October 01, 2014, 08:27:14 AM

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Messages - g2

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1
Technical Support / Re: Pink/purple streak in pics when using live view
« on: September 24, 2014, 08:30:32 AM »
When the IR filter is removed, the camera sensor will pickup heat from inside the body.  There are various shields for light, and they must be carefully replaced.  I'd ask the company that did the work about a normal expectation.  They should have tested it after the conversion.

Will check with them.

By the looks of the images, it appears to be a light leak and not heat, especially dswtan image, though I could be wrong.

2
Technical Support / Re: Pink/purple streak in pics when using live view
« on: September 24, 2014, 08:27:59 AM »
I have this, but my pattern is a more defined flare.

Mine's on a 5D2, also full spectrum (clear sensor filter) converted by Life Pixel. They may know more about this, since they've probably had comments on it over the years unless it's extremely rare (just you and I!). But I've not got around to reaching out to them, and I'm not at the point of complaining about it, since the simple workaround is just not to use Live View during astrophotography except for focusing.

You can see my posts on it from just a couple of weeks ago, with photos, here:
http://www.dpreview.com/forums/post/54257998
https://groups.yahoo.com/neo/groups/Infrared_Photography/conversations/topics/22481

Mine -- complete dark, same with no lens attached, only source of light must be within body -- 30s at 1600 ISO:


So appears to be a common issue after conversion.

I'll write them a mail over the weekend and see what they say, will update here once I have a reply from them.

Thanks guys for all the help.

3
Technical Support / Re: Pink/purple streak in pics when using live view
« on: September 23, 2014, 09:32:28 AM »
Kinda looks like light spot from single directional source at narrow angle.
If you have IR/UV filter removed, then it could be IR radiation from some component inside the camera, something that belongs to screen circuitry. Sometimes voltage stabilisers or voltage reference are made with LED sources.

If it's 600D, then I find it unlikely to be screen itself - screen is articulated and separated.

*I guess there is no IR detector below VF*

Hi KacperP,

The UV/IR cut filter has been removed from the camera, it could be, as you say, something with the screen circuitry but the screen is on even when using the VF and goes off when taking a shot in both LV and VF.

One question, would the sensor heat up by the same amount whether ISO 100 or 3200 is used? I assume higher ISO will just amplify the signal stronger or would the sensor emit more heat as well?

Thanks.

4
Technical Support / Re: Pink/purple streak in pics when using live view
« on: September 23, 2014, 09:19:26 AM »
Do you see the artifact when you capture the LV image first after the camera has been off for a while?  The issue might not be light, but heat.  It looks like 'amp glow' but that's usually in a corner. 

Have you tried contacting the company that did the spectrum conversion (assuming you didn't DIY)?

Hi neuroanatomist,

The conversion was done by lifepixel around 2 years back, I only noticed the issue last week, I usually stick to ISO 100 for most of my shots but we went out for star trails this past Saturday and I bumped up the ISO and noticed this, I had seen it in ISO 100 shots sometime back but only when the exposures were really long (4-5mins+) and assumed it was heat from the sensor due to the long exposure.

The issue is present whether the camera has been off or in use for a while.

I am wondering whether it is heat as I tried a 30sec exposure in LV and the steak was there and then turned off LV and did a 2min exposure and it wasn't.

Thanks for your reply.

g2

5
Technical Support / Re: Pink/purple streak in pics when using live view
« on: September 23, 2014, 08:26:06 AM »
Hi Graham,

Thanks for the reply.

Could it be a light leak, try it in a dark room or in a box to remove external light sources? Did you cover the eyepiece with the little cover (or hang a lens cap over it)?

I tried in a dark room with the lens cap on and the eyepiece covered and the streak is still there.

Quote
How about a scratch, or a fibre trapped under the replacement glass for the IR filter, could something like that apply pressure to the sensor and would that pressure cause an effect? Thinking like when pressure is applied to the front of an LCD screen?

This appears unlikely as the streak doesn't show up when live view is off.


Can the camera LCD cause a light leak from within the camera?


6
Technical Support / Pink/purple streak in pics when using live view
« on: September 22, 2014, 06:17:37 AM »
Hi guys,

Need help with a technical issue I am facing, any help would be much appreciated.

