A bit of advice required. (help!!)


Link Posted 11/02/2010 - 15:14
I would like to use some of the older Pentax lenses on my K20D namely Primes 50mm----300mm.
do I use K mount only and I gather it's to be manual focused
do I need to set f stops and what about metering

I've seen some reasonable ones on e'bay and I'm itching.

Thanks in anticipation




Link Posted 11/02/2010 - 15:19
Try searching this forum as there are plenty of posts on this very subject.

In summary, manual focus lenses remain manual focus, but those with a "A" on the aperture ring will work normally with the K20D as reagrds metering. Eralier lenses (K series and M series) which have no electronic contacts on their mounts can be used for manual exposure measurement, but are less convenient in use.

All AF lenses will be fine.
Best regards, John


Link Posted 11/02/2010 - 15:23
You can use any Pentax lens - M42 mount lenses need an adapter, of course!

KA and later would be best as all exposure functions are available - just set the aperture ring to 'A' and use it like tke the kit lens. Non AF lenses will need to be focussed manually, but will have focus confirmation and you will have to tell the camera the focal length.

K and M lenses are best used as manual exposure manual focus.

Edit - John got in first!

Last Edited by myles on 11/02/2010 - 15:23


Link Posted 11/02/2010 - 15:46
Thanks John and Myles for such a quick response, I'll check the earlier forums as you suggested John.
and I'll take onboard your comments on KA lenses Myles.

If I can add a comment about this forum..
There is a friendly and helpful community here, well controlled with everyone giving each other respect
as individuals whose hobby/profession brings them to a place where they can feel at ease.

Just my opinion and the reason I am a constant visitor.




Link Posted 11/02/2010 - 15:50
Cheers albert, if you need any more info just ask!
Best regards, John


Link Posted 11/02/2010 - 16:42
Albert, I can highly recommend using old glass on your K10. I've found you can build up a collection very economically, if that's a factor and it's so interesting bolting on a "new" acquisition and trying it out. When you have to focus manually and (with non "A" lenses) set the exposure manually as well, it slows you down and makes you think about your photography. I've also found its great discipline going walkabout with just one prime lens and find photigraphs which suit the framing.

I hope Womble (Kris) sees this because I know he's an enthusiast and very knowledgable He's sure to have some sage advice and I beleive he retains a comprehensive data base of old lenses.

I'm glad you've enjoyed your involvment with this group: I too have found the experience very rewarding. Everyone's views don't always coincide, but respect and good manners are always present. Your photography will improve as well!

Post some images when you've got your "new" lenses.

Best wishes,

Best wishes,


"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference. All of them can record what you are seeing. But, you have to SEE."
Ernst Hass
My website: http://www.ephotozine.com/user/bwlchmawr-199050 http://s927.photobucket.com/home/ADC3440/index


Link Posted 11/02/2010 - 17:32
Thanks Andrew for your advice, I shall be busy getting to grips with everyone's advice/input.

I will let you know how I'm progressing.

There are still some values left to find in our life time.




Link Posted 11/02/2010 - 21:41
I see you are in Derbyshire, which isn't a million miles away from the Wolverhampton camera fairs that are held about 4 times a year.


You've just missed one last Sunday, the next is on April 18th, and there's always a lot of old stuff going at decent prices.
I've come home with M42 lenses that I've paid as little as 2 for, some I've paid a tenner for! OK, they're not mint Takumars for that money, but they're lenses that I'm enjoying using and learning from. If I find a range of lens that I really like then maybe I'll buy some Takumars?


Link Posted 12/02/2010 - 00:31
I've just acquired a 50mm f/2 manual lens for my K20 and it was a bit fiddly to make it work at first, but it seems fine now. I had to 'allow aperture ring' on the 'custom' menu and select the focal length on the 'record' menu. Then set the desired aperture on the ring, press the green button next to the shutter release (which allows the aperture to close down and sets the 'correct' i.e. metered speed), and if necessary adjust up or down. After a couple of sessions it becomes much more intuitive than it sounds.

I've only tried a couple of test shoots but the extra couple of stops make a lot of difference for portraits, flowers etc (it's the first prime I've owned for about 10 years). However, it's highlighted the limitations of the standard focal screen for manual focussing, and a Katz Eye replacement is on its way.
K5IIs & ME Super with FA24-90, DA17-70, DA55-300, misc old primes; Fuji X20.


Link Posted 12/02/2010 - 11:13
great to hear about the wolverhampton camera fairs seems an excellent way to view/buy into the older lenses,
thanks for the info Lloydy. I'll pencil it in on the calendar.

The 50mm f/2 seems to be a good lens I guess the fiddly bits go with wanting to explore into the domains of older and from what I can gather sharper lenses.

thanks for the advice Stanovich.




Link Posted 12/02/2010 - 11:31
The "A" (auto) versions of the 50mm f1.7 and 28mm f2.8 are very good, common and reasonably priced, so I'd recommend them for the convenience. It's rare or expensive to get better optical quality from manual-exposure lenses of these focal lengths.

It's different for other lengths and more often worthwile to put up with the fully manual nature to get good optical quality or speed.


Link Posted 13/02/2010 - 15:44
I have obtained 2/hand some Tamron adaptall fast prime lenses, which when used on my K20D with the adaptall PK/A adaptor (rare to obtain) gives all metering, aperature & speed adjustment and AF indication.
However I have not as yet assessed the improvement over the kit AF lenses.
K20D/DBG2 | Pentax DA 18-55/3.5-5.6 AL| Tamron DiAF 70-300/4-5.6 | Pentax A 28/2.8 | Tamron ad2P/KA 28-70/3.5-4.6 | Tamron ad2P/KA SP90/2.5 +macro 1.1-1.2 extn | Teleplus KAX 2x | Vivitar PK 2x22 |Metz 58AF1 Flash| Canon FD Bodies: T90; T70 | FD Lenses C50/1.8; Vivitar S1 70-200/3.5; Sigma 400/5.6; Vivitar AT4 ext tubes; CFD 2xA extender; Tamron ad2CFD 28-70/3.5-4.5 | Cullman CX35 + offshoe cables |
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