Best & Worst Cameras for Conversion (Updates Welcomed !)

[KhanhDam]

 

[KhanhDam]

well confirmed a7r II has IR sensor shutter
post # 60 describes how to cover the IR sensors 
Sony a7RII Astronomy + Cooling Modification (2-in-1) - Page 3 - DSLR, Mirrorless & General-Purpose Digital Camera DSO Imaging - Cloudy Nights
 

 

Hacker's Guide to a Full Spectrum Modification of the Sony A7R II

 

Results:

646 second (10.77 minute) Bulb exposure at ISO 640, followed by the same image with the exposure cranked up many stops.

 

Out of camera:

Exposure boosted:

 

As you can see, no IR spill. The reason for ISO 640 is the fact that this camera has dual gain amplifiers with a linear noise response. The second amp starts (effectively) at ISO 640, and noise is linear with gain. So if you expose at ISO 640 and boost in post to ISO 6000 you will get the same noise profile, however you will keep from blowing out any highlights in your image.

 

Problem:

The A7R II as well as almost all cameras in Sony's A7/9 lines use Nidec-Copal shutters that make use of an IR optocoupler to keep account of the actuation of the bottom shutter curtain. This sensor, positioned inside of the shutter mechanism, shines a continuous beam of IR light that reflects its way around the inside of the shutter, finally spilling forth from between the housing of the shutter frame itself. Quite literally from between the shutter curtains. As the shutter is located proximal to the flange, no amount of baffling around the sensor inside the camera will have any effect. The light source itself will always be in front of the sensor.

 

One possible solution would be to completely block off this component and use full electronic (silent) shutter, however this mode is capped at 30 seconds and no BULB mode is available. If you are a terrestrial photographer looking to do sub-30 second IR photography using either internal or external filters, then you have a relatively easy solution, friend: the optocoupler needs to be popped out of the shutter mechanism, some opaque tape can be jammed inside it, and then it can be taped up and tucked into a convenient spot inside the camera frame (there is such a location directly below the shutter box on the grip-side of the camera, and the cabling is long enough to allow this).

 

If you wish to do a full-spectrum mod for astrophotography and need access to BULB mode, then unfortunately this optocoupler must be preserved. For some reason, even in electronic front curtain mode, the camera needs to actuate both curtains. In full mechanical shutter mode there are a total of three mechanical actuations. So, how the heck does one get around this?

 

Method:

In this case, for a full-spectrum modification, we need to find a way to block all light spill coming off of the optocoupler - inside the shutter

This requires that a light seal be created, however it also needs to accommodate for the fact that a portion of the bottom curtain needs to actively move through it.

Not a great situation, eh!

 

However, it is not insurmountable. The hack involves some of the foamy double sided tape, black electrical tape, and a sharp craft knife.

Note: the aspect ratio of the images got mucked up for some reason, if they display weird that's whats up.

 

First order of business was to fill the gap below the lower shutter curtain, to stop light from leaking out below. I didn't bother to test which end of the optocoupler was the emitter, and I'm not sure it matters.

 

Next step was to cut a piece of the double sided foam tape that would isolate the optocoupler but also provide a consistent area for the shutter curtain below to move beneath. If there are any edges to the tape that the little fins on the curtain could grab onto it would literally gum up the works. Here it is pictured with it's red plastic backing intact so you can get an idea of the shape. The top side of this tape will be adhered to the top frame of the shutter mechanism.

 

Now we are going to re-purpose a little piece of the camera. During disassembly, on the side of the camera with the ports you will notice a small piece of shiny black plastic that is attached to the top two internal frame components with a little adhesive. It features a hole that provides passage for the screw that attaches the outside frame (beneath the audio port flap) to the internal frame). It is perfect for our purposes: thin, black, and low friction.

 

A section of this plastic is cut out to match the shape of the foam tape, as it will be stuck to the bottom of the double sided foam and make contact with the shutter curtain beneath it. Note, rather than cutting out a notch for the optocoupler we instead cut a T to create two lateral flaps. These will be folded up in between the notch in the tape, with their top edges resting on the top sides of the optocoupler. This will stop the tape from gumming its way into the optocoupler, but more importantly this plastic will provide a low-friction surface for the shutter curtain to slide against. The little flaps cut will also prevent the fins on the shutter curtain from grabbing onto our little light seal, as they will provide a smooth curved surface for the fins to slide beneath.

