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Forum: Film Processing, Scanning, and Darkroom 2 Hours Ago  
B&W Developer starter kits
Posted By Bob 256
Replies: 13
Views: 429
One other tip is when you decide on a developing tank and reels, practice loading those reels before you step into a darkroom or use a changing bag. Take a roll of film you can do without and practice opening the film canister, and then putting that film onto your reels. There's a technique to it depending on the type of reels you have, but it takes a few try's to perfect it. You don't want one layer to touch the layer above or below it or marks can result in the finished images. The last thing you want is to open the film canister and then not be able to get it properly loaded onto the reels. However, once you get a good load and get it in the tank, the lights go on and the rest is pretty simple.
Forum: Pentax DSLR Discussion 23 Hours Ago  
Focus dilemma
Posted By Bob 256
Replies: 18
Views: 514
If it's only happening with one lens, then it's an issue with that lens. If it's happening across a range of lenses, then it could be a camera issue or, respectfully, an operator issue. If after using liveview and mag to get a crisp image (manual focus lens), you end up with something else, it's a camera shake issue which occurs when the shutter trips or when you press the shutter release. You can try a remote release to verify the latter issue.

If it's really random, it's going to be hard to determine the cause.
Forum: Pentax Film SLR Discussion 2 Days Ago  
Digital or Film
Posted By Bob 256
Replies: 49
Views: 1,055
I was film up to the point Pentax came out with the K-1 which offered full-frame at resolutions comparable or greater than film offered. I still shoot film but 90% is now digital and the K-1 is partly to blame for that, having the same great features (and more) that my Pentax PZ-1p had.

Practically speaking, film is going to become a commodity in the not too distant future since demand for film has tanked with the advent of digital photography, particularly that available in everyone's phone these days. I'm a pragmatist in that I see film manufactures scaling back because of those falling sales, so my move to digital was partially one of realizing film would increase in cost and become less available (not to mention the availability of developing).

That said, both film and digital have their pluses and minuses and much is still to be found in either for those who choose to do so.
Forum: Visitors' Center 3 Days Ago  
sd card problem
Posted By Bob 256
Replies: 4
Views: 376
Usually you push the card in until you feel a slight click which should lock it in. If it's not pushed in far enough, it will come back out. Does this happen if you try another card? If it is a failure of the locking mechanism, the repair shop is pretty much the only option.
Forum: General Photography 3 Days Ago  
Use of UV filters to reduce purple fringing?
Posted By Bob 256
Replies: 23
Views: 797
Since most digital cameras have a UV/IR blocking filter in front of the sensor, it doesn't make too much sense that an additional UV filter over the lens would have any effect. Perhaps on a film camera where the film has noted UV sensitivity, but I don't think it would be worth the effort with a digital camera (there might be some exceptions since some lower cost digital cameras forego the blocking filter) .
Forum: Film Processing, Scanning, and Darkroom 4 Days Ago  
B&W Developer starter kits
Posted By Bob 256
Replies: 13
Views: 429
Personally, I'd stay away from "kits" and just pick up the three components: developer, stop bath, and fixer. Then get a set of basic instructions geared toward your developer and film and have at it. Kits are ok but usually you pay a price premium whereas the individual components result in a lower cost (though you may find yourself with large quantities of each). Stop bath and fixer keep relatively well and developer will last for several months if kept in a sealed bottle. With some developers (particularly concentrated liquid developers), it's possible to mix partial quantities to suit your present needs. Stop bath will keep a long time and can be made by diluting acetic acid (use caution when handling glacial acetic acid). In fact, you can replace it with a water wash but a stop bath provides better and more consistent results.

There are some good books out there (see below) which can guide you through the process. Temperature control is fairly important not so much in itself, but for having consistent results from batch to batch, and only the developer is finicky that way. Be sure to wash you film thoroughly after fixing to preserve it long term (fixer residuals can discolor film and ruin images).

