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Forum: Pentax SLR Lens Discussion 15 Hours Ago  
D FA 21mm F2.4 Limited reports/samples starting to appear
Posted By interested_observer
Replies: 26
Views: 1,173
There were a couple of late evening/night star images included. The images look sharp, crisp with good contrast, and no coma (that I could see) in the corners or along the edges. It looks like a nice lens - nice landscapes with good color, nice rendering with details.

:cool:
Forum: Pentax SLR Lens Discussion 2 Days Ago  
Pulled the trigger (almost) on the D-FA 21 ltd
Posted By interested_observer
Replies: 5
Views: 533
21mm is very appealing. Normally, I would say that f2.4 would be great - however, shooting the Milky Way leaves me wanting for something with a faster aperture. f2 or f1.8 would be better. My 31 has coma - so I will be waiting to read the reviews. Then there will be the $ticker $hock. It does appear that it will come in at around $1,500 USD or above.

A while back I made the mistake of comparing everything I had at 28mm. The 28-105 @ 28 was sharper and had all-around better image quality than the 15-30 at 28mm - which left me disappointed. I have to say for a kit lens, the 28-105 is absolutely wonderful. Since then I have wandered away from the 15-30, and the 21 seems to be a pretty nice fit. I have the Voigtlander 20/f3.5, like the width, but hate giving up aperture.

I hit my camera budget for a copy of Capture One - to cure the K1 white dot noise problem. If only the aperture was faster, it would remove part of the acquisition $ting.

:cool:
Forum: Troubleshooting and Beginner Help 5 Days Ago  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
Michael, you have LENR (long exposure noise reduction or dark frame subtraction) enabled or lens correction or something else enabled on your body. It should only take a couple of seconds for the file to write out to the card. If you are taking a 60 minute exposure, and the camera "waits" for an additional 60 minutes, then its LENR for sure - just disable LENR and you will save yourself a lot of time.



Yes, the camera body is sealed, but it does have a rather large hole where the lens mounts. The lens can be WR/AW too, but the lens still "breaths" letting air in and out - especially when focusing. What is happening is that humidity within the air is getting in the camera body and then condensing on the colder parts. You can cold soak the camera prior to going out - just let it equalize in temperature on the back porch or somewhere cool. Also, after use - let it gently warm up gradually before bringing everything in the house.

Also, here is a video tutorial that covers all of this...















You Tube




:cool:
Forum: Welcomes and Introductions 6 Days Ago  
Long time lurker lookinng to restart my love of photography.
Posted By interested_observer
Replies: 6
Views: 226
Welcome to the Forum!!!!

The German company Berlebach has an excellent line of wooden tripods.Many years ago, I came across a Pentax 1000mm lens and posted a link to the sale. I had no interest since I shoot night wide angle. One of the guys up in British Columbia picked it up. Upon shooting with it, even with a good sized rock solid tripod, he still needed an additional stabilizing bar. Right now for the life of me, I can't remember the generic name of this part - but it added some needed stability.

You can also try leaving SR enabled. On a tripod, you are supposed to disable it, however with large heavy lenses (where you are just going to get a lot of vibrations), or shooting on a tripod say from a bridge, where some vibrations are going to carry through the setup, leaving SR enabled can help.

:cool:
Forum: Troubleshooting and Beginner Help 10-07-2021, 09:45 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
Forum: Troubleshooting and Beginner Help 10-07-2021, 06:51 AM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
I was going to write this last night, but was too tired from a hard day of being retired - and just went to bed. There is a surprisingly wide array of approaches to both shooting and processing star trails one can use. Probably hands down the best definitive guide to all things star trails, is available for free (as in beer) at.... You don't have to read through it first - but just scroll thru it beginning to end - just looking at the images for ideas.There are two main shooting approaches 1) single long exposure - say for 20 minutes; and 2) many long - but relatively shorter exposures - say 40 exposures at 30 seconds each, taken in rapid succession (continuous shooting mode). Each of these approaches affords a wide range of results.
  • Single-shot very long exposure - you wind up with getting what you get, a single frame of star trails. You can control the heaviness or the thickness of the star trails somewhat by stopping down the aperture. Wide-open the lens will produce a sharp but possibly somewhat overblown thick star trail. However, stopping down some 2/3 to 1 stop, will produce a much sharper, better-defined trail (much less overblown).

