Forgot Password
Pentax Camera Forums Home
 
Log in or register to remove ads.

Showing results 1 to 25 of 58 Search: Liked Posts
Forum: Mini-Challenges, Games, and Photo Stories 05-03-2021, 12:00 PM  
Game Pentax Gnome - will travel
Posted By jon.partsch
Replies: 155
Views: 7,208
Yesterday, the Pentax gnome came wine tasting with us in California's Napa County wine country. He was a good sport, but says he still prefers mead or ale to wine.

Next up in the rotation to host the gnome are:
  1. Sidney Porter

  2. pbancr


The gnome will be on his way to Sidney Porter today (with tracking number)

Attachment 533457

Attachment 533458

Attachment 533459
Forum: Mini-Challenges, Games, and Photo Stories 05-01-2021, 07:25 PM  
Game Pentax Gnome - will travel
Posted By jon.partsch
Replies: 155
Views: 7,208
....finally getting out on a beautiful but windy day!

I used an old K110D with DA 18-55mm kit lens for these shots. I received this as a non-working "parts" body to harvest for "white Japan" solenoids for repair of aperture block failure in later model cameras. However, everything seems to be working fine with this "parts" body.

Attachment 533137



Attachment 533138
Forum: Pentax DSLR Discussion 04-20-2021, 11:46 AM  
Wasabi battery pack rebuild
Posted By jon.partsch
Replies: 58
Views: 5,266
Addendum:

This looks like a very good test result. 1919 mAh exceeds the rating of a new name-brand Pentax D-LI90 battery pack. Note that the typical load placed on one of these packs when used in camera for various functions is unknown, and a higher load than the test load will yield less apparent capacity. However, the voltage drop under load in this test (and assuming that the test did cut off properly at 6.0v) is between -0.20v and -0.65v, which seems similar to voltage drops under load as recorded in EXIF data (noted in various other threads). Therefore, I am assuming that the roughly 500 mA (or roughly 0.2C) load applied in this test is a fairly good approximation of the load placed on a battery pack in actual use.

Another note: This is a constant resistance test, *not* a constant current test. I expect probably around a 20% drop in current between the beginning and end of the test. Because the discharge curve for Li-ion batteries is fairly flat, with maybe just a it of increase rate near the upper 4.2v and lower 3.0v levels, It is safe to assume that the average current during the test is somewhere around 500 mA. The cells tested are Panasonic NCR18500A, rated at min.1940 mAh, typical 2040 mAh. This amounts to a roughly 0.2C discharge rate for this test.
Forum: Pentax DSLR Discussion 04-20-2021, 09:59 AM  
Wasabi battery pack rebuild
Posted By jon.partsch
Replies: 58
Views: 5,266
Early results are in!!

My first pack certainly won't win any beauty contests, but it works. My soldering was much better on the second pack, but that one also yielded some lessons to apply on the third and fourth packs.

Attachment 531415

A couple of the main takeaways from the rebuilding:
  • The flat nickel lead wires are extremely thin and tear easily

  • The cells are a very tight fit in the pack, so excess solder can create a problem - I will try to get away with using less or carefully sanding down the solder joints on the next packs

  • The order of construction is very important - best to solder into place the ends of cells near the PCB first.

  • The leads are spot welded to the PCB. To avoid damage to the PCB, I decided to separate these leads from the old cells rather than from the PCB. I may do the opposite next time because, in the way I did it, the positioning of the leads on the battery cells must be exact in order for the leads to be the correct length to fold up neatly when the pack is assembled. If I had clipped the leads from the PCB I may have been able to assemble everything and then solder the leads down to the PCB where they fell and trim any excess. I had excess lead wire on the first pack, so it ended up sort of crumpled where it attaches to the PCB. Since the lead strips are so thin, I am a bit worried that they will break. I did a much better job on the second pack, but it was very tricky to get the cells and leads positioned perfectly.


