Testing Sony A7S for leaks and internal LEDs

[Avalon]

So any reliable filter replacement window sellers?

[ulf]

Why not try the Aliexpress source you already found?

 

The market for DIY conversion windows is not that big and it might be good enough.

At least you will get a feeling of how to do the conversion.

 

Be careful and work systematically and slowly.

Get all tools needed before you begin and prepare the working area. Clean the working area sa much as you can.

Store small parts from the camera like screws from each disassembly step in individual compartments. There can be many different types.

Sometimes it is a good idea to take pictures with your phone during the process if the guide pictures are not enough.

 

Sometimes a long strip of double sided tape can be used to hold small parts and keep them in the disassembly sequence.

That makes the assembly much easier

I you do that a big warning is that when pulling off tape from a reel it can generate much static electricity that can kill electronics.

 

By the way do you have any experience with cleanroom procedures?

As you are attempting a conversion with a replacement window it is extremely important to avoid trapping any dust on the sensor's window and the inner side of the replacement window. You cannot clean them off afterwards and noise blobs on your images can be very frustrating.

I have worked in and visited many cleanrooms during my career so I knew rather well how to prepare and work when converting my Canon 60D.

I trapped only a few very small dust particles. If you make a mess of the conversion you can always take out the replacement window and add spacer washers instead.

If you are careful the camera will survive a few disassembly/ assembly sessions.

I think that the most common problem if the camera is dead after a modification is that some flex cable has not been properly inserted when the camera is put together again.

 

Another thing to be aware of is the risk for ESD damage of the electronics. 

it is a good idea to work in a ESD safe environment. That is especially true when the air indoors is very dry.

An ESD-mat and a ESD bracelet are recommended, but you  might be lucky not zapping anything.

Most soldered circuit boards are reasonably tough, but in industrial production and assembly those measures are always used.

I must confess that I cheat on that some times, but I at least try to discharge myself against the grounded parts of what I am working on before proceeding.

[ulf]

2 hours ago, Avalon said:

So any reliable filter replacement window sellers?

https://www.lifepixel.com/shop/filters/internal-diy-filters/sony-internal-diy-filters

For your camera it is $199 + shipping and possibly customs and VAT if you have to pay that in your country. 

[Avalon]

  I'm having second thoughts about adding a window. Maybe it's not worth adding since there will be light loss due to reflections. So moving the sensor to 0.5 - 0.6mm closer to the front will be enough? Infrared spectrum should have a longer focal range, UV shorter.  

 

I have converted multiple camera's such as Sony A3000 but I expect A7s to be packed tightly with more complex electronics.

[ulf]

4 hours ago, Avalon said:

  I'm having second thoughts about adding a window. Maybe it's not worth adding since there will be light loss due to reflections. So moving the sensor to 0.5 - 0.6mm closer to the front will be enough? Infrared spectrum should have a longer focal range, UV shorter.  

My first guess of 0.5-0.6mm was a bit conservative. Sorry about that. You need a bit more distance.

 

Based on the statement from the seller at Aliexpress that a window thickness of 1.5mm fused silica would be OK for your camera I have done calculations that give the difference in optical path length to without any window.

A forward shift of the sensor of 0.69mm is needed.

For the calculation I used a refractive index of 1.46. The value varies with wavelength. 1.46 is for 600nm.

 

There would not be a big problem if you could set lenses a bit beyond infinity, so thick enough is OK to make sure all lenses reach infinity. 

[Avalon]

Is replacement window really important? If I leave air gap with replacement window there are going to issues with reflection loses. 

[ulf]

9 hours ago, Avalon said:

Is replacement window really important? If I leave air gap with replacement window there are going to issues with reflection loses. 

IMHO adding a replacement window is not at all important and can cause more problems than benefits.

 

The reflection losses in general is relatively small (ca 9%) but you also increase the risk for increased hotspots and similar problems.

I listed all pros and cons I thought of in my first answer in this thread.

One con for adding a window that I did not list there is to find and pay for and wait for a window that you know works correctly.

 

My guess is that you are doing the conversion yourself to save money and for the fun and challenge of doing it.

The cost for not buying a window is $0, but you have to get some extra spacer parts.

 

If i should do that no window conversion and creating spacers, I would either

print them with my resin printer with 50um pixel resolution using a good stable resin.

or find some brass metal 0.7 - 0.75mm thick, like a big good washer or sheet metal of that thickness and drill 1.8 - 2.0mm holes and file to a a suitable proper shape.

It is very important that the three added spacer parts are really flat and of the same thickness. 

[Avalon]

Ok, so I have disassembled Sony A7s and removed the sensor module from the camera chassis. But I'm not getting how adding spacers could shift the sensor closer to the front, opposite can be done by adding them. I see three brass spacers I marked in the photo which removal could shift the sensor up front by 0.4mm. Not sure what else I can do, maybe I'm looking in the wrong place?

[dabateman]

That sounds right. You want to remove them, to move the sensor closer to the camera mount, to compensate for the removal of the coverglass. 

[Avalon]

Not sure how to achieve ulf recommended 0.7mm forward sensor shift, removing 0.4mm thick spacers wont achieve this.

Wont missing dust shaker cause malfunction of camera?

[Avalon]

Good news, I was able to convert Sony A7s to full spectrum :) I was afraid I damaged the camera since it did not turn on but I later learned that I forgot to lock the flex cable that was connecting the upper body that contained the power button.