 

This little addition gets stuck to the inside top of the shutter assembly. It will press down onto the shutter curtain enough to stop light from leaking out, but will also permit the curtain mechanism to slide easily beneath it at the end of the exposure. It is important that it is shaped in such a way that it does not impede on any other areas of the inner workings, such as the other half of the bottom curtain's actuator.

 

Here you can (kind of) see edge-on, where it the little flaps fold up into the alcove created for the optocoupler in the tape.

 

Here it is assembled. Note: I covered mostly everything after with some black electrical tape, save the curved windows that allow the free movement of the curtain actuators (the grey plastic rectangular posts. I forgot to upload an image, but use your imagination.

 

All in all, this proved the first successful method I encountered that didn't require the battery to be ejected after each exposure. It required some iteration to get right, and multiple tries opening up the camera. The whole exploratory process probably saw it disassembled 20 times with multiple contraptions tested, haha!

 

But, problem: SOLVED.

 

So naturally I'm going to completely undo this hack, and try adding in a filter from a different camera to see if I can find one that is able to successfully block the specific wavelengths of IR spill from the shutter. This will likely provide a more workable solution for astrophotographers, but it is cool to know that a full spectrum Sony (other than the A7III) is possible!

I hope you had fun reading this, as I had fun hacking it!

 

[KhanhDam]

further down on the above web page it states that the A7RII shutter was updated to the same one used in the A7III at some point. This has been verified by this tear down of this camera. Seems like easiest solution is to just have any company that is doing the full spectrum conversion to swap out the shutter unit which is about $135, or do the foam tape hack above.  the shutter is under the sensor and takes maybe 10 more minutes to swap out.   Now I understand why people say this camera MAY have an IR issue, because it depends on the shutter put into the unit. 
 

Want to see something amazing? A dissected A7R2 with a 3360... 

http://leojar.blogsp...bit-by-bit.html

[KhanhDam]

 

 

apparently the gh4 full specgtrum + 25mm 0.95 lens does well. it's the only fast glass I've seen used for uv above video goes over how he filmed it.

 

[Andy Perrin]

I doubt that lens is passing a lot of UV. He's showing his inexperience with UV shooting, going for the fastest possible lens rather than the one with the best transmission. Also, despite what he said, I think he has a bit of IR contamination in there, although it's hard to be sure without knowing the white balance.

 

Nearly all lenses pass enough UV to get flower patterns and show sunscreen is dark. 

[ulf]

Going for fast lenses instead of lenses with good uv-transmission is a very common error made by newbies to this art.

 

It is true that most fast lenses or complex modern zooms transmit some upper UV and can give some UV-images.

 

I get AF to work with my EF 70-200L 4.0 IS and even the old FD 85/1.2 aspherical with all thick lens-elements and SSC-coating, pass usable amounts of the very top UV-A band.

However both would be really lousy for proper UV-work with a wider palette of false colours.

 

[KhanhDam]

If you watch video he shows a old common 35mm 3.5 lens so he did some homework. Besides it worked to make his very interesting video and he got tons of views so kudos to anyone that promotes uv imaging 

[Andy Perrin]

The 35mm/3.5 is labeled as a Kuri "clone" so probably one of Iggy's frankenlenses. I have no idea why he went with the Voigtlander lens since I would think the Iggy monster would have worked better, but perhaps he just liked the autofocus and didn't care if the result was monochrome.

[dabateman]

1 hour ago, Andy Perrin said:

The 35mm/3.5 is labeled as a Kuri "clone" so probably one of Iggy's frankenlenses. I have no idea why he went with the Voigtlander lens since I would think the Iggy monster would have worked better, but perhaps he just liked the autofocus and didn't care if the result was monochrome.

His Voigtlander Nokton 25mm f0.95 lens is manual focus and is a type 1 lens. This lens is very soft wide open, he most likely wants to get his money worth out of it, using it for many projects. 

Its 11 elements in 8 groups. I am not sure what the transmission would be, but the type 1 didn't have great coatings, or any at all. Its possible its great for 370nm and up with a 350nm glass cut off. Or its crap and the fast aperture is saving him. I am not sure, I would like to see someone here test it.

But I still can't afford one.

