Testing manual focus lens on the *ist DS

Well, here are my findings from the testing of my manual focus lens. Apologies, but my http code isn't good; ie. I couldn't format my data in columns here after copying from my original Excel spreadsheet:

Conditions Sunny day, light wind , slight cloud which had minimal affect on exposure readings.

Subject Garden sun-dial from @ 20m, constant sensor to subject distance throughout, except for 400mm. This beast was tripod mounted, hence moved the camera sensor back about 80mm.

Camera Pentax *ist DS, meter on Spot Correct Exposure achieved using Aperture priority : f-Stop and Shutter Speeds

External meter Sekonic L558 1 Degree Spot, used as a reference for continuity throughout the test while attaching different lens to camera. I only took single spots on the sun-dial.

Test Results

Method 1 Camera MF, Dial M, Set aperture on lens, Half-press shutter and press AE-L for shutter speed.

Method 2 Camera MF, Dial M, DOF preview lever and thumbwheel to obtain 0.0 on camera exposure meter for shutter speed.

Note N/A means Not Availablle on the lens under test.

• Zenitar MC 16mm Fisheye
  (f2.8-f22) f1.7 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
  Method 1 N/A 4000 2000 1000 500 250 180 90 N/A N/A
  Method 2 N/A 4000 2000 1000 500 250 180 90 N/A N/A
  Sekonic L558 (1deg Spot) N/A 4000 2000 1000 500 250 125 60-125 N/A N/A

• Pentax A SMC 20mm
  (f2.8-f22) f1.7 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
  Method 1 N/A 1000 500 250 125 60 30 15 N/A N/A
  Method 2 N/A 4000 500 250 125 60 30 15 N/A N/A
  Sekonic L558 (1deg Spot) N/A 4000 500 250 125 60 30 15 N/A N/A
  Lens on A and Camera on Av N/A 4000 500 250 125 60 30 15 N/A N/A

• Pentax A SMC 50mm
  (f1.7 f22) f1.7 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
  Method 1 4000 2000 1000 500 250 125 60 30 N/A N/A
  Method 2 Out of Range 4000 1500 750 250 125 60 30 N/A N/A
  Sekonic L558 (1deg Spot) 4000 4000 2000 1000 500 250 125 60 N/A N/A
  Lens on A and Camera on Av Out of Range 4000 2000 1000 500 250 125 60 N/A N/A

• Pentax M SMC 100mm Macro
  (f4-f32) f1.7 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
  Method 1 N/A N/A 3000 1500 750 250 125 60 20 N/A
  Method 2 N/A N/A 3000 1500 750 250 125 60 20 N/A
  Sekonic L558 (1deg Spot) N/A N/A 4000 1 to 2000 500-1000 250 125 60 15 - 30 N/A

• Pentax M SMC 400mm Tele
  (f5.6-f45) f1.7 f2.8 f4 f5.6 f8 f11 f16 f22 f32 f45
  Method 1 N/A N/A N/A 1500 1000 500 250 125 90 30
  Method 2 N/A N/A N/A 1500 1000 500 250 125 60 30
  Sekonic L558 (1deg Spot) N/A N/A N/A 1000 500 250-500 125-250 60-125 30-60 15-30

Observations

1. Using an outside subject, in daylight, both the Methods 1 and 2 corroborated well with the Sekonic meter, particualry the M-Series lens.

2. The A-Series lens seemed to perform with more consitency, as compared with the Sekonic meter, when set to A. The aperture Av was then set in-camera.

Any views or constructive criticism welcome.

Drew,
Thanks for your input:
I will try both methods on three manual K lens at the weekend and publish findings here.


Regards, Colin

ps What's a match-needle ?!

Steve,
You pretty much confirming my findings.
This weekend I'll do some testing on three manual K lens I have and report back.

Regards, Colin

Hi John,
Thanks for the reply and, yes, it helps.

The lens I used does not not have an A setting. I don't understand why the shutter speed remains the same when I stop down, as you describe. Will a power On/Off help ?

You are spot on with limited depth of field !

I understand the constant exposure, ie shutter speed & aperture relationship. It is the fact that it doesn't work here that is perplexing.

Reciprocity failure is a phrase I know but don't really understand. However, comparing our explanations does seem to point to it as being a possible cause. Perhaps the use of a macro lens is not helping either.

Maybe someone else has explored this with CCD cameras.

Regards, Colin

Hi,

I am seeking advice on the use of a fully manual Pentax K lens on *ist DS. There is a previous post on this topic but I’ve been unable to find it.
The gist of it was to:

1. firstly set 2 menu Custom Settings to allow the use of manual lenses,
2. switch to MF, and dial to M on the camera body,
3. followed by selecting an f-stop, then compose and focus.
4. Half press the shutter release button and press AE-L button, which sets the shutter speed.
5. Fully press the shutter release button and take the shot.

