full frame with old lenses

So as I am sure you all know by now, pentax Ricoh have announced that later this year the full frame dlsr will be released. My concern is whether or not we will be able to use our old lenses. I have many old K Mount smc's and DA lenses, but will I be able to use these lenses normally on a new full frame? I have heard that with DA lenses cropping will be required. What is this all about?

The KAF mount used on current Pentax DSLRs with aps-c sensors is the same size as on previous film - era cameras, and current DA lenses have the same mount size as well. Both film-era lenses and modern DA lenses will fir on and work and will work on all Pentax SLR bodies (digital and film).

A Full Frame digital camera will have the same mount as the current aps-c models, so the compatibility continues .... that's something that is great about Pentax!

There are differences in the mount and lens technologies over the years (K, KAF, KAF 2 etc) and these are to do with various electronic contacts that added extra functions over the years. But the oldest film era K lenses will still work on all (D)SLR bodies, with some reduced metering functionality in the case of the oldest lenses. This situation will be the same for the new FF SLR.

In fact we are all waiting with baited breath to see what the image quality from old film-era lenses will be like once we get them onto a new FF body .... a matter subject to great debate right here on PU!!

The film - era lenses will project their full image circle onto the FF sensor, therefore revealing the outer edges of the glass's performance, which has all been not visible on the aps-c cameras as the sensor is smaller than the image circle projected onto the sensor .... that is what is meant by 'crop' in this case.

Although Pentax DA (APS-C) lenses should fit the new FF K-mount body, I am curious regarding whether some DAs will be usable as FF lenses rather than "crop mode" lenses.

One problem could be vignetting of the image on the larger sensor, due possibly to a smaller image circle. I have just tried my DA 18-135 on an old MX film body, which has a clear bright FF viewfinder - that lens shows circular vignetting throughout its range. However, there appears to be no such problem with either my DA 55-300 or my DA 35 Limited prime.

But, of course, this simple viewing test does not show up any other problems (sharpness, distortion, etc.) that might arise in a FF image from a DA lens. I wondered if anyone here has any more information relevant to this.

Cheers.
Philip

Fairly comprehensive list of compatible lenses here but no mention of IQ etc. We will have to wait for those I think.

Hey Philip, easy, you can just call on PentaxPete to see if he's got any OUTDATED AGFA XP TRI-TONE CHROMA-DI PANO-MATT rotting in the fridge for you to try so you can see the full framed image!! ) ... Or can you still buy Fuji Superia at Boots?

(Sorry Peter, my knowledge of old films is so poor I had to make it up

I'm sure that all the old lenses will work to some degree. Hopefully even with DA lenses it will be possible to turn off the crop, as some are FF capable, though they may have a bit more vignetting than would be desireable.

If Pentax don't un-cripple the K-mount for this camera it will be a crime. Imagine being able to use all the old M and K series primes as you would on an old film camera - either metered manual or A modes. People who want a digital Leica but can't afford one would flock to it.

There are already quite a few digital FF images from Pentax lenses out there to pixel peep- have a Google for 'Pentax lens on Canon 5d' or 'Sony A7'.

Mike-P, thank you for that helpful link.

Cheers.
Philip

That sounds amazing!! I didn't even know about those modes .... A mode ... Is that like on the flashes where you set the aperture and ISO manually? I guess on a camera body, if it knows the aperture and ISO it will calculate the time value? Does it still take a reading with a half press? (But that pre -supposes it knows the full open aperture) .... So many questions!

You're having us on aren't you Greg? 'A mode' is just an abbreviation for automatic exposure modes like Aperture or Shutter priority.

Truth to tell 'uncrippling' the lens mount isn't going to give us that much. It will give the old M and K mount lenses some of the functionality of the old A series lenses and that's all. I don't think it will happen though - Pentax do want to sell new lenses and we should be grateful for the compatability we already have. Mind you, I have a few old lenses myself so *if* the aperture coupler came back it would be welcome, five years ago it would have been a deal breaker - but now I have a few modern lenses as well so for me it isn't any longer.

Hmmm, maybe I'm getting a little carried away there Must be my age! I remember now, 'A Mode' is an old term for Av. I was thinking of Auto flash mode where the aperture and ISO are dialed into the flash and letting my imagination run riot!

So we might only get metering without the green button?

No way, I knew this would happen. If I go ff I have to say goodbye to my sdm 16-50. My god, that is a real problem

No because you can still use it in crop mode (although you won't get the benefit of FF). If the new body is 36MP with no AA filter then you should basically be getting a 15.4mp K-5IIs.

Nah, use it on a cropped body and use the FF with another lens. Nothing wrong with having two cameras with you and it saves changing glass.

Best regards

To correct my earlier mistake, I should have stated "Av" mode (aperture priority) rather than "A" mode (full auto).