  • Multiple shots - relatively long exposures - can yield the same result as the single shot, but also affords a lot of additional processing choices. There is free stacking software available - StarStaX, StarTrails, etc. or lightroom, photoshop, gimp, etc. The software affords you a number of options. Let's say you shoot 150 frames of 20 seconds each. You can control the length of the star trails by just processing together 50, 75, 100, 120, or all 150 frames together. You can process the results with the very short gaps (frame to frame) in them, or have the software fill them into a full continuous star trail. You can also, have the software weigh the trails differently as they are stacked together, resulting in a "comet" like appearance - with the start of the trail being fainter, and as the trail lengthens it gets somewhat brighter. Lots of user post-processing variations.

Anyway - lots of things you can do with both shooting the frame(s), along with post-processing them together. You can even process them into videos - with the trails getting longer and brighter over time. Only limited by your imagination.

Here is a good overall startrails tutorial....
:cool:
Forum: Pentax SLR Lens Discussion 10-05-2021, 07:18 AM  
Which long lens for astrophotography?
Posted By interested_observer
Replies: 11
Views: 553
There is a lot of expertise and experience on the topic down in the Astrophotography social group.
:cool:
Forum: Troubleshooting and Beginner Help 10-05-2021, 07:12 AM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
If you look closely, it's actually two very dim parallel lines - it's a plane. There is also a very faint second set off to the left of the frame - a second aircraft (the fainter set is flying at a higher altitude). You have a set of wingtip navigation lights (actually they should be red and green - but since they are white, they are anti-collision strobes), but the right-hand side set is brighter than the left-hand set, and that is because you are getting a better angle on the airframe from one side.
:cool:
Forum: Troubleshooting and Beginner Help 10-04-2021, 10:30 AM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
Forum: Troubleshooting and Beginner Help 10-03-2021, 08:19 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
I took one of your test images and ran it through an online plating utility that identifies the area in the sky you captured and identifies all the stars and their constellations.

  • Astrometry.net - here are the results from the plating, providing all the data it was able to extract from your image (just not the exif data).

Here is a link to an article on the web about the color of the night sky. The guy is an astronomer. His website has about 50 articles on just about any topic dealing with astrophotography.One of the better general raw processing utilities that is good for astro is raw thearpee, which is available on Linux.
:cool:
Forum: Troubleshooting and Beginner Help 10-02-2021, 10:15 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
The key to a good location is to keep the major light dome in the area to your back, and there by be pointing from a light area into a darker area.

Find Polaris - the north star and point at it (or just point to the north) and you will get actual star circles around Polaris.

Get a copy of Stellarium for your PC (its a free download) to show you where everything is. I think that it's about $10 for your smartphone, so that you can just hold your smartphone up to the night sky and it will overlay on the screen where all the stars are located. Also, Photopills ($10) on your smartphone will do that and more, especially well suited for the milky way shooting and planning.

:cool:
Forum: Troubleshooting and Beginner Help 10-02-2021, 09:57 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
With Bulb, depending on how you have your camera setup a)push to open, wait, push to close - as long as you want to wait. b) you can stack a long series of 30-second frames to get longer star trails. 3) Using an intervalometer you can set it up to take up to 24 hours 4) with a wired external shutter release, you can push to open the shutter, then lock it open until you are ready to close it.

Here is the light pollution map for West Virginia - _________________

It's all experimentation based on your location. It is also a balance between how much light is in the sky and the light domes in the surrounding areas.

That was a good capture! I see that you are starting to get some fall colors back there....

:cool:
Forum: Troubleshooting and Beginner Help 10-02-2021, 09:08 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
Disable all of the additional image processing items. They are probably delaying the saving of the image. Image save should be pretty immediate and fast.

I added a couple of thoughts to the initial post. Don't be afraid to up the ISO to start to get something. If you are using one shutter push to open and then a subsequent second shutter release to close, put a hat over the lens to block the light just before the second push. Also use a 2 second delay.
__________________________

I would start with 5 minutes - you will get star trails but not really long ones. This would be a good test period rather than waiting 20, 30 40 or an hour. Get everything working and then go for a 20 minute duration.

:cool:
Forum: Troubleshooting and Beginner Help 10-02-2021, 08:44 PM  
My dismal first attempt at star trail(s)
Posted By interested_observer
Replies: 78
Views: 2,446
Well, I would suggest trying....
  • ISO - 400 to 800, start off high and adjust. Perhaps go as high as 1600. With my old K5, ISO 800 was a stretch, 1600 better. I've gone as high as iso 4000 with my k5 and captured good results

  • Aperture - Go with your fastest lens - if f4 is it, then start with ISO 1600 to compensate.

