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Forum: Pentax SLR Lens Discussion 06-01-2017, 02:39 PM  
FA 43mm infinity focus adjustment
Posted By Rapfl
Replies: 7
Views: 1,012
Hi Pål, I can hardly argue with this - thanks for naming your source and sharing this bit of information! I will then leave the lens as-is.

Still, that's a shame, as what used to be one of my favourite lenses in autofocus is much less of a joy to use in manual focus - I do like hand-held landscape shots when hiking, and having the physical feedback of the hard focus stop is just very comforting.
Forum: Pentax SLR Lens Discussion 06-01-2017, 07:27 AM  
FA 43mm infinity focus adjustment
Posted By Rapfl
Replies: 7
Views: 1,012
hey :). I have read the thermal expansion argument as a reason before online, however I doubt that. I've used the lens in quite a remarkable temperature range, and always had it focus on the very same position slightly before the infinity hard stop. Aluminium has a linear expansion coefficient of approx. 2x 10^-5 (brass even less) -- on a temperature change of 50°C, the length of the ~30mm barrel would then only change by 0.03mm.
Then, all other of my Pentax lenses do focus correctly at the hard stop, I don't think that the barrel of the FA 43 is in any way special as that it'd require that much more tolerance to expand. - if I am mistaken, please correct me; otherwise I'd proceed with the adjustment this weekend. Thanks!:)
Forum: Pentax SLR Lens Discussion 06-01-2017, 05:35 AM  
FA 43mm infinity focus adjustment
Posted By Rapfl
Replies: 7
Views: 1,012
Hi! Thanks for your two replies - I am using the lens on a Sony A7, but I noticed already on my K5ii (not any more mine) and on film (MX) that I reach focus earlier than the hard stop. I am confident that it's not an adapter issue, as all my other Pentax lenses - even lower focal length lenses which should be more critical regarding the adapter tolerances (A20 2.8, K30 2.8, K28 3.5, M 50 1.4) - reach infinity focus spot on.
Cheers!
Rapfl
Forum: Pentax SLR Lens Discussion 05-31-2017, 01:39 PM  
FA 43mm infinity focus adjustment
Posted By Rapfl
Replies: 7
Views: 1,012
Hi!

I'd like to adjust the infinity focus position of my FA 43mm lens - it reaches infinity before the hard-stop of the focus ring.
I've done this before on an FA 50 and a Distagon 28, but the FA 43 seems to be constructed in a different way.

Did someone of you already do this? Which are the screws to loosen?

I'd be happy about any piece of advice!
Rapfl
Forum: Post Your Photos! 03-29-2015, 01:31 AM  
Streets Isfahan
Posted By Rapfl
Replies: 6
Views: 858
Thank you very much! :) If you have any suggestions what kind of (digital) post-processing to apply, I'm curious to learn.
Forum: Post Your Photos! 03-28-2015, 07:14 AM  
Streets Isfahan
Posted By Rapfl
Replies: 6
Views: 858
Isfahan, this summer, MX with 43mm, APX 100 in Rodinal, "scanned" with a K5ii and a SMC-A 50mm Macro.
Forum: Pentax News and Rumors 03-08-2015, 04:17 AM  
HD PENTAX-DA 18-50mm F4-5.6 DC WR RE
Posted By Rapfl
Replies: 167
Views: 33,155
Looking at the schemes in http://www.ricoh-imaging.co.jp/japan/support/catalog/pdf/lenses_accessories.pdf , optically the lens shouldn't be a big surprise; I wonder if focal length and aperture were changed just to distinguish it when searching for it on google ;)
Let's keep our fingers crossed that the lens is well built and rather sturdy, with the splash resistance this would make a cool travel lens, especially when paired with some fast small prime.
Forum: Pentax Film SLR Discussion 07-26-2014, 12:27 PM  
daycase/pouch for MX + 43mm advice needed
Posted By Rapfl
Replies: 2
Views: 812
Dear fellow film fotographers,

I very much enjoy my MX when coupled with the wonderful Pentax 43mm lens.

