camera lens question

[bigegg]

just bought a "opteka super wide fisheye lens 0.20x" at the car boot. (it