Pentax K mount or Canon FD? at DVinfo.net

Andy Young · June 21st, 2011, 06:15 PM

I am getting ready to go on a shoot to Africa. I am taking a 50mm 1.8 and a 90mm 2.8 along with the kit lens. I would love to get a Sigma 30mm 1.4 before I go, but I don't think my pocket book will allow that before I leave. I have been looking at both Canon FD lens and Pentax K mount lens with adapters as a low cost option to get something a bit wider before I leave. I was hoping someone with some experience could let me know if they like one option over the other, or if I am wasting my time with both of them. Any help would be appreciated.

Jeremy Pevar · June 22nd, 2011, 10:46 AM

I would go with Pentax K mount lenses over Canon FD lenses for one simple reason - there is no focal length multiplier. That is, a 50mm K mount lens is still 50mm when adapted to the EF mount, but there is a 1.25x multiplier when dealing with FD lenses. This may not be a bad thing at longer focal lengths, but is a problem if you're looking for a wide-angle lens.

Andy Young · June 23rd, 2011, 08:05 AM

Thanks for the reply. I am leaning towards the K mount as well. The only thing that was scaring me was that I have read of people removing a tab on the Pentax K mount lenses. Depending on what you read, the tab may or may not interfere with the mirror on the camera body. Do you know anything about this?

Jeremy Pevar · June 23rd, 2011, 12:31 PM

I have a number of Pentax Takumar M42 (screw mount) lenses that I use on my 7D with an adaptor. One of the lenses had a similar tab. I took the lens to a local camera repair shot and he removed the offending appendage.

John Wiley · June 23rd, 2011, 05:04 PM

I'd definitely try to aviod FD, as they will require an adaptor with an additional glass element. This will give you more crop as well as a much softer image.

I'm using a Pentax 50mm f/1.7 on my 550D at the moment without any problems. I believe some lenses are worse that others, and the problem is also less of an issue on APS-C cameras than of the 5Dmkii - the bigger mirror on that is more easily obstructed.

Andy Young · June 24th, 2011, 05:24 AM

Thanks for the replies/advice all. I read a few things in various places, but it is nice to hear from people with real world experience. I am definitely going the K mount route. From what I have gathered, the tabs on the lens are an issue on full frame mirrors and not on crop sensor bodies. I may still remove the offending tab as it seems like a pretty easy modification to make. Thanks again, as always this forum has proven invaluable.

Kin Lau · June 24th, 2011, 03:22 PM

If you're hoping for someone faster and wider with Pentax K or Canon FD, then I would say you're wasting your time with both of them.

You're much more likely to find a Pentax M42, Nikon or OM mount 35/2, 28/2 or 24/2. An OEM lens will likely cost the same as a Sigma 30/1.4, so you're looking for a 3rd party like a Vivitar or Kiron.

Realistically, your best economical choice is probably the kit 18-55IS lens.

Chris Barcellos · June 24th, 2011, 05:14 PM

I have both a Canon 5d and a T2i. My first was the 5D, and I adapted several Nikon and and Pentax lenses. I did do some minor surgery to flanges on the back of a lens or two, to avoid the mirror interference. In one case I recall just pealing of a "flance on the back of a Nikon lens. On a Pentax lens, I had to shorten a tab. Probably not a clean a job as a shop would do, but it was over and done without issue quickly.

June 21st, 2011, 06:15 PM	#1
Andy Young Regular Crew Join Date: Dec 2010 Location: Indianapolis, IN Posts: 34	Pentax K mount or Canon FD? I am getting ready to go on a shoot to Africa. I am taking a 50mm 1.8 and a 90mm 2.8 along with the kit lens. I would love to get a Sigma 30mm 1.4 before I go, but I don't think my pocket book will allow that before I leave. I have been looking at both Canon FD lens and Pentax K mount lens with adapters as a low cost option to get something a bit wider before I leave. I was hoping someone with some experience could let me know if they like one option over the other, or if I am wasting my time with both of them. Any help would be appreciated.

June 22nd, 2011, 10:46 AM	#2
Jeremy Pevar Regular Crew Join Date: Mar 2010 Location: Los Angeles, CA Posts: 48	Re: Pentax K mount or Canon FD? I would go with Pentax K mount lenses over Canon FD lenses for one simple reason - there is no focal length multiplier. That is, a 50mm K mount lens is still 50mm when adapted to the EF mount, but there is a 1.25x multiplier when dealing with FD lenses. This may not be a bad thing at longer focal lengths, but is a problem if you're looking for a wide-angle lens.

June 23rd, 2011, 08:05 AM	#3
Andy Young Regular Crew Join Date: Dec 2010 Location: Indianapolis, IN Posts: 34	Re: Pentax K mount or Canon FD? Thanks for the reply. I am leaning towards the K mount as well. The only thing that was scaring me was that I have read of people removing a tab on the Pentax K mount lenses. Depending on what you read, the tab may or may not interfere with the mirror on the camera body. Do you know anything about this?

June 23rd, 2011, 12:31 PM	#4
Jeremy Pevar Regular Crew Join Date: Mar 2010 Location: Los Angeles, CA Posts: 48	Re: Pentax K mount or Canon FD? I have a number of Pentax Takumar M42 (screw mount) lenses that I use on my 7D with an adaptor. One of the lenses had a similar tab. I took the lens to a local camera repair shot and he removed the offending appendage.

June 23rd, 2011, 05:04 PM	#5
John Wiley Trustee Join Date: Oct 2008 Location: Byron Bay, Australia Posts: 1,155	Re: Pentax K mount or Canon FD? I'd definitely try to aviod FD, as they will require an adaptor with an additional glass element. This will give you more crop as well as a much softer image. I'm using a Pentax 50mm f/1.7 on my 550D at the moment without any problems. I believe some lenses are worse that others, and the problem is also less of an issue on APS-C cameras than of the 5Dmkii - the bigger mirror on that is more easily obstructed.

June 24th, 2011, 05:24 AM	#6
Andy Young Regular Crew Join Date: Dec 2010 Location: Indianapolis, IN Posts: 34	Re: Pentax K mount or Canon FD? Thanks for the replies/advice all. I read a few things in various places, but it is nice to hear from people with real world experience. I am definitely going the K mount route. From what I have gathered, the tabs on the lens are an issue on full frame mirrors and not on crop sensor bodies. I may still remove the offending tab as it seems like a pretty easy modification to make. Thanks again, as always this forum has proven invaluable.

June 24th, 2011, 03:22 PM	#7
Kin Lau Major Player Join Date: Mar 2009 Location: Ottawa, ON Posts: 385	Re: Pentax K mount or Canon FD? If you're hoping for someone faster and wider with Pentax K or Canon FD, then I would say you're wasting your time with both of them. You're much more likely to find a Pentax M42, Nikon or OM mount 35/2, 28/2 or 24/2. An OEM lens will likely cost the same as a Sigma 30/1.4, so you're looking for a 3rd party like a Vivitar or Kiron. Realistically, your best economical choice is probably the kit 18-55IS lens.

June 24th, 2011, 05:14 PM	#8
Chris Barcellos Inner Circle Join Date: Nov 2005 Location: Elk Grove CA Posts: 6,838	Re: Pentax K mount or Canon FD? I have both a Canon 5d and a T2i. My first was the 5D, and I adapted several Nikon and and Pentax lenses. I did do some minor surgery to flanges on the back of a lens or two, to avoid the mirror interference. In one case I recall just pealing of a "flance on the back of a Nikon lens. On a Pentax lens, I had to shorten a tab. Probably not a clean a job as a shop would do, but it was over and done without issue quickly. __________________ Chris J. Barcellos