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Forum: Pentax K-5 07-04-2015, 10:28 AM  
Depth-of-field bracketing -- is there a way to do this?
Posted By baj
Replies: 16
Views: 3,028
Nope. I'm going to be shooting some portraits, and would like shallow DOF (f/2.8) but would also like to have a back-up shot at maybe f/4 as insurance against inperfect focus. Bascially I want shallow DOF but need a sharp subject, and am trying to hedge my bets.
Forum: Pentax K-5 07-04-2015, 04:47 AM  
Depth-of-field bracketing -- is there a way to do this?
Posted By baj
Replies: 16
Views: 3,028
I am wondering: on a K-5, is there a way to bracket depth of field (aperture) while keeping overall exposure the same? Here's what I'm looking for:

Press the shutter once, the camera takes a photo at both f/2.8 and f/4 with the same overall exposure (automatically changes shutter speed or ISO by a stop to compensate for aperture change).

Is there a way to do this?
Forum: Pentax DSLR Discussion 02-03-2015, 07:32 AM  
Using K-3's SR as Improvised Tilt-Shift?
Posted By baj
Replies: 8
Views: 1,400
Forum: Pentax Forums Giveaways 12-15-2014, 12:13 PM  
3 Million Post Giveaway: Confirm your entry!
Posted By baj
Replies: 2,854
Views: 80,009
Hope I'm not too late.
Forum: Pentax News and Rumors 12-04-2014, 06:37 AM  
Sigma 18-35mm F1.8 Coming for Pentax!
Posted By baj
Replies: 1,185
Views: 169,146
Does it now work as well as the Nikon version? Is it really possible that the AF issues with this lens can be fixed with the USB dock (this means that the AF is not inconsistent but simply miscalibrated)?!? Since you had already sent your lens in for service I assume that what you did with the USB dock was focus adjustment only and not firmware update?
Forum: Pentax SLR Lens Discussion 07-22-2014, 05:55 AM  
Good Wide angles for k5iis
Posted By baj
Replies: 66
Views: 6,442
My understanding (which could easily be incorrect) is that Pentax and Tokina are no longer collaborating. So we can't buy the Pentax version of the newer Tokina lenses, yet Tokina still doesn't make lenses in Pentax mount.

The 12-28 looks like a great lens (as does the 11-16 of course), and I like that it goes all the way from ultrawide (though not as ultrawide as others) to a true normal focal length -- very versatile.
Forum: Pentax SLR Lens Discussion 07-21-2014, 09:36 AM  
Good Wide angles for k5iis
Posted By baj
Replies: 66
Views: 6,442
The wide angle lens I'd most like to get is the Tokina 12-28mm f/4. If only Tokina made it for Pentax. :(
Forum: Pentax K-3 07-10-2014, 01:53 PM  
L Bracket K3 with Grip Mestos PD-K3HL
Posted By baj
Replies: 44
Views: 5,943
Great, thanks! I forgot to ask before: it looks like the "L" part is held on with 2 screws. Can these be removed to use it as a regular non-L camera mounting plate?
Forum: Pentax K-3 07-10-2014, 08:43 AM  
L Bracket K3 with Grip Mestos PD-K3HL
Posted By baj
Replies: 44
Views: 5,943
What about the K-5 without the grip? Is it reasonably sturdy and well made? Thanks for any information you can share about it.
Forum: Pentax SLR Lens Discussion 09-26-2013, 06:50 AM  
No Sigma USB Dock for Pentax?
Posted By baj
Replies: 16
Views: 3,133
I got word from Sigma yesterday that they will in fact produce the dock for Pentax:

"If you are receiving this, it is because you had expressed interest in the past regarding a USB Dock for Pentax or Sony. Please know that we have received word from our parent company that we will indeed be making a Dock for both Pentax and Sony in the future. The bad news is that it probably will not be released until March of next year. But I did want to let you know that they have decided to go through with production and that it will be available next year."
Forum: Photographic Industry and Professionals 09-26-2013, 06:49 AM  
A quick look at Sigma's new Lens dock & Customization
Posted By baj
Replies: 9
Views: 1,579
I got word from Sigma yesterday that they will produce the dock for Pentax:

