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500mm reflex lens plugin filter

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sybersitizen View Drop Down
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 17:24
Originally posted by gigo gigo wrote:

When the filter is included, the optical path length is increased by the length of the filter multiplied by the refractive index.
In other words, without a filter, the focus will not be exactly at infinity.
However, since the difference is slight and the stroke of the helicoid of the AF lens has a margin, it is rarely a problem in practice. Or no one notices.
Maybe it's just a remnant of the MF era when the amount of infinity was strictly determined.

^ That explanation is misleading. There will never be a focusing error at infinity because the lens is designed with plenty of room to focus beyond infinity. I will explain why the two filters are included, and why the clear filter is called "an integral part of the lens' optical design" in the user manual even though it's not needed. In reality, the situation is this:

1. Mirror lenses have no adjustable diaphragm, so every manufacturer pretty much has to supply an ND filter or two as a way to reduce light when necessary (and in the past often provided some other colored filters for shooting B&W film).

2. If there's a need to use an ND filter or colored filter, seeing through a mirror lens and focusing it correctly with a filter in place can be difficult... so it might be nice to consider composing and focusing without any filter, then putting it in just before shooting.

3. The presence of any filter - even a perfectly flat filter like the ones in these lenses - at the rear of the lens slightly changes its focal plane. If you were to focus the lens on something without using a filter, then insert a filter to make the shot, the subject would no longer be in precise focus.

4. The way to handle the issue above is to focus with a clear filter of the same thickness in place first. That way when you switch the clear filter for a darker filter, or vice-versa, the subject will remain in precise focus. The manufacturer tells you that a filter is always required; but it's really only a placeholder used in order to maintain focusing consistency.

5. If the manufacturer neglected to provide ND or colored filters, or you lost yours, or simply never need to use one, then the need for the clear filter completely goes away.

6. Another factor specific to the Minolta/Sony 500mm AF Reflex is that it can autofocus - even with the ND filter in place. That means that you never* have to manually focus first with a clear filter just so you can swap the ND filter in later and retain the precise focus. (*There could be a rare situation where you want to shoot with the ND filter in place, but light is insufficient for AF to work. Only then would it be advantageous to do the filter swap thing to obtain good focusing.)

Ergo... you can use the lens without any filter if you want to, and your shots will be just fine. Again, I know this contradicts what we are told. But many of us have tested this with numerous mirror lenses in general and the Minolta 500mm AF specifically. Nobody has ever demonstrated any ill effects resulting from shooting without a rear filter... as long as no light leaks through the side hole.

Edited by sybersitizen - 04 September 2020 at 17:38
 



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bharnois View Drop Down
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Post Options Post Options   Quote bharnois Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 18:39
When I looked at mine today the post for the lock broke! I took the one off the ND filter and put it on the clear.

Go easy on the lock as it isn't any kind of robust at all! It is just a metal pin pushed through a hole in the end of the lock knob.
Just luvin' DYXUM.
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Post Options Post Options   Quote Howard_S Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 19:34
I'm embarrassed but happy to report that I found my filter today. It had dropped out of the lens onto the back seat of the car, a black object on black leather.

I am interested in the idea that these parts might be 3D printed, and a winter project might be to learn how to do this sort of thing (and get access to a printer).

So here's the object, priced north of £170 (£205 with tax) on the Sony parts distributor (EET Europarts) in Europe (https://uk.eetgroup.com/i/A1199446A-Sony-A-Normal-Filter).

Howard Stanbury Instagram | Flickr | Web
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djfoxy View Drop Down
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Post Options Post Options   Quote djfoxy Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 22:06
Originally posted by Howard_S Howard_S wrote:

I'm embarrassed but happy to report that I found my filter today. It had dropped out of the lens onto the back seat of the car, a black object on black leather.

I am interested in the idea that these parts might be 3D printed, and a winter project might be to learn how to do this sort of thing (and get access to a printer).

So here's the object, priced north of £170 (£205 with tax) on the Sony parts distributor (EET Europarts) in Europe (https://uk.eetgroup.com/i/A1199446A-Sony-A-Normal-Filter).



Damn expensive for what it is...    I'd prefer to put this money in a 150x150m from Haida
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gigo View Drop Down
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 22:18
Good morning. For whatever reason, when I wake up in the morning, nothing makes me happier than solving the problem.

If you are interested in 3D Printer, I think it would be fun to put in keywords as you can think of and look at everyone's data on a data search site.

