Questions about M42 adapters

peterjcb · 02-26-2015, 07:35 PM

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..so I got my first non-Pentax screw mount lens and the M42 adapter. I have never used one and didn't know what to expect.
I got the one that focuses to infinity and the little spring on the side to hold it in the Pentax body.
I had a couple of issues, the first being that the screw that was holding the clip must have been too long and it was protruding slightly past the threads of the adapter causing the lens to not fully screw into it.
I finally saw this and removed the screw and clip so now the lens fully threads onto the adaapter.
I damaged the screw threads on the lens a bit from the grinding on the screw but with a touch of WD-40 it seems to have smoothed everything....fortunately it was only a $30 lens but it's working fine anyway.

The other issue is that when I screw the lens into the adapter on the camera, the index is on the bottom and not top & center where you would normally see it. Is this something that I have to live with when using M42 screw lenses or have I missed something about adapters? I can still adjust f stop but it's just inconvenient to see it on the bottom instead of the top.

Not a Number · 02-26-2015, 07:47 PM

With most of the 3rd party knock-off infinity adapters it is best to simply remove the screw and spring clip. More often than not the screw is too long or the spring will or lens will jam.

Misalignment of the distance scale is typical. Even with the genuine Pentax adapters they will be a little off. It depends on both the adapter and the lens.

You just missed out on some New-Old-Stock for sale of some of the genuine Pentax adapters by a few days.

peterjcb · 02-26-2015, 08:10 PM

I'm thinking that I'll probably get an adapter for each M42 lens and just keep them with the lens instead of moving the adaptor from body to body...they are pretty cheap.

**dms** · 02-26-2015, 08:19 PM

Unless experienced I suggest only use the pentax made adapter. the pentax one will not damage anything and will ensure focus at infinity.

This comes up all the time and there are too many stories about damage, etc. You still may want to remove the spring so the adapter stays on the lens, but that is your choice.

**jatrax** · 02-26-2015, 09:31 PM

Originally posted by peterjcb

I'm thinking that I'll probably get an adapter for each M42 lens and just keep them with the lens instead of moving the adaptor from body to body...they are pretty cheap.

Cheap is the operative word. Quality is hit or miss and some are really bad. Beware the spring, it can get stuck and prevent the lens from being removed from the camera. As you already experienced it can mess up the threads and in severe cases the entire lens has to be dismantled to remove it. Most who use the knocks offs remove the spring immediately.

While having an adapter on each lens seems intuitive I would suggest getting the Pentax one and putting it on the camera. I've tried both and greatly prefer the OEM adapter on the camera. The only exception is long lenses 300mm and up, they are awkward to screw into the camera so I do have an adapter on those.

**UncleVanya** · 02-26-2015, 09:37 PM

If you find a KALT I have it and the Pentax and find both equally good.

excanonfd · 02-26-2015, 10:09 PM

Originally posted by peterjcb

I'm thinking that I'll probably get an adapter for each M42 lens and just keep them with the lens instead of moving the adaptor from body to body...they are pretty cheap.

Remove the screw and the spring from the 3rd party adapter, cinch on the adapter tight to the m42 lens with a PK mount lens cap and you have a pseudo k mount lens. The batch of 5, 3rd party m42 adapters that I'd ordered from this eBay merchant: Focus Infinity M42 Lens Mount Adapter FOR PK Pentax K10D K20D KM K7 K200D SY | eBay arrived today and I can report the lens' focus index sits at a very acceptable 11 o'clock position when mounted on my K-5.

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**Scorpio71GR** · 02-27-2015, 06:06 AM

I have several M42 lens that I use on my K3 and K10D. I only use the genuine Pentax adapter and I have no issues with. Yeah it is $50 on B&H but it works without any problems. Yes the lens will not line up perfectly and this is normal. With the genuine adapter you just need something with a point on it to remove it. A ballpoint pen will work just fine. I do no recommend leaving the adapter on the lens. My advice is is to just avoid third party knock offs, they are more bother then they are worth.

excanonfd · 03-01-2015, 01:29 AM

I disagree. Using the genuine adapter might be safer than the 3rd part one but it's tedious, especially changing lenses outside. By removing the screw and the spring from the knockoff adapters, the possibility of getting the adapter stuck on the camera becomes a non-issue and the lenses mount and dismount just like a k mount lens, albeit that it can't be locked to the body. Since most knockoffs fit much tighter than the genuine adapter to the body, there's almost no need to worry about unscrewing the lens from the adapter while focusing the lens. It only happened to me once when I was trying out a 300mm telephoto lens that required two hands to turn the focus ring - which I have since re-lubed. Finally the cost; it costs $50.00 for the genuine article from B&H, I paid $20.00 for 5 knock offs. I have one genuine adapter and more than a dozen knockoffs and the latest batch that I bought are about as good as they get. I haven't put them all on the m42 lenses just yet - I don't have enough PK rear lens caps.

