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Forum: Flashes, Lighting, and Studio 6 Hours Ago  
Effect of Flash Zoom on GN
Posted By Lord Lucan
Replies: 2
Views: 154
I noticed an advert for a Nissin ND60A-C Flash :
Nissin i60A Wireless Compact Flash ? nissindigital.us
... and was surprised to see that for a compact flash it had a Guide Number of 60 (meters). Then I saw that it had a 24-200 mm zoom head and that was at maximum zoom . At 50mm they say the GN is 39. I think their zoom figures refer to Full Frame equivalent, and they are for ISO 100.

This set me thinking about the relationship between GN and the flash zoom setting. The advert gives this table of relationship :-

24mm GN 27
50mm GN 39
105mm GN 50
135mm GN 54
200mm GN 60

In this table it looks like the GN is proportional to the square root of the zoom "length" (with rough mental arithmatic anyway). But I would have thought it should be linear.

That is because, taking the zoom length to mean that the spread angle of the light is the same* as the angle of view of a lens of that same focal length (FF equivalent), the illumination of a frame-filling target will always be the same as long as the flash zoom length is set to the same as the focal length of the lens being used. With all other things equal (ie F-stop, ISO, and max flash energy) the effective GN will therefore be in linear relationship to that lens focal length and flash zoom length.

Looking at it another way, in the flash formula the GN and distance are linearly related (unlike the ISO number which appears as a square root).

Am I missing something here ?

* In practice it will be a bit more to avoid edge fall-off.
Forum: Troubleshooting and Beginner Help 7 Hours Ago  
mirror lens mount advice sought
Posted By Lord Lucan
Replies: 12
Views: 575
Yes, mine is somewhat like that. The rear circular closing plate, with the grooved stub on it, is held with three tiny cross-head screws. I have just taken it off out of curiosity. I have not taken another photo, but the rear lens element came with it together with a matt black light baffle in the form of a partial cone tapering towards the object end.
Forum: Troubleshooting and Beginner Help 10 Hours Ago  
mirror lens mount advice sought
Posted By Lord Lucan
Replies: 12
Views: 575
I have this lens. I bought it used with a K mount.

Years later I realised that the basic lens barrel ended at the back end in a cylindrical stub with a groove around it. A K mount adaptor was fixed to this by means of three recessed radial pinch screws 120 degrees apart. I have just taken mine apart for this photo, for which a jewellers screwdriver is needed. You can see one of the screw recesses at the top of the adaptor. The inner ends of the screws pinch into the groove to make a firm attachment, and in my photo you can see a tiny bright witness mark that a screw has made.

I don't know anything about the Adaptall or T-mount systems - is this it?


.... While Pentax is 45.46mm. But with the structure of my lens, the Pentax adaptor would simply need to be 1.06mm deeper than a Practika one, so I would not see a problem (unless you envisage frequent swapping back and forth). I guess the whole point of Centon making it this way was to use the same lens barrel with different simple adaptors for different camera brands. Of course, at F8, this lens has no diaphragm control to complicate things.

Not a problem on my K-1. In fact there is more clearance than with my 24-70mm F2.8 DFA lens

Forum: General Photography 20 Hours Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
It's a CARENAR EEK

"EEK!" is what the buyer will say when they realise it is not a Tamron.
Forum: General Photography 1 Day Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
Boots "Ticky" Flash Gun

Boots is a UK chemist chain that also used to sell low-end photo kit, some of it as their own brand.

This ancient Boots-branded bulb flash gun has surfaced on Ebay. He wants 2.99 (+ 3.60 post), but the joke here is that it still has the original Boots price label on it showing 1.69 ! I would date this as early 1970s, and even allowing for inflation that was dirt cheap. I expect it was a loss leader and they made money on the bulbs.

Tiny though it is, it packs a decent punch (or should I say kick?) with a GN of 32m. Whether you can get flash bulbs or its weird battery nowadays is another matter. Interestingly it says set the camera sync to "X" and use 1/30 sec, but I thought you were supposed to use the "M" sync setting for bulb flash on cameras of that era. I suppose 1/30 sec was long enough to bracket anything.

Vintage Boots Ticky 77 Camera Flash Gun Unit | eBay


Forum: Mini-Challenges, Games, and Photo Stories 1 Day Ago  
=Capture a stranger street style=
Posted By Lord Lucan
Replies: 8,939
Views: 910,945
Reminds me of a production I saw of "The Glass Menagerie" by Tennessee Williams. The stage scenery was of a living room (as the narrator remembered his home ) but set in a ruined building (as the narrator found it when he returned years later). I don't think he did return in the original story. Though only a teenager I was very moved by the play and have often looked out for a chance to see it again.
Forum: General Photography 2 Days Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
It really worries me to see all those vintage flash guns on Ebay, the vast majority cheap and nasty even in their heyday, probably with high trigger voltages but with no warning in the advert. I had one from my father (Sunpak GX18 AFAIR), measured the voltage at 200+, and threw it away rather than risk anyone putting it on a digital camera at some time in the future.
Forum: General Photography 2 Days Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
Kaput Starblitz

If you really must pick a broken feeble (GN 18 metres) vintage flash unit from among the hundreds of similar non-broken ones on Ebay, you can't really complain about the price of this because the "free" postage will cost the guy 3.10 (small parcel rate) leaving him only 90 pence for the brown paper, Sellotape, and his trouble.