The Photographer's Black and White Handbook: Making and Processing Stunning Digital Black and White Photos: Harold Davis: 9781580934787: amazon.com: Books?tag=pentaxforums-20&

http://stores.photoformulary.com/http://
Forum: Troubleshooting and Beginner Help 5 Days Ago  
Problems with Tamron SP 90mm f / 2.8 Di Macro
Posted By Bob 256
Replies: 5
Views: 283
I've used that lens with my K-1 and haven't noted any AF issues at non-macro distances. In most cases using the VF, focus is spot-on every time as it is even using macro. It could be the focus limit switch but sound's like something else might be going on?? Do the cameras you're using have a selective focus "spot" that shows in the VF? If that's the case, you have to be very careful to place that spot where you want the focus when you activate focusing. The lens is so sharp that if you miss your focus point even slightly, it will show in the shot.
Forum: Pentax DSLR Discussion 6 Days Ago  
Focus dilemma
Posted By Bob 256
Replies: 18
Views: 514
The K-1II would certainly be a step up and though it has a not too special focus screen, it does offer liveview and focus peaking, along with the ability to magnify the liveview image electronically for critical focus requirements (though that mainly applies if you have the camera on a tripod and you're not trying to focus on moving content). The K-1II AF is very good and you have the ability to place the focus within the image if desired (I just use the center position, capture focus with a half-push of the shutter button, and then move to compose as desired - old habit). If you do go the K-1 route, I don't think you'll be unhappy.
Forum: Troubleshooting and Beginner Help 11-03-2019, 04:25 PM  
Irix 15mm on K-1 infinity focus issues
Posted By Bob 256
Replies: 13
Views: 433
It sound's like you're doing everything ok by using liveview and mag, so that most likely defaults to the lens itself. You might just have a bad copy with a decentering issue or other problems. Sorry about that. As others have noted, you might have to wade through several returns to find a good one or resort to a Pentax issued lens in that focal range. Still, even with a good lens, don't be surprised with less than excellent performance wide open. Few lenses will give their best performance until they are stopped down somewhat. Star images are very unforgiving where you're trying to image a point source and get it to be a point source, so closing the lens from full aperture may be needed even with a better example of a lens as well. That said, shooting stars is a good test for helping to find a good copy.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 11-03-2019, 03:56 PM  
Retrieving usable film from EOS500
Posted By Bob 256
Replies: 3
Views: 163
Since you're going to remove the film canister anyway, why not do that in a dark room or changing bag and manually rewind the film into the canister, feeling the amount remaining until you have it to a point where the lights can be turned on? It shouldn't be too much film to rewind being there are only a few frames exposed and you can turn the canister film shaft until a tab remains. Then you can load it in your Pentax and advance it with the lens capped until you feel you're past the exposed frames and you're in business.
Forum: Troubleshooting and Beginner Help 11-03-2019, 11:40 AM  
Irix 15mm on K-1 infinity focus issues
Posted By Bob 256
Replies: 13
Views: 433
Fully opened, you can expect some issues with the corners and even the center field. WIth the K-1, use liveview with magnification to obtain the sharpest focus. It's possible your lens won't focus at infinity and in that case, you may consider asking for service, but it's also possible that it focuses beyond infinity, in which case you just can't dial it in to infinity and expect the best focus. That's where liveview and magnification come into play and they should allow you to get a much better focus than by using the optical viewfinder.

Stopping the lens down a bit should improve center and particularly edge sharpness but of course at the cost of less light. Also, there can be the issue of star movement if the exposure is too long. 15 seconds shouldn't pose an issue with a 15mm lens but keep star motion in mind. From your center crops, it looks like there's really no problem with star motion in this case, and the edge problems are lens issues (to wide an aperture and or focus).
Forum: Photographic Technique 11-02-2019, 04:09 PM  
Positive effects of increasing ISO?
Posted By Bob 256
Replies: 23
Views: 720
If you had an ideal sensor, no light would translate to 0000 0000 0000 00 with a 14 bit D to A conversion, but in the real world, there is no zero output from a sensor due to noise (except for the occasional random zero value in that noise). At the lowest ISO value for a given camera (let's say that's 100), all 14 bits have worthwhile information and the dynamic range is theoretically 16384:1 or about 84 dB.

If the lens is stopped down 2 f-stops from the previous exposure, the sensor receives one-fourth the light (all pixels) and the upper 2 bits of the D to A conversion revert to 0s. To compensate, the ISO is changed to 400 (which amplifies or rescales the output of the sensor prior to D to A conversion) and now the two uppermost bits regain information. We again have 14 bits of data, however, the noise which previously didn't affect any of those 14 bits, is amplified by 4 and now affects the lowest two bits making them somewhat random (we are considering an ideal system). If those two lower bits are thrown away because they really aren't useful, we have a 12 bit image with a dynamic range of 4096:1 or about 72 dB. Those two bits can still be useful if they are time averaged since that will average out some noise, but that has to be done in camera and before the image is captured. The shorter the shutter speed, the fewer samples to average so there's a conundrum to be considered.