  • Exposure - I would put the camera in manual 30 seconds, then set it for continuous and lock down the external shutter release. Then stack the results (see the links below) No external shutter release, then I would then suggest Bulb and 20 minutes should be more than enough for good star trails.


Here are some good links...
:cool:
Forum: Welcomes and Introductions 08-23-2021, 11:50 PM  
Astrophotographer from Tokyo
Posted By interested_observer
Replies: 12
Views: 414
There are so few folks doing anything with Pentax, those that do - stand out.


No, the sensor does not tilt. If it were to tilt, and break the sensor plane, you would lose focus. That is the main reason all the movement is within the X / Y plane. The trailing of the stars in the corners and along the edges is purely due to "propeller" effect (where the stars appear to move faster along the edges than in the center of the frame. If it were due to anything being out of the sensor plane, then you would see the problem immediately, rather than resolving the problem with shorter exposure times.


The Pentax approach is perfect for this use case.


There was a lot of discussion when it originally came out. It's somewhat similar to Sony's attempt with their "stareater". However, whatever they actually do - they have avoided Sony's "stareating" results. It apparently does some signal processing in terms of noise reduction, but exactly how it accomplishes it - we don't know.

Pentax offered to update the original K1 to the K1 mkII. At the time from what I read, it was thought that it would start processing at around 1600 ISO. I passed and kept my original body - unmodified. In looking at the charts, it actually starts at ISO 640. There is another gentleman back east on Cape Cod who only shoots with the original K1 - Cape Nights Gallery - Cape Night Photography. He has a couple of YouTube videos on astro and somehow managed to damage his original K1 and went looking for a used K1 (unmodified) for a replacement.

The folks down in the astrophotography area which is pretty much devoted to deep space should be able to provide a lot of knowledge on the lenses.

:cool:
Forum: Welcomes and Introductions 08-23-2021, 02:58 PM  
Astrophotographer from Tokyo
Posted By interested_observer
Replies: 12
Views: 414
I've actually watched (and enjoyed) a number of your videos - particularly on the K1. Excellent work!!! Pentax really is in need of all the good exposure they can get.

I've been shooting with Pentax AstroTracer since it came out (I always seem to be experimenting with it) - initially with the o-gps1 using the K5 with the Sigma 18-35/f1.8 lens. Then about 5 years ago I bumped up to the K1 (mk I). I upgraded to the K1 to capture better star colors in the Milky Way. Let me add here that I ran into a gentleman out in the field one evening - he had just picked up a K70 and was trying to shoot the Milky Way. I pulled out my GPS unit and we put the Sigma 18-35/f1.8 on his body and he shot his first really great MW image right out of the gate. The K70 with the 18-35 is an absolutely perfect (and fairly inexpensive) combination for MW shooting. It equals the K1 (mk I) in terms of dynamic range (mainly due to the Acceleration Chip) especially in terms of star color. The K70 was announced about the time I picked up my K1 - I might have actually went for the K70 (I feel that it's that good - especially with the 18-35 which is the perfect MW lens).

In terms of astro, all I really shoot is wide field milky way - have not really gone into any deep sky. I did do some stacking with an old Tak 85mm/f1.8, at 3-second subs. Aligned and stacked several hundred of them.

I'm a software engineer/systems architect that had an opportunity to design the star tracking system for a little telescope down in Texas. As such, I've been somewhat frustrated to understand the source of the edge/corner distortion of astrotracing.

Pentax has done a good job in describing the system at a high level, especially their use case. However in terms of differences - in particular with respect to EQ mounts, really nothing has been addressed. You may/probably already realize this - but just in case, let me bore you to death for a minute.

There are a couple of fundamental differences between an EQ mount's approach when compared to Pentax AstroTracer's approach
  • EQ Tracking - A EQ tracking mount, takes the traditional approach treating the camera (sensor) and lens as a single monolithic unit and rotates it around the earth's polar axis to stabilize the stars. If you take successive shots, the stars will/should stay stationary within the frame (given error-free tracking).

