Opticron Scope and Eyepiece Focal Length Information (1 Viewer)

pete_gamby

Birds? What Birds?!

• Jun 22, 2016

• #1

A (hopefully) comprehensive list of the focal lengths of various Opticron scopes and more or less all current and discontinued eyepieces.

Hope someone finds it useful!

Cheers, Pete

 

Attachments

• Scope and Eyepiece Focal Lengths.xlsx

  10.6 KB · Views: 412

G

giosblue

Well-known member

• Jun 22, 2016

• #2

Excellent Peter, thank you very much. I'm using the 40809 on my Pentax 65mm and 80mm scopes.
This gives me 24x on the 65 and and about 33x on the 80mm.
It's an excellent ep, tack sharp with a fairly wide afov. Pete, why have you discontinued it?

 

Last edited: Jun 22, 2016

Crake Dude

Well-known member

• Jun 22, 2016

• #3

Thanks loads for that, Pete......snag is I cannot open that zip file on my old Mac comp. Any chance of doing it as a pdf, please?

AT LAST...someone from an Optics company who cares about us!

Steve

 

J

jring

Well-known member

• Jun 23, 2016

• #4

Hi Pete,

thanks a lot for the list - this helps a lot!

Joachim

 

pete_gamby

Birds? What Birds?!

• Jun 23, 2016

• #5

PDF version attached for those of us with steam-powered computers ;-)

Cheers, Pete

 

Attachments

• Scope and Eyepiece Focal Lengths.pdf

  179.1 KB · Views: 226

Crake Dude

Well-known member

• Jun 23, 2016

• #6

Muchos thanks for ye olde pdf version, Pete.

The coal merchant has just delivered some coal, I can stoke up my ancient computer now. I wonder what this looks like in colour....

Steve

 

T

tommybj

Well-known member

• Jun 30, 2016

• #7

Is it just me or is the 40936 (SDL v2) not missing? Can see 40935 are mentioned twice.

 

J

jring

Well-known member

• Jun 30, 2016

• #8

Hi,

yes, I saw this too - I suspect a typo which is irrelevant here since the focal length for both is 8-24mm.

Joachim

 

P

Patch67

Patch Hopcroft

• Jun 30, 2016

• #9

Also is the SDL v2 not 18-54x on the current HR66, which would mean the scope has a focal length of 432mm?

 

pete_gamby

Birds? What Birds?!

• Jun 30, 2016

• #10

Well spotted Joachim and Patch67 - I don't think I've ever published a spreadsheet or PDF without some kind of error in it!

Attached are revised versions.

Cheers, Pete

 

Attachments

• Scope and Eyepiece Focal Lengths.xlsx

  10.7 KB · Views: 130
• Scope and Eyepiece Focal Lengths.pdf

  179.1 KB · Views: 286

Crake Dude

Well-known member

• Jul 12, 2016

• #11

I know it may be obvious to some how to use Pete's very useful focal length(FL) info but, just in case, to find out the magnification of an eyepiece on a particular spotting scope you divide the FL of the scope's body by the FL of the eyepiece. I realise this info may be engraved, in part, on the eyepiece or, more fully, on the eyepiece box...but not everybody may still have the eyepiece's box! Also, especially for astro scope users, the FL of an eyepiece can be worked out by dividing the scope's FL by the eyepiece's magnification.

Steve(President of the State the Obvious Club of GB)

 

M

Malcolm Stewart

Well-known member

• Jul 16, 2016

• #12

pete_gamby said:

Well spotted Joachim and Patch67 -...

Attached are revised versions.

Cheers, Pete

Click to expand...

Thanks Pete for the PDF version.
I'd far prefer to spend my money on optics than on modern MS software! I bought a full set of MS_Office way back when Win 95 or some such was the latest kid on the block!

 

J

jring

Well-known member

• Jun 17, 2021

• #13

Hi Pete,

any chance to get the afov of part number 40831? Focal length should be 16mm - does it also have 67 deg afov as the old part number 40809?

Joachim

 

pete_gamby

Birds? What Birds?!

• Jun 18, 2021

• #14

Hi Joachim - AFOV for the 40831 is 65º. Focal length is 15mm.

Cheers, Pete

 

J

jring

Well-known member

• Jun 23, 2021

• #15

Thank you, Pete, you are the best!

Joachim

 

B

Boogieshrew

Well-known member

• Aug 1, 2021

• #16

Opticron SDL v3 zoom eyepiece - 41270 The Birders Store.
This site has a chart of SDL V2 vs SDL V3 specs on various MM scopes.
It implies that there is a difference in FL between MM3 and MM4 scopes. I wasn't expecting that.

 

Last edited: Aug 1, 2021

J

jring

Well-known member

• Aug 1, 2021

• #17

Hi,

I would attribute those (fairly small) differences to measuring and/or rounding errors... or all the magnifications given on the Opticron pages are wrong as they give 12-36x for the 50x body and 15-45 for the 60mm bodies - for both MM3 and MM4 and SDLv2 and V3.

Joachim

 

B

Boogieshrew

Well-known member

• Aug 1, 2021

• #18

Hi Joachim,
Yes I wondered if maths errors were responsible. I can't think of any other reason.
Bit if the MM3 / MM4 have matching FLs, as do the e/ps, then I don't see where errors can creep in.
I wonder where the chart came from?