Testing results are in the table below. One odd thing I noticed before charging the rebuilt packs is that, even though the measured voltage of the cells is as expected (measured where connected to the PCB), the external terminals on the pack read zero volts until I place the pack on the charger. The pack seems to "wake up" after being connected to the charger for a few minutes, and the terminal voltage then equals the voltage of the cells. Any idea why this is?

CriteriaValueRebuild attempt1Old pack #3Fresh replacement cell voltage (new)3.51v, 3.51vNew cells soldered into series7.01vCharger usedPentax D-BC90Pack external terminals prior to charging0.10vPack external terminals after a few minutes on charger7.12vPack external terminals freshly charged8.38vPack external terminals 24hr self discharge8.33vPack external terminals 48hr self discharge8.32vDischarge cutoff voltage6.0vDischarge load15 ohmInitial discharge current544 mA (roughly 0.25C)Initial voltage drop under load-0.20v (8.12v)Measured capacity1919 mAhPack external terminals resting voltage after test6.65v
Forum: Pentax SLR Lens Discussion 08-03-2021, 05:01 PM  
Appalling quality (sample variation) of Samyang 14mm f/2.8 lenses
Posted By jon.partsch
Replies: 12
Views: 1,250
Sorry, I did not mean to respond as if you were suggesting that I buy the 15-30mm. I was just offering my thoughts on it, since you mentioned it. I think if I wasn't interested in astro, then the 15-30mm would be a logical choice, but as soon as I got and used the Sigma Art 35mm f/1.4, my focus shifted to primes. For me, wide angles below 35mm will be primary used for astrophotography and landscapes, where care is taken to set up the shot carefully, so a zoom isn't necessary, though I'm sure it's a better choice for many.

Oh I also just got the old SMC Pentax-FA J 18-35mm f/4-5.6. It came with a *ist D parts body I purchased. That should be fun for comparison LOL
Forum: Pentax SLR Lens Discussion 08-03-2021, 07:39 AM  
Appalling quality (sample variation) of Samyang 14mm f/2.8 lenses
Posted By jon.partsch
Replies: 12
Views: 1,250
Absolutely, even with (and maybe especially with) a $2000 USD new Pentax lens. I have a historic brick building just down the street, and my office building (should I ever return there post-COVID) is a concrete monolith with fluted or grooved patterns in the outside walls - both provide great detailed texture for testing. I am finding shooting the night sky stars to be a great torture test for these wide angle lenses because certain flaws show up with points of light that may not be visible shooting a brick wall.
Forum: Pentax SLR Lens Discussion 08-02-2021, 01:14 PM  
Appalling quality (sample variation) of Samyang 14mm f/2.8 lenses
Posted By jon.partsch
Replies: 12
Views: 1,250
Folks,

Understanding the highly variable quality (sample variation) of the Samyang/Bower/Rokinon lenses, I recently purchased two copies of the 24mm f/1.4 (a Bower and a Samyang). I was pleased to test them and discover that they both performed very well! Infinity focus was correct, and resolution was great, distortions/aberrations minimal. I sent the Bower back due to slightly higher coma in one corner.

I then purchased 4 copies of the Samyang 14mm f/2.8, and was appalled to discover major flaws with all of them. All four of them didn't focus to infinity. Lend #1 and #2 were off by at least 1/2 inch turn of the focusing ring. I adjusted all of them, which is easy to do with tutorials in various forums and on YouTube. I then took them out to my favorite semi-dark sky location to test them. Aimed at the zenith, Vega was in just about the middle of the frame. I was further frustrated upon opening my raw images in Lightroom to discover additional flaws. Having the constellation Lyra in the center of the frame was great because it also gave me the visual double Epsilon Lyrae to work with along with the super-bright star Vega. I tested all the lenses at f/2.8 and f/1.4.