But now indeed I can't focus to infinity with a Minolta f/1.4 manual lens. Sony 50mm f/1.8 lens can sometimes autofocus to infinity but in manual mode it cannot. So I will need to add glass to compensate for that.

 

In the astronomy forum a guy suggested I should multiply the original filter stack thickness by 0.3408. Also he mentioned that I should use clear glass with BBAR coatings 20/10 surface quality minimum. Is this correct suggestion and what type of glass as well as coatings I would need to correct focal distance? Those lowest reflection green color AR multicoatings are bad for UV/NIR photography?

 

[Andy Perrin]

Avalon, the LifePixel people sell the full spectrum glass pre-cut to the right thickness for A7S and you can just buy it from them. They will sell you just the glass, you don’t need to pay for any other services. 

[Avalon]

  I have a hard time finding such a clip-in window for a Sony camera. I could of course just order a glass window alone but where will I find the clip-in window? Or just glue it to the camera?  

[Andy Perrin]

No, you put it in place of the original IR blocker. It isn't something you clip in, and it's not meant to be removable.

[Avalon]

So I finally got a fused silica 2.4mm 20/10 polish quality window that I decided to order from a company in my city. Kolari Vision said that a 2mm thick window is more than enough to fix focus distance. I ordered an uncoated version since the coatings are not only expensive but also are not resistant to mechanical cleaning. 

Now I plan to glue that window into my A7s and wanted to ask how to clean surfaces without causing any damage? while removing glue residue from sensor some of it got on visible part of glass. Visible part of glass also seems have to less reflectivity than corners indicating AR coatings? Can I use pure ethanol or acetone to clean the glass? There is nice polymer called First contact that cleans well optical surfaces without risk of scratching.

[ulf]

I would avoid using acetone if there are other sensitive materials near by as acetone is quite aggressive to many organic materials.
I think pure ethanol is better.

Otherwise acetone is a good solvent for cleaning many coated glass surfaces.

I worked for a period of time as a design engineer at a company designing and producing specialised optical devices.
During a training period as all new engineers had to do, I learned to assemble one of their main products in the cleanroom.
One of the final steps in the process was to clean up the internal ar-coated lens elements from some very special glue that sometimes got astray.
We then used acetone on cotton tipped long pins.
The trick was to work from the center outwards to avoid smearing more glue onto the active area of the lens and use many tips, discarding the used ones often.

Beside the lens and glue there was only tough hard-anodised aluminium close by.

[Avalon]

Acetone is bad for AR coatings? Maybe I can use some liquid between sensor glass and fused silica window to reduce reflections?

[ulf]

21 minutes ago, Avalon said:

Acetone is bad bad for AR coatings? Maybe I can use some liquid between sensor glass and fused silica window to reduce reflections?

That is NOT what I said!
I said that we used acetone on AR-coated lenses without any problem. Those coatings were of modern type. 

HoweverI would not dare to use acetone on some very old types of early coatings, as they might be more sensitive.

The same goes for some very sensitive front side coated metallic mirrors as thin layers of metall are much more sensitive.

 

Normally many AR coatings are quite durable.

[ulf]

32 minutes ago, Avalon said:

Maybe I can use some liquid between sensor glass and fused silica window to reduce reflections?

It will be quite difficult to contain the liquid and make a good seal at the edge,

 

For filters I have experimented with glycerin between several stacked filter rounds to reduce surface losses.

It was a bit leaky liquid-wise.

Optically it worked well, even if the refractive index wasn't quite ideal.
I took something I had available with a good UV-transmission.

[Avalon]

I remember seeing "disapparing" glass in glycerin filled jar due to similar refractive index.  But it could affect focusing so maybe leaving air gap could be good idea. Does very thin layer of glycerin block UV and NIR?

[ulf]

Focussing is only affected by the optical path length so replacing air with a thin layer of glycerin would not affect that.

The main risk here is the risk of escaping glycerin in places it is not intended to be. If it migrates to the front of the window that you will need to clean from time to time it will cause a lot of problems.
Transmission-wise pure glycerine (also called glycerol) is a media with good transmission for both UV and NIR, well beyond the UV-range your camera can see.

https://www.sciencedirect.com/science/article/pii/S2666821122000187 

[Avalon]

Does it degrade, evaporate, react with air oxygen and water? what glue you used, would for example B-7000 work?

[ulf]

My setup was very temporary to measure a stack of 3(?) filter rounds to see how much I gained in reality by avoiding glass-air surface losses from 4(?) filter surfaces.

I tried to hold them together with tape at the edges, and a short bit around over the edges.

I wanted to simulate bonding filters in a stack.

I noticed that the glycerin is difficult to handle as it is creeping everywhere and wetting surfaces I wanted clean.

I never tried using it together with any glue and have no idea if that is possible. Sorry.

I would like to say that it is not a good idea with glycerin  in this application.

[ulf]

Here is the topic where I described using glycerol when preparing the temporary stack for measurement:

https://www.ultravioletphotography.com/content/index.php?/topic/4742-chinese-filters-a-positive-experience/page/3/

It was three filter rounds and thus four air-glass passages that was eliminated.

 

 

[Avalon]

Interesting result, I'll think I will try using glycerin through I imagine this is going to be somewhat messy. Not sure how adhesive would react with it, should I encapsulate it with some epoxy or silicone to seal it from air? Higher altututes or warmer temperature wont cause significant expansion? Maybe there are special gels for this purpose?

 

I also was wondering if it's not possible to move ultrasonic self cleaning on to fused silica window?