Olympus UK E-System User Group
Olympus UK E-System User Group

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Search: Posts Made By: Petrochemist
Forum: Nostalgia Nexus - early and pre-digital discussion 1 Week Ago
Replies: 18
Views: 744
Posted By Petrochemist
Re: Thornton Pickard 5x4" half-plate view camera?

I believe symmetrical lens designs could be quite high quality, many of them are still quite usable today (at least by those of use who don't obsess about sharpness)


Ansel Adams certainly got...
Forum: Nostalgia Nexus - early and pre-digital discussion 1 Week Ago
Replies: 18
Views: 744
Posted By Petrochemist
Re: Thornton Pickard 5x4" half-plate view camera?

These massive cameras weren't the norm in the 1930s, they were more routine prior to the release of 120 (& similar) films (around 1900), but still offered considerable advantages for those wanting...
Forum: Flash 1 Week Ago
Replies: 6
Views: 256
Posted By Petrochemist
Re: Flash Which Tilts Forwards

I often find one flash gives too much light unless held quite a way back (even in TTL). So a simple reflector to fill shadows is adequate instead of second/third flash.


Perhaps not suitable for...
Forum: Flash 1 Week Ago
Replies: 6
Views: 256
Posted By Petrochemist
Re: Flash Which Tilts Forwards

I simply use my flash off camera, linked by a TTL cord. This gives complete freedom to point it any way I want :)
Forum: Nostalgia Nexus - early and pre-digital discussion 1 Week Ago
Replies: 18
Views: 744
Posted By Petrochemist
Re: Thornton Pickard 5x4" half-plate view camera?

Modern large format lenses are all sized for Copal shutters, which probably wouldn't work well with this. They have elements either side of the shutter.

If you can identify the thread on the lens...
Forum: General photography discussion 2 Weeks Ago
Replies: 5
Views: 379
Posted By Petrochemist
Re: sensor protection

Several of the adapted lenses I use have no position for the locking pin, so the camera still thinks the lens isn't engaged when it's fully mounted...


I'd much rather have the camera work than...
Forum: General photography discussion 2 Weeks Ago
Replies: 5
Views: 444
Posted By Petrochemist
Re: Camera versus The Human Eye

I suspect it might be because the ideal degree of curvature wanted varies with the lenses focal length...
Could be rather tricky with a zoom.
Forum: General photography discussion 2 Weeks Ago
Replies: 13
Views: 404
Posted By Petrochemist
Re: Mapping/ aeriel photos

I've stitched several composites of 6 to 10 images from moving ships using ICE. All handled automatically, the only significant error being on a join that was 80% water & 15% sky - not leaving it...
Forum: Lens focus 1st January 2019
Replies: 4
Views: 751
Posted By Petrochemist
Re: Lens hoods and polarising filters

There are similar openings on several of my Pentax hoods. A very useful feature well worth the minimal extra cost in manufacture IMO.
Forum: Standard zoom and mid range 30th December 2018
Replies: 16
Views: 1,318
Posted By Petrochemist
Re: "What"...it don't focus stack?

It's only nonsense because you missed the 'S' :)
In macro photography (by far the main use of focus stacking) you frequently can't get enough DOF for the subject. At really high magnifications...
Forum: For sale or wanted small ads 29th December 2018
Replies: 6
Views: 826
Posted By Petrochemist
Re: today only - 15% discount on eBay

So that's where the discount on my new camera came from! :)
I was worried it was something my wife had earned...
Forum: Foto Fair 13th December 2018
Replies: 1,729
Sticky: Picture trail
Views: 206,309
Posted By Petrochemist
Re: Picture trail

Stressed acrylic (with Olympus 17mm/2.8 & polarisers)
https://farm1.staticflickr.com/890/41468699545_98477c9206_c.jpg (https://flic.kr/p/26brVCn)stressed stencil (https://flic.kr/p/26brVCn) by Mike...
Forum: Legacy Lenses 4th December 2018
Replies: 42
Views: 10,891
Posted By Petrochemist
Re: Lens Fungus

