petrochemist

Joined: 27th February 2010

All Forum Comments

Topics Created Topics Contributed Forum Comments Photo Comments

All Forum Comments

petrochemist
Even better than the telescope shots IMO.

I might find myself wanting a Q sometime

Comment by petrochemist posted on Bellows on a Q at 02/12/2012 - 15:58

petrochemist
The flashing F just means the camera doesn't know what the F stop is. It doesn't need to be set.
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

petrochemist
ilovesaabs wrote:
generator wrote:
ilovesaabs wrote:
I reserve judgement...all very much trial by youtube....
You don’t need Utube ? the video says it all if i seen the video footage on TV or anywhere else i would say the same MY GOD WHATS HE DOING
But then again you see only one side of the story, I would have presumed he was a back up photographer... and had some idea given the L glass he had....

If you'd read the comments you would have seen it repeatedly that he was the only photographer (A friend of the family with fancy kit IIRC). Having high grade pro kit just means there is money to spend, so the L glass gives NO clue to how much he may now.

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

petrochemist
reso wrote:
love no 1 & 7
Same here! All are brilliant as Charlotte says, but these two have something extra.

Comment by petrochemist posted on Brazilian Grand Prix at 26/11/2012 - 17:09

petrochemist
Smeggypants wrote:
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.
Try this portrait comparison
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

petrochemist
steven9761 wrote:
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!!
Actually it merely blocks the visible portion, leaving the IR signal pretty much unchanged. Earlier digital cameras often have weaker hot mirrors (The internal filter that blocks most of the UV & IR) so have more sensitivity to IR. The weak hot mirror still blocks so much infra red that the image it creates can only be seen when the visible light is not present.

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

petrochemist
I love the second! All the feathers are clearly visible & you've captured their metallic sheen.

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

petrochemist
dannyh wrote:
[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......
It seems to me the 'You' would apply to anyone in that situation (including me - My K100 is generally sitting idle, kept as a emergency spare/occasional IR body/Kids camera).

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

petrochemist
gartmore wrote:
I'd imagine that there is light loss with the K/Q adapter much as there is with an extension tube.
Surely the adapter just makes up for the difference in flange distances for the cameras. Total distance from lens to sensor will be the same either on a K mount DSLR, or an adapted Q mount.

Comment by petrochemist posted on How sensitive is your camera? at 21/11/2012 - 17:04

petrochemist
Smeggypants wrote:
My last post will win no awards for spelling or grammar
True enough but it's content was spot on - not that there are usually awards for that either. At least you have the excuse that it was posted at 5.20am. I wish I could type so well in my sleep

Comment by petrochemist posted on Flat looking at 21/11/2012 - 08:25

Proudly supporting Pentax User

Samsung Logo Asahi Pentax Logo