I used a Pentax K 100mm Macro lens on a tripod-mounted *ist DS for this exercise, aperture settings were f4 through to f22. The test was performed indoors (it’s brass monkeys outside), WB set to tungsten lamp, table-top subject(s) at about 1.5m to 2.5m distance from the camera.

The resulting exposures, using in-camera ‘judgement’ for shutter speed (from Step 4), deteriorate as the aperture is stopped down; ie. there was an increasing underexposure using AE-L button. Although one can obviously compensate by manually increasing the shutter speed, it kind of defeats the object.

As a reference I used the histogram to approximate Ev consistency throughout, as I manually changed the aperture on the lens and took shots.

The correlation to achieve comparable exposure (ie. histogram) at reducing apertures is approximately:

Increase 1full f-stop => increase 2 shutter speeds
Eg. f5.6 => 0.2 s (baseline histogram)
f8 => 1 s (should be 0.5s ?)
f11 => 4 s

I need to emphasise the above values are approximate but the smaller the aperture opening, the more I needed to increase the shutter speed to achieve comparable exposed shots (histograms).

Is the methodology and my method correct ?

Thanks, Colin

I just read this post string whilst looking for something else , last night I also read the latest BIG 2 review in this week's AP: Canon D5 v. Nikon D200 . The latter corroborates most of what has been said above. The reviewer was dancing around the subject like "a cat on a hot tin roof", for fear of upsetting two of their main income streams, possibly their highest in monetary terms.

OK, these two camera's are probably higher spec'd than the "entry level" *ist D range, but this article is typical of its genre, regardless of a camera's "level".

I am now about to compare apples and pears in 'spec terms' but bear with me. I have now had an opportunity to use, albeit for a short period of time, both a Canon D-350 and Nikon D-70. I own an *ist DS.

All three are comparatively easy to use, and output 'quality' was comparable, to A4 at any rate. Where they differed was their build and design, all those things that are so difficult to put numbers too; like ergonmics, feel, aesthetics, style, look, balance. Comparing the three models just mentioned Pentax wins hands down. I am not knocking Canon or Nikon, they are good cameras, but Pentax seems to make the difference, for me at any rate. Try the eyes closed test: handling them will point you someways to what I mean.

I asked the owners, who I know well, why they opted for the choice they made. They both basically cited the sales blurb. When they asked the same question of me, I replied that the DS fulfilled my criteria and it felt right in my hands.

There's another article in this week's AP letters page, forecasting the demise of Pentax, and I have to be honest and say that a seed of doubt is germinating in my mind. For those with greying temples, my concern is that Pentax could be heading down the Betamax cul-de-sac; in the front row with sound technology AND design, but lagging way behind when it comes to communicating it to the market-place.

ps How do I find the Yahoo Pentax User Forum please ?

Hi all,

What does one look for when trying to assess the above ?

Regards, Colin

Bonjour Patrick,

I am not sure where one starts to answer such an open ended question, and even if I did my technical knowledge would limit me to about 3 lines.

This site is frequented by photographers (and those who simply enjoy taking photographs !) at every level , ranging from novice to expert. I put myself towards the latter end of the scale, but hey, ability is only part of it because enjoyment is way up there too. Personally, learning is a big part of the enjoyment. Those at the right-end of the scale will find a lens' limitations very quickly, but that in itself doesn't make it an inferior piece of glass.

There are also those (I call them "Kit Monsters"), who "talk the talk" and often can't "walk the walk": ie. their kit is the latest and debateably greatest, but they rarely venture past either the "Green dial-setting" or one that doesn't have a picture next to it. They are MISSING OUT on so much, but c'est la vie !

I suppose the tool-box your lens is mounted upon has some bearing (particulalry in these days of digital), but how YOU use it is probably more important. The more skilled one becomes, the more discerning we are about the tools we use.



Well, it is a Pentax marque lens so we start the assessment at Good: because Asahi specialise in optics, (not photocopiers !), and work up from there. The "how" is a bit more challenging but if the question were edited slightly to:

...... then experience over time will tell. Some (like me) will take a little more time than others, but as long as you enjoy the journey, who cares how long it takes.

So, ...... unpack the lens and mount it on your tool-box of choice, .... enjoy, ...... and then share with us know how you find working with what is very likely quality glass.

Bon weekend mon ami, Colin

Dave,
Thanks for this. I read last night on Adobe's site that Camera RAW V2.4 list of supported makes was *ist D only.
I will download and try.
Regards, Colin

Thanks Matt,
I uploaded P1 C1P V3.7 last night; it installed OK on my laptop. I'm unable to try it yet because I'm working away this week (no PEF's to edit).

I RTFM last night and it only lists the *ist D under Pentax. I'm guessing the DS is simply an omission from the list.

Do you know what the DS compatibility is with Adobe's CS ?

Regards, Colin