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Forum: Flashes, Lighting, and Studio 1 Day Ago  
PTTL vs Manual Mode, Full Power Output
Posted By Digitalis
Replies: 7
Views: 289
Maximum flash power ratings are difficult to measure on ones own, different manufacturers have different metrics which usually stop well short of the flash bulb physically detonating. Adding in flash power compensation won't increase power if it is already maxed out: the ultimate limit is the flash capacitors, which can only dump so much energy into the bulb*.


*and also they have narrow limits on how high their operating temperatures can get before they lose efficiency or physically self destruct.
Forum: Pentax News and Rumors 2 Days Ago  
Development update regarding the HD PENTAX-D FA★50mmF1.4 SDM AW
Posted By Digitalis
Replies: 644
Views: 47,213
Having handled the Opera 50mm f/1.4 and Pentax D-FA*50mm f/1.4 lenses personally there is little to distinguish the fit and finish of the two lenses. They are both Superb....regrettably, I have not been able to put them through their paces on my optics bench.




not this un-bearded feckless cretin again.
Forum: Digital Processing, Software, and Printing 2 Days Ago  
Need Advice On Custom Desktop Computer Build...
Posted By Digitalis
Replies: 48
Views: 1,046
You should also make a careful choice of which case you choose to put the components in - a good, well designed case will give you plentiful options for cable management, plentiful Hard drive support*, filtered fan intakes

The Corsair Obsidian series and Lian Li cases are well worth a look.


*Tool less hard drive trays are very common and depending upon design allow for hot swapping.
Forum: Travel, Events, and Groups 5 Days Ago  
Antarctica kit
Posted By Digitalis
Replies: 84
Views: 4,127
That will work - many consider polarisers on lenses wider than 28mm to be an acquired taste.
Forum: Travel, Events, and Groups 5 Days Ago  
Antarctica kit
Posted By Digitalis
Replies: 84
Views: 4,127
The 4 stop ND grad and the 10 stop ND should work nicely. A thought did occur to me, are you taking a polariser?
Forum: Photographic Industry and Professionals 5 Days Ago  
Canon starting to butcher Sony in FF mirrorless (as predicted)
Posted By Digitalis
Replies: 50
Views: 1,809
Except in the underwater camera market - The Nikonos system SLAYED Canons paltry offerings.



Agreed - however I think the market will shrink as demand will fall as the existing userbase "upgrades" to the new MILC. The biggest obstacle I see is with lens releases, Fuji did a good job with this by consistently releasing interesting lenses for their X system. If Nikon/Canon can keep their userbase needs fulfilled they will rise to the top of the heap with ease.
Forum: Travel, Events, and Groups 5 Days Ago  
Antarctica kit
Posted By Digitalis
Replies: 84
Views: 4,127
Some people would have an existential crisis over the 45mm focal length gap.




I'd take two filters: a ND grad filter [the dynamic range between snow on land and bright skies can be difficult to tame] and a strong ND for long exposure work.
Forum: Film Processing, Scanning, and Darkroom 11-06-2018, 08:44 PM  
Push Portra 400 or Not?
Posted By Digitalis
Replies: 5
Views: 300
Negative films are pretty forgiving - you can pull them several stops without issue, pushing film involves more compromises with image quality the further away from the box speed you get. Fortunately box speeds on films are only recommended values, that when the film is developed as standard the negatives will reach a specific density and contrast. The density and contrast will change with each stop you diverge from the recommended value, if you keep your expectations to modest levels you will get something usable. I've seen people push T-max 400 to 6400 and complain that their images looked like they were shot in a snowstorm....
Forum: Film Processing, Scanning, and Darkroom 11-06-2018, 08:10 PM  
How long does a dedicated film scanner last?
Posted By Digitalis
Replies: 11
Views: 467
I haven't heard of the SCSI interface in YEARS.
Forum: Pentax K-1 11-05-2018, 01:45 PM  
Vibration reduction in mirror Lock-up vs. Live View on a K-1 Mark ii
Posted By Digitalis
Replies: 14
Views: 595
When you view the movement of a camera mirror in slow motion you'll see why MLU is so important.

