I get a purple streak in long exposure pics when shooting using live view (I'm using a full spectrum converted 600D (T3i)) The streak is always at the same spot (bottom left) and is not present if I shoot via the viewfinder.

It's there at all ISOs, though less visible in lower ISO settings (I just tried at ISO 200 and it was not visible until I did shadow recovery in post)

Pic below was taken with a lens cap on.



Any idea what's causing this?

Cheers,
g2


7
Black & White / Re: Black and White Landscapes!
« on: November 11, 2013, 06:04:36 AM »
Thank you Krob78 and Mr Bean :)

Playing around with some Antelope Canyon shots from a couple of years ago...people typically accentuate the colors, thought I'd try something different.  Hopefully I didn't go overboard  ;D

Awesome! Amazing shades in these.

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Black & White / Re: Black and White Landscapes!
« on: November 09, 2013, 12:24:52 PM »
Few from me :)




Seascapes okay?







Cheers! :)

9
The spectral sensitivity curve of digital and film are fairly different (and films differ widely, too, which is why there were so many types available).   The CFAs differ between cameras, too, so you'll even see differences between converted dSLRs of different models.

Thanks.
Possible to develop filters matching some film frequencies to emulate the same look?

10
The AA filter blurs the image to remove moirĂ©.  Noise is introduced later in the image chain, at the sensor and after.  Fine detail tends to mask noise, actually.  I expect you're seeing the aliasing that results from the reduction in strength of the AA filter (AA = anti-aliasing, after all...).

Thanks.
That makes perfect sense, noise is generated by the sensor (and not present in the scene) so AA filter would not make any difference.
I just found the pics had more noise than from my ex 30D, guess it's just the 18mp sensor.

One more question.
When I see pics taken on film they seem to have different colour tones when compared to digital, is it anything to do with film being sensitive to IR (and UV perhaps) and distorting the colour a bit? We can see the colours being distorted in the example hgraf has posted.
Does that make sense? Sorry late Friday night and have had a few ;D

Cheers ;D

11
Half correct.  Literally!  ;)  The AA filter is actually a two-part filter, with separate horizontal and vertical filters.  The horizontal part is in the 'outer' stack (which vibrates as part of the self-cleaning sensor) - that's removed as part of the conversion.  The vertical part of the AA filter is fused to the CMOS sensor itself (along with the microlenses and CFA), and is not removed with the conversion.

 ;D ;D Thanks.

Wold removal of half of the filter result in more noise in pics?
AA blurs fine details a bit so I'm guessing it would blur the noise too and make pics appear cleaner.

12
One question.

I mentioned the images from my converted cam seemed crisp with more noise, my assumption was that when they replaced the hot mirror filter with a clear glass filter the anti aliasing filter was removed as well, I assume it would be part of the hot mirror filter.
Is this correct?

13
@hgraf
Thanks for all the info mate :)

Funny, this post was started in September last year and is generating interest now ;D
All info is still appreciated of course.

14
Some pics from my end.
Not shot anything in ages and I miss it so terribly  :(
These were shot a while back.

Cheap 720nm



Cheap 720nm



UV-IR



Tiffen Red (600nm or so)

15
I got the full spectrum conversion done from lifepixel, pretty pleased with their service  :)

I like the IQ I get from the camera, pics are nice and crisp, noise seems a bit more, not sure if these are due to the conversion or just the output from a 600D in general as I bought it and directly sent it in for the conversion.

You need to custom WB everything, auto WB will not work, also I have read that the phase detect AF won't work in IR very well as the cameras are calibrated for visible light and IR focuses at different wave lengths, contract detect (the slow live view focus) works fine.
 
I use the MaxMax UV-IR cut for visible light and have Marumi 700nm, Tiffen red (around 600nm) and a cheapo 720nm for IR  :)

I wouldn't touch the insides of the camera myself and what you have mentioned about the screws is very scary indeed.

Liepixel sells only the filters for DIY conversion but they cost 2/3 of the cost of the conversion, check them out if you are in need of the filter only.

Cheers,
g2

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