  • AstroTracer (AT) Tracking - The AstroTracer tracks by moving the internal sensor in opposition to the earth's rotation, within the clamped and immobile camera body with the attached lens. Essentially, Pentax uses X-axis, Y-axis, and combined XY-axis twisting movement to simulate the EQ Trackers polar axis rotation. This works very well for periods of time of about 1.5 to 2.5 minutes (even though the mirror box within the camera body has space for the sensor to move for about 5 minutes of tracking time) and depending on the amount of star trailing you are willing to tolerate. This approach does introduce some error into the image (the star trailing within the corners and along the edges). This induced error has a couple of sources; 1) rotational distortion - when the sensor moves in the XY plane in a twisting motion - think of an airplane's propeller. The tips of the propeller move (angular distance) at a much faster rate than does the center of the propeller - hence the bulk of the star trailing in the corners/edges. 2) Lens distortion - lenses are designed to have the light come through a single point on the lens face to strike the sensor. With AT, both the sensor and the stars are in motion, so during the long exposure, the light hitting the sensor will be moving across and through the stationary lens. The corners/edges of a wide-angle lens will slightly amplify this distortion a bit with its movement across the lens. Also, since the camera/lens are immobile, when taking a series of frames, the stars will move out of the frame, forcing the photographer to reframe the overall image in time.

With the difference in tracking approaches - why use the Pentax AstroTracer? For me, I'm looking for good natural star colors across the Milky Way over landscape frame. Out in the field, the MW is not really all that colorful and blown out as it appears in many images. Using a 15mm lens, with a 90 second tracked exposure, which works out to be 6x longer than a non-tracked shot (~15 seconds) [Note, I like to use the online calculator at Night Sky Photography Shutter Speed Calculator – tl-photography ]. I have an easier setup, no alignment problems, an easy 1-minute calibration and I'm ready to shoot. Even though I'm in the Arizona Territories, I usually have an unobstructed horizon, but up north there are forests, where the trees obscure Polaris, which leaves you guesstimating your polar alignment.

My friend (with the K70) picked up a star tracker (which works very well) for 4-minute exposures and they look absolutely stunning. He uses AT about 70% of the time and the tracker about 20%. We bring an extra tripod for the star tracker, so that he shoots using AT while he's futzing with the polar alignment on his EQ tracker. I just like the ease and simplicity of the Pentax astrotracer approach. I get more star light, better star color, while maintaining a very natural overall pleasing image.

A couple of months ago, my friend decided to upgrade to the K1 mk II, which with the Acceleration Chip has an improved dynamic range of about 1.5 stops. The choice of the body was easy, The difficult decision was the lens. The K mount does have a limited selection of fast wide-angle lenses, especially faster than f2.8. He picked up 2, the Sigma 35/f1.4 and the Rokinon 14/f2.8. The problem is, with the fast wide lenses, comes vignetting and coma, where stopping down to f2.8 or so removes a lot of the problems. You wind up having to stop down your fast wide lens, for improved image quality - thereby somewhat removing the advantages of the lens. You can also stitch (50%) to cover the corners/edges with the center of adjacent frames. This is where Sony, Nikon, Fuji, and Canon have some lens advantages - but you give up the astrotracer. So, it all comes down to balancing and selecting your tradeoffs in terms of how you shoot along with the results that you want to capture. As touched on earlier, the combination of the K70 and Sigma 18-35/f1.8 is the best of both worlds. The K70 has an excellent, matches the K1 with dynamic range - especially at ISO 640 and above. The 18-35 lens has no coma, no vignetting (on the crop sensor), well-controlled distortion and for the MW is really the perfect lens. There really is no full-frame lens to match its performance (unfortunately).

I've been shooting with the Pentax DFA 15-30/f2.8 along with the Zeiss 25mm/f2.8 ZK. The prime is sharper than the zoom. I would like something faster, but then you inherent additional problems. The FA 31/f1.8 Ltd is excellent, but has coma. Other wide-angle lenses are available, but slower in aperture.