For my digital SLR, I use the "Crumpler Bowl" pouch which I carry in my usual backpack, which is closed by a zipper, and I can throw the largish K5ii inside and forget it when I want to; also there's a side compartment for a second small lens, which is great because like this I can carry the 43mm and 20mm lenses and the K5ii in one single pouch.
For the MX the pouch is quite a bit too large; I'd love to find a similar zipper-closed "bowl" only large enough to pad the MX and the mounted 43mm lens;

could you recommend any such specific pouch? I've been googling quite a while and find no such pouches smaller than the "Crumpler Bowl", and I don't like complicated pouches with straps and belt-adapters and outside-pockets... as I just want a safe "damping" within my backpack, and a zipper to avoid the camera falling out of the bag.

Have a nice evening :)
Rapfl
Forum: Pentax SLR Lens Discussion 07-09-2014, 09:16 AM  
Help me pick lenses for a month in Iran! : ]
Posted By Rapfl
Replies: 5
Views: 1,076
Good evening !

I will spend September in Iran visiting friends, it will be my first trip to the country; I very much enjoy photography of nature and architecture and friends, and certainly will take my camera with me -- though recently I kind of fell in love with a 6x6cm Yashica TLR, I will take a Pentax K5ii and a MX with me.

Now I am in the lucky position to decide which lenses to take -- the goals are to keep luggage small; I will have a safe place to leave my stuff, but quite a significant amount of time I'll only take a backpack and only one camera (which one depends on me, if it feels like a film or a digital day :D ).

Because I wanted compatibility between my DSLR and my SLR (it started with a k100d and a P30 back in high school), I never bought any of the newer zoom lenses, and I don't even own a kit zoom lens. These are the lenses I could take with me: A 20mm f/2.8, M 28mm f/3.5, FA 43mm f/1.9, M 50mm f/1.4, A 50mm f/2.8 Macro, M 85mm f/2.0 . Certainly these are way too many lenses :confused: , but it's rather fun to argue which lenses to pick, and I want to include you in this discussion as I suppose many of you had to face similar decisions, and noticed only on the journey that they should have better picked another lens :o .

Right now I'd go for the 20mm f/2.8 and the 50mm f/1.4, but then I certainly like the 43mm and maybe even the Autofocus could help sometimes? The M28mm is smaller than the 20mm and I could use my 49mm Polariser on both lenses... so..?

Or should I now finally move into zoom territory?

I'm looking forward to hearing your comments and opinions!
Rapfl
Forum: Maintenance and Repair Articles 06-10-2014, 10:47 AM  
SMC-A 20 2.8 Aperture blade shifted, focus stuck - advice needed
Posted By Rapfl
Replies: 3
Views: 2,493
Oh well, I opened the lens from the back to get to the diaphragm mechanism, which is broken; first of all, it's a much more difficult construction than the SMC-M lenses I cleaned / repaired so far; evidently I am not the first person to open the lens, as some internal screw heads are pretty much stripped; I have JIS screw drivers so at least I managed to remove most of them, but one last screw is stripped so deeply that the head has a conical hole instead of a cross (the equivalent screw on the other side does have a cross, so it's not a feature, as I can also tell from the metal dust...).
Not sure how to remove this one (I guess it's the last I need to open the diaphragm mechanics and put the blades to their original position)....

Raphael
Forum: Maintenance and Repair Articles 06-08-2014, 01:56 PM  
SMC-A 20 2.8 Aperture blade shifted, focus stuck - advice needed
Posted By Rapfl
Replies: 3
Views: 2,493
Good evenig!

Some months ago, I bought a used SMC-A 20 2.8 lens, which in this period is my most used lens. I was on a hike this weekend, the camera was well protected in my backpack, but when I wanted to take a picture of reflections in a lake, I noticed that I could not focus to infinity anymore. I did not want to force anything, so I put the lens away and looked at it at home: one aperture blade shifted; it moves with the others, but it "lags behind", it does not open compleately at f/2.8 and at f/16 it block almost the entire pupil. I can't focus to infinity any more independently of the chosen aperture, the focus ring does block earlier than usual.