Bottom line is dynamic range is decreased when ISO is raised. When that becomes apparent in a photo depends on a number of things and in many cases, a one (or even two) stop change in ISO may produce no visible changes, but it always has the potential for doing so, and the dynamic range of the system is decreasing.
Forum: Pentax Film SLR Discussion 11-02-2019, 09:46 AM  
About trying some iso push...
Posted By Bob 256
Replies: 15
Views: 526
"Pushing" is increasing film ISO by extending film development time and "pulling" is decreasing film ISO by decreasing that time. Be sure you're clear to your processing lab which you want. I had the unfortunate experience of the lab getting 6 rolls of Kodachrome (when it was a widely used film) pushed when they were supposed to be pulled (and yes I was clear in my instructions) which resulted in a total loss for those shots.

By telling them you want to increase the ISO, it should be pretty clear, but make sure they understand.

Also, the extent film can be pushed is determined by the film (in your case, you should be fine). You will have more grain & contrast, and fog will increase when you push the ISO of a given film so be ready for that.

One of the advantages of digital cameras is the ISO can be varied from shot-to-shot whereas with film, you're limited to single rolls as Photoptimist mentioned (unless you clip those rolls into segments and do the processing yourself).
Forum: Flashes, Lighting, and Studio 11-01-2019, 03:01 PM  
Help with Equipment for Lab
Posted By Bob 256
Replies: 8
Views: 286
I would avoid fluorescent lamps altogether because of color rendering issues and the need for a ballast. The LED lamps I listed don't need a ballast and have a high CRI (color rendering index), plus they are easy to wire. You just need a socket (for each LED unit), a switch, and a 110VAC plug (maybe a fuse if you want to play safe). Two or more of these wire in parallel. They put out a good amount of light but you need to be able to use a line type light source (stick style light source) rather than a point or reflector style. Sheet polarizing material is available which can be worked into the enclosure design.

I wouldn't think light intensity would be that much of an issue since you can lengthen exposure time (assuming what you're going to photograph doesn't move). The same applies to pixel shift mode. In fact, the K-1 allows you to dial in f-stop and aperture, and then it will select shutter speed based on what's needed. The exposure can be fine tuned as needed.
Forum: Pentax K-1 11-01-2019, 02:54 PM  
k-1 focus
Posted By Bob 256
Replies: 13
Views: 528
Ok. Let's approach this another way. Pick the lens you have the problem with and try to find a test shot which duplicates the issue (by examining the image right after it is taken using the rear LCD and magnifier). Make sure the focus is soft as you described. Now switch to live view and without refocusing, examine the image again using magnification. Is it still out of focus? Can you adjust lens focus to get a sharper image? If the later is the case, you may have an AF issue or something else going on. With liveview, you see the image exactly as the sensor sees it. If it's sharp, taking an exposure should capture it in focus. If the viewfinder AF system says it's in focus and it isn't, it's the phase AF autofocus or something else. You can also try for critical focus using liveview with magnification, and then switch back to the viewfinder and see if the phase AF agrees (beeps). It should.
Forum: Flashes, Lighting, and Studio 10-31-2019, 06:29 PM  
Help with Equipment for Lab
Posted By Bob 256
Replies: 8
Views: 286
Actually for some lighting applications, I discovered that LED replacements for U-tube fluorescent lamps can be configured in housings for very practical lighting sources. I have two fixtures using these, filtered with linear polarizers as described previously by AstroDave, which I use for flat copy work to reduce reflection issues.

The LED assemblies are ballast bypass types so they operate directly from 100 - 277 VAC applied to two end pins. This might address your need for continuous lighting depending on other requirements. Tube types are 91262 "Superior Life" (4000K). Bases for these are readily available from lighting sources. Longer LED units are also available (the ones described are about 18 inches in length).

