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Old 26-08-2016, 12:44 PM
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pluto (Hugh)
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Advice regarding full spectrum mod to A7s

Hi all,
I've been considering getting a full spectrum mod done to my A7s and I just wanted to ask if anybody here has any experience with full spectrum modded cameras.

Specifically I want to make sure I can still shoot "normal" visible light images using a filter like this: https://www.lifepixel.com/shop/filte...pass-filters-2
And, assuming the shop that does the conversion gets the correct type of replacement filter, I should still have good autofocus?

I emailed Whiltons Camera in Sydney but they haven't replied (in well over a week!) so I'll probably chase them with a call next week. I've contacted "Sydney Camera Repairs" in Ashfield and they've quoted me $600 including the replacement filter.
I know there's a reputable camera shop in Melbourne which does these mods but I'm trying to stay local if I can.

Anything else I should be aware of?
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Old 26-08-2016, 03:59 PM
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Hi Hugh.

I havd had my a7s full spectrum modified in the USA. I got both fulters removed, just leaving the cover glass on front of the chip. I didn't get a quartz glass instalment to preserve the refractive index for auto focus, instead, the chip was moved. Auto focus works on both my lenses, although the infinity focus mark has changed.

I bought a hot mirror filter from kolari vision so i can still use the camera for normal daylight photography. The only thing that is a bit of a pain at times is the dust that gets on the chip when changing lenses. When both filters are removed, the auto sensor cleaning function goes add well. So now I'm just carefull when changing lenses and i keep cleaning equipment in my camera bag for when dust spots start to be a problem in photos (usually only at high f numbers).

Regards, Josh
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Old 26-08-2016, 04:18 PM
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Not to put a dampener on it but are you sure a Sony A7S is ideal for DSO work in the first place before you invest extra $s?

Sony has a poorly implemented hot pixel suppression algorithim much like Nikon had for years that damages long exposures. Also the noise suppression algorithim leaves wormy looking grain.

Sony has class leading sensors but its the little things like that they lag in.

If I were getting a camera for DSO imaging I am not sure an A7S is it despite its high ISO performance (lots of cameras do ISO6400 these days anyway).

I have seen some bad examples of the star eating algorithim that kicks in when you use Bulb. Up to 30 seconds it doesn't.

If you have seen excellent A7s images please link me in case this data is not correct. I have read several threads about this issue.

Also with these ASI1600's being so cheap and working so well it does not seem bang for buck and probably no filter will give you good daylight performance. I had a clear glass modded 20D and XNite CC1 filter and the filter partially corrected but not really. So it still was only useful for DSO work.

Greg.
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Old 26-08-2016, 08:05 PM
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pluto (Hugh)
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Thanks for the info Joshua.

Greg, I already have the A7s and I also have a STT8300m for proper DSO stuff.
I'm thinking of getting it modded partly for a bit of extra Ha sensitivity for widefield stuff and partly just to play around with IR, and maybe UV, photography.
I've definitely seen the wormy noise you referred to. Thanks for the input
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Old 27-08-2016, 06:57 AM
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Mark at JTW Astro might be able to help, he's very knowledgeable and knows of other issues like preserving focus for terrestrial lenses.
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Old 27-08-2016, 07:53 AM
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Quote:
Originally Posted by pluto View Post
Thanks for the info Joshua.

Greg, I already have the A7s and I also have a STT8300m for proper DSO stuff.
I'm thinking of getting it modded partly for a bit of extra Ha sensitivity for widefield stuff and partly just to play around with IR, and maybe UV, photography.
I've definitely seen the wormy noise you referred to. Thanks for the input

My A7r2 works quite well but I hope to see future improvements in this area.
I suspect one way to beat the star eater algorithim is to make sure your exposures are long enough so the signal isn't mistaken for a hot pixel.

One thing to consider is the thickness of the stack.

I've read about a Kolari mod which is a thin stack (glass on top of sensor). That may be more for the A7. But worth finding out about.

Greg.
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Old 29-08-2016, 08:47 AM
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Thanks for the info guys.
One more question:
If I want to image with "normal" colours plus Ha, like what one would get with an 810a or 60Da, would I just put an "L" filter in the train?
Like this one: http://www.bintel.com.au/Astrophotog...oductview.aspx

In fact can I just use that "L" filter instead of that LifePixel or Kolari hot mirror filter? It seems that they basically do the same thing except I assume the "L" filter will pass more light at Ha wavelengths...?


FYI just got off the phone with Whilton Camera Service in Sydney and they won't do the mod. Strange as I thought I'd seen someone on here mention that they'd had theirs done buy them... perhaps not a Sony A7s though...