Has anyone of you ever taken apart an SMC-A lens? I have cleaned and/or repaired several SMC-M lenses (with fungus) and a FA 50 1.4 (where the focus barrel detached), but I never took apart an A lens. I certainly have JIS screw drivers, but before opening the lens, I hope to get some suggestions / pieces of advice how to proceed / what might have happened / if this happened to you / how to fix it.

Best regards,
Rapfl
Forum: Pentax SLR Lens Discussion 04-02-2014, 06:22 AM  
Pentax FA - electronics and focus brush - what for?
Posted By Rapfl
Replies: 3
Views: 951
Dear Ole, thanks for you kind reply.

Does anyone of your then have a clue of how the FA 43 measures the position of the focus ring w/o the brush?

I must admit I naively thought that the focus distande as reported in the EXIF files would originate from the sort-of-triangulation which the phase detection autofocus sensors deliver;

if someone of you has a K or M lens at reach, could you try to focus using the AF sensors, e.g. via trap in focus (to make sure the camera thinks the camera is actually focused on the central focus point) and then check if in the EXIF files there still is an estimated object/focus distance?

Cheers,
rapfl
Forum: Pentax SLR Lens Discussion 04-01-2014, 04:28 PM  
Pentax FA - electronics and focus brush - what for?
Posted By Rapfl
Replies: 3
Views: 951
Hey guys,

I have some very basic questions regarding FA lenses.
I once had to partly disassemble a FA 50 1.4 lens; there were quite a few electronic components hidden inside, namely some microchips on a flexible board and a golden "brush" close to the focus scale (see e.g. this thread for many nice pictures of a disassembly made by another forum member: https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/197889-fa50...djustment.html ).

What is this brush being used for? And the microchips?

I am a bit confused as in this disassembly blog post ( vjacesslav: SMC PENTAX FA 43mm 1.9 LIMITED DISASSEMBLE IN 37 PICTURES ) on a FA 43 1.9, I can see neither such a brush, nor microchips.

Do also A-lenses contain electronics other than the conducting pins in the lens mount?

Best regards!
rapfl
Forum: Pentax SLR Lens Discussion 08-05-2013, 04:15 AM  
Whats the overall average lens review rating of your bag? Tongue in Cheek!
Posted By Rapfl
Replies: 71
Views: 6,455
Ok here we go...

Kiron 28 2.0 -- 9.00 (6 reviews)
FA 35 2.0 -- 9.10 (51 reviews)
M 50 1.4 -- 9.16 (71 reviews)

Thus the average is 9.09 ...
But unfortunately the rating of the Kiron is not as significant as the others, given the small number of reviews...

Let's introduce a portability-weighted average

defined as follows:

we call M the weight of the lens (I'll use grams, following strictly the SI units, but feel free to use what you like, we normalize in the end :p ), and r the average rating of the lens.
The smaller M, the more portable is the lens, thus we use as weighting factor 1/M, and consequently the sum over all 1/M's to normalize the final result.

W(Kiron) = 261 g (with lenshood)
W(FA 35) = 202 g (with lenshood)
W(M 50) = 241 g (with lenshood)

Thus A == r/W (Kiron) + r/W (FA35) + r/W (M50) = 0.1175.... rating-units/g
The normalizing factor is, B == 1/W (Kiron) + 1/W (FA35) + 1/W (M50) = 0.01293.... /g
And as final result we get A / B = 9.0865.... rating-units

Though this didn't change much for me, but for those of you trying to score high by adding you A* and FA* telephoto lenses :P :P....

Forum: Pentax SLR Lens Discussion 08-05-2013, 01:43 AM  
A set of three fast prime lenses (if you're on a budget)
Posted By Rapfl
Replies: 2
Views: 1,829
NOTE: Somehow the images I uploaded aren't visible in the post if I access pentaxforums via https. I included them using the command [ IMG ] http://www.erraph.square7.ch/Pentax/lenses.JPG [ / IMG ] (w/o the spaces), but the image is being included automatically as https://www.erraph.square7.ch/Pentax/lenses.JPG when accessing pentaxforums via https, resulting in a 404...


