When do you use aluminium foil on M42?

justtakingpics · 04-05-2011, 02:50 PM

I don't understand when you know to use tinfoil on the lens to short out pins (or something like that). I don't want to tear up my camera. Can anyone comment?

JeffJS · 04-05-2011, 02:52 PM

I think, and could be wrong, that if you want to use Catch In Focus, would be about the only time for doing so. I've never found any issues with not using foil in any other case (I've never foiled my lenses).

**dadipentak** · 04-05-2011, 02:57 PM

I had to use foil to get the AF 1.7x TC to work with my screw-mount Tak.

aleonx3 · 04-05-2011, 03:06 PM

I do it for catch-in-focus when I use MF lenses including m42 and K-mount.

selar · 04-05-2011, 03:27 PM

Originally posted by dadipentak

I had to use foil to get the AF 1.7x TC to work with my screw-mount Tak.

Ditto

**Lowell Goudge** · 04-05-2011, 03:28 PM

I think it depends on camera and lens. Some cameras don't give focus confirmation without the 7th pin of the lens shorted to the mount It's really too bad pentax can't give a menu setting to correct this

Lloydy · 04-05-2011, 04:08 PM

Find a heating engineer and get a bit of the sticky aluminium tape that they use inside boilers, it's stronger and the sticky holds it in place.
It's way better than cooking foil.

There's a picture of my Helios somewhere on a catch in focus thread on this forum showing the foil tape, but I scratched the paint off in the end as it's a cheap lens and the foil tape eventually came off.

wasser · 04-05-2011, 04:40 PM

I also use it on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off.

RioRico · 04-05-2011, 06:05 PM

Rolls of metal duct tape (not the plasticky DuckTape sort) are quite inexpensive. My roll of Nashua tape, maybe 50 feet, cost under four bucks at a non-discount hardware store in a pricey resort town. Even with my hundreds of lenses, it's enough for several lifetimes. Cut a strip about 1/4 inch | 6.5mm wide. Then cut that in half lengthwise. Note where the lens base covers the contacts. Stick the tape there. VOILA!! Another lens converted to CIF!

I use the tape on any screwmount lens with a base wide enough to cover the contacts. Most 3rd-party K-mount lenses have steel bases that short the contacts nicely. A few K-mount lenses, and more than a few cheap K-mount macro tubes and thread-reversal rings, are painted black and thus don't short the contacts. DO NOT APPLY TAPE TO K-MOUNT BASES!! The slight thickness of the tape will cause the base to jam onto the camera!! Instead, use a file or sandpaper to scrape off the paint in the appropriate place.

**Spodeworld** · 08-15-2011, 02:14 PM

I'm brand new to Pentax (been using Nikon, but decided to pick up a K20D for the M42 lenses since Nikons don't focus to infinity with them, even with the infinity adapters!). I'm expecting my K20D to arrive tomorrow, and am looking forward to it.

So, is the tin foil just used for the Catch in Focus functionality? And, someone mentioned they use the tin foil "on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off." Why would the use of tin foil have any bearing on metering, or did I read the intent incorrectly?

Thanks

Steve

newarts · 08-15-2011, 03:31 PM

Originally posted by Spodeworld

So, is the tin foil just used for the Catch in Focus functionality?

Not entirely. If you short out the recessed "A" pin on the camera, auto flash will work. Try turning the e-wheel to lowest f-stop & setting whatever f-stop you like on the lens.

Quote:

And, someone mentioned they use the tin foil "on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off." Why would the use of tin foil have any bearing on metering, or did I read the intent incorrectly?

It is a mystery. but without the foil the camera has no way of even knowing there is a lens on it.

**Spodeworld** · 08-15-2011, 04:14 PM

But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct?

newarts · 08-15-2011, 04:21 PM

Originally posted by Spodeworld

But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct?

Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does. In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work.

newarts · 08-15-2011, 04:22 PM

Originally posted by Spodeworld

But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct?

Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does

In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work

**Spodeworld** · 08-15-2011, 05:09 PM

So, the foil is for CIF, not if you want to just use it for manual focusing in M or A modes....do I have that correct?

Thanks

Originally posted by newarts

Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does

In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work

04-05-2011, 02:50 PM	#1
justtakingpics Senior Member Join Date: Apr 2010 Posts: 288	When do you use aluminium foil on M42? I don't understand when you know to use tinfoil on the lens to short out pins (or something like that). I don't want to tear up my camera. Can anyone comment?