But the joke is in the script :
Doesn't work, but what matters is that It looks OK, fits on a camera, and the owner didn't smoke!

Starblitz 218A Flash Unit For SLR Cameras - for Parts | eBay

Forum: General Photography 3 Days Ago  
Interesting gear seen on Craigslist/Shopgoodwill/eBay etc
Posted By Lord Lucan
Replies: 67
Views: 2,686
Doryu Camera Pistol

This should create a stir at a public event. The ad says the flash cartridges even look like bullets. Yours for 12,830

@RARE@ Doryu 2-16 Flash Camera Pistol Subminiature Camera w/leather case | eBay

Forum: Pentax Medium Format 3 Days Ago  
Digital 67
Posted By Lord Lucan
Replies: 38
Views: 1,225
Here is a line-up of a 35mm film LX, an APS-C digital K10-D, a FF digital K-1, and a film 6x7.

The K-1 digital sensor is the same size as the LX film gate, yet how much bigger the K-1 body is! The K-1 is getting on for the body size of the 6x7, yet the 6x7 film gate has over four times the K-1 sensor area. Now imagine how large a 6x7 digital body might be.

Forum: Pentax K-1 5 Days Ago  
Post your K-1 pictures!
Posted By Lord Lucan
Replies: 30,231
Views: 2,712,052
That last shot is amazing, surrealist.
Forum: Pentax SLR Lens Discussion 5 Days Ago  
Which Pentax lens do you most enjoy showing off to friends?
Posted By Lord Lucan
Replies: 76
Views: 3,152
I used to have a servant, but I did her in, mistook her for Lady L. LORD LUCAN'S FULL STORY - THE MYSTERY SURROUNDING LORD LUCAN. Can't afford any more, and anyway they might blow my cover now
Forum: General Photography 5 Days Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
You dont even need to wonder about coincidences. I sold some antique software, still boxed and shrink-wrapped (yes, people collect that stuff) on Ebay for a reasonable price. Three days later, presumably as soon as the buyer received it, it was back for sale by my buyer for twice the price.
Forum: Pentax SLR Lens Discussion 6 Days Ago  
Which Pentax lens do you most enjoy showing off to friends?
Posted By Lord Lucan
Replies: 76
Views: 3,152
Most of my photography is in places where there are no people nearby. It would not occur to me to show off any of my gear anyway, or believe that anyone would be interested (apart from on this forum)
Forum: General Photography 6 Days Ago  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
They say :Maybe we should ask if there is any fungus?
They also say there is Pentax in there; can anyone spot any Pentax?
Love the flash bulb gun - my father had one like that, took three size D batteries in the handle.
Forum: Pentax News and Rumors 09-13-2020, 03:02 AM  
Sticky: An important message from the moderators
Posted By Lord Lucan
Replies: 323
Views: 24,917
It is the Dunning-Kruger effect.

But people still give wrong advice or state falsehoods even when they must realise they don't know much about the subject. I am concious of what I don't know and when it comes to discussions in those areas I keep my mouth shut (or only ask questions). Seems that many people are incapable of this.
Forum: Video and Pentax HDSLRs 09-12-2020, 01:01 PM  
Should Pentax Focus Their Limited R&D Resources On "Stills" Cameras?
Posted By Lord Lucan
Replies: 39
Views: 1,692
Exactly this : Joe Public buying a camera or anything else is looking at how many "feature" boxes are ticked when he compares models. Even if the feature is not implemented particularly well (he probably would not know that), and even if he never uses the feature more than once in a blue moon (if ever), or even if he can't be bothered to read the instructions how to use it when he gets home.

I am thinking of the story that many (most?) people who bought a DSLR worried themselves sick about which model had the most exposure and focusing modes that the salesman rattled on about, but after they got it they only ever used the green button setting.

So Pentax needs to keep that video feature, though I have no use for it.
Forum: Photographic Industry and Professionals 09-12-2020, 05:22 AM  
Olympus will sell their Imaging business to Japan Industrial Partners
Posted By Lord Lucan
Replies: 253
Views: 11,630
When I bought my first SLR, my father was using a Minolta SRT, his friend a Yashica, and my boss an Olympus OM-1. The Olympus looked built like a scientific instrument, a plus point for me as an engineer.