Many of us share the joy of using prime lenses, so do I.
I enjoy that they force me to think more about composition, and because they are generally fast - I don't like flashes.
Though I have to admit that I don't like primes only because of their optical performance - but also because
of their looks. Especially if they are small. And have an all-metal body. And a big front lens. And colourful
letters all over them.
You see, I'd be one of those "FA Limited-guy". If only the prices were lower. Oh dear. *1*

I've got two bodies, a MX and a k100d. Thus I need lenses with an aperture ring.
And on the digital body, I find an "A" setting is enormously comfortable.
For most shots on the streets I like "normal" focal lengths,
a bit wider if possible, for example on my MX I like something between 35mm and 50mm, and consequently on the k100d something between 24mm and 35mm.

There are many discussions on this forum about the choices of prime lenses, and I would like to present one choice that I find reasonable.
These are the lenses I bought over the last four years, spending significantly less than 500 Euro in total.*2*


http://www.erraph.square7.ch/Pentax/lenses.JPG

(Left) The Kiron 28 f/2.0, which sells for roughly 100 Euro.

(Middle) The Pentax FA 35 2.0, which sells for roughly 300 Euro.

(Right) The Pentax M 50 1.4, which sells for roughly 70 Euro.

The Kiron 28 2.0 is sufficiently sharp wide open, has an A setting, and is a compact and a rather fast standard lens for the k100d.
The FA 35 2.0 is pretty good. But so expensive :D. Still, on my MX it gives an excellent focal length for travelling,
and with its AF it's my lens for "quick shots" with the k100d.
Then there's the M 50 1.4, nice for portraits on the k100d, and a great walk-around standard lens for the MX, when I'm afraid of
taking the FA 35 ;). When not in cities or in the mountains, I find 50mm to be a very versatile focal length, just in cities and in
the mountains I prefer a wider field of view.

Now that I've justified rationally why I enjoy these lenses so much, I want to point out their looks :P.
Doesn't the Kiron with its metal hood (no vignetting on the k100d) compete very well with the FA ltd's in terms of built quality? ;)
Not to mention the M 50 1.4, which only lacks an A setting to be flawless ;) (well I might be exaggerating. but given the price!).
Ok, the FA 35 is pasticky, and still so expensive...but it has an A setting, AF and delivers the best image quality of the three.
Thus it has its place.

There are many sample pictures of the M50 and FA 35 already on the forum, thus below I'll just post a few center 100% crops of
the Kiron lens at various apertures.

f/2.0 100% crop (original: http://erraph.square7.ch/Pentax/f2.0_full.JPG )

Another picture at f/2.0: http://erraph.square7.ch/Pentax/f2center.JPG

f/2.4 100% crop (original: http://erraph.square7.ch/Pentax/f2.4_full.JPG )


f/2.8 100% crop (original: http://erraph.square7.ch/Pentax/f2.8_full.JPG )

Another picture at f/2.8: http://erraph.square7.ch/Pentax/f2.8center.JPG

f/4 100% crop (original: http://erraph.square7.ch/Pentax/f4_full.JPG )


That's all what I wanted to share with you.
There are many other possible choices, but maybe someone of you has similar requirements and desires as I do,
and maybe this thread helps him or her decide.

Best regards,
Raph


*1* The 31mm f/1.8 sells used for roughly 800 Euro, the 43mm f/1.9 for roughly 450 Euro, and the 43mm f/1.9 for roughly 550 Euro.
I just can't justify spending that much money on a single lens; if I have some money and the luck to find some free time,
I enjoy travelling, and each lens would cost me more than 10 days of travelling...
Maybe these lenses will be an option one day, when I'm old and wealthy :P, but not for now.

*2* It seems that in the US lenses are usually cheaper than in Europe, and I guess that replacing Euro with USD without
changing the numbers gives quite a good estimate for the prices in the US.
Forum: Troubleshooting and Beginner Help 06-14-2013, 03:13 AM  
Pentax FA 50 1.4 mechanical play
Posted By Rapfl
Replies: 9
Views: 1,522
Thank you very much for your replies!
Knowing that also the F 50 1.7 has the same screws certainly increases my probability to find original spare parts.
Otherwise I'll improvise just as Ben suggested.
Forum: Troubleshooting and Beginner Help 06-12-2013, 03:45 AM  
Pentax FA 50 1.4 mechanical play
Posted By Rapfl
Replies: 9
Views: 1,522
Thank you very much for this reply. Though I think it's a non-standard screw -
do you know any lens which attaches in a similar way the decorative ring around the front lens?
(FA 50 1.7 ? F 50 1.4/1.7 ? A 50 1.4/1.7?)