We go out with 3 bodies, 6 lenses, 3 tripods, a tracker, 2 chairs - and lots of water. Here is a link to his IG page - Login ? Instagram

:cool:
Forum: Welcomes and Introductions 08-23-2021, 04:59 AM  
Astrophotographer from Tokyo
Posted By interested_observer
Replies: 12
Views: 414
Welcome to the Forum!!!! What type of astrophotography are you interested in - wide-field (Milky Way landscapes) or deep space? The Pentax AstroTracer capability is better suited to wide-field, than deep space (the longer the focal length lens used, the shorter the exposure time with tracking). There is also an Astro group within the Forum - that is very active.
:cool:
Forum: Pentax SLR Lens Discussion 06-16-2021, 12:20 PM  
Night photo/Astrotracer best lens advice
Posted By interested_observer
Replies: 18
Views: 5,470
Morning All, I just logged in and saw that I had 2 more likes - and was wondering where they came from - and the link took me here. A post 3 years old, and the information is still good. However, I thought that I would add a bit more to bring it up to date.

A friend of mine - we go milky way shooting together as often as possible, shoots with a K70 using my Sigma 18-35/f1.8. I'm pretty astonished with his results. The acceleration chip in the K70 essentially pulls up the dynamic range to match my K1 - and he gets excellent results. Here is his InstaGram page with a wide range of shots - Login ? Instagram [Note, he likes natural processing - so the milky way is not going to be blown out.] So, for a crop sensor body, you will be hard pressed to match or exceed the results of the Sigma 18-35/f1.8 If you go wider, you loose aperture area (as explained in my prior posts above), thus loose light. If you go longer to get a larger aperture area (to gain additional light), you loose field of view and will need to stitch. Also, on a crop sensor - if you choose to stitch, the 18-35 has really no vignetting, so the panos comes out with excellent results,

Earlier this year, we were talking and he wanted to get a K1mkII - but the question was, what lens. Thus the quest - we looked at everything that had a Pentax K mount. Yes, that does present some limitations - but there are enough of the best recommended lenses available in the K mount that you can make a selection.

With a full frame sensor, the lens selection available (and I will say across any camera brand), you will find problems with everything, regardless. You wind up making a selection on minimizing the problems that you find being the worst. The problems are....
  • Vignetting - The really fast lenses f1.4, vignette a lot. In order to get around the problem, you either have to stop down at least one stop - and probably two (which has the advantage of sharpening up the details), or shoot wide open and use post processing utilities to remove or reduce the vignetting.

  • Coma - Again the really fast lenses usually suffer from some degree of coma - some more than others. You really need to read the reviews.

  • Build Defects - DeCentering - This comment is aimed squarely at Rokinon. Their lenses (especially the 24mm) are notorious for being de-centered.

So, for a full frame sensor - the Sigma 35/f1.4 is probably the best available (and you just deal with the vignetting).

My friend took an acquisition strategy of buying used - from Lens Rentals. They carry K1mkII and will test the bodies (since they only have about 5 of them in stock), essentially cherry pick for the white dot problem. They will also cherry pick the best Sigma 35/f1.4 lens - align and calibrate it on their optical bench, before shipping it to you. So, for slightly less that full retail price - he picked up a body (used/rented once) along with a lens - used/rented once - that were each the best they had available. So far the combination has preformed stellar - and he is very happy.

Let me touch on post-processing software here also.
  • DXO Raw Prime - denoises and also removes vignetting from raw files, This works great, as it removes the white dots that some K1 sensors have.

  • Camera One - Probably the best raw processor that also removes the K1 white dots and reduces the vignetting. My problem is that overall I get better results with LR, even though C1 has the better raw processor and just removes all traces of the white dots - but it runs $300+.

  • Raw Tharepee - Removes the K1 white dots (under denoise impact noise) and does vignetting also.

  • LightRoom / PhotoShop - Does a poor job on the K1 white dots and does remove a lot of the vignetting - but most of the time not everything.

  • PTGui - is a stitching utility. You can process in LR and then export TIFF files to PTGui for stitching. Check off Exposure Blending which will do some additional vignetting on each of the frames so that you will not get the window pane effect across your pano.

My work flow is to import the K1 DNG files into LR, use DXO Raw Prime to process the K1 DNG files into DXO DNG files in a subdirectory, then use LR to touch things up, export to PTGui, stitch and then use PS to composite sky and foreground together.

:cool:
Forum: Pentax K-1 & K-1 II 06-15-2021, 04:03 PM  
K1 - LiveView Zoom Manual Focusing
Posted By interested_observer
Replies: 7
Views: 755
Afternoon Kiwi - Yea, that tripped me up a couple of years ago, and was one of the first things I checked. Bob, this is getting very close to what was occurring. That sequence sounds very familiar.