Search Engine for 3D printable Models
https://www.yeggi.com/

Have a good day.
ILCE-1, FE:14/24/35/STF/135/10400GM, 90M/24105/200600G+6, 1.4x/2xTC
ILCE-QX1, Full Sprctrum NEX-5R, E:2
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Howard_S View Drop Down
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Post Options Post Options   Quote Howard_S Quote  Post ReplyReply Direct Link To This Post Posted: 04 September 2020 at 22:26
@gigo - what a resource! Thanks for sharing.
Howard Stanbury Instagram | Flickr | Web
 



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bharnois View Drop Down
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Post Options Post Options   Quote bharnois Quote  Post ReplyReply Direct Link To This Post Posted: 05 September 2020 at 00:22
Might be nice if I could print another lock pin for my ND, I have all the metal bits.
Just luvin' DYXUM.
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gigo View Drop Down
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2020 at 06:42
Originally posted by Howard_S Howard_S wrote:

Originally posted by gigo gigo wrote:


SUPPLIED ACCESSORIES:

Normal Filter: A-1211-996-A
ND4X Filter : A-1211-998-A

You can't order this?
Where did you find those? Do you have a link?

The price I quoted for the normal filter was from Sony EU parts. Not worth £170+!!


I found the link:
https://learncamerarepair.com/index.php
https://learncamerarepair.com/product.php?product=594&category=2&secondary=45

ILCE-1, FE:14/24/35/STF/135/10400GM, 90M/24105/200600G+6, 1.4x/2xTC
ILCE-QX1, Full Sprctrum NEX-5R, E:2
LA-EA5, A:35G/100S/200M/500R,3x-1x +7, SIGMA MC-11 + Canon EF8-15 FishEye
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gigo View Drop Down
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Post Options Post Options   Quote gigo Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2020 at 06:49
Originally posted by bharnois bharnois wrote:

Might be nice if I could print another lock pin for my ND, I have all the metal bits.


Designing for 3D printers often eliminates the need for metal parts.
3D printers that can handle metals are expensive, but it is not uncommon for shops that have them to receive printing services. I think it's probably cheaper to buy a 500REF junk, though.
ILCE-1, FE:14/24/35/STF/135/10400GM, 90M/24105/200600G+6, 1.4x/2xTC
ILCE-QX1, Full Sprctrum NEX-5R, E:2
LA-EA5, A:35G/100S/200M/500R,3x-1x +7, SIGMA MC-11 + Canon EF8-15 FishEye
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zk-cessnaguy View Drop Down
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Post Options Post Options   Quote zk-cessnaguy Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2020 at 05:08
by coincidence, I just watched this on the youtubes... someone repairing/modding the filter holder catch:

https://www.youtube.com/watch?v=1F-a39HSyJ8
There is nothing, absolutely nothing, half so much worth doing, as simply messing about in boats
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SnowFella View Drop Down
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2020 at 07:04
Neat little fix!
I'd do that in a heartbeat if the previous owner of my 500RF hadn't superglued the locking knob to the filter body
Guess the plastic broke and he/she lost the pin and spring. So to plug the hole in the body the knob has just been glued into place and the filter is held in place with gaffa tape.

Someone with a lathe and some basic skills could likely crank out the parts in next to no time if he/she had the measurements. Only really 3 parts needed (one needing machining) knob, spring and a roll-pin of appropriate length.
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gman62 View Drop Down
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Post Options Post Options   Quote gman62 Quote  Post ReplyReply Direct Link To This Post Posted: 05 August 2022 at 13:05
I experienced the same issue - broken knob on the filter holder of my Sony 500mm F8 reflex, and the filter holder kept falling out of the lens body. I found a black silicone wristband which happens to fit perfectly around the base of the lens and holds the filter holder quite securely, and looks good. I've purchased some spares in case anyone is interested - https://www.ebay.ca/itm/185526889056 And here is a photo of what it looks like:
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 16 August 2022 at 14:52
Originally posted by gigo gigo wrote:

Good morning. For whatever reason, when I wake up in the morning, nothing makes me happier than solving the problem.

If you are interested in 3D Printer, I think it would be fun to put in keywords as you can think of and look at everyone's data on a data search site.

Search Engine for 3D printable Models
https://www.yeggi.com/

Have a good day.

and a 60mm Sigma lens hood extension
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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