Lens #1 was astonishingly sharp in the center! Epsilon Lyrae was clearly resolved as two distinct points of light and Vega as a very small round white dot with no color fringing. There was virtually no difference between f/2.8 and f/4.0. Oh, if only performance across the frame was so good!!! I assume one of the elements controlling coma correction was de-centered as the coma distortion was extreme on the left hand side, rendering stars as thin lines pointing toward the center of the image - coma was also terrible here at f/4.0. As I look at the coma distortion all the way around the edges of the image, the lines of light do not point to the center of the image, but to a point about 2/3 of the way across the image in the area of the middle-right side of the image. Coma on the right side of the image was significantly better, and what I would call acceptable.

Lens #2 had about 3/4" of free play in the focusing ring. The action was dampened, but change in focus was not actually engaged until the ring is turned about 3/4". Turn the ring back the other way, and it has to move about 3/4" again for the plane of focus to actually start changing. I thought perhaps I had not tightened the set screws on the focus ring enough when I adjusted the infinity focus point, so I tightened them and tried focusing again the next day, but the free play in the focus was not improved. This lens is not usable.

Lens #3 had optical de-centering - the left side was completely out of focus at both f/2.8 and f/4.0

Lens #4 was the best all-around performer (across the frame), but it was worse in the center than #1 and #3 (#2 couldn't be evaluated due to the play in the focus ring). Vega wasn't as sharp and Epsilon Lyrae was barely resolved as two points of light. In addition, there was hazy color fringing on the left side of stars (not green, magenta, or purple, but instead the expected color of the star e.g. blue for Vega). I don't know what kind of distortion or issue this is, but it was also somewhat evident on lens #3.

Anyway, I am keeping lens #4 for the time being and sending the other three back for replacement, so I will receive three more copies to test. I am hoping to be able to improve upon lens #4.
Forum: Welcomes and Introductions 07-14-2021, 04:54 PM  
Hello to all Pentax lovers
Posted By jon.partsch
Replies: 22
Views: 855
Hello, and welcome to the forums!
Forum: Troubleshooting and Beginner Help 07-14-2021, 07:09 PM  
lens disassembly help
Posted By jon.partsch
Replies: 26
Views: 1,430
Yes! a total dust and crud magnet! so much so that I doubt it would shed any dust into what I am working on, if only it was grippy enough to actually remove any lens rings! Mine is chinese, light gray, apparently made of silicone, and purchased on AliExpress. Perhaps it is a cheap knockoff of a better set that was the same light gray color, but I don't know.
Forum: Pentax SLR Lens Discussion 07-12-2021, 01:21 PM  
Help with testing Bower / Samyang 24mm f/1.4 lens
Posted By jon.partsch
Replies: 8
Views: 728
What is the reason for such condescension and semantic nit-picking? Did you get up on the wrong side of bed today? You should consider whether you have something positive and constructive to say before you post.
Forum: Photo Critique 06-23-2021, 10:27 AM  
Landscape Stormy Mountain
Posted By jon.partsch
Replies: 18
Views: 1,137
Awesome! The crop really helped with the "balance" in this image. You didn't lose too much of the area at the top where the mountain fades into the mist to reduce the impact of that affect. Your adjustment to the shadows is subtle and very good.
Forum: Welcomes and Introductions 06-20-2021, 04:52 PM  
Hello Pentaxians
Posted By jon.partsch
Replies: 30
Views: 1,200
You are welcome! I am envious that your wife enjoys snow camping. My partner will have no part of it, but I should be happy that she *does* enjoy camping and will let me indulge my fire building and cooking over the open fire. I have a collection of antique cast iron we use camping and also cook on it every day at home.

- Jon
Forum: Film SLRs and Compact Film Cameras 06-26-2021, 10:55 AM  
Gear P0rn - post it if you got it.
Posted By jon.partsch
Replies: 9,468
Views: 1,219,646
I set up this display in my office yesterday (five Minoltas and a Pentax). Sorry about the picture quality - this is a quick snapshot from my phone.

