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07-26-2013, 01:41 PM   #526
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Pentacon 1.8/50mm m42

Hello,
It is the first my post on PentaxForums but I am reading the forum for some time.
So greetings from Poland for everybody!

Below there are photos taken with Pentacon 1.8/50mm m42 lens. It was the most popular standard lens for Praktica M42 film cameras from East Germany.
Lens was mounted to Pentax Q through M42-K converter and K-Q converter (non Pentax genuine converter).
Photos:
1: Full scene taken with this lens.
2-8: Crops of the center part of photos (1:1) for apertures: 1.8, 2.8, 4, 5.6, 8, 11, 16.
The focus point was set to centre stick of Bell H-13 cockpit.
Photos were developed in LR with default settings.
I think that the best result is for 4 aperture value.


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Last edited by bladawiec; 07-28-2013 at 02:03 AM.
07-26-2013, 09:26 PM   #527
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Hi bladawiec,

Welcome to the forum!

Your first post and already contributing -- very impressive!

I agree with you that f4 is probably the best aperture, but f2.8-f5.6, or even f8 looks very usable to me, so I wouldn't hesitate to use any of these if there is a reason that might make them useful.

We look forward to some future posts -- Are there many Pentax (especially Q) users in your country and area?

Scott
07-27-2013, 01:30 AM   #528
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Hello snostorm and thank you for your answer.
In Poland here are some Pentax users but most popular brands are Nikon, Canon, Sony.
We have Polish Pentax forum (www.pentax.org.pl) but activity in Pentax Q section is very low.
In future I will post more tests with other lenses.

Last edited by bladawiec; 07-28-2013 at 02:07 AM.
07-28-2013, 02:00 AM   #529
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Pentacon 2.8/29mm m42

Next tests...
Below photographs from Pentacon 2.8/29mm m42 lens. This is lens especially for Praktica M42 film cameras from East Germany.
Lens was mounted to Pentax Q through M42-K converter and K-Q converter.
Photos:
1: Full scene taken with this lens.
2-8: Crops of the center part of photos (1:1) for apertures: 2.8, 4, 5.6, 8, 11, 16, 22.
The focus point was set to centre stick of Bell H-13 cockpit.
Photos were developed in LR with default settings with one exception. Exposure value of photos for 16 and 22 aperture value were incerased in LR because of underexposure due to limited exposure time (2 seconds).

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07-30-2013, 12:43 PM   #530
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QuoteOriginally posted by bladawiec Quote
Next tests...
Below photographs from Pentacon 2.8/29mm m42 lens.
Welcome and thanks for adding to our data enjoy your Q. I have added your lenses to our chart

Hans
07-31-2013, 03:39 PM   #531
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SMC Pentax-M 1:3.5 28mm

This time the SMC Pentax-M 1:3.5 28mm lens.
Lens was mounted to Pentax Q through K-Q converter.
Photos:
1: Full scene taken with this lens.
2-7: Crops of the center part of photographs (1:1) for apertures: 3.5, 5.6, 8, 11, 16, 22.
The focus point was set to centre stick of Bell H-13 cockpit.
Photographs were developed in LR with default settings with one exception. Exposure value of photo for 22 aperture value were incerased in LR because of underexposure due to limited exposure time (2 seconds).
In my opinion this lens gives very good IQ with the Q in wide range aperture values.
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08-03-2013, 07:20 AM   #532
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SMC Pentax F 80-200mm f4.7-5.6

Just got this little gem on Ebay for $20.00 including a ZX-50 camera and 35-80 zoom. I only wanted the 80-200 because it is rated by this site @ 9 for sharpness. It works great on my K30 and could become one of my go to lenses on the Q. The zoom is internal so the lens stays small and short. 200mm is not too bad to hand hold and this lens is lighter than my ST 200 f4. I shot it @ 2 stops down on the Pentax OEM adapter first shot @200, 2nd @ 80, last shot @200 SR set @ 200 for all images ISO @ 125 for all shots. The 4th shot is with my Super Tak 200 f4. CA is almost nonexistent where it is quite pronounced on the ST. The last shot at about 135 mm. It is not quite as sharp as my ST200 @200 but very close. At 135 mm it gets a little sharper than at 200mm

Hans
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08-06-2013, 05:34 PM   #533
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Super Takumar 28mm/3.5 and Q. Getting closer on focus.


Last edited by lukulele; 07-13-2014 at 11:18 AM.
08-18-2013, 10:29 PM   #534
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Original Poster
Thanks for the recent submissions everyone.
I have updated the index with the last entry.
Hans, appreciate your efforts in keeping up the index as well.
08-20-2013, 12:23 PM   #535
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Fujian 35mm f/1.7

I think the Fujian is a good match for the Q system, and the feel is nice. Its most evident downsides are blooming in bright light (but gone by f/4), overall low contrast, and marked field curvature. All of these issues can be worked around. As you will see with these 98% to 100% full frame shots, excellent sharpness can be achieved in any portion of the frame. All of these shots were enhanced for contrast, but none were corrected for CA or any kind of fringing. The flower shot was from a JPEG, others converted from RAW. Take note that the diaphragm is 12 blades. When managed properly, bokeh is very pleasant. The last shot was taken at f/5.6. Maximum sharpness in a specific area of the frame is achieved at f/4, but with field curvature issues you need to stop down a bit further if your goal is sharpness across the frame (clearly not a design goal of the lens.) The lens is sharp enough at f/2.8 for portraits (but on the long side at 195mm equivalence). Anything less than f/2.4 will yield soft focus effects. However, I don't see this as a toy lens in build or image quality (even if it costs only $29 with an adjustable c mount adapter).
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08-20-2013, 03:41 PM   #536
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QuoteOriginally posted by ScooterMaxi Jim Quote
Take note that the diaphragm is 12 blades.
I'm pretty sure you get whatever diaphragm they happened to have available. Mine has six uneven blades.

