapter and it works fine with lenses that have the A/M switch.
The adapter pictured has a flange on it that depresses the pin, allowing for use of the aperture ring on the lens.
The Pentax adapter lacks this flange to depress the pin, so the lens stays wide open.

I've seen other lenses like this on the flea, but have been hesitant to bid on them.

I may have found an adapter like this made by Kipon. Ever heard of them?

Is that the dreaded Rioch pin?

Will this help?
http://www.theatreofnoise...pentax-cameras-ricoh.html

[snoid]

I know all about stop down metering....
It's not the dreaded Ricoh pin.......That's K mount anyway. Been there done that. Taught others how to fix it, even.

The lens in question is an old Albinar zoom.
Pictures might help.........Aaaahhhhh photographers......

First up is the Albinar. It lacks the Auto/ Manual switch. It just has the pin. Set the ring and push on the pin and the aperture will close down.
Second is a classic Pentax m42 mount. It has the pin plus the switch, either one will close the aperture to the desired setting.
The switch makes stop down metering and focus a breeze.
Third is the genuine Pentax mount adapter.
Fourth is the adapter with the flange to push the pin in when you mount it. With the pin pushed in you can control the aperture from the lenses aperture ring.
My guess is that older film cameras pushed in the pin when you mounted it to the camera, allowing full aperture control.
DSLRs lack this.

[spyglass]

Good Morning Snoid,

I figured you probably had a firm grasp on the concept and practice of stop down metering, but for others following this thread I thought I would put it out there - an Admin / Mod practice.    (hell if left unchecked I would probably run off on a two paragraph "shoe tying" instruction check list to consider before heading out to take photos..... now was that left over right or right over left... and what was the part about the rabbit circling the tree and heading back down the hole)  



Thanks for including some photos so we can see what you are talking about in regards to the adapter and the mysterious pin on the lens. We can see now that the Pentax adapter lacks the inner return lip required to depress the pin on the lens.


Spyglass

[blackcloudbrew]

I'd add here that I'm stumped with this one (I'm not saying that my knowledge of the mysteries of the M42 world is vast but I do read stuff on it).

[snoid]

I found a work around, at least for this lens.
It took removing the mount and putting a section from a plastic Q-tip on the pin and re-assembly.
Works just fine. Thanks for bearing with me on this one.
Now, if only I could get the filter off................

[spyglass]

If you are taking about the filter on the end of a lens, I have had great success with the following :

Place a metal cookie sheet in the freezer (a thick plate would work as well) so that it gets really cold (an hour would be plenty)
Use a Q-Tip and apply rubbing alcohol to the thread area. This can help dissolve salts, and debris.
Use a hair dryer and warm up the end of your lens (direct the warm air around the end of the barrel where the filter meets the lens). This will cause the female threaded portion of the lens to expand. (thermal expansion)
Then quickly place the filter against the cold cookie sheet  / plate. (lens pointing straight down to the cold surface). This will shrink the filter and its male threads.
Then try unscrewing the filter.  When unscrewing a filter it is best to apply an even pressure around the outer end of the filter. Gripping the filter hard from opposing sides actually causes the filter to oval and increases friction. I find that I can hold the end of the lens by wrapping my thumb and pointer finger around the barrel of the lens. As for the filter you can try the same thumb and pointer finger wrap, or place your palm over the filter and try and create an even pressure around the filters circumference by cupping my hand.
For really difficult lenses you can allow the hand that will make contact with the lens to be warmed by the hairdryer. While cooling the filter hand against the cold plate. This just extends the length of time the two surfaces will experience the greatest temperature difference.


Let us know how you make out. 

Spyglass

[blackcloudbrew]

Gee, Spyglass, I was just going to recommend my never fail technique, channel locks or vice grips. The filter will come off with that for sure (so will a lot of other stuff too but it will come off).

[xjjohnno]

I think snoid is asking about a slightly modified M42 adapter which has an inner flange which depresses the aperture actuation pin. Finding one is like finding hens teeth, a formidable task but they do exist. I have a feeling Photodiox might list one in their catalogue but I might be wrong. I bought mine through a chap in Hong Kong who has since stopped making them.