Attachment 540228
Forum: Photographic Technique 06-26-2021, 10:35 AM  
Physical red filter vs digital red filter for b&w
Posted By jon.partsch
Replies: 24
Views: 2,529
This is beautiful!
Forum: Welcomes and Introductions 06-24-2021, 09:20 AM  
Hello Pentax people
Posted By jon.partsch
Replies: 17
Views: 1,687
Welcome! You can also try a bent staple if you need a thinner wire.
Forum: Film SLRs and Compact Film Cameras 06-24-2021, 09:17 AM  
45 years in between
Posted By jon.partsch
Replies: 28
Views: 1,471
I think your age estimate is about right. You can also narrow it down by serial number. It looks to be in fantastic condition. The first generation MC lens is also a match for the camera. I am not aware of a "sticky aperture" problem with the SRT series bodies, but with age, the mirror return mechanism can get jammed - I have seen this on several bodies. Also, these early SRTs (slotted screws, black knurled dial) have a reputation for a less-reliable shutter than the later SRT bodies. I don't know if it's just due to age or if there is anything different about the shutters.

When it comes to sticky apertures, the MC lenses (all three generations of them prior to the MD lenses) tend to develop oily aperture blades. Some lenses in particular are very prone to this. I think it's a combination of old petroleum-based lubricants that have a tendency to separate, releasing oil, and the design of the lenses that fails to keep this oil away from the aperture blades. In my experience, a simple flush cleaning is not sufficient. Only a complete tear-down of the lens and cleaning and replacing with modern, synthetic lubricant reliably solves the problem. Most of these lenses are easy to work on with the exception that the aperture cam has to be precisely positioned with respect to the blade assembly. A reference mark must be made with a stylus during disassembly to ensure that the aperture is reassembled in the correct position.

~ Jon
Forum: Post Your Photos! 06-19-2021, 04:42 PM  
Nature Seagull on Sunny Day
Posted By jon.partsch
Replies: 6
Views: 410
Great BIF shot!
Forum: Welcomes and Introductions 06-19-2021, 04:56 PM  
Hello Pentaxians
Posted By jon.partsch
Replies: 30
Views: 1,200
You are a kindred spirit! I love the camp cookery and bushcrafting shots. Welcome!
Forum: Welcomes and Introductions 06-15-2021, 04:58 PM  
Hello From Austin, Texas!
Posted By jon.partsch
Replies: 25
Views: 1,192
Welcome from California!
Forum: Post Your Photos! 06-15-2021, 04:56 PM  
Night Astrotracing in the Badlands
Posted By jon.partsch
Replies: 19
Views: 1,107
Stunning! I have just started trying this kind of work and can't seem to get enough exposure at iso 3200 f/2.8 and 10 seconds. I don't know what I'm doing wrong!
Forum: Photographic Technique 06-03-2021, 12:49 PM  
Astro Need advice: Star Trails and Milky Way Wide Field Planned First Attempts
Posted By jon.partsch
Replies: 26
Views: 2,385
I hadn't realized it before, but I was already inspired to try a "stitched" Milky Way image by one of his tutorials:
















You Tube





This seems to be a great one on the use of Sequator in the method you are suggesting:
















You Tube





I am now a subscriber to his channel.

~ Jon
Forum: Pentax KP 06-02-2021, 03:22 PM  
NEED PART for KP Body - lens mount
Posted By jon.partsch
Replies: 23
Views: 1,891
Hard to tell, but looks the same as the one on a K100d parts body I have. I am happy to send the mount ring to you for he cost of shipping if you want to give it a try. No guarantees of course!