Last edited by pluto; 29-08-2016 at 09:32 AM.
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Old 29-08-2016, 02:11 PM
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If you use a L filter in the train, asuming its a sharp cutoff where the IR spectrum begins, you are going to get to much red in your image. If you use a kolari vision UV/IR filter like the one i mention before, you're not going to get the Ha in your image.

i can recommend the HEUIB -II filter. 3rd one down on this page... it lets in normal visible and ha... while nog being too red. It can also be usdd for normal daylight photography.
Ot only works with canon mounts though... if you use an e mount to ef mount it will work in the ef part of the lens adapter.

Josh
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Old 29-08-2016, 05:03 PM
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pluto (Hugh)
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Quote:
Originally Posted by Joshua Bunn View Post
If you use a L filter in the train, asuming its a sharp cutoff where the IR spectrum begins, you are going to get to much red in your image. If you use a kolari vision UV/IR filter like the one i mention before, you're not going to get the Ha in your image.

i can recommend the HEUIB -II filter. 3rd one down on this page... it lets in normal visible and ha... while nog being too red. It can also be usdd for normal daylight photography.
Ot only works with canon mounts though... if you use an e mount to ef mount it will work in the ef part of the lens adapter.

Josh
Thanks for that info Josh!
When I use the A7s with my WO71 I do use an eos adapter and a Canon t-ring so I can screw it in there. Also the second one on that list, the 52mm, would be perfect if I want to so some widefield stuff with a lens.

Cheers,
Hugh
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Old 30-08-2016, 01:33 AM
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I guess you could use a Tring and eos to e mount adapter.
The 52 mm filter on that list looks good... its the same filter in terms of light transmission except it screws on the end of your lens whereas the one i linked to goes in the adapter... what ever suits.

However, and I made this mistake, I bought the 52mm filter to use on my widefield lenses and it will vignette a little, but the main thing is the wierd colours you get when using the 52mm filter on the end of the lens.

Its to do with the angle that light hits the filter before entering the lens. When the filter is inside the adapter as it is with the 3rd filter on that list, there is not a problem. It becomes sn issue with FOV above about 60 deg.

I'll find a paper on it for you later... I had these issues, then i bought the 3rd filter on that list. So if you do want the 52mm filter, i have one for sale

The alternative is to use another adapter (which I also bought trying out different things) where the 52 mm filter slots in... its a sony e mount to ef mount with a 52mm filter holder. I also have that for sale haha... might not be an issue to use when on a telescope, but i wanted to use a lens with aperture control and this adapter has no electronic contacts.

In the end I bought the 3rd filter on the linked to list.

Josh
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Old 30-08-2016, 08:51 AM
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Hey Josh,
I might be very interested in the 52mm and the e mount to ef adapter!
I don't plan to do any astro stuff wider than with my 35mm and the FOV is about 55deg on that. That 35mm is also a 49mm filter so I can just use a step-up adapter to get to 52mm.

I'll let you know soon as I'm just about ready to pull the trigger and get it done - just waiting for the shop to confirm if they can retain autofocus for at least one of my lenses, and they're soooooo slow to reply to emails...


So just to lay out my thoughs:
I'll get the full spectrum mod.
I'll get a Kolari hot mirror front-of-lens filter for everyday stuff.
I'll get some IR, and maybe UV, filters for fun.
And I'll get a HEUIB -II filter for visible+Ha astro stuff.

Any red flags?
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Old 06-03-2017, 11:36 AM
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Just thought I'd post an update on this in case anyone is looking into this stuff in the future.

I finally got the full spectrum mod done on my A7s. I initially took the camera to a place in Sydney called Sydney Camera Repairs in Ashfield but they screwed me around a bit. They got the replacement clear filter in and had my camera for over a month but didn't get around to doing the mod. Anyway I got the camera back from them, and a refund, and I took it to Camera Clinic in Melbourne. They did a good job and I've been playing with it for a couple of weeks now.

I haven't had a chance to use it for anything astro related yet but here are some notes so far:

- I've only tried one lens with autofocus (FE35mm f2.8, this was the lens that was with it when they did the mod) and autofocus works fine and is accurate.

- On that lens I've got a front of lens hot mirror filter from Kolari and with that I get images which basically look normal - that is, like they did before the mod.

- I wasn't expecting to be able to take shots with no filter at all as I assumed that the lenses wouldn't be able to sharp focus the whole spectrum. However, especially when shooting/converting to black and white, the full spectrum images are excellent.

- I got a couple of these adapters with slide in filter trays (EF to E and Ai to E) - thanks to Josh for bringing them to my attention!! - They let you put 52mm filters behind any Canon or Nikon lens when using them with a Sony E mount camera. Very useful especially as I only have to get filters in 52mm that will work with many of my lenses. The EF one will be particularly useful when I want to attach the A7s to my scope.

Here are a few images shot with it. The first 2 are full spectrum and the second 2 are with a 760nm IR filter.
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