[hrishi]

Friends,

I have Pentax SMC 300mm f/4 lens which I use on my z50p...Its a very old lens and doesnt have A setting on its aperture ring..I use it in Av mode and exposure is more or less perfect..

Now I wish to buy K10D, but heard it doesnt expose well with this lens..is it true? any solutions?? I usually shoot Wildlife ( for macro I use FA50/1.4+2xTC+25mm Ext. tube)..

Also, apart from shooting at its effective focal lenght (450mm), I plan to use a 2x teleconverter on it to make it 900mm...Will K10D exposure or Shake reduction will have any probs wid it??

regards

[Peter Zack]

Welcome to the forums.
The lens is a good one but will show some issues with CA/PF in certain situations (purple fringing) where there is strong backlight against a tree branch etc.

As for metering. The camera doesn't do these older M and K series lenses well. The new camera mount is 'crippled' and gives incorrect meter readings by as much as 3 stops in many cases. I used to own this lens and it took some practice to get used to the metering at different f stops. There is no 'workaround' other than practice and getting to understand the combination and how they work together in various situations. Once you do, it's a great lens to work with.

I suspect it's going to be tough to use with a 2x TC for accurate focus though. The K10D viewfinder is bright and very good but not made for manual focus lenses. At about f8 (with the 2x added) the screen will be dimmer unless the light is good. The focus screen is not the old style split screens from the film days and has less of a ground glass profile as well. So it's tougher to focus it sharply when the light is low.

So it is all about practice and getting to know what to expect from the lens in different situations.

[hrishi]

Thanks for welcoming me, Peter Zack- I joined today itself..

I bought the lens coz it was offered to me 4 Rs8000 i.e. $200..That n the prospect of attaching a 2x TC with it was too overwelming..Its an excellent lens and I have quickly learnt to focus manually (along with 2x TC) hence I dont think focussing will be an issue (unless K10D viewfinder is darker than Z50P)..

I have just started with SLR photography (Feb end...Till then I used my excellent cellphone SE W810i since 8months) n willing to practice as much as i can..being an Ecology student, I do get more oppurtunities to practice...With Z50P, due to film developing costs, I couldnt practice much n photographed handheld with keepin a simple rule in mind- to change aperture in the aperture ring to keep shutterspeed is 1/350. (1/750 wen using 2x TC). With K10D, I wud b abl to do lot more things..Its price is low too- Rs 31000, i.e. $ 775 in India..

[Lowell Goudge]

I have the 300 F4 and use it but not much with the K10D.

Mostly I use it on my *istD, along with the pentax 1.7x AF TC.

Here is a shot with the 300 F4 and teleconverter using flash

https://www.pentaxforums.com/forums/106132-post4.html

Note that the 300F4 will only meter correctly on the K10D wide open. By F8 it will over expose by 1 stop ultimately getting to +2 stops by F11 and falling back to +1 1/2 stops by F32.

As long as you know this, and check the histogram, youcan use it quite well.

The lens does produce a little Crhomatic abberatios with back lighting especially on the out of focus areas (branches etc) but this is a good lens, especially if you own it already.

The reason I use this lens moire on my *istD is due to the fact that the *istD a) meters better with manual lenses than the K10D, and b) has TTL flash.

The K10D only has P-TTL flash, where it meters flash by taking a full apature preflash, and then calculates the flash exposure needed for the stopped down shot. Without having apature contacts and an A setting, clearly the camera can't meter for flash on manual lenses.

[hrishi]

Note that the 300F4 will only meter correctly on the K10D wide open. By F8 it will over expose by 1 stop ultimately getting to +2 stops by F11 and falling back to +1 1/2 stops by F32.

What will happen when I use a 2x teleconverter with it?? the (over)exposures as u mentioned will change??

[Lowell Goudge]

it basically (with my Takumar 2x TC is 2 stops over exposed all the time (except F32 which is about 1 stop over (but I doubt you will ever use F32)

[wavecurrent]

I'm using the K300 F4 with my K10D and it works well, it over exposure quiet consistent, about one stop. But it's quite easy to compensate for it in manual mode, also use the histogram for evaluate the exposure. I find focusing the hardest problem with the lens. It performs very well stopped down to F8, there is some CA in some situations, but you can correct in ARC.

Regards,

Mike

[Ben_Edict]

I use several older M- and K-lenses, including the K 4/300 with my K10. The unreliable exposure issue can be remedied to a satisfactory extend by replacing the K10's focusing screen with an older modell from the istD series. I personally use the grid screen LL-60 (the official K10D grid screen is the LL-80). The size and thickness is the same, but it seems there is a brightness difference, which is responsible for the K10's exposure problems in M mode.

The 4/300 is a nice lens, heavy and bulky, but sharpness and contrast are quite good, though not as good as the later A 4/300 or the F/FA 4.5/300 lenses. The CA can be very noticeable in strong backlit situations, but if there is no such backlight, the CA goes unnoticed. As with most of these old tele lenses, focusing is tedious, because the focusing ring's rotation spans nearly a full turn between the nearest point and infinity. That is inconvenient and a real annoyance if you photograph moving objects. Not the best solution for sports... But otherwise a capable combo.

Ben