You Tube




I will point out the Pentax K-1 has a better damped mirror mechanism than a Canon 5D. MLU is also very important for macrophotography especially at extremely high magnifications.
Forum: Pentax SLR Lens Discussion 11-05-2018, 01:37 PM  
Sigma 100-300 F4 APO EX DG
Posted By Digitalis
Replies: 25
Views: 1,094
The Sigma 100-300mm f/4 has been discontinued for a considerable length of time, Legacy glass is a very low priority for manufacturers.

If sigma re-released the lens [ which I hope they do, it is superb] A user defined focus limiter would be a must-have feature for this lens. Along with AF adjustment Via the Sigma Lens dock.
Forum: Sold Items 11-05-2018, 06:40 AM  
For Sale - Sold: Sigma 18-35 f1.8 Art
Posted By Digitalis
Replies: 18
Views: 1,571
The only firmware updates related to this lens are for Sigma,Nikon and Canon mounts only - are they are only minor compatibility fixes. Nothing for Pentax.
Forum: Pentax DSLR Discussion 11-05-2018, 06:30 AM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
Not all lenses have collars, or provide the faculty to use one.
Forum: Pentax DSLR Discussion 11-05-2018, 05:23 AM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
Does it have a tripod mount? If so, it would provide the user with the option to use more stable shooting platforms.
Forum: Pentax DSLR Discussion 11-05-2018, 05:01 AM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
I see what you are getting at Rondec, but it seems to me that making a mount larger to simply accept lens adapters seems to me a rather tedious kludge. M42 placed a lot of lens design restrictions on manufacturers. I don't think the industry will ever go back to a "universal" mount ever again- the shareholders want companies to make money, the best way to do that is to force end users into accepting their solutions - not adapt the camera to work with their competitors products.



It has a considerable effect upon a cameras ergonomics - any excess bulk has an effect upon how the camera fits the hand and balances with various lenses and accessories that may be attached. Why do you think the Canon #D and Nikon D# series cameras have built in vertical grips? not only do the grips provide space for more powerful batteries and offer additional controls for the user, they help the camera balance well when used with long fast lenses. What is added to a camera and what is taken away is no trivial matter to camera designers.


Rondec is just pointing out the nonsense of "compact" interchangeable lens cameras - which, at present, aren't in any way poketable in any practical sense*. I will remind you the spirit of 35mm was "take anywhere convenience" - A break from the tiresome pursuit of hauling a medium format, or 4X5 camera around with you. The Pentax ME super, Olympus OM, Leica M cameras were an exemplars of this design goal, the Nikon F4 was perhaps the most egregious diversion from that concept.


* Insert a crass is that a camera in your pocket or are you just happy to see me? joke here.
Forum: Pentax K-1 11-04-2018, 06:37 PM  
Vibration reduction in mirror Lock-up vs. Live View on a K-1 Mark ii
Posted By Digitalis
Replies: 14
Views: 595
I will point out that with longer lenses the 2s MLU timer will not be long enough to allow for all vibrations to dissipate, so using the alternate two press MLU mode is more appropriate for telephoto lenses over 100mm
Forum: Pentax DSLR Discussion 11-04-2018, 04:42 AM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
There would be big problems with infinity focus though. I don't think there will ever be a "universal" lens mount in the future.
Forum: Pentax Medium Format 11-03-2018, 08:39 PM  
Recommend Zeiss or Contax 645 Lens for 645D
Posted By Digitalis
Replies: 14
Views: 529
I work with the Leica APO-Elmar 180mm f/3.5 CS lens which like the CZJ 180mm, is absolutely superb for portraiture on the Leica S. I'm just saying it - Leica could make a killing if they decided to make those lenses for other camera mounts.




I think this has more to do with the quality and number of optical coatings than any inherent optical design philosophy. The later PS series lenses from Bronica held a distinct advantage* in image contrast compared to the older S line, merely by improving the coatings.