[KhanhDam]

What’s an iffy Frankenstein?   He probably used the 0.95 because the bokeh looks nice. The nice thing about video is grain and lens issues are less noticible

[colinbm]

Some people use derogatory terms for this lens.
Igor has purchased & refurbished these 35mm f3.5 lenses that have the same optics & are good for UV photography in UVA light.
We should be grateful for Igor for doing this for our hobby.
Search on eBay for this eBay item number: 273863933139
 

[Andy Perrin]

I don’t like it because he has cornered the market on actual Kuri lenses and is now selling them back to us at a profit. I would rather the Kuris, which were once inexpensive, were still around. I am certainly not grateful to him. 

[colinbm]

Andy that is so unfair.
There are many people that have horded many copies of the Kuribayashi 35 / 3.5 lens to take them off the market & make them artificially expensive.
Igor sells reconditioned 35/3.5 lenses for a fraction of the price of a Kuribayashi 35/3.5, like USD142 against USD500 if you can find one to buy !
 

[Andy Perrin]

You can have your opinion and I can have mine. (Also I don't know of anyone else who has bought them up in large numbers.)

[lukaszgryglicki]

I Have his 35/3.5 lens, lens is OK. I don't know why blame him for making a business. Is it forbidden or so? Guy make a great job of creating affordable UV-capable lenses for beginners, this is good IMHO, but as you said, everybody can have his/her own opinion and that is great too.

 

[KhanhDam]

so he sells a 24mm 3.5 uv lens for aps sony nex/fuji is this lens any good? I've not run across something simialr on this site. 

[photoni]

I would also like a 24mm full format ... as good as the Soligor 35 f3.5 ... but I can't find any suggestions

[lukaszgryglicki]

I only tried full format lenses, now I even moved to medium format, but still using FF lenses, sometimes with cropping.

 

[KhanhDam]

2 hours ago, photoni said:

I would also like a 24mm full format ... as good as the Soligor 35 f3.5 ... but I can't find any suggestions TRY NIKKOR 24MM 2.8? LINK BELOW:

 

[photoni]

in fact I have a Nikkor-H 24 f: 2.8 but it is not very good like the Soligor
Today I let go of a 21mm f: 4 because it had reached €150 ... and then I really didn't need it

[KhanhDam]

There are some 24mm 3.5 old lenses on eBay I think Pentax m42 takumars? Around $100 wonder if they would be any good? Searched forum did not find any mention

[ulf]

2 hours ago, KhanhDam said:

There are some 24mm 3.5 old lenses on eBay I think Pentax m42 takumars? Around $100 wonder if they would be any good? Searched forum did not find any mention

This has nothing to do with what this thread is about. (Best & Worst Cameras for Conversion) and the question should be posted elsewhere.

The focus has drifted for quite some time in this thread now. I am also guilty of answering about non related tings here.

Please start a new topic fo such questions in the future.

 

It all depends on how you define "good"

Do not expect anything like the "Kuri" or old Soligor 35/3.5 performance. An old 24mm lens will be quite far from that.

 

The general trend for accidentally UV-capable lenses is that below 35mm they become increasingly less capable.

A 35mm lens can have a rather simple design formula with few and thin lens elements.

 

Shorter FL demands a more complex design, with more lens elements to bend the incoming light more and give a usable back flange distance with a retrofocus-design.

http://camera-wiki.org/wiki/Retrofocus

 

There are three things that limit the UV-reach in lenses.

1. The glass material. Some types of glass do not transmit UV well. Some modern glass types tend to be worse in that respect.
2. The thickness of lens elements, especially if the glass has bad UV-performance. (equivalent to different thickness of filter glass of the same type)
3. AR-coating. Coating improves transmission in the wavelength range it is designed for and normally decrease transmission outside that range, more so with modern types of multicoating. (older types of coating like on the old "Kuri", Soligor and EL-Nikkor lenses seam to be OK. For specialised lenses going really deep there cannot be any coating at all.

[photoni]

3 hours ago, ulf said:

This has nothing to do with what this thread is about. (Best & Worst Cameras for Conversion) and the question should be posted elsewhere.

 

 

@ulf You're right, back to the dilemma:

 

For me, ultraviolet photos are not a job ... it's just a hobby
I would probably need a Sony A7 that works well ... mine has many problems.
Yesterday I saw a used one for sale with two batteries for € 350.
Basic conversion is 169€   LINK , it seems to me a reasonable price.
.
For convenience (and my little memory in finding the buttons and functions)

it would be better my Nikon Z5 that I use very little (for work I use the Z7)

conversion with filter <300nm is 269€ LINK

[Yves W]

Interesting link for EU, Thanks Antonio

For Fuji prices comparable to those of Sven Lamprecht IRreCams.de