sterretje · 03-01-2015, 02:47 AM

There are different approaches

When I fit the Pentax adapter on the camera, I will only use M42 lenses (leave K-mount lenses at home). Unscrewing an M42 lens takes a little longer than removing a K-bayonet, but I'm never in a hurry when I use M42

**jatrax** · 03-01-2015, 02:44 PM

Originally posted by sterretje

There are different approaches When I fit the Pentax adapter on the camera, I will only use M42 lenses (leave K-mount lenses at home). Unscrewing an M42 lens takes a little longer than removing a K-bayonet, but I'm never in a hurry when I use M42

^^^^ this. +1

excanonfd · 03-01-2015, 07:10 PM

Each to his own, eh? Spending four bucks for an adapter that removes the distinction between M42 and K-Mount lens, is money well spent in my book.

**jatrax** · 03-01-2015, 08:47 PM

Originally posted by excanonfd

Each to his own, eh?

Exactly. Many ways to make this work. I paid $30 for a real adapter. And $20 for 5 knock off adapters that I threw in the trash. I'm glad you got good ones, but it really is a gamble whether you get good ones or junk. The real ones always work, the knock offs might work. And only if you remove the spring that keeps the lens from falling off accidentally.

If you are happy with your method, great.

edri · 03-02-2015, 11:20 AM

I have two original Pentax M42-K adapters, which I rarely use. I mounted cheap adapters on each M42 lens, of course after I removed the spring. I recently bought some black M42-K adapter without spring from factory (double price compared to cheapest adapters ). I had no problems so far, not fell any lens with these permanent cheap adapters on the lens. The main problem, indeed, is the alignment index (aperture, focus) on the lens. For cheap adapters, each has a different alignment, they are not two similar. For one the the lens inscriptions are offset by about 180 degrees!. The index is on the bottom. With black adapters alignment is almost correct .Original adapters allow always correct alignment, but for me it is uncomfortable changing lenses in this way, with adapter mounted in body.

sterretje · 03-03-2015, 08:06 AM

Originally posted by edri

Original adapters allow always correct alignment

Not on my systems; they're always off a bit (10-20 degrees or so). But it's a non-issue for me.

02-26-2015, 07:35 PM	#1
peterjcb Veteran Member Join Date: Dec 2013 Location: Weddington, NC Posts: 468	Questions about M42 adapters Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. ..so I got my first non-Pentax screw mount lens and the M42 adapter. I have never used one and didn't know what to expect. I got the one that focuses to infinity and the little spring on the side to hold it in the Pentax body. I had a couple of issues, the first being that the screw that was holding the clip must have been too long and it was protruding slightly past the threads of the adapter causing the lens to not fully screw into it. I finally saw this and removed the screw and clip so now the lens fully threads onto the adaapter. I damaged the screw threads on the lens a bit from the grinding on the screw but with a touch of WD-40 it seems to have smoothed everything....fortunately it was only a $30 lens but it's working fine anyway. The other issue is that when I screw the lens into the adapter on the camera, the index is on the bottom and not top & center where you would normally see it. Is this something that I have to live with when using M42 screw lenses or have I missed something about adapters? I can still adjust f stop but it's just inconvenient to see it on the bottom instead of the top.

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02-26-2015, 07:47 PM	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	With most of the 3rd party knock-off infinity adapters it is best to simply remove the screw and spring clip. More often than not the screw is too long or the spring will or lens will jam. Misalignment of the distance scale is typical. Even with the genuine Pentax adapters they will be a little off. It depends on both the adapter and the lens. You just missed out on some New-Old-Stock for sale of some of the genuine Pentax adapters by a few days.

02-26-2015, 08:10 PM	#3
peterjcb Veteran Member Join Date: Dec 2013 Location: Weddington, NC Posts: 468 Original Poster	I'm thinking that I'll probably get an adapter for each M42 lens and just keep them with the lens instead of moving the adaptor from body to body...they are pretty cheap.

02-26-2015, 08:19 PM	#4
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	Unless experienced I suggest only use the pentax made adapter. the pentax one will not damage anything and will ensure focus at infinity. This comes up all the time and there are too many stories about damage, etc. You still may want to remove the spring so the adapter stays on the lens, but that is your choice.

02-26-2015, 09:31 PM	#5
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by peterjcb I'm thinking that I'll probably get an adapter for each M42 lens and just keep them with the lens instead of moving the adaptor from body to body...they are pretty cheap. Cheap is the operative word. Quality is hit or miss and some are really bad. Beware the spring, it can get stuck and prevent the lens from being removed from the camera. As you already experienced it can mess up the threads and in severe cases the entire lens has to be dismantled to remove it. Most who use the knocks offs remove the spring immediately. While having an adapter on each lens seems intuitive I would suggest getting the Pentax one and putting it on the camera. I've tried both and greatly prefer the OEM adapter on the camera. The only exception is long lenses 300mm and up, they are awkward to screw into the camera so I do have an adapter on those.