Biometar/Biotar** is east German parlance for Planar. "..A rose by any other name..."

The name Biometar/Biotar/Planar pre-date WW2. Naming conventions were adhered to more strictly than they are now.



* what made this more obvious is a lot of the optical formulas used in the S and PS line were identical.
** Biotar is an Assymetrical Planar, a Biometar is a tweak of the planar formula, which is comprised of 5 elements. Where the Biometar diverges from the Planar design only by substituting the rear doublet by high curvature singlet elements.
Forum: Pentax DSLR Discussion 11-03-2018, 08:25 PM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
still working fine for the equipment I have..
Forum: Pentax SLR Lens Discussion 11-02-2018, 08:46 PM  
Sigma 100-300 F4 APO EX DG
Posted By Digitalis
Replies: 25
Views: 1,094
You could average the adjustment and shoot at f/8 all the time, that way the focus shift will be just enough to keep your subject within the plane of focus. This will be problematic if you shoot distant subjects or close up subjects.

I seem to have been very fortunate with my copy of the Sigma 100-300mm f/4 APO EX DG, even on the K10D - which under normal circumstances, has no option for AF adjustment, it worked fine.


Yes, the lens is very sharp - there is a slight drop in contrast @ 300mm f/4, however stopping down to f/5.6 delivers consistently high performance across the entire focal length range - with one caveat being:


The Sigma lens does experience diminished performance at the minimum focus distance at focal lengths over 100mm, so it is best to use a macro lens for close ups.



Pentax K5IIs - Sigma 100-300mm f/4 APO EX DG - 1/250th ISO 2500 f/5.6


Pentax K10D - Sigma 100-300mm f/4 APO EX DG - ISO 200 1/180th f/4 off camera AF540FGZ + 1/2 CTO Gel used.
Forum: Pentax SLR Lens Discussion 11-02-2018, 07:17 PM  
Sigma 100-300 F4 APO EX DG
Posted By Digitalis
Replies: 25
Views: 1,094
Unfortunately it does, so if you correct for a 280mm focal length that will, in all probability, throw out focus at 135mm. That is the nature of global lens adjustments.

I wish Sigma allowed for focus adjustment VIA the lens dock with all current and legacy glass.
Forum: Pentax DSLR Discussion 11-02-2018, 07:14 PM  
The End of the DSLR?
Posted By Digitalis
Replies: 223
Views: 8,087
I once had a student come to me for advice on purchasing a new camera, he mentioned going over the comments on new cameras on DPR - which is, arguably, the single worst place for camera buying wisdom. I'm convinced a sweeping majority of the commentators on DPR actually kill brain cells.
Forum: Pentax Medium Format 11-02-2018, 04:13 PM  
Recommend Zeiss or Contax 645 Lens for 645D
Posted By Digitalis
Replies: 14
Views: 529
The Pentax D-FA 55mm f/2.8 ASPH lens has a flatter focus field at closer distances than the 67 55mm f/4 lens, but that field curves a bit as focus shifts towards infinity which introduces slight astigmatism.
Forum: Post Your Photos! 11-02-2018, 05:14 AM  
Nature Burnished
Posted By Digitalis
Replies: 2
Views: 131
Stitched panoramas I presume?



That storm was crackling and roaring as it tore the skies asunder with godly wrath over my head several hours ago. I have been in quite a few heavy, electrically active storms in my life and that one easily makes the top 3.
Forum: Pentax SLR Lens Discussion 11-02-2018, 05:01 AM  
Pentax A* 135mm f1.8
Posted By Digitalis
Replies: 68
Views: 4,715
135mm lenses have been a contentious issue for reasons that continue to mystify me. It's a focal length I hardly ever use on full frame or even on APS-C : too short for wildlife - too long for portraiture. I've used the Sigma 8-16mm f/4.5-5.6 more than I have ever used any 135mm lens.




That flute player is going to have problems with his right hand wrist with a thumb position like that...the thumb should be under the index finger for proper balance.
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