I'll send you a PM

~Jon
Forum: Post Your Photos! 06-03-2021, 01:02 PM  
Landscape First post here, beach in Ireland
Posted By jon.partsch
Replies: 9
Views: 351
Lovely shot! Taken with the cheap-o kit lens, no less!
Forum: Photographic Technique 06-01-2021, 11:53 AM  
Astro Need advice: Star Trails and Milky Way Wide Field Planned First Attempts
Posted By jon.partsch
Replies: 26
Views: 2,385
Yes, I was wondering what is the best exposure value to use to get (1) thin lines, (2) good color in the trails, and (3) maximize number of trails. The way I see it, there is no option for trial and error, so I need to decide on the EV that I will use and hope for the best. This is one of my primary concerns. Also, I don't see a way to use the K-1ii internal intervalometer for exposures longer than 30 seconds. If there is a way to do this, please explain.



My plan was to shift the frames to cover the blurred foreground with my sharp foreground exposure.



This is confusing to me. Are you saying that Sequator will basically shift the starts in each exposure so that they all line up, but will *not* also shift the foreground? If so this is interesting, and I may want to try this approach. It sound like it may be difficult to implement this along with additional offset frames intended for a stitched panorama. Are you suggesting this as an alternative approach to a single frame milky way scene *not* using Astrotracer?



Thanks!



This is an excellent suggestion! I have not explored user modes yet, but I did change a lot of settings in preparation for my lunar eclipse photos, so I will look into this. Thanks, Grimmus!





Thanks, DeKay! I have now read the entire document and have it saved on my phone, there are a few good tips in here for sure that I hadn't considered.




Thanks Papa_Joe! I have stellarium on my phone. Is the PC version substantially different?



Thanks, Kevin B! I had completely forgotten about this function.



Thanks for all this, gifthorse! I am not worried about stability as I plan to bring a very heavy tripod with me, but will consider weighting it also. For startrails at ISO 400, what aperture are you using? I want to keep color in the trails, but maximize the number of trails that I can pick up. What stacking method do you use in post? Is it "brightest" method? Does that effectively eliminate long-exposure noise?

I am camping again in late July, so I'll try to catch the Southern Delta Aquariids / Alpha Capricornids. Thanks for the tip!

As for YouTube videos - yeah, I am totally comfortable learning the finer points of PP later on. I just want to make sure I collect the best exposures when I am in the field. complicated PP does not scare me. I can learn.


~ Jon
Forum: Pentax K-1 & K-1 II 04-22-2021, 11:57 PM  
Old Canon & Minola User; considering Pentax K-1
Posted By jon.partsch
Replies: 9
Views: 878
Wow, no offense intended, but it kinda sounds like you are all over the place with this. You mention your love of Minolta manual-focus SLRs (the X-570 is a favorite of mine too), old (expired) film, and then you also talk about shooting video and such.

I think you have to decide where your priorities and interests are, and then go form there. There is no camera or even platform that is going to give it all to you.

Are you a stills photographer or a videographer? What kind of stills do you want to shoot? Fine art, landscape, wildlife, portraiture, macros, etc???

IMHO Pentax is a platform for stills photographers. I don't see that changing anytime soon. Pentax lags in AF performance for things like wildlife and sports photography, but they are catching up. I belive that Pentax is geared primarily toward fine art photography, landscape, astrophotography and adventure/outdoor photography. Portrature, and macro photography are secondary, where Pentax is on even footing with competitors. With autofocus catching up to Nikon, and the extreme ruggedness of Pentax equipment, it's becoming a serious contender for wildlife photography, notwithstanding the current lack of third party lens support, so it's a mixed bag when it comes to wildlife. Sports photography and video are the weakest points for Pentax - there are better options if this will be your focus. Many folks here use Pentax for stills and Sony for video, running two systems. There is also the thought that if you want to use classic Minolta manual focus lenses, you will need a mirrorless camera to which they can be adapted. Pentax will not help you there.

I feel there is nothing left of the old Minolta within today's Sony. I see zero reason to look to them for nostalgia. I'm a huge classic Minolta nut, and Sony means absolutely nothing to me.

Best of luck! I hope you stick around here if Pentax suits you.

- Jon
Search took 0.01 seconds | Showing results 1 to 25 of 58

 
Forum Jump


All times are GMT -7. The time now is 09:03 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top