I only have access to the parts list of the FA 50mm.

http://dl.dropboxusercontent.com/u/9718909/IMGP5734.JPG



[metric scale, the distance from 0 to 1 equals 1 cm \approx 0.39 inch]

http://dl.dropboxusercontent.com/u/9718909/Screenshot.png

Forum: Troubleshooting and Beginner Help 06-07-2013, 10:45 AM  
Pentax FA 50 1.4 mechanical play
Posted By Rapfl
Replies: 9
Views: 1,522
Thanks for your feedback. You might be right that I could have been more persistent to get back the screws... (of course I won't let him look after my lenses any more :P) but as I didn't pay for his try to open it (and most probably would not have even if he fixed the problem...) I can't really ask him to get me a new lens or look for spare parts himself :-/
Forum: Troubleshooting and Beginner Help 06-07-2013, 09:22 AM  
Pentax FA 50 1.4 mechanical play
Posted By Rapfl
Replies: 9
Views: 1,522
Hey,

i took apart the lens and fixed the problem.
There are two spacers which keep the extending cylinder containing the optics in two rails of the exterior lens housing (see figure below). There was a gap of about 1mm between the spacer and the rail on each side, causing significant mechanical play when focusing. I could easily loosen the screws holding the spacers, moving them further out, and then tighten the screws again. Luckily, I did not have to take apart the helicoid.

There are several posts in this forum of users who experienced the FA 50 to separate in two halves during use ( see e.g. https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/76666-wtf-my-...-my-hands.html ) - and some users point out that most probably these spacers jumped out of their rails during focusing. As it is a rather simple operation to take apart the lens to reach these spacers ( see e.g. https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/197889-fa50-d...djustment.html for a detailed guide ) I guess that it seems to be a good idea to check, when you are experiencing mechanical play just as I did, if these spacers are still there where they should be.

I am still looking for a broken FA 50 1.4 lens for spare parts (my local repair shop cant find the screws any more which I showed in the first picture (...), I already contacted Pentax, but there are no spare parts available any more.)

http://dl.dropboxusercontent.com/u/9718909/lens.JPG



Have a good day,
Rapfl

p.s.: @moderators: it might be a good idea to move this thread to the lens sub-forum, as the problem is solved and the explanation - i guess - would be better "stored" in the lens sub-forum.
Forum: Troubleshooting and Beginner Help 06-04-2013, 03:02 AM  
Pentax FA 50 1.4 mechanical play
Posted By Rapfl
Replies: 9
Views: 1,522
Hello!

I'm using a FA 50 f/1.4 lens for about 5 years now, and I'm very happy with the image quality it delivers. It's my primary lens, and thus has travelled quite a bit - and suffered. The cylinder which contains the lenses and extends or retracts while focusing is suffering from quite significant mechanical play. It was already evident when I bought the lens, but it became worse. Now I'm using the lens in manual focus on a Pentax MX, and the play makes focusing rather hard as the cylinder containing the lenses can "flip", thus shifting the image slightly (though not knocking it out of focus).

I showed the lens to a local repairman, who in a failed attempt to open the lens lost 2 of the three screws which hold the decorating ring in front of the primary lens, and made an estimate I just can't afford (additionally, I wouldn't trust him my lens any more :P) . (I did pay 120 Euro in a clearance sale 5 years ago for the new lens, I'm more than surprised seeing how the price increased over the last years! - unfortunately, repair costs of ~100 Euro are just out of reach right now.).

I found several guides how to disassemble a FA 50 f/1.4, I've got JIS screw drivers and thus think it should be possible to solve the problem on my own. (...The crucial part seems to be to mark the position of the helix which guides the moving cylinder when disassembling as the thread has multiple entries.)

