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Forum: Lens Clubs
07-28-2019, 11:26 PM
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I found Irix 15/2.4 Blackstone ideal for photographing miniature dioramas, those in the pictures are 1:25. Great thing is you can control the DOF as much as you like. At practical distances of 25-100 cm, the DOF can be entirely flat (f/2.8), intermediate (f/5.6) or encompass the whole diorama depth (f/11). All pictures from Pentax K-1.
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Forum: Troubleshooting and Beginner Help
07-26-2019, 02:18 AM
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I did the following test:
Using Pentax K-1 (FF mode) I put the test table and the camera was mounted on a tripod. I was setting distances at the Irix 15 mm f/2.4 Blackstone according to the lens distance scale. The camera was in LiveView mode with magnification on. I was moving the camera from and to the test table to achieve the sharpest text of the table, Focus Peaking on. The actual measured distance was from the test table plane to the camera's focal plane.
Results:- From 0.25 to 0.5 m (or 0.875 to 1.75 ft) the distance scale is about correct
- The point on the distance scale when all goes wrong begins at 0.7 m (ca. 2.3 ft)
- For longer distances, the lens distance scale is completely wrong
As you can see from the result table, while the lens claims the distance is 3 meter, it is actually less than 1.5 m. Or, where Irix claim the distance is 8 ft, it is actually 4.5 ft.
The distance scale of the lens cannot be trusted at all, same with Hyperfocal Distance markings. I have calculated proper Hyperfocal Distances for a 15 mm FF lens and put the results in the table as well. As you can see, the lens will give you far higher DOF than Irix claim. You do not need to stop down to F/11. Even with F/5.6, just set the distance to "3 meters" (it is indeed 1.5 meter) and in reality you would have pictures sharp from 0.75 m to infinity. This is what the extremely wide lenses are for.
How could Irix make such fundamental error with their distance scale remains a mystery to me.
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Forum: Troubleshooting and Beginner Help
07-25-2019, 06:07 AM
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I have also noticed the DOF scale markings on the Irix 15/2.4 seem to be wrong.
I use Pentax K-1. If you check HyperFocal app for Android, use Pentax K-1, 15 mm, f/8, you will see the hyperfocal distance is 0.992 m (3 ft). Very similar results come from DOFMaster (use Canon 5D Mark III, 15 mm, f/8, hyperfocal distance is 0.95 m).
While Irix gives around 2.5 m (8 ft) for hyperfocal distance at f/8 at the lens scale. Something must have gone very wrong.
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Forum: Pentax K-1 & K-1 II
08-09-2017, 12:27 AM
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Ah, OK. It was only 88 MB left on your card.
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Forum: Pentax K-1 & K-1 II
08-07-2017, 06:39 AM
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I didn't quite catch what you are saying. Does the camera prevent you from taking more pictures even if there still is free space on the SD card? Or?
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Forum: Pentax K-1 & K-1 II
07-31-2017, 07:04 PM
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Thank you for the workaround.
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Forum: Pentax K-1 & K-1 II
07-31-2017, 01:04 PM
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Thank you. That is convincing. I took a shot at maximum ISO and the resulting file was 67 MB. In fact, switching to Pixel Shift Resolution also decreases the number of available shots, which seems legit.
What I therefore miss from K-1 is reporting the number of taken shots along the free shot number estimate. A friend told me Nikons give a number such as 138/146 where 138 is the number of shots already taken and 146 is the number of shots still available. If anyone can tell me where I can find the number of shots already taken in the K-1, then I dismiss the case completely ;-)
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Forum: Pentax K-1 & K-1 II
07-31-2017, 08:44 AM
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Right.
An uncompressed RAW (worst case scenario) takes 63.35 MB. Not 80. Why to use the wrong estimate.
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Forum: Pentax K-1 & K-1 II
07-31-2017, 05:17 AM
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Thank you very much. Very useful answer.
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Forum: Pentax K-1 & K-1 II
07-31-2017, 03:40 AM
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1. I was almost convinced with the answer (thank you very much) before I started little thinking.
2. Calculation of size of an uncompressed 36 Mpx RAW file
7360 * 4912 = 36152320 pixels
36152320 * 14 bit = 506132480 pixels
506132480 / 8 bit = 63266560 Bytes
63266560 / 1024 = 61783.75 KB
61783.75 / 1024 = 60.34 MB (approximate size of 36 Mpx uncompressed RAW file, add a small amount for EXIF data, let it be 60.35 MB)
Now, 32 GB * 1024 = 32768 MB;
32768 / 60.35 = 542 shots available (rounded down to next integer number).