"If you are receiving this, it is because you had expressed interest in the past regarding a USB Dock for Pentax or Sony. Please know that we have received word from our parent company that we will indeed be making a Dock for both Pentax and Sony in the future. The bad news is that it probably will not be released until March of next year. But I did want to let you know that they have decided to go through with production and that it will be available next year."
Forum: Pentax SLR Lens Discussion 09-11-2013, 02:16 PM  
No Sigma USB Dock for Pentax?
Posted By baj
Replies: 16
Views: 3,133
Sure, you can make that argument. You could just as easily argue that they shouldn't bother to make Pentax and Sony (and especially Sigma! How many of those do they sell? :) ) mount lenses at all. Or you could just send a message to Sigma asking them to support Pentax. :)
Forum: Pentax SLR Lens Discussion 09-11-2013, 02:12 PM  
No Sigma USB Dock for Pentax?
Posted By baj
Replies: 16
Views: 3,133
I think the 35mm f/1.4 and 18-35mm f/1.8 are fairly high-end lenses, no?
Forum: Pentax SLR Lens Discussion 09-11-2013, 12:49 PM  
No Sigma USB Dock for Pentax?
Posted By baj
Replies: 16
Views: 3,133
I don't know how the communication protocols of the camera makers differ. However, when these new lenses were first announced it was only for Canon, Nikon, and Sigma mounts. It would be a funny coincidence if the "afterthought" Pentax and Sony mounts coincidentally were the only ones for which this correction was not possible. Also, Sigma America didn't tell me they couldn't do it, just that they had not yet decided to do it. Of course the person responding to my message was probably not their chief AF engineer. :)
Forum: Pentax SLR Lens Discussion 09-11-2013, 12:30 PM  
No Sigma USB Dock for Pentax?
Posted By baj
Replies: 16
Views: 3,133
Sigma has announced that they will make their new "Global Vision" lenses (like the 35mm f/1.4 and 18-35mm f/1.8) for Pentax, but there has been no mention of the Sigma USB Dock for Pentax. I asked Sigma America about this and surprisingly/unfortunately they are not planning to make the USB Dock for Pentax or Sony. Apparently several people have asked about this; Sigma America has forwarded the requests to the mother ship and hopes that somebody there is listening.

If you think this is as silly as I do, you might want to send Sigma a note and ask them to make the USB Dock for Pentax:
Contact Us | Sigma


If you don't know what I'm talking about: Sigma's new lenses have a software interface that allows, among other things, the setting of autofocus fine adjustments at 4 focal lengths (for zooms) x 4 focal distances. So the dreaded "my expensive zoom lens front focuses at the wide end and back focuses at the long end" is no more. It's supposed to be pretty nifty:
LensRentals.com - Sigma Optimization Pro and USB Dock
Sigma USB Dock quick review: Digital Photography Review

But without a USB Dock for a particular mount there's no way to interface the lens to the software.

EDIT 9/26: Sigma has decided to produce the USB Dock for Pentax! See below.
Forum: Non-Pentax Cameras: Canon, Nikon, etc. 01-29-2013, 08:09 AM  
Sigma Announces New 30mm F/1.4
Posted By baj
Replies: 17
Views: 2,710
I would be really interested in this lens if they made it in Pentax mount (assuming it really is an improvement over the current 30/1.4 as they claim). I wrote to Sigma and asked them to please please make a Pentax version. If you would like to see this happen too, then please do the same! I'm hoping this might be a poor man's 31mm LTD.
Forum: Pentax Camera and Field Accessories 08-05-2012, 09:58 AM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
My reference to the EL Nikkor 80mm having an oddball 34.5mm filter thread apparently applies only to the older-style lenses without illuminated aperture scale. The newer N-type 80mm lenses have 40.5mm filter threads, which is easy to find in step-up rings. All of this information comes from scanned Nikon brochures that I found online, so assuming I'm interpreting the drawings correctly it should be accurate (as things you read on the internet go, anyway). The old-style 75mm and 50mm f/4 (but not the 2.8) have the same 34.5mm thread.

I realized that the old-style 80mm won't just be problematic when reversed; even when mounted forward for slide copying it's necessary to attach the front of the lens to the slide copier bellows. So unless it's only going to be used for forward-mounted macro (without the slide copier), or you don't mind duct tape solutions, or you have a very rare Nikon adapter ring laying around, or you are friends with a machinist, it seems best to avoid the old-style 80mm EL Nikkor.
Forum: Pentax Camera and Field Accessories 08-04-2012, 04:20 PM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
What kind of bellows do you have? The one I bought is supposed to go to 170mm (but at this point all I know about it is the instructions I downloaded) .
Forum: Pentax Camera and Field Accessories 08-04-2012, 02:05 PM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
Thanks. I understand the relationship between magnification and extension. What I don't know is the distance from the mounting surface to the rear principal plane (or the flange focal distance) for enlarger lenses (and I realize that it may not be consistent in any way between different lenses). I was hoping to get some real-world "this lens works, this one doesn't" kind of experiences.

