All Forum Comments
Comment by petrochemist posted on Bellows on a Q at 02/12/2012 - 15:58
You might need to set the menu option to 'allow aperture ring' (I can't understand why this isn't the default), and perhaps have the camera set to manual focus - so that you can do test shots without having to get the focus sharp enough for the AF system.
Connecting telescopes & cameras can be complicated especially as there are multiple options (with eyepiece & camera lens, eyepiece but no lens, no eyepiece or camera lens...) Not all options work with all systems. My camera would have to be inside the telescope tube to reach focus without an eyepiece on my Newtonian.
Good luck, I think it's worth persevering on.
Comment by petrochemist posted on K5, telescope adapter and F stop.... at 01/12/2012 - 18:52
I reserve judgement...all very much trial by youtube....
The side of the story I found most noticable was that he took more shots of the backs of the procession than of them as they came in (he could see their faces then!) Can't see how his side of it would differ there.
I have to say I wouldn't want to do wedding photography. If I had very poor friends I might do their wedding for nothing, but only after explaining that I'd offer no garantee's & reminding them that my portraits are nothing special... (More likely I'd pay for a more suitable photographer from amoung my contacts)
Comment by petrochemist posted on Wedding Photographer Shuts Down Business at 29/11/2012 - 16:16
love no 1 & 7
Comment by petrochemist posted on Brazilian Grand Prix at 26/11/2012 - 17:09
Personally I think to be really worthwhile, photography of the non visible electromagnetic spectrum must reveal stuff that couldn't normally be seen in the visible spectrum.
All the IR images I've seen so far just look like judicious post processed versions of regular images. And while they might look creatively pretty I can't see anything than can't be produced by just being creative with tone curves in post pro.
I think the visible one must have been taken after showing her the UV one!
Comment by petrochemist posted on how make IR photos with Pentax DSLRs at 26/11/2012 - 08:02
I was always of the belief that the in-built IR filter in a DSLR "opened up" the sensor's sensitivity range to allow it to "detect" IR wavelengths, and incorporate this additional information into the picture. Maybe I've got it wrong, or I haven't really explained it properly.
I suppose the best way to compare/describe it is like a guitar amp's volume control goes from 0-10, but in the Spinal Tap movie, the amp's all go up to 11, as 11's a bit louder!!...
Okay - I'll get my coat!!
With my unconverted K100d in strong summer sunshine hand held shots are possible (1/15s, f2.8, ISO 200 on one I've just checked) The K7 needs the ISO turned up all the way to have any chance of being handheld, and realistically needs a sturdy tripod. The few IR shots I've tried with the K7 have all been severely underexposed, but do not show such clear IR effects as the K100. I think there is still a significant part of the image being formed by visible light, as the filters do not block ALL the visible. (I think my 720nm filter transmits ~1% of the light at 700nm)
Comment by petrochemist posted on how make IR photos with Pentax DSLRs at 25/11/2012 - 20:17
My own experiences are similar to Bjorn's but with the cormorants rather than the herons (I got quite a few semi reasonable heron shots whilst on the Norfolk Broads in the summer).
Whenever I've tried photographic cormorants, they've always been a bit too far away for whatever lenses I have with me, and the birds have always seemed significantly out of focus, when I get to check them on a bigger screen. The same lenses seem to work fine for other subjects...
Comment by petrochemist posted on Grey Heron & Cormorant at 23/11/2012 - 16:56
[quote:3496ace15f="DaveHolmes"]You could (and I imagine you won't) do something really very diferent...
BTW who is the "You" above? me or one of the other posters? and how do you know what I or someone else you've probably never met would or wouldn't do?
Just wondering......
With regard to knowing what we'd do, Dave doesn't, which is why he included the word 'imagine'.
I wish I could afford to follow his advise, beyond just lending it to family members on a sunday walk. At least it does get some use.
Comment by petrochemist posted on K-r betrayal at 22/11/2012 - 13:29
I'd imagine that there is light loss with the K/Q adapter much as there is with an extension tube.
Comment by petrochemist posted on How sensitive is your camera? at 21/11/2012 - 17:04
My last post will win no awards for spelling or grammar
Comment by petrochemist posted on Flat looking at 21/11/2012 - 08:25


I might find myself wanting a Q sometime