-> I will need new lubricating grease when putting back together the lens - in fact I hope that new grease might solve entirely the mechanical play. Can you advice which product to use and where to buy it?
-> Looking through other disassembly guides, I did not find any retaining ring / screw which might cause mechanical play when loose - do you have any advice if there might be other reasons for the play than issues with the lubrication? I never dropped the lens, thus I guess I can exclude significant internal mechanical deformations.
-> Do you have any suggestion where I might find spare screws that got lost during the "professional" (...) attempt to remove the play? You find a picture of the missing screws attached to this post.

Would be great to get some pieces of advice. As soon as I know how to proceed exactly and which lubricating grease to use, I'll keep you informed about the progress and of course post pictures of the disassembly.

Best regards,
Rapfl

http://dl.dropboxusercontent.com/u/9718909/IMGP5659.JPG

Forum: Troubleshooting and Beginner Help 12-04-2012, 07:34 AM  
2nd lens: SMC-A 24mm f/2.8 or Distagon 28mm f/2.8?
Posted By Rapfl
Replies: 7
Views: 1,893
Hey, thank you very much for your feedback.
I think I won't save for the 28 /2.0 - It sells for more than 300, which is 50% more than my budget, which to me seems already now too high. Maybe on day if I shall be old and rich... :D.
The Kiron 24mm /2.0 seems to be available from time to time for a little less than 200 euro, but I couldn't find any recent offers in Europe; I'll definitely keep my eyes open - the same seems to be true for the Sigma Super Wide, for a little less than 150 euro.
Yes, there is a Zeiss Distagon 25 / 2.8; but sells for twice the price as the 28 / 2.8, so it's out of range.

Still, it's not easy :D - though it seems that most probably different lenses would all make me happy in the end.
The Zeiss 28 / 2.8 seems to be a good deal at 200 euro incl. the Leitax-Adapter; so does the Pentax 24/ 2.8 SMC-A, and so would (as soon as there'll be offers in Europe) the Kiron and the Sigma.
Certainly, I could go now for the Pentax / Zeiss, and if I don't like it, resell it and try an other one, given that they don't loose value too fast..

If you have further thoughts or suggestions, I'd be happy to hear them!
Forum: Troubleshooting and Beginner Help 12-03-2012, 02:19 PM  
2nd lens: SMC-A 24mm f/2.8 or Distagon 28mm f/2.8?
Posted By Rapfl
Replies: 7
Views: 1,893
Good evening,

I have come up with quite a wired question. I'm using using a k100d and a FA 50mm f/1.4. I don't use flash, and focus with a split-image screen, so the availability of a big aperture is quite crucial. Too often I'm missing a wider lens, and now I saved for a quite a while and want to get a second lens. Budget is ~ 200 euro.
Before I started studying 2.5 years ago, I was in the middle east for a year, and used a FA 35mm f/2 whenever I had time to go out. I sold it immediately when I moved. I had the impression that for most situations, it was too short (then I used the 50mm), or still slightly too long. Then I really didn't like how it rendered the parts not in focus. The good thing was the aperture of f/2, and that it was easy to focus, and did not have too much CA.

Now I'm looking for a second wide-ish prime which shall become the lens I use in most situations. I don't care if its fully manual, auto A or auto focus&A, and, just to give a first direction of ideas, thought of a Pentax SMC-A 24mm f/2.8 or a Zeiss Distagon 28mm f/2.8. I could get each for about the same price of ~200 Euro used, the Zeiss being slightly more expensive in the end because of the Leitax adapter I'd have to get.
I looked at many pictures on Flickr shot with these lenses, and the 28mm Distagon seems to provide the sharpness I'm looking for; but it seems still a tad too long; the 24mm Pentax seems to provide the frame I'm looking for, even has auto A which can be very comfortable, but seems overall softer than the Distagon.
And both are not really fast.

What are your opinions, what would you suggest? I guess I'm asking for a decision between two lenses that are difficult to compare; but, with my budged, which lens would you got for?

Best wishes,
Rapfl
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