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06-09-2007, 09:01 AM   #1
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Mount Adaptor K and old Pentax lenes on K100D

I just joined this forum early this week - primarily to continue my 'education' of digital photography and my K100D. I just purchased a Mount Adaptor K so that I could use 2 old lenses that I have from Pentax Spotmatic 35 mm camera - a Super Takumar 1:1.8/55mm and a SMC 1:3.5/135mm - both with a manual and automatic setting on the aperture ring.

First of all I could not see either of these lenses on the lens review page - are they considered 'good' lenses?

At first I was using only the Manual mode and pressing the AE-L button - then after reading several of the threads I realized I could put the aperture ring setting on automatic and use P, Av, Tv or M mode without pressing the AE-L. I have been pleased with the results - it's great to be able to have a really shallow depth of field. Also I had never used the 135mm lens and it was a bit 'weird' having the telephoto capability - I'm used to thinking of filming from a 55mm point of view....

Just a few questions - can I do focus lock when using these lens - so far I have been centering everything... I do find focusing a bit of a problem - it's not always possible to tell if the intended subject is in fact focused - even when the view finder indicates focusing is okay - on my old spotmatic there was a 'grid' that would assist in focusing.

Any other hints when using old A series lenses?

I am also a bit nervous about changing lens and getting dust, dirt etc on the CCD - any suggestions about that.

As you can see I am still somewhat of a newbie to photography - but am enjoying it immensely...

06-09-2007, 04:25 PM   #2
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I do well over 95% of my shooting with the old Takumar lenses. I don't know what the consensus opinion is on the two lenses you mentioned, but I have them both and like them just fine. The S-M-C Takumar 135/3.5 is the lens I normally keep mounted, and it accounts for the vast majority of my photos.

You mention having a really shallow depth of field....Does this mean you are only using the lenses wide open? If you have set the Auto-Manual selector switch for "auto", you lose the ability to use anything other than the wide open aperture. The camera has no way of closing the aperture down for you, since there is no mechanism in the camera for doing that. Put the selector on "manual", put the camera in "Av", focus wide open, then turn the aperture ring to your desired aperture. The viewfinder will go dark, but that's to be expected.

Also, you may find it beneficial to adjust your EV. I find that with those old M42 lenses I have to use +1.5.

For focusing....the best thing, in my opinion, is to remove the stock focus screen and replace it with one that has the split-prism and microprism collar in the center. The kind that was considered normal back in the days when manual focus was par for the course. Many people believe that the screen can't be changed, but the fact is that it not only can be changed, it can be changed easily. Took me about two minutes to install a split-prism screen, and the ease/accuracy of manual focusing went up tremendously.
06-09-2007, 09:36 PM   #3
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Thanks for the reply Mike, I can see why you would use your 'old' lenses - I have been very pleased with the results - great color and detail.

My comment concerning 'shallow depth of field' was in reference to the fact that with my Super Takumar 1.8/55mm I can actually get a shallow depth of field, much less than what is available with the kit lens. I have been shooting at various f stops to see 'the difference'.

Also I noticed you (as well as others on other threads that I have read) refer to M42 lens - can you explain to me what that means?

Also can focus lock be utilized with these old lenses?

How does one go about changing the 'stock focus screen'? I think it would be great to have a more friendly manual focus screen.

I can see myself using my old lenses and looking into getting other ones as well.

Are you concerned at all with getting dust on the CCD?

I will try your suggestion of adjusting the EV by +1.5.

Being able to use my old lens has added to the enjoyment of my K100D!
06-09-2007, 09:59 PM   #4
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QuoteOriginally posted by schmikey Quote

Also can focus lock be utilized with these old lenses?
Focus lock is a technique used with auto focus lenses. It does not aspply to manual focus lenses.

With manual lenses you can use "trap focus" on moving objects: Camera must be set to auto focus. Lens must be a manual focus lens. You press the shutter while following a moving object. The camera will first fire when the object comes into focus.

06-09-2007, 10:10 PM   #5
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QuoteOriginally posted by schmikey Quote

Are you concerned at all with getting dust on the CCD?
Yes, but so much as when I first got a digital SLR! The idea with an SLR is after all to change lenses to fit the scene, so I don't hold back any more.

Just be careful when changing lenses - do it swiftly and avoid blowing dust hitting the camera. Hold the camera with the lensmount pointing down when changing lenses.

Always bring an air blower like the Giotto Air Rocket, with that you can most often blow off the dust which might get on the sensor. It is also good for blowing dust off of your lenses - keep the rear elements clean.

So far I have been able to keep my sensor clean by using the dust removal of the camera (K10D) and the Rocket Blower. My *istD is more prone to dust, and has to be taken in for professional cleaning about twice a year.
06-10-2007, 02:35 AM   #6
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"M42" refers to the old screwmount lenses (42mm diameter threads) such as the Takumars.

Changing the focus screen simply involves using a tool (I used a dental pick) to open the latch of the frame that holds the screen in place, using tweezers to remove one screen and insert another, and finally pushing the frame back into place until it latches. Easy as pie.

Screens can be had from Katz-Eye, or much cheaper (yet perfectly fine) knock-offs from China. I got mine from a fellow in China via eBay for about $30 or so. Katz-Eye runs somewhere around $100 +shipping, I think.

To see if you need to adjust the EV, just check the histograms in the camera back display. It isn't necessary to understand what all the hills and valleys in the histogram mean. All you need to look at is whether the hills are kinda-sort in the middle of the display, left-to-right. If they tend to be crowded to the left, you're underexposing and need to boost the EV. If they tend to be crowded to the right, you're overexposing and need to make a minus EV adjustment.
01-03-2008, 09:13 AM   #7
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F stop setting - old M lenses - camera modes

I have the two kit lenses with my K100D but have recently been using my old 50F2 lens off my K1000 for doing indoor basketball shots using the trap method described in another thread. The op manual explains that manual lenses in Av, Tv, P modes all act as though it is Av mode - but what I missed/finally figured out was that in these three modes the aperature is always wide open vs the actual manual aperture setting on the lens. You can see this in Av mode - if you change the aperture setting the shutter speed does not change. The actual f-stop setting on the lens is only applicable/functions in Manual camera mode. This explained why I was getting a blast off white with the flash with my manual lens in Av mode. If you're in a rush - start with Av mode - knowing that it is using a wide open ap - you may be at max 1/4000 sec speed for bright settings - for indoors you'll get a slower shutter speed. I put the ring on the F2 setting and then I switch to Manual mode and adust the aperture and shutter speed - with experience I am normally shooting around F2.8-4, shutter of 1/90-125, ISO 800 and 1600 for gyms. My next efforts will be with my old F3.5 135 prime. For anyone that is interested in this more - check out pg 188 of manual - I missed this detail regarding manual lenses and the wide open aperture in modes other than Manual the first time through. I'm considering purchasing the FA 50 1.4 for bball but sense that my old lens and trap function is working reasonable well given that I still need a bit of DOF. Just something that took me a while to figure out with my old lenses but thought it might be of use. Ken.
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