This is not a rocket science.
I cannot explain why RAW DNG files from the K-1 are significantly smaller than the file size as calculated above. Either those are compressed or delivered at significantly reduced bit-depth of 10-bits (that would be BAD). Same applies to PEF files (these are about 42 MB in size). So far, I never got a RAW DNG file bigger than 50 MB.
3. On the other hand, a RAW DNG file taken from Pixel Shift Resolution has a quadruple size of a single RAW file. It could be as much as 156 MB. 156/4 = 39 MB. I'm pointing to the fact that a K-1 user might want to take Pixel Shift Resolution pictures only. In such situation, a 32 GB card would be able to store about 32768 / 160 = 204 shots instead of promised 401.
Is it possible that Ricoh engineers might not understand what they were doing?! So sophisticated camera and so unreliable with simple calculations with different picture-taking modes? Very disappointing indeed. I am not so experienced to know how Canon and Nikon do it but as a Pentaxian I can only say I am very much disappointed in this respect. I am an engineer myself.
P.S. I am very happy with the K-1 as such. I might want just invest into larger SD cards. Still, is it a wedding or a large music festival coverage, an aspiring professional photographer must be aware how many shots are still available on their memory cards. Otherwize, a prize-winning shot might be unexpectedly lost.
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Forum: Pentax K-1 & K-1 II
07-29-2017, 02:00 AM
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First, sorry to ask somewhat naieve questions perhaps.
1. The camera is loaded with two SD cards: Slot 1 with SanDisk Extreme Pro 16 GB, Slot 2 with SanDisk Extreme Pro 32 GB. The frame counter reads for RAW DNG:
Slot 1: 401 frames
Slot 2: 200 frames
If we divide 32 / 400 it gives 80 MB per frame estimate (it applies to both cards). Actual size of a RAW DNG file in FF mode is 40 GB. How comes I was covering a wedding and could take over 700 frames on the 32 GB card although K-1 said it would be only 401. How does K-1 calculate available shot space?
2. I was expecting that when the Slot 2 has been chosen as the first slot, and the slot sequence was 2 -> 1 then the K-1 should automatically switch to Slot 1 when the SD card in Slot 2 got full. Instead I got the message "Memory Card Full" and since I was a fresh user, I had to remove SD2 to be able to continue shooting. Now I can understand I could have switched the cards using the menu. Should not K-1 switch the slots automatically in the sequential mode?
3. The bug already reported on Page 12. With Sandisk Extreme Pro 32 GB (a Micro SD card mounted in a SD adapter), an only card in Slot 1 reports "This image cannot be displayed" in Preview after a RAW DNG has been captured. The only solution is to insert the SD card into Slot 2 or use both slots with SD cards inserted. No cure for over 1 year?
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Forum: Pentax SLR Lens Discussion
06-29-2017, 10:18 PM
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I clearly say the parameters defining a top lens are its sharpness, lack of vignetting, lack of distortion, lack of CAs, colour rendition capability, and pleasant bokeh. Cartier-Bresson shoot black and white and certainly he could not use a modern, high resolution digital camera.
EDIT:
D1N0: I thought we were talking a full-frame sensor....
EDIT: It is hard to distinguish which photo was taken with which 35 mm lens on *APS-C*, save the bokeh circle (one is decidedly better than the other one - see it at the right hand side). The difference might be visible on FF, though, especially for corners and sides. Both pictures at f/2.8.
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Forum: Pentax DSLR Discussion
06-29-2017, 12:33 AM
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Sorry for re-living this old thread. Does anyone know for sure the two parameters of the K-1 sensor:
1. Pixel size (for diffraction limit calculation)
2. CoC?
I am more interested in the sensor pixel size. Any paper for actual diffraction limit for the K-1, provided a perfectly good optics of the lens?
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Forum: Pentax SLR Lens Discussion
06-28-2017, 10:47 PM
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Although I much agree with these views, let us bear in mind the fame of the FA31 originated in the times when none of Pentax-brand owners ever planned making an FF digital SLR. FA31 is certainly excellent with APS-C but I believe it is not the top lens for high resolution FF sensor; it is enough to study the MTF figures. The FA31 was tested by Photozone at 10 Mpx and the center resolution at f/1.8 was 1848.5 lw/ph. Sigma A 35 as tested on an FF Nikon gave center resolution of 3262 lw/ph at f/1.4. You don't need pixel-peeking to determine that: It is clearly visible in pictures taken.