It's actually more useful to inspect an out of focus image of that bright light. Muck in the lens system can be seen in the Bokeh.
Forum: Legacy Lenses 4th December 2018
Replies: 42
Views: 10,891
Posted By Petrochemist
Re: Lens Fungus

These days white LEDS generally have phosphors to widen the wavelength range. The LED it's self will excite the phosphor. But as you say very little IR from them especially compared to tungsten...
Forum: Lens focus 24th November 2018
Replies: 10
Views: 1,162
Posted By Petrochemist
Re: Lenses: relative length & diameter

There are a couple of crafty lenses designs that were invented around 100 years ago:
Telephoto lenses use a design that allows the lens to be physically shorter than it's focal length. Today the...
Forum: General photography discussion 21st November 2018
Replies: 56
Views: 4,769
Posted By Petrochemist
Re: Tony Northrup believes micro-four-thirds is dead

If I tried to carry around the FF equivalent of my MFT grab bag, I'd be hospitalised pretty quickly! Either from damage to my back in carrying too much or damage to other parts from my wife finding...
Forum: Converters, adapters and extension tubes 12th November 2018
Replies: 21
Views: 2,074
Posted By Petrochemist
Re: Easy lens changing

One of my cameras does not have a dust removal system due to being converted to IR. So I always fit a lens back on the body as quickly as possible.
Take cap off the lens I'm going to fit - but the...
Forum: General photography discussion 1st November 2018
Replies: 30
Views: 2,364
Posted By Petrochemist
Re: Flickr changes - the end of the free 1TB

But Instagram is not photographer-focused at all, more suited to snapshots from phones with digital filters applied
Mind you Flickr has been photographer focused for about 5 years - hopefully it's...
Forum: General photography discussion 15th October 2018
Replies: 8
Views: 1,054
Posted By Petrochemist
Re: Laowa Lenses

'The body is willing but the mind is weak'
In my case the bank balance has helped keep the mind under control. There's no way I can get all the lenses there that look interesting - and they didn't...
Forum: Tutorials, Informative & Classic threads 9th October 2018
Replies: 23
Views: 3,087
Posted By Petrochemist
Re: Using the P mode?

Far from it. P allows you to adjust any of the settings it suggests. Green box auto which doesn't let you change anything is useless!
Forum: Looking for improvement 7th October 2018
Replies: 24
Views: 5,135
Posted By Petrochemist
Re: Discussions on improvements

I too prefer the colour version.

I think the lack of the headland at the extreme LHS helps the colour version as well as the more obvious colour differences.


I have to say a longer exposure...
Forum: Standard zoom and mid range 18th September 2018
Replies: 6
Views: 2,254
Posted By Petrochemist
Re: Lens size versus distance...

Could I suggest changing 'lens size' to 'focal length'? There is actually very little relation between the two!
A 1000mm element is thinner than a 10mm one of the same diameter, even before we get...
Forum: For sale or wanted small ads 14th September 2018
Replies: 21
Views: 1,384
Posted By Petrochemist
Re: E-M5 MkI converted to IR

Nearly all the long pass IR filters I've looked at transmit at least 90% from around 20nm above their listed cut off. So the usual loss would be around 5% (1/10 stop). I think the only exception has...
Forum: For sale or wanted small ads 13th September 2018
Replies: 21
Views: 1,384
Posted By Petrochemist
Re: E-M5 MkI converted to IR

A 665nm conversion images using wavelengths from 665nm to 1100nm. If you add a 720nm filter it blocks the light below 720nm so the result is the same as a 720nm conversion. You can also add a 850nm...
Forum: Foto Fair 13th September 2018
Replies: 21
Views: 932
Posted By Petrochemist
Re: Boys' Toys

I think that was pretty much what him & his friend did - until they both got private pilots licenses and started flying for real. Now THAT gets expensive! :)
Showing results 1 to 25 of 495

 
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