04-05-2011, 06:05 PM	#9
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Rolls of metal duct tape (not the plasticky DuckTape sort) are quite inexpensive. My roll of Nashua tape, maybe 50 feet, cost under four bucks at a non-discount hardware store in a pricey resort town. Even with my hundreds of lenses, it's enough for several lifetimes. Cut a strip about 1/4 inch \| 6.5mm wide. Then cut that in half lengthwise. Note where the lens base covers the contacts. Stick the tape there. VOILA!! Another lens converted to CIF! I use the tape on any screwmount lens with a base wide enough to cover the contacts. Most 3rd-party K-mount lenses have steel bases that short the contacts nicely. A few K-mount lenses, and more than a few cheap K-mount macro tubes and thread-reversal rings, are painted black and thus don't short the contacts. DO NOT APPLY TAPE TO K-MOUNT BASES!! The slight thickness of the tape will cause the base to jam onto the camera!! Instead, use a file or sandpaper to scrape off the paint in the appropriate place. Last edited by RioRico; 04-05-2011 at 06:12 PM.

08-15-2011, 02:14 PM	#10
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370	A little confused I'm brand new to Pentax (been using Nikon, but decided to pick up a K20D for the M42 lenses since Nikons don't focus to infinity with them, even with the infinity adapters!). I'm expecting my K20D to arrive tomorrow, and am looking forward to it. So, is the tin foil just used for the Catch in Focus functionality? And, someone mentioned they use the tin foil "on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off." Why would the use of tin foil have any bearing on metering, or did I read the intent incorrectly? Thanks Steve

08-15-2011, 03:31 PM	#11
newarts Inactive Account Join Date: Dec 2008 Location: Ames, Iowa, USA Photos: Albums Posts: 2,965	foil for flash Originally posted by Spodeworld So, is the tin foil just used for the Catch in Focus functionality? Not entirely. If you short out the recessed "A" pin on the camera, auto flash will work. Try turning the e-wheel to lowest f-stop & setting whatever f-stop you like on the lens. Quote: And, someone mentioned they use the tin foil "on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off." Why would the use of tin foil have any bearing on metering, or did I read the intent incorrectly? It is a mystery. but without the foil the camera has no way of even knowing there is a lens on it.

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04-05-2011, 02:52 PM	#2
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	I think, and could be wrong, that if you want to use Catch In Focus, would be about the only time for doing so. I've never found any issues with not using foil in any other case (I've never foiled my lenses).

04-05-2011, 02:57 PM	#3
dadipentak Site Supporter Join Date: Jul 2008 Location: Baltimore, Maryland Photos: Gallery Posts: 11,590	I had to use foil to get the AF 1.7x TC to work with my screw-mount Tak.

04-05-2011, 03:06 PM	#4
aleonx3 Veteran Member Join Date: Jul 2007 Location: Brampton, Ontario Photos: Gallery \| Albums Posts: 3,996	I do it for catch-in-focus when I use MF lenses including m42 and K-mount.

04-05-2011, 03:27 PM	#5
selar Veteran Member Join Date: Jul 2007 Location: Sydney, Australia Photos: Gallery \| Albums Posts: 2,042	Originally posted by dadipentak I had to use foil to get the AF 1.7x TC to work with my screw-mount Tak. Ditto

04-05-2011, 03:28 PM	#6
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	I think it depends on camera and lens. Some cameras don't give focus confirmation without the 7th pin of the lens shorted to the mount It's really too bad pentax can't give a menu setting to correct this

04-05-2011, 04:08 PM	#7
Lloydy Veteran Member Join Date: Aug 2007 Location: Shropshire, UK Posts: 1,114	Find a heating engineer and get a bit of the sticky aluminium tape that they use inside boilers, it's stronger and the sticky holds it in place. It's way better than cooking foil. There's a picture of my Helios somewhere on a catch in focus thread on this forum showing the foil tape, but I scratched the paint off in the end as it's a cheap lens and the foil tape eventually came off.

04-05-2011, 04:40 PM	#8
wasser Veteran Member Join Date: Jan 2009 Location: northern ca Photos: Gallery Posts: 427	I also use it on my Km to get proper exposure in Av mode. Wiithout it it's consistently 2 stops off.

08-15-2011, 04:14 PM	#12
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370	But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct?

08-15-2011, 04:21 PM	#13
newarts Inactive Account Join Date: Dec 2008 Location: Ames, Iowa, USA Photos: Albums Posts: 2,965	Originally posted by Spodeworld But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct? Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does. In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work.

08-15-2011, 04:22 PM	#14
newarts Inactive Account Join Date: Dec 2008 Location: Ames, Iowa, USA Photos: Albums Posts: 2,965	Originally posted by Spodeworld But, even without the foil, doesn't it meter in M and A modes? I thought it did, it's just that it doesn't know what the aperture is. Is that correct? Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work

08-15-2011, 05:09 PM	#15
Spodeworld Site Supporter Join Date: Aug 2011 Location: New Joisey Photos: Gallery \| Albums Posts: 1,370	So, the foil is for CIF, not if you want to just use it for manual focusing in M or A modes....do I have that correct? Thanks Originally posted by newarts Could be, maybe you can reverse software engineer it & guess at why it behaves the way it does In the end it is likely easier to short a contact. You'll need to do that anyhow to get CIF to work