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Forum: Lens Clubs 02-08-2018, 10:33 AM  
Carl Zeiss Jena medium format lenses on K-1 and 645D
Posted By JensE
Replies: 15
Views: 814
Out of my 50mm 1:4, 80mm 1:2.8 and 180mm 1:2.8 (old), the 80mm still has the most distinct rendering on small formats. At f/2.8 it lacks a little contrast and CAs are fairly heavy, but at f/4 it often produces a nice accentuated in-focus rendering.
Forum: Pentax K-5 01-30-2018, 01:18 AM  
No more tests! just pictures
Posted By JensE
Replies: 7,836
Views: 1,172,165
Great light on the 1st. It's a shame that it has been decades since I've last been there! I really need to convince my family to go east sometime soon ...

---------- Post added 2018-01-30 at 09:25 ----------

A shot that I wasn't able to get with the K-1.

X-post from, more pictures and some details why on/linked on Playing with Fire - PentaxForums.com.

Forum: Pentax SLR Lens Discussion 01-30-2018, 01:12 AM  
Anybody use the square lens hood on a DA 35mm f/2.4?
Posted By JensE
Replies: 10
Views: 509
If it was, in the case of the DA35 to the filter thread, it could easily ruin your focus mechanism. It's a different story with the barrel-mounted hoods like the one on the D-FA50 Macro, which did indeed save my lens on occasion.
Forum: Post Your Photos! 01-29-2018, 04:44 PM  
Macro Playing with Fire
Posted By JensE
Replies: 2
Views: 242
When the spark hits, it erodes a tiny amount of material from the burner - enough to fire up sodium orange in the pictures above.
Forum: Post Your Photos! 01-29-2018, 04:39 PM  
Macro Playing with Fire
Posted By JensE
Replies: 2
Views: 242
After finding out about the long and unpredictable K-1 shutter lag with mirror lock up, I used the K-5 for the shots below.

For the first, the camera was fired at the ignition moment, so exposure starts about 10ms into the process, for the the second, the shutter was timed to open a few milliseconds before the spark.
Forum: Pentax Camera and Field Accessories 01-28-2018, 06:18 PM  
Camera adapter for a Pentax bellows
Posted By JensE
Replies: 15
Views: 571
You should have a flange on the bellows side (ø 58.2mm), which secures a correct fit against the face of the bellows standard. Check the bellows unit out, you'll find the smooth ring that it fits flush to. The grove is just there to secure the mount, not for a precise fit. The groove extends to about 3.2mm from the flange, measured at the top. It is angled, maybe to 60 degrees (instead of 90 degrees). Check your locking crew, best to ask the shop to fit its angle. This way, the pressure to the flange is progressive as you tighten the locking screw. The outer diameter of the tube would be 48.5mm, the inner 43.8mm - with groves (ripples) some tenth of a millimeter deep to diffuse residual reflections in addition to the blackening. You may however just line it with some astro anti-reflection material. The groove bottom diameter is 46.4mm, it starts about 1.0mm from the flange - not overly critical but that 1mm should aid positioning.

Hope this helps to get a correct fit.

I'd strongly advise to make the adapter no longer than necessary to avoid extra strain on the rail/prism - a K-1 is very rear-heavy compared to most mechanical cameras already. My 11mm extension is plenty for the K-1 to mount cleanly. Best take your cameras and give it a try. Remember to share a picture of the result!
Forum: Pentax Full Frame 01-23-2018, 03:19 PM  
Focus method in landscape photography
Posted By JensE
Replies: 54
Views: 5,148
For pictures which extend to the horizon, I don't think that the hyperfocal concept is dead in any way for 36MP. Depending on the subject, it can even work at 28mm. I almost always focus my two very wide primes (Color Skopar 20mm on K-1, DA 15mm on K-5) by DoF marks, stopping down two stops further though.

The sensor pitch of the K-1 is about 0.005mm, or 0.008mm diagonally. A circle of confusion about twice the linear pitch (d=0.01mm) is used for a 36MP image by Schärfentieferechner mit Zusatzfunktionen, a reliable and thoroughly discussed and checked calculator. Traditional lens DoF marks usually assume a circle of ~0.03mm, e.g. the Pentax F 28mm does, the HD DA 15mm uses 0.2mm. You'll see that for f=28mm, only at f/14.6 diffraction gets as big (by 50% falloff) as the geometric 0.01mm circle of confusion. "Optimal" aperture is at f/9.7, i.e. the aperture at which diffraction starts to theoretically outweigh the increase in sharpness when stopping down further. In practice, I start to see a very subtle difference under careful examination at f/16 for pictures without pixel shift. Choosing something around f=11 would give you greatest depth of field, which still appears critically sharp, resulting in a hyperfocal distance of 10.4m, or a range from 5.2m to infinity. It translates to a human observer looking at e.g. a 65cm wide print from 30cm distance (=naked eye of a pixel peeper) perceiving it as sharp within the limits of human eyesight.

