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Triumph guy66

6d mod problem!

23 posts in this topic

Morning. I'm wondering if anyone can shed any light on my problem. I had my eos6d modded or astro and daytime use. Tried it last night with very unexpected results. 6d plus 4x power mate and field flattened on 100ed ds pro. light pollution is quite bad. I tried a cls clip filter but problem remained. Many thanks

20170420213830_IMG_0076.JPG

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Posted (edited)

Hi. Maybe reflections in the barlow, something isn't square or WHY. Maybe best without it. Could you post two flat frames?

1: Attach a Canon lens, set to Av and point at even daylight sky.

2: Same but attached to your telescope with the same orientation as you took the original snap. 

Edited by alacant
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Why do you need the Powermate?

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I'm at work currently but should be able to sort something tonight . Here's another ive downliaddd off the camera just now without the power mate and with a field flattener. Shorter exposure time with  higher iso. I've noticed with lower iso and longer exposures the problem gets exponentially worse

20170420220523_IMG_0085.JPG

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Yep looking much better. Maybe something not quite square, but otherwise fine. Just lose the barlow;) HTH.

capt.JPG.a0a0e634ccda6c17196932877c68c6f3.JPG

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I need the power mate for the magnification especially as I'm using full frame. ( I know bit of an obvious answer sorry)

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Here's a shot with longer exposure lower iso. It's the shape of the vignetting that's bothering me. Lower left has a square shape almost like theirs either reflection bouncing back or somethings out of line

20170420221055_IMG_0087.JPG

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Elimination... So it's not the barlow. Do you have  a shot without the ff? Everything looks offset to the left. Does a laser or a pinhole with a torch shining through centred in the focuser hit the centre of the objective lens? Is your camera heavy enough to misalign the focus tube? HTH.

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By ff do you mean focal reducer? The shot with the Barlow didn't have the focal reducer on. The camera is heavy and extended quite far, though it was the same before the mod. Vignetting has always been a problem without the reducer  but never suffered from the squaring. Maybe I should send a shot to andy at astronomiser, he did the mod

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6 hours ago, Triumph guy66 said:

Morning. I'm wondering if anyone can shed any light on my problem......

20170420213830_IMG_0076.JPG

....I think you discovered a new comet!

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Have you blanked off the dslr viewfinder, as extraneous light gets in there?

Michael

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New comet? Great, will they name it after me😁. Have done a leakage test and it's not the cause. Seems to be light pollution I think coupled with the 4x power mate.  also getting bad coma too. Fine during planetary just long exposure dso

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On 21/04/2017 at 09:47, Triumph guy66 said:

Morning. I'm wondering if anyone can shed any light on my problem. I had my eos6d modded or astro and daytime use. Tried it last night with very unexpected results. 6d plus 4x power mate and field flattened on 100ed ds pro. light pollution is quite bad. I tried a cls clip filter but problem remained. Many thanks

20170420213830_IMG_0076.JPG

Light leakage from the LCD back light (if you have not set it off when taking an image) or through the view finder if you did not cover it. Both of these will only show up in longer exposures and generally appear red tinted, just like what you are seeing. 

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It's a known issue on the Canon 6D though the exact cause seems to be a matter of debate.  In any case, the solution appears to be to switch off liveview and/or silent shooting:

https://www.cloudynights.com/topic/466027-filter-mod-eos-6d-extraneous-signal-in-live-view/

https://www.cloudynights.com/topic/545012-weird-bloom-problem-canon-6d-and-astronomik-uvir-clip-filter/

You can easily test it by taking long exposure darks.

Mark

 

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Have you tried to take some images with just lenses or without the powermate insitu through the scope?  My own thoughts are that I would ditch the powermate for now and try some imaging at the telescopes native focal length first.

 

Mark

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Just my 2 cents; you really, really don't want to be doing DSO imaging with a 4x powermate. This means you're imaging at F/36, which would require extremely long exposures and very accurate tracking.

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Posted (edited)

Some good replies there thanks. I'll try the live view off. I do use it in order to use the WiFi remote on the smartphone. I've already decided to ditch the power mate for my next session and compare use with and without the field flattener . I've not heard of this being a know problem despite a good while googling, a relief in some respects. as for shooting at f36 shibby it's not such a big issue as the light pollution prevents me from exposures longer than a few minutes even with a cls clip. I did try some dark shots after I contacted the guy who moddel it so we could rule out sensor damage. Came out fine. Though when I took darks outside at the same time as the shots I've posted,  the effect was visible on the darks with the lens cap on, I later took some inside but stuck a wooly hat over and they were fine (though the camera had probably cooled a bit which could have an effect)

Edited by Triumph guy66

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Further note. Remembering when I took the darks inside I will have disabled the remote app which will have turned off live view.

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. as for shooting at f36 shibby it's not such a big issue as the light pollution prevents me from exposures longer than a few minutes even with a cls clip. I

he means you're using it at f36 and would  require about an hour exposure to get the same data as a minute exposure without one( maybe slightly exaggerated)..a Barlow is for planets where you be doing a high frame rate minute exposures with a ccd type camera..with dso you need long exposures..

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While I'm going OT here with this reply, this is one of the issues you start hitting when fighting LP. Basically for RGB DSO you'll want fast optics (f4 or faster with a dslr can give some great results) & short subs. Otherwise as you've seen LP saturation becomes a big issue. A power mate or Barlow will just kill your chances let alone give you some serious vignetting issue, especially with a full frame sensor. You'll have this with your frac anyway as it won't fully illuminate your sensor so will need flats. The other type of imaging to combat LP is Narrowband, but not so easily done with a dslr. Really this is mono CDC territory. Lots of threads on here so have a trawl about.  When I used my 1000D (ok not full frame) it was mainly with the 80ED & a 2" IDAS LP filter in the FF/Reducer which gave me reasonable results upto 5 mins. But it depends on the freq. of the LP.. these days more LEDs are broad spectrum & just worse than the old sodium which I wish we still had around me!

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Thanks for the replies, much appreciated. I understand the relation between aperture and exposure time as I've done long exposure daytime for a few years (or does lp data increase exponentially in relation to object data I  regards to exposure time or Is  it purely a matter of tracking plus upstream and downstream noise ratios? In still at the novice stage so there's no doubt a few obvious things I'm missing). I find I can manage subs of several minutes (binning a few) with the power mate quite easily as I  regularly check polar. The vignetting doesn't worry me so much as down the line I'll be adding flats etc. I also understand the basic problem with colour, the Bayer matrix. I'll be ditching the power mate for dso however as I realise it's pushing things too far, wasn't a huge issue before the mod but the added sensitivity is obviously wreaking havoc on my sensor.

  Does anyone know of a reasonably priced white balance correction filter 77mm? I can buy a clip but that's far from ideal for daylight. Ir filter I presume is what I need

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If you shoot in RAW then you don't need to worry about white balance as it can be corrected in software by aligning the histogram.

The only filter that will help is a CLS type filter to help eliminate light pollution.

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I do shoot in raw yes.  the filter is for daylight use.  I've not processed any shots yet taken in daylight and I'm well versed in light room but looking at the shots I think it will be difficult to get an accurate adjustment as it's not just a case of the colours being warmer or cooler, the mod allows a different part if the spectrum through . Hopefully I'll be proven wrong on that

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