02-26-2015, 09:37 PM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	If you find a KALT I have it and the Pentax and find both equally good.

02-27-2015, 06:06 AM	#8
Scorpio71GR Loyal Site Supporter Join Date: Nov 2014 Location: Michigan Photos: Gallery \| Albums Posts: 6,005	I have several M42 lens that I use on my K3 and K10D. I only use the genuine Pentax adapter and I have no issues with. Yeah it is $50 on B&H but it works without any problems. Yes the lens will not line up perfectly and this is normal. With the genuine adapter you just need something with a point on it to remove it. A ballpoint pen will work just fine. I do no recommend leaving the adapter on the lens. My advice is is to just avoid third party knock offs, they are more bother then they are worth.

03-01-2015, 01:29 AM	#9
excanonfd Veteran Member Join Date: Jan 2010 Location: Vancouver, BC Posts: 1,421	I disagree. Using the genuine adapter might be safer than the 3rd part one but it's tedious, especially changing lenses outside. By removing the screw and the spring from the knockoff adapters, the possibility of getting the adapter stuck on the camera becomes a non-issue and the lenses mount and dismount just like a k mount lens, albeit that it can't be locked to the body. Since most knockoffs fit much tighter than the genuine adapter to the body, there's almost no need to worry about unscrewing the lens from the adapter while focusing the lens. It only happened to me once when I was trying out a 300mm telephoto lens that required two hands to turn the focus ring - which I have since re-lubed. Finally the cost; it costs $50.00 for the genuine article from B&H, I paid $20.00 for 5 knock offs. I have one genuine adapter and more than a dozen knockoffs and the latest batch that I bought are about as good as they get. I haven't put them all on the m42 lenses just yet - I don't have enough PK rear lens caps.

03-01-2015, 02:47 AM	#10
sterretje Veteran Member Join Date: Dec 2008 Location: Roodepoort, South Africa Photos: Gallery \| Albums Posts: 3,561	There are different approaches When I fit the Pentax adapter on the camera, I will only use M42 lenses (leave K-mount lenses at home). Unscrewing an M42 lens takes a little longer than removing a K-bayonet, but I'm never in a hurry when I use M42

03-01-2015, 02:44 PM	#11
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by sterretje There are different approaches When I fit the Pentax adapter on the camera, I will only use M42 lenses (leave K-mount lenses at home). Unscrewing an M42 lens takes a little longer than removing a K-bayonet, but I'm never in a hurry when I use M42 ^^^^ this. +1

03-01-2015, 07:10 PM	#12
excanonfd Veteran Member Join Date: Jan 2010 Location: Vancouver, BC Posts: 1,421	Each to his own, eh? Spending four bucks for an adapter that removes the distinction between M42 and K-Mount lens, is money well spent in my book.

03-01-2015, 08:47 PM	#13
jatrax Site Supporter Join Date: May 2010 Location: Washington Cascades Photos: Gallery \| Albums Posts: 12,991	Originally posted by excanonfd Each to his own, eh? Exactly. Many ways to make this work. I paid $30 for a real adapter. And $20 for 5 knock off adapters that I threw in the trash. I'm glad you got good ones, but it really is a gamble whether you get good ones or junk. The real ones always work, the knock offs might work. And only if you remove the spring that keeps the lens from falling off accidentally. If you are happy with your method, great.

03-02-2015, 11:20 AM	#14
edri Veteran Member Join Date: Jan 2009 Location: walking in the air Posts: 1,315	I have two original Pentax M42-K adapters, which I rarely use. I mounted cheap adapters on each M42 lens, of course after I removed the spring. I recently bought some black M42-K adapter without spring from factory (double price compared to cheapest adapters ). I had no problems so far, not fell any lens with these permanent cheap adapters on the lens. The main problem, indeed, is the alignment index (aperture, focus) on the lens. For cheap adapters, each has a different alignment, they are not two similar. For one the the lens inscriptions are offset by about 180 degrees!. The index is on the bottom. With black adapters alignment is almost correct .Original adapters allow always correct alignment, but for me it is uncomfortable changing lenses in this way, with adapter mounted in body.

03-03-2015, 08:06 AM	#15
sterretje Veteran Member Join Date: Dec 2008 Location: Roodepoort, South Africa Photos: Gallery \| Albums Posts: 3,561	Originally posted by edri Original adapters allow always correct alignment Not on my systems; they're always off a bit (10-20 degrees or so). But it's a non-issue for me.