For me in practice, for 20mm it is 3m to infinity at f/11, and most of the time I go slightly into the diffraction-limited range with f/16 to give the corners a little extra boost for overall best performance.
Forum: Pentax K-1 01-19-2018, 11:15 AM  
K-1 shutter lag increase with MLU / Mirror Lock Up
Posted By JensE
Replies: 11
Views: 769
The problem is that with the incredibly thin depth of field in the macro range, you can't predict when your subject is in focus with enough precision and timing. It enters/leaves that predictable range within a few ten milliseconds - much shorter than the shutter normally needs to open (87ms on the K-1 without M-LU), but still frequently requires you to wait several seconds. That is the reason that I have been working on an electronic trigger in the first place, not freezing the motion blur as such. With the 10ms on the K-5, it gets feasible to detect and fire with a reasonable success rate. For a much more elaborate implementation than I'm aiming at, see fotoopa on flickr.

The traditional approach is to create artificially constrained flight paths - which is fine for purely documentary purposes. But it also limits what you can capture in terms of interesting natural habitat/context and requires a lot more time.
Forum: Film Processing, Scanning, and Darkroom 01-19-2018, 11:00 AM  
Rodinal gone bad
Posted By JensE
Replies: 25
Views: 1,158
What I meant with "R09" is the actual recipe - which this number originally referred to. In your case, that means the product did very likely not follow R09.
Forum: Film Processing, Scanning, and Darkroom 01-19-2018, 03:18 AM  
Rodinal gone bad
Posted By JensE
Replies: 25
Views: 1,158
My "ORWO Rezepte" book from 1977 indicates that R09 stock solution stays good "for several months" in an opened, air-tight bottle. It further states that a small amount of white salt forming and an increasingly dark solution would not impacting the development capability.

From experience, storage for even more than a decade, significant amounts of the white salt and a pitch-black solution don't deteriorate it so much that actual R09 wouldn't develop film at all anymore. It either wasn't actual R09 or there was indeed some user error involved.
Forum: Pentax K-1 01-17-2018, 01:59 PM  
K-1 shutter lag increase with MLU / Mirror Lock Up
Posted By JensE
Replies: 11
Views: 769
Unfortunately bees tend to fly in bright daylight, so keeping the shutter open for a long time (much longer than X-sync) isn't an option. I'd fry the bees with a flash powerful enough for that :-)
Forum: Pentax K-1 01-17-2018, 01:12 PM  
K-1 shutter lag increase with MLU / Mirror Lock Up
Posted By JensE
Replies: 11
Views: 769
I still have a fine working K-5 :-)

The wider field of view of the K-1, at the same resolution/magnification, would have made my application, an automatic trigger to photograph insects (especially bees) in flight, a little less time-critical.
Their speed reaches about 5m/s or 5mm/ms. That's 50mm in 10ms, so I will likely only be able to catch slower flights anyway. But you see how a wider field of view may help.
I wonder if by mistake the sensor may be cleared out needlessly. Maybe I'll try an old pre-ES firmware when I get a little time and see if anything changes.
Forum: Pentax K-1 01-17-2018, 09:43 AM  
K-1 shutter lag increase with MLU / Mirror Lock Up
Posted By JensE
Replies: 11
Views: 769
So yes, both correct: Measured from the 2nd shutter press (with a delay of 2s after the first shutter press) until the flash fires. And obviously no live view - which is not very fast either, but I haven't noted down the times for it.
Forum: Pentax K-1 01-17-2018, 02:49 AM  
K-1 shutter lag increase with MLU / Mirror Lock Up
Posted By JensE
Replies: 11
Views: 769
For an automated trigger project, I measured the time from triggering the camera with external cable release to firing a manual flash for both K-5 (done previously) and K-1. Expecting a slight improvement due to faster X-sync time, to my surprise, those were the results:

K-5 w/o MLU: ~80ms
K-5 MLU: 10ms

K-1 w/o MLU: 87ms
K-1 with MLU: 130ms - 230ms

I turned off every conceivable feature in the K-1 in order to speed this up and make it as much K-5ish as possible, but I always end up with times that are longer than the non-MLU lag.
Things I turned off: SR, Horizon correction, AF (used a manual lens), GPS, any exposure automation (X with M-lens and fixed ISO), ES, Catch-In-Focus, Auto-WB, status display, focus confirmation in viewfinder, ...