So, we drove 2 hours up to Sedona, grabbed a quick meal from the MickeyD's drive through with the teal colored arches. Drove back to the secret trailhead (yea, that's the Forest Service official trail name - everyone knows about it). Hiked 3/4 mile to the slick rock area, getting there right at early blue hour - setting up to shoot the milky way over Cathedral Rock. I even used auto focus to AF on the notch and yes flipped into manual focus. Checked a test shot for focus and framing (it all looked good - but when I got home that was even off). Shot for 3 hours, packed up - hiked out, then drove back home. .....and I don't have one single shot worth a dam. But, the view was magnificent and I had a good time. There were 2 other photographers also make the hike in, who lived in the area. We all exchanged where the best shooting locations are - added another 5 or 6 places to our list of spots. So, overall it was a worthwhile evening.

Even though we were a couple hundred feet above Oak Creek - the mosquitos still found us.

:cool:
Forum: Pentax K-1 & K-1 II 06-14-2021, 10:01 PM  
K1 - LiveView Zoom Manual Focusing
Posted By interested_observer
Replies: 7
Views: 755
Hi Guys, I've done it hundreds of times. It works well - well until it doesn't (for whatever reason). I just pulled out the K1 from my backpack - it's still setup exactly as it was when it came off the tripod (in astro tracking Bulb mode) the other night, and yes - pressing OK pops it right into zoom mode (there was a hint of some lag) but it works - 10 out of 10. My friend who I was out with, who now has his new K1 and he walked over and said did you try just [OK]? Yup - and no joy.... and I even turned on my flashlight to make sure I was hitting [OK].

So, right now I have no idea (which is bad for a retired software engineer).... Perhaps, I'm just going delusional. The only thing I can come up with is that I might not be pressing [OK] square on.

.... anyway, Thanks all!!!!

:cool:
Forum: Pentax K-1 & K-1 II 06-14-2021, 12:13 AM  
K1 - LiveView Zoom Manual Focusing
Posted By interested_observer
Replies: 7
Views: 755
I've had my K1 for nearly 5 years now. It's a beast of a camera - way more camera than what I really need, except for Milky Way Landscapes. For this, I need every ounce of performance out of the sensor and I get it.

Most of the time, I have things setup, ready to go and everything goes just fine. However, things go bump in the night from time to time - and for various reasons, I need to manually refocus, in liveview with the zoom capability. Hence, my problem.

There are times that, regardless of what I do - I can not get into the capability to zoom within LiveView in order to refocus on a star. I can get in to LiveView, actually I shoot most of my shots from LiveView. At times, I just can not get into being able to zoom so as to refocus - regardless of what I do.

The vast majority of the time, I'm in Bulb and either 1) using the extended shutter time to shoot foregrounds (1, 2, 3, 4 minutes); or 2) using astrotracing to shoot the sky.

So, does someone have a foolproof approach/process of getting into the zoom capability within LiveView - regardless of what you may be doing or the current configuration of the camera?

:cool: - the idiot behind the camera.
Forum: Digital Processing, Software, and Printing 05-21-2021, 08:33 PM  
DXO PureRaw - K1 White Dots removal
Posted By interested_observer
Replies: 3
Views: 813
Evening all, This week I downloaded the 30 day trial for DXO PureRaw to give it a trial. I was looking to it, to perform a couple of tasks for me, on my low light (actually no light) Milky Way landscape images. 1) Remove the White Dots from the K1 foreground frames; and 2) Handle the ever inherent noise from shooting in the middle of the night.

So, how did it actually perform?
  • White Dots - It cleaned them up perfectly. There were a couple left (as in 2 or 3) in the images I tested - but it took care of the other several thousand quite well. I've been shooting LENR to get rid of them, so this just returned half my life to me. Shooting 2 to 4 minute foreground images - turns in to 4 to 8 minutes instantly - which just makes for a long night. A 6 frame pano takes forever.

  • Inherent Noise - Again, overall it did quite well. With low light or no light imagery, you tend to get a lot of graininess - as in having the images printed on sand. This did remove that, however it also tends to be a bit aggressive. You can back off a lot of this, the images tend to be about 1/3 of a stop darker, contrast tends to be pushed up a bit more, and shadows tend to be much darker, and the image tends to be a bit brighter. Also, the color rendering tends to be ever so slightly different.

  • Stars - I see absolutely no difference between the Pentax DNG files, Adobe LR processing and the DXO processing. - This suits me just fine.