15W Non-Dimmable 16.3" 4000K 4-Pin Single Twin Tube 2G11 Base LED Bulb, Ballast Bypass | LED PLL 15WT5/120/FR/40K/2G11/100-277V | Bulbs.com
Forum: Pentax Film SLR Discussion 10-30-2019, 07:13 AM  
plastic film can - dumb question
Posted By Bob 256
Replies: 35
Views: 1,064
The old metal ones make excellent storage for electronic devices (e.g. SD cards and mini thumbdrives), providing environmental protection from moisture as well as protection from those items being zapped by static electricity or EMP sources. Unfortunately, the plastic ones aren't quite as good at the latter.
Forum: Photographic Technique 10-26-2019, 08:10 AM  
Shutter shock format dilemma
Posted By Bob 256
Replies: 45
Views: 1,087
In a DSLR, I would think the mirror vibration would be the major contributor since the mirror has much more mass than the shutter. Once the mirror starts a shock wave, the shutter determines how long that vibration would affect the exposed shot, so it would be an interaction of the two (plus some minor vibration due to the shutter itself).

Leaf shutters which are placed in the lens near the iris position produce less vibration (than a linear shutter) since the motion is rotary rather than linear (up/down or sideways), but they are a moot point in most cases unless the lens/camera combination was designed for a leaf shutter to begin with.

There are ways to deal with most mirror/shutter induced vibrations which brings it back to the point photoptimist made, it's a matter of operator technique and experience more than one of the camera itself.
Forum: Visitors' Center 10-25-2019, 02:09 PM  
Girlfriend's birthday and anniversary soon - need help before making a purchase!
Posted By Bob 256
Replies: 61
Views: 2,604
In as far as the K-1 being compatible with her existing lenses - no issues. If these aren't full-frame, the K-1 operates in crop mode and would give the same or better results than an existing APS-C camera.

What this means is you would be purchasing for the extra features the K-1 offers (several), and providing full-frame capability for future FF lenses should she go that route. It's a fine camera, but I would do some research with her for the final decision. It may be that something else in that $$ bracket would make her happier and it's easy to superimpose your own feelings when buying a gift, but it can be a bit like buying music for someone else - what you love doesn't make the cut. The only way to find out is to talk with her and involve her in the final decision.
Forum: Pentax SLR Lens Discussion 10-24-2019, 03:20 PM  
Need advice on wide angle lenses
Posted By Bob 256
Replies: 20
Views: 932
Keep in mind, you can always crop from a wider lens to achieve an effect of a longer focal length (given some image quality reduction dependent on the lens and camera), but not the other way around. If you have any doubts, go wider so you have all the important picture elements included in the shot.
Forum: Sold Items 10-19-2019, 01:44 PM  
For Sale - Sold: Vivitar Series One 13MM f2.8 - Price Reduced
Posted By Bob 256
Replies: 8
Views: 917
I have one of these and it's got outstanding sharpness nearly to the edges (puts my K-1 to the test). Low color and distortion. Hard to find in K mount.
Forum: Pentax Price Watch 10-19-2019, 11:06 AM  
Great Deal on Lexar Memory Cards at Amazon -- 64 GB 95 Mbps U3 $9.99
Posted By Bob 256
Replies: 40
Views: 1,637
Got a long ways from the OP. News is 64Gb @ 10$ (and 128Gb @20$). Make your own decision on buying. Historically, Lexar has been good but that may have changed.

Bottom Line: Memory cards for a good price. You decide.
Forum: Visitors' Center 10-19-2019, 10:58 AM  
manual lenses on digital camera body?
Posted By Bob 256
Replies: 16
Views: 531
Yes, there are professionally made adapters for 675 to K, 67 to K, and screw mount to K (Pentax adapter B previously mentioned). Check with B&H photo.
Forum: Visitors' Center 10-17-2019, 10:08 AM  
manual lenses on digital camera body?
Posted By Bob 256
Replies: 16
Views: 531
I've even used a Pentax 67 lens on my K-1 (with a 3D printed adapter). Manual almost all the way - you set the aperture with the camera in manual, push the green button and the camera determines the shutter speed. You still have to focus manually but the camera gives a "beep" when the proper focus is obtained. Old screw mount Pentax lenses can also be used with an adapter.
Forum: Troubleshooting and Beginner Help 10-15-2019, 03:20 PM  
Need advice please is my lens faulty what is causing the coloured circles.
Posted By Bob 256
Replies: 28
Views: 805
That could also be diffraction off the iris and can also be caused by diffraction occurring at the sensor (you say it is specific to this lens so the latter probably doesn't apply). The "spikes" are caused by each of the blades in the iris and light skipping across the edge of the blade. Try an exposure with the lens wide open if you can (low ISO and fast shutter). If the pattern disappears, it's most likely diffraction. At full aperture, the iris blades are fully retracted leaving a round aperture which produces little diffraction. In any case, you have to live with it. Nothing is wrong with your lens.
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