FAQ FAQ  Forum Search   Events   Register Register  Login Login

white rear lens cap purpose?

Page  12>
Author
roger2 View Drop Down
Groupie
Groupie

Joined: 24 December 2015
Country: United States
Location: indiana
Status: Offline
Posts: 128
Post Options Post Options   Quote roger2 Quote  Post ReplyReply Direct Link To This Post Topic: white rear lens cap purpose?
    Posted: 17 April 2019 at 00:15
Is there a reason that some rear lens caps are white instead of black? If there is a reason, then why are so few of them white?

Allows some light inside to help prevent/minimize fungus perhaps?
a57 | Sony DT 35/1.8 | Minolta 50/1.7, 28/2.8, 28-105/3.5-4.5, 28-75/2.8 D, 75-300/4.5-5.6 New
 



Back to Top
Bob J View Drop Down
Admin Group
Admin Group
Dyxum Administrator

Joined: 23 December 2005
Country: United Kingdom
Location: London
Status: Offline
Posts: 24963
Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 00:20
The white cap allows you to inspect the lens against light filtering through the cap while it keeps the diaphragm open.

Some like them, but fit tends to be a bit sloppy compared with the black ones.
Back to Top
lomitamike View Drop Down
Senior Member
Senior Member

Joined: 23 September 2006
Country: United States
Location: CA.
Status: Offline
Posts: 707
Post Options Post Options   Quote lomitamike Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 00:26
White are the old Minolta ones. Never seen a white Sony cap.

They seem to be made of a softer plastic and fit better IMO.
Don't know if there's a purpose or not.

I do like spinning it on my 85 f/1.4 and being able to see through the translucent plastic just how wide the aperture gets.
A900, A850, A6000, Canon S95, SAL 70-400, 70-200, 35/1.4, 50/1.4. KM 85D, 28-75D, 17-35D,100macroD. Mino 28/2, 35-70. Rok14/2.8. Many flashes, Phottix Odin. E16-50, 18-200LE, 50/1.8, Rokfish 8mm
Back to Top
roger2 View Drop Down
Groupie
Groupie

Joined: 24 December 2015
Country: United States
Location: indiana
Status: Offline
Posts: 128
Post Options Post Options   Quote roger2 Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 01:43
Thanks guys
a57 | Sony DT 35/1.8 | Minolta 50/1.7, 28/2.8, 28-105/3.5-4.5, 28-75/2.8 D, 75-300/4.5-5.6 New
Back to Top
al View Drop Down
Senior Member
Senior Member

Joined: 10 August 2008
Country: United States
Location: SF Bay Area
Status: Offline
Posts: 1693
Post Options Post Options   Quote al Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 02:10
The plastic used in the white caps are soft. I took one and cut out the center portion. I use the modified cap to help easily open up the aperture so I can inspect the glass.
Back to Top
michelb View Drop Down
Senior Member
Senior Member

Joined: 26 August 2009
Country: Canada
Location: Montréal
Status: Offline
Posts: 602
Post Options Post Options   Quote michelb Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 02:11
The white ones came late into the AF era. early rear caps (and body caps) were black ( Most marked LR-1000 or BC-1000) but around 2001, which coincides with the arrival of the (D) lenses, they became white. My guess is they were cheaper to make and contained less chemicals (read petroleum) to make them black. Boxes of the same era replaced the foam inserts by cardboard (read recyclable).

Some of the white rear caps also bear the "Konica Minolta" name instead of just Minolta as the 2 companies merged in early 2003 ( i don't remember seeing a "Konica Minolta" body cap yet)and some products were changed to the new logo "Konica Minolta" like the LF-1300 series of front lens caps.

I personally find them less gripping to the lens (easy to get loose) and more difficult to mount since the lens mount index for proper alignment is difficult to see.
Michel B
 



Back to Top
QuietOC View Drop Down
Senior Member
Senior Member

Joined: 28 February 2015
Country: United States
Location: Michigan
Status: Offline
Posts: 2426
Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 02:58
My white ones are all grippy, but I do have some Minolta black ones that aren't. I think the locking mechanism gets worn. Genuine Minolta caps seem to be rising in value.
Sony A68 A77II A6000 A7II LA-EA3 LA-EA4 MC-11
Minolta Maxxum 600si
Pentax Q7 5-15 15-45/2.8
Back to Top
roger2 View Drop Down
Groupie
Groupie

Joined: 24 December 2015
Country: United States
Location: indiana
Status: Offline
Posts: 128
Post Options Post Options   Quote roger2 Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 03:27
Originally posted by michelb michelb wrote:



....and more difficult to mount since the lens mount index for proper alignment is difficult to see.


I noticed that. On one of mine I used red Sharpie to highlight the arrow. The white plastic accepted the ink easily. And the arrow is slightly raised from the surrounding area, so I was able to apply ink only to the arrow with no red anywhere else, making the modification neat, almost "factory" looking.