Is this a firmware bug? Any ideas what unusual things to watch out for?
Forum: Pentax News and Rumors 01-16-2018, 03:41 PM  
Next hours or days we get a new firmware for K-1
Posted By JensE
Replies: 190
Views: 20,859
I'd really like the camera to record the EV (one in a custom tag) with open aperture and again after stopping down for K and M lenses - enabled as a custom function similar to the aperture ring, as it may take a few milliseconds. This way the aperture could be estimated in post-processing.
Forum: Pentax SLR Lens Discussion 01-16-2018, 02:09 PM  
Macro lens
Posted By JensE
Replies: 23
Views: 1,016
The DFA 100 WR version is a very good choice. Among your two zoom lenses it will look tiny, so there's a good change you actually have it with you when you need it. It renders beautifully with nice smooth out-of-focus areas in the macro range and I also like it for non-macro shots. I posted some examples, e.g. Battle of the Nations Monument and even use(d) it for portraits. And, it's a joy to handle with its nice barrel, excellent included narrow hood and smooth manual focus.
Forum: Post Your Photos! 01-14-2018, 07:37 PM  
Macro Playing with Fire
Posted By JensE
Replies: 2
Views: 242
Playing with fire. No cameras or lenses were harmed in making this image.

Shot with the help of a makeshift electronic trigger reacting to the previous - unsuccessful - spark in order to capture the ignition moment.
Forum: General Photography 01-11-2018, 12:21 AM  
Landscape or portrait orientation? Definitely landscape!
Posted By JensE
Replies: 18
Views: 849
It definitely used to be this way for me. In the pre-digital age, I actually made an effort to shoot entire slide series for projection exclusively horizontally oriented, because this is how the silk screen was set up. In contrast to the monitor or digital projector today, there was no fast way to change magnification on the projector. So you were left with smallish projection or the single choice of orientation. I did add vertically oriented shots exclusively for printing.

It took a while to "unlearn" that. Maybe that should not be past tense, but I e.g. have a preference for vertical fish-eye landscapes now.
Forum: Pentax K-30 & K-50 01-05-2018, 05:29 PM  
New old-stock K-50
Posted By JensE
Replies: 15
Views: 896
Those funds were not relevant to the above cameras. They exclusively went to the other part of Germany. The soviet sector, later the GDR, needed a lot longer for (relative) economic recovery.
A significant share of the camera production and remaining production equipment from the eastern sector went to the Soviet Union as part of reparations.
Forum: Pentax DSLR Discussion 01-05-2018, 05:34 AM  
Sigma 70-200mm Lens problem with KP / ideas?
Posted By JensE
Replies: 37
Views: 1,269
I'd be really interested in a comparison of the two, the Tamron comparison in the PentaxForums review was very useful to me already. As it is not available new anymore, I patiently sought a reasonably priced used Sigma HSM OS, mainly because of the lower weight. With the occasional 33% off offers by SRS (see market watch), I was still tempted by the DA* for its weather proofing.

My Sigma OS HSM identifies as Lens ID 8 23 and works well on K-1 and K-5.
Forum: Pentax K-30 & K-50 01-05-2018, 05:11 AM  
New old-stock K-50
Posted By JensE
Replies: 15
Views: 896
Just as an off-topic note: It wasn't until 1957 that Ashai adopted the M42x1 thread, they used smaller diameters earlier. M42x1 had been used by the post-war east German cameras about 10 years earlier: prototypes first shown 1946 for the Contax S, 1948 used in Praktiflex, followed 1949 by the first Praktica. All from Dresden, where also the first 35mm SLR, the Kine-Exakta was built. Even the name "Pentax" was purchased from Dresden. It was a registered trade mark, formed originally out of "Pentaprism Contax". Guess what Pentacon stands for ...
Forum: Pentax K-1 01-05-2018, 03:34 AM  
Extreme Cold
Posted By JensE
Replies: 32
Views: 1,883
But at least the rubber ring will have done its job then: keeping the water out of the camera interior. Even though we have a lot more wet snow, melting and freezing or even freezing drizzle here, due to higher temperatures, and I had a lot of things like car doors or shifter cables or even the whole chain on a bicycle getting stuck due to that, it never happened on a camera mount so far. Good to know to be careful there as well.
Forum: Pentax K-1 01-04-2018, 08:11 AM  
Mirror Lock Up on K1
Posted By JensE
Replies: 33
Views: 3,111
Most of us have long run the update firmware, you can safely go ahead.
Forum: Pentax K-1 12-31-2017, 11:08 AM  
Extreme Cold
Posted By JensE
Replies: 32
Views: 1,883
With a nice glass of your favorite hot beverage, MJKoski's stories in IBIS failure at -28C temp - PentaxForums.com, which the above gives you the essence of, are an interesting read.
Forum: General Photography 12-28-2017, 06:15 PM  
52 Weeks, 52 Photos in 2018
Posted By JensE
Replies: 9
Views: 689
I really enjoyed Project52 right here in the forum, which ended around the end of 2016, after an 8 years run. In contrast to the parallel Weekly Challenge, it really inspired to go and create a new image for each theme. Passing the judgement duty between participants brought out a lot of different viewpoints and ways to look at the submitted pictures. Could it be revived here?
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