I get that the idea of flange focal distance doesn't exactly apply to enlarger lenses in their intended application. But the concept is still valid: An object at infinity comes to focus a distance behind the rear principal point that's equal to the focal length, but I don't know (except for the one lens that newarts kindly provided) the distance from the mounting flange to the focal plane.

I'm sure I can get 0.67x with a 105mm enlarger lens. The only question would be if the bellows and slide copier rails are long enough.
Forum: Pentax Camera and Field Accessories 08-04-2012, 10:40 AM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
If I have to go longer than 50mm, I was thinking about the EL Nikkor 80mm, since it has 6 elements (the 75mm only has 4). I read somewhere on here an 80mm lens _should_ work (can't find the thread now). How's the image quality with the 75mm?

Eventually I'd like to use the bellows for macro as well. For that, I think I'd prefer to use a longer lens (105 or 135mm). Would the 105mm EL Nikkor work, or is that too long for the slide copier? The 105mm has another nice feature: it's easy to reverse mount because it has 34mm female threads and 39mm male threads on the front (at least this version did: Nikon 105mm f/5.6 enlarging lens review), compared to the 80mm's oddball 34.5mm female threads, so it's much more attractive to me for macro than the 80mm. I don't know about other brands of enlarger lenses; I haven't been able to easily find details like this about them.

Just trying to buy as few lenses as possible to do what I want to do.
Forum: Pentax Camera and Field Accessories 08-04-2012, 06:36 AM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
Thanks (but bummer). Do you (or does anyone else) know the effective "extension" of different enlarger lenses? I'd rather not do a lot of experimentation (by which I mean buying stuff I can't ultimately use).



The problem is that, with a shorter lens, the minimum extension with the bellows collapsed all the way provides too much extension. If the minimum magnification is too high, I won't be able to get the entire 35mm frame onto my sensor (it will be a "crop" sensor in the truest sense I guess).

According to the instructions (pdf here: Pentax auto slide bellows A, Pentax Slide copier A instruction manual, user manual) the minimum extension with the lens mounted in the normal orientation is 38mm. This gives a minimum magnification with a _camera_ lens of 0.76x, which is too much. A longer lens would work (but I realize that a non-macro camera lens might not be the best for copying slides/film). The image quality will be better with the lens reversed, but then the minimum magnification is even higher.

If a 50mm enlarger lens came to a focus further from the mounting flange than a Pentax camera lens then it could work (for instance Pentax, Nikon, and Canon 50mm lenses will all focus infinity at a different distance from their mounting flanges, since each camera brand has a different distance from mounting flange to film/sensor. This is why you can use a Nikon lens on a Canon camera but not the other way around). That was the basis for my question.
Forum: Pentax Camera and Field Accessories 08-03-2012, 08:17 PM  
Bellows and Slide Copier A with EL Nikkor 50mm f/2.8?
Posted By baj
Replies: 14
Views: 2,938
I just bought a Pentax Auto Bellows-A with slide copier. My understanding is that my 50mm camera lens won't work for slide copying on a K-5 because the minimum magnification will be too high (need 0.67x magnification to get the whole slide).

Will an EL Nikkor 50mm f/2.8 work for this? I understand how to calculate magnification based on extension, but I don't know how much "extension" (or the opposite thereof) is built into the mounting flange of enlarger lenses. These lenses are cheaper than longer enlarger lenses (probably because they were used for 35mm and are therefore more common) so I'd rather use a 50mm if I can.

Thanks for any advice!
Forum: Site Suggestions and Help 05-15-2012, 05:50 PM  
Suggestion Additional Sub-Category to Tripod in the Accessory DB
Posted By baj
Replies: 3
Views: 773
Yes please! I just started this thread:
https://www.pentaxforums.com/forums/pentax-k-5-forum/186218-arca-swiss-camera...tax-k-5-a.html
If the category bdparker suggests existed I likely would have found what I'm looking for in it.
Forum: Pentax K-5 05-15-2012, 02:19 PM  
Arca-Swiss camera plates for Pentax K-5
Posted By baj
Replies: 10
Views: 4,688
That is a very useful reference that I haven't seen before, thank you. I had looked for a K-5 specific plate from RRS (which I didn't find), and I forgot that they made an L-bracket for the camera.
Forum: Pentax K-5 05-15-2012, 02:16 PM  
Arca-Swiss camera plates for Pentax K-5
Posted By baj
Replies: 10
Views: 4,688
The one concern I have with that plate (which is a universal one with no anti-rotation flange) is that it's curved with the outer edges applying most of the pressure on the camera. I realize the K-5 is pretty robust, but the plate is essentially trying to bend the bottom of the camera. This is why I'd prefer a K-5-specific plate that doesn't rely only on the tightness of the screw to prevent rotation.
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