Edited by roger2 - 17 April 2019 at 03:31
a57 | Sony DT 35/1.8 | Minolta 50/1.7, 28/2.8, 28-105/3.5-4.5, 28-75/2.8 D, 75-300/4.5-5.6 New
Back to Top
Photosopher View Drop Down
Senior Member
Senior Member
Knowledgebase Contributor

Joined: 13 June 2010
Country: United States
Location: St. Louis Mo
Status: Offline
Posts: 4177
Post Options Post Options   Quote Photosopher Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 03:40
White caps are made of fairy dust, and only appear in the lives of the most ardent A-Mount fans. You are very lucky to have one come across your path. The Mind of Minolta has smiled upon you. Hence forth, you will be seen as irresistible to the romantic. Traffic lights will shine green upon every journey. Your computer will never crash again. Keep an eye on your mailbox for that vacation giveaway sure to come.   If you're a gambling man, now is the time to lay it all on the table. From this day forth, your horse always wins.

Welcome to the club.

Edited by Photosopher - 17 April 2019 at 03:44
Back to Top
Jozioau View Drop Down
Alpha Eyes group
Alpha Eyes group

Joined: 13 May 2007
Country: Australia
Location: Melbourne
Status: Offline
Posts: 4426
Post Options Post Options   Quote Jozioau Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 05:04
Hasn't been mentioned here as yet, but my understanding is that the rear white lens cap could be used to set white balance by simply placing it over the lens and taking an image and using that as the reference for custom white balance.

Found this YouTube clip demonstrating the technique on a Canon, but the principle is the same Using a white rear lens cap to test white balance.

Apart from that, as has been said above, the white rear lens cap was a soft, flexible plastic that actually gripped onto the steel lens bayonet mount in a way that the hard black plastic version doesn't.
"Your first 10,000 photographs are your worst" - Henri Cartier-Bresson
My FlickrPro site
Back to Top
addy landzaat View Drop Down
Senior Member
Senior Member

Joined: 22 April 2006
Country: Netherlands
Location: Netherlands
Status: Offline
Posts: 9418
Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 06:30
Originally posted by michelb michelb wrote:

My guess is they were cheaper to make and contained less chemicals (read petroleum) to make them black.
It has been a while since I was trained in Material Science, but plastics do not work like this. They do not get softer by reducing one ingredient. Plastics are all "chemical" and made in a chemical process. Why do you think it is petroleum that makes the plastic harder? The white caps are a completely different material then the black ones, it is not just reducing one ingredient - the material is made in a completely different process with different ingredients. Oh, and petroleum is not a dye, plastics are not black because of petroleum.

I do not know why Minolta decided to go with the white ones, but here are a few thoughts:

1. The white ones were cheaper to produce.
2. To differentiate from the competition.
3. To let in light (fungus is unlikely, but it helps checking the glass).
4. They were thought to be better hold (I have seen experiences from people stating the whites are better and the other way around. In my experience both are easier to loose then Canon rear lens caps).
Why not follow me on Instagram? @Addy_101
Back to Top
Atom Ant Oz View Drop Down
Senior Member
Senior Member

Joined: 02 September 2016
Country: Australia
Location: Melbourne
Status: Offline
Posts: 195
Post Options Post Options   Quote Atom Ant Oz Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 12:29
Originally posted by Photosopher Photosopher wrote:

White caps are made of fairy dust, and only appear in the lives of the most ardent A-Mount fans. You are very lucky to have one come across your path. The Mind of Minolta has smiled upon you. Hence forth, you will be seen as irresistible to the romantic. Traffic lights will shine green upon every journey. Your computer will never crash again. Keep an eye on your mailbox for that vacation giveaway sure to come.   If you're a gambling man, now is the time to lay it all on the table. From this day forth, your horse always wins.

Welcome to the club.

Thank you!

I've never really liked the white caps, and I've tend to shuffle them on to whichever lenses I use least so I don't have to see them so often. Now I realise my fortune, I'll swap them on to my favourite lenses as talismans. I can see many prizes coming my way in my near future.
A99ii + 16-35Z | 24-70Z | 24-105D | 70-200G | 100-300D | 70-300G | 70-400G
20/2.8 | 28/2.8 | 50/1.4 | 135/1.8Z | 300/4 | 500/8
A6500 + 10-18 | 16-70Z | 18-135 | 70-200/4G
28/2 | 56/1.4 | 85/1.8
Back to Top
Miranda F View Drop Down
Senior Member
Senior Member

Joined: 11 January 2014
Country: United Kingdom
Location: Bristol
Status: Offline
Posts: 3248
Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 13:36
Originally posted by addy landzaat addy landzaat wrote:

Originally posted by michelb michelb wrote:

My guess is they were cheaper to make and contained less chemicals (read petroleum) to make them black.
It has been a while since I was trained in Material Science, but plastics do not work like this.

I can't confirm the material of lens caps, but quite a lot of things have carbon black added to make them black. Arguable whether the carbon comes form fossil fuels or not.
Miranda F & Sensorex, Sony 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 . . .
Back to Top
owenn01 View Drop Down
Alpha Eyes group
Alpha Eyes group

Joined: 20 May 2008
Country: United Kingdom
Location: Kent
Status: Offline
Posts: 10074
Post Options Post Options   Quote owenn01 Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2019 at 13:53
Simple. It's to allow you to write your name and address on them for when you have/will loose them out in the field

Best regards, Neil.
My Mantra: "Comment on other's work as you would wish to have yours commented upon". Go on - it's fun!
Back to Top
Dyxum main page >  Forum Home > Equipment forums > Lens Talk > A-mount lenses Page  12>

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.063 seconds.

Monitor calibration strip

Dyxum.com - Home of the alpha system photographer

In memory of Cameron Hill - brettania

Feel free to contact us if needed.