Although certainly the FA31 is a respectable lens, its high price and the old design make the lens natural to be reused by existing owners on the K-1 body but I would think thrice before I recommended the FA31 to a new user. Why to pay twice what you spend for Sigma to buy a lens that is outresolved by the K-1 sensor? And well, a 6-degree angle of view difference between both lenses? Is it worth paying the double price? I doubt and that's why I chose the Sigma for my coming K-1 body though I could afford the Pentax Limited lens.
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Forum: Pentax SLR Lens Discussion
06-28-2017, 01:29 AM
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I've been busy taking photos with my K-5 for past couple of years with all necessary lenses at hand, so I did not pay attention to the Forum until I felt I really needed an FF Pentax. Thank you for the useful information!
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Forum: Pentax SLR Lens Discussion
06-27-2017, 09:43 AM
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I tried the DA 14/2.8 on a film body and only centre of the frame was covered... So I thought it would be the same for other lenses. Thank you for the hint.
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Forum: Pentax SLR Lens Discussion
06-26-2017, 11:53 PM
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Does it. An APS-C lens? In the FF or Crop mode?
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Forum: Pentax SLR Lens Discussion
06-26-2017, 08:09 PM
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Sorry to say it but I asked an Australian friend of mine to take several back lit photos with fully open aperture of the 31 and after I saw the RAWs I went right for Sigma. I cannot afford soft concert photos, not for the price of the Limited.
Interestingly, DxOMark places the Sigma as the #1 lens for Pentax with the 35/2.4 Plastic Fantastic as the fourth best but that is not an FF lens while the Sigma is.
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Forum: Pentax SLR Lens Discussion
06-26-2017, 07:16 PM
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There's only one answer. Sigma A 35/1.4. No Pentax lens can ever beat it, and sharpness, bokeh, colour rendition, virtually any lack of aberration and the speed make it an unrivalled lens. Bulky it is, true. Arthritis... well, I'd compete with arteriosclerosis and still I chose the Sigma ;-)
Please anyone make a photo like this with fully open aperture of 31 Limited...
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Forum: Digital Processing, Software, and Printing
03-29-2014, 09:13 AM
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Thank you. i believe Perfect Photo Suite is just perfect. So I bought a full license now.
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Forum: Winners' Showcase
03-24-2014, 04:53 PM
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Photography appears to become computer game imagery nowadays. So sad the banal shot after applying tons of effects won the contest.
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Forum: Digital Processing, Software, and Printing
03-23-2014, 05:49 PM
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Thank you very much! Now, I can use Perfect Effects to full capacity! The software has become my necessary everyday tool. If you want to see some samples, there are three sessions I used the program for, I hope you'll enjoy it.
I mostly create my own presents using, among others, the Tone Enhancer, Color Enhancer, Portrait Enhancer, Sunshine, Sharpness, Vignette and Adjustment Brush. Less often Lens Blur, Black & White, Grunge. There was a single photo where I used "HDR".
A session to cover the audience of a small club. Click for more
A session with a musician. Click for more
A session where I was the model myself. ;-) Click for more
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Forum: Digital Processing, Software, and Printing
03-22-2014, 06:30 PM
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I meant "Magic Eye Fixer" that is one of presets of the Adjustment Brush. I cannot see any way I could control the size of the circular brush.
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Forum: Digital Processing, Software, and Printing
03-22-2014, 05:25 PM
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Yeah, the program is just perfect and it really got me sucked in. ;-)
I cannot grab one matter though. When I use Lens Blur effects and the Lens Blur effect is not the first in the filter stack, I'm getting a "grille" in the final PSD, which is not what I wanted.
Also, no idea how to control the size of the Magic Eye circle.
Apart from above, one of the best effect programs I had a chance to use. It makes your pictures stand out from the crowd with only minimal effect application.
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Forum: Film SLRs and Compact Film Cameras
09-23-2013, 11:28 PM
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Nice collection indeed. I used to take pictures with Prakticas in 1980/90s. Recently saw a guy with the MTL-3 really taking pictures. Do you use the cameras Paddan?
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