It also has far too much play in the focus ring.

Otherwise it seems to match yours. I'll also note that there is considerable focus shift when stopping down, so it must be focused at the shooting aperture.
08-20-2013, 04:53 PM   #537
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QuoteOriginally posted by drougge Quote
I'm pretty sure you get whatever diaphragm they happened to have available. Mine has six uneven blades.

It also has far too much play in the focus ring.

Otherwise it seems to match yours. I'll also note that there is considerable focus shift when stopping down, so it must be focused at the shooting aperture.
Hmm, I suppose they could be evolving with the design. I did notice just a bit of grit initially, but the damping is near perfect - very solid overall. I did notice that the helicoid is screwed in - have you tried hand tightening it?

I had read about focus shift as you stop down (which is virtually a non-issue, as the plain c mount has no auto stop down mechanism). I would never leave focus to anything other than my last task in the routine. Most of my fast lenses have at least as much focus shift as this one - which is negligible on my copy.

Obviously, these lenses have been redesigned. Perhaps when SLR magic came calling for this lens, a decision to do a slight upgrade was the result.
08-20-2013, 06:28 PM   #538
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Most of the 35 / 1.7s are, indeed, six blades on the aperture. Even the SLR Magic units are specified as six blades (at least the few references indicating that).

However, I did come across a review of the newer SLR Magic cine lenses that are specified as f/1.4. These very apparently have the same diaphragm as my f/1.7 - as seen here:
http://www.thephoblographer.com/2013/05/29/review-slr-magic-35mm-t1-4-for-micro-four-thirds/

This isn't to say that SLR Magic and Fujian are the same genetics entirely. I see a quality of coating on the link above that pretty clearly is not included on my lens (although my version has very nice inset optics - essentially a hood).

As for "pretty much what's available" on the diaphragm - it doesn't work that way. The construction has to be properly mated to the lens design - it isn't an off the shelf kind of match.
08-20-2013, 06:50 PM   #539
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QuoteOriginally posted by ScooterMaxi Jim Quote
Hmm, I suppose they could be evolving with the design. I did notice just a bit of grit initially, but the damping is near perfect - very solid overall. I did notice that the helicoid is screwed in - have you tried hand tightening it?
Not sure what I could tighten. The focus ring itself can be pushed forward/back a bit, and when switching direction it will move the ring instead of the focus for a bit. But only sometimes. (But if I actually wanted to use a lens like this I should just buy a new one.)

QuoteOriginally posted by ScooterMaxi Jim Quote
I had read about focus shift as you stop down (which is virtually a non-issue, as the plain c mount has no auto stop down mechanism). I would never leave focus to anything other than my last task in the routine. Most of my fast lenses have at least as much focus shift as this one - which is negligible on my copy.
You have so much light available. I often want to focus wide open (or close at least) to be able to see what I'm doing. (Of course with the ridiculous 2 second limitation I often can't usefully shoot at the aperture I would like anyway.)

The biggest problem seems to be around f/2.8, where it's actually quite sharp, but not if focused wide open. At f/4 it's ok again, as long as you only wanted what you focused on and stuff behind in focus.

QuoteOriginally posted by ScooterMaxi Jim Quote
As for "pretty much what's available" on the diaphragm - it doesn't work that way. The construction has to be properly mated to the lens design - it isn't an off the shelf kind of match.
Why not? As long as it's the right size of course. The large format world doesn't seem to think you need specially mated diaphragms at least. (Of course it's more than the opening size that must match, but I still don't see a problem. Any other explanation for why your lens wouldn't match most of them?)

QuoteOriginally posted by ScooterMaxi Jim Quote
Most of the 35 / 1.7s are, indeed, six blades on the aperture. Even the SLR Magic units are specified as six blades (at least the few references indicating that).
I'll attach an image of my diaphragm at f/4, maybe someone will enjoy that.
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08-20-2013, 07:32 PM   #540
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QuoteOriginally posted by drougge Quote
Not sure what I could tighten. The focus ring itself can be pushed forward/back a bit, and when switching direction it will move the ring instead of the focus for a bit. But only sometimes. (But if I actually wanted to use a lens like this I should just buy a new one.)
On mine, I noticed the slight grittiness, so I wanted to find where there might be some play. When I grabbed the outer end of the barrel (where the slide-on front cap attaches), I was able to hand tighten slightly. This seated the helicoid better, and everything has been buttery smooth since.


QuoteQuote:
Why not? As long as it's the right size of course. The large format world doesn't seem to think you need specially mated diaphragms at least. (Of course it's more than the opening size that must match, but I still don't see a problem. Any other explanation for why your lens wouldn't match most of them?)
It has to be the right size (how many 39mm lens barrels are in current production? Not many). It also has to match to the aperture ring as machined (these are not off the shelf), and in the precise location required by the optical design, then match aperture range and throw. A lot of factors are involved. In any event, I'm not aware of any other cheap lens sporting a 12-blade aperture. Come to think of it, I don't recall hearing of 12 blades on any consumer lens other than the two versions mentioned here (not that I've been looking for them).


QuoteQuote:
I'll attach an image of my diaphragm at f/4, maybe someone will enjoy that.
So sorry to see that. This explains the strange bokeh experienced in many of the images from these lenses. That's a far cry from what I got.

Last edited by ScooterMaxi Jim; 08-20-2013 at 07:49 PM.
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