So I looked at those, and did some wider research before buying. I could only have afforded the OM-10 but it seemd weird - needed a crummy adaptor to get manual mode (my father said auto is fine, but a manual mode is a must) and the aperture ring seemed at the wrong end of the lens (for an engineer). The Minoltas of the time looked plasticky and I did not like the name "Yashica" - too Japanesy!

So it came down to Pentax, Nikon or Canon, and I got the ME Super. Looking back it was the right choice - I still have and sometime use the M50mm F1.7 lens on my K-1.

I cannot say I have noticed particular Olympus hate on the internet, but a general view that they made the wrong choice going with 4/3. There is certainly Pentax hate although it is never clear why, just nudge-nudge-wink-wink stuff. Things like in a discussion of thefts, someone said to stop anyone stealing your camera, put a prominent "Pentax" stap on it. ????

OTOH many people think Sony is the of Holy of Holies, beyond criticism, again for no clear reason except maybe they are good for video (which seems to be most YouTube bloggers only interest - well it would be for what they do). I am put off by "Jack of all trades" companies, and the fact Sony make all sorts of consumer stuff including toys is a big downside for me.
Forum: Pentax News and Rumors 09-12-2020, 02:49 AM  
Sticky: An important message from the moderators
Posted By Lord Lucan
Replies: 323
Views: 24,917
Enlighten me, what features have you in mind?

I am on some other forums that don't even have pictures, so PF looks jazzy to me
Forum: Pentax Full Frame 09-12-2020, 02:38 AM  
Prime lens for my K1000
Posted By Lord Lucan
Replies: 25
Views: 801
I get the impression that you have been looking at old lens catalogues, but not prices, like this? :

http://www.lucan.org.uk/IMGP6726_is.jpeg

In the day, not many 35mm lenses were made compared with 28, 50 and 135mm, which made up a popular kit to have. Today those can be found at reasonable prices, but it is hard to find a 35mm F2.8 at all, let alone a F2 (or the "almost mythical" F1.4 I referred to previously) and if you do it will be expensive.

Generally, prices go up exponentially with aperture, and you do not really need a large aperture on a wide angle lens. The extra large apertures (say below F2) are primarily for throwing backgrounds out of focus, and with a wide angle you are starting on the wrong foot for that anyway. As far as light is concerned the difference from F2 to F1,4 is only one stop, and it matters for little once you are out in the field.

For a beginner, even an old hand, a 28mm F2.8 is more than adequate for wide angle shots except ultra-wide (which would be 15-20mm). I used one with ASA200 film for years, including for historic interiors, and there was never an occasion when I wished for more aperture.

Despite the fact that 85mm is meant to be the ideal portrait lens, there has always been a dearth of prime lens production between 50 and 135mm. Prime 85's themselves tend to be very expensive, partly because of their rarity, partly because taking such portraits is considered a professional activity, and partly because they have large apertures - not because they need the light but to throw backgrounds out of focus. I think the M85mm prime was mentioned above, but for most of us it is only a dream lens - I'd love one. But 50mm is fine for a full length portrait, and 100mm (if you can find one) or 135mm (lots on Ebay) are fine for head and shoulder shots if your room is not too small.
Forum: General Photography 09-12-2020, 01:54 AM  
The man who owned 3000 cameras,GAS gone mad!
Posted By Lord Lucan
Replies: 8
Views: 711
With rows of identical Brownies, I think it is more of a monument to a man's obsession than a museum. A museum would have only one of each type.
Forum: Photographic Industry and Professionals 09-12-2020, 01:51 AM  
Olympus will sell their Imaging business to Japan Industrial Partners
Posted By Lord Lucan
Replies: 253
Views: 11,630
I think the younger generation sees people using DSLRs in the same way as people using (D)SLR sized cameras would see people using large bellows cameras.
Forum: Pentax Full Frame 09-11-2020, 03:27 PM  
Prime lens for my K1000
Posted By Lord Lucan
Replies: 25
Views: 801
LoL! We have just been discussing that lens on another thread and it is belieeved that only 5 of them were ever made!
Any M-Series lens will fit a K1000.
Forum: Mini-Challenges, Games, and Photo Stories 09-11-2020, 03:21 PM  
People and their cameras!
Posted By Lord Lucan
Replies: 2,560
Views: 282,445
I'm guessing he is doing some candid street photography, controlling the camera from his smartphone because it has no flippy screen.
Forum: General Photography 09-11-2020, 08:21 AM  
The worst of Craigslist/Shopgoodwill/eBay etc.
Posted By Lord Lucan
Replies: 1,755
Views: 70,901
He claims :.... damned with faint praise.

It looks like the body is designed around a 3.5" floppy disk. As it happens I still have a PC that can read those, but I think I am a rare exception. Otherwise it is a museum piece, and if I wanted one I'd keep an eye open in junk shops and car boot sales.
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