Downsides of the utility. There are several....
  • Files Sizes are doubled from about 42MB to 93MB for the K1. Also, I read somewhere that it uses just the standard Adobe RGB and no expanded gamut.

  • Processing can be a bit long - 45 to 120 seconds for each image - based on a 6 core i7, 32 GB ram, 1TB SSD and a Nvidia GTX 2060 with 6GB graphics ram.

  • I had several images that would not convert, resulting in small 14MB black/blank images - bug report made.

  • The utility does not let you manually select the lens used - it reads the EXIF meta data and goes off from there, so if you are using a M42, K, M, A type lens - it just selects something for you based on your focal length.

  • Color Rendering - I found the colors to be ever so slightly different. They tended to be a bit brighter overall, even after LR processing

Here are some images.
  • Two full size images - first is the DXO with the second being the Pentax DNG directly from LR

  • Some chip outs of a smaller area over on the extreme left hand side - These are side by side for better viewing and comparison. 1) DXO with LR post processing; 2) DXO with no LR post processing; 3) Pentax DNG with LR post processing. The processing done on #3 was applied to #2 resulting in #1 with some additional LR adjustments.

I have not purchased it yet. I see that there is another new noise reduction utility that I really should also trial too. I also have a copy of Topaz noiseAI that tends to be very heavy handed.

I do like the standard LR processing overall - especially the colors. Being able to get rid of the white dots and not have to use LENR, while doing a better job of rendering the raw is excellent - especially if they dial back the aggressiveness of the somewhat over sharpening is an improvement. Also, getting rid/ reducing by 50% of the graininess that LR does is good, but they need to dial it back some.

As in everything - there are both pros and cons. The re-rendering has benefits - but also brings some negatives.

:cool:
Forum: Pentax DSLR Discussion 05-13-2021, 12:29 PM  
What do we lose in image quality with a 10-Bit RAW file versus a 14-Bit RAW file?
Posted By interested_observer
Replies: 15
Views: 1,098
I just thought that I would add a bit more here. There is an association or correlation if you will, between bit depth and dynamic range (dynamic range simply put, is the range between the blackest black and the whitest white in an image). Also, this may be an easier read....Digital photography can get pretty deep into the computer science of things. Digital cameras are essentially a computer with a lens bolted to the front. That said, the bottom line of all of this is not the specs - number of bits, theory of this and that..... It's viewing a scene, composing a picture, capturing an image. The rest of everything else is just a tool - a shovel, rake or hoe.

You do not need to get caught up in all of the details. Digital photography is great, since it essentially give you an endless roll of film. Take a shot, look at it and then perhaps make a change and shoot it again. This high turn around rate, enables you to shoot, determine if you can do better, shoot again with some changes for a better image, there by creating a very effective learning loop.

I still have my K5 that I shot with for years. I now have a K1 which is an absolute beast of a camera. I very well may never upgrade - it just has everything that I need and could want. However, my k5 - being pretty simple and straight forward is a tremendous camera - and really fun to shoot. Its technology does not get in the way of capturing the image. The ONLY reason why I upgraded was that I could get better star color in my night milky way landscape images.

I also still have my first digital body - the K100D, which is only a 6MP body, but is a CCD sensor, which captures very colorfully saturated images. Its images are wonderful. Upon getting my K5, I put some of the K100D images up on a large 50" screen TV and compared them with the K5 images. The first thought that came to mind is - why did I upgrade?

:cool:
Forum: Pentax DSLR Discussion 05-12-2021, 09:40 PM  
What do we lose in image quality with a 10-Bit RAW file versus a 14-Bit RAW file?
Posted By interested_observer
Replies: 15
Views: 1,098
Here is probably one of the better explanations of the difference. Probably way more that what you are really wanting to know. Essentially its about the theory of information in computer science as it pertains to color science.Your K50 is a wonderful camera body. Here is a tutorial video on the K-s2 which is similar and may help you with things....















  • You Tube





:cool:
Forum: Photographic Technique 05-12-2021, 02:59 PM  
Landscape How to stitch panorama of waves
Posted By interested_observer
Replies: 25
Views: 1,365
It didn't do absolutely everything perfectly, but it did handle about 80% of normal stuff very well. I have no idea as to why they pulled it. I had to get a new laptop, and as I was reloading it with everything, I needed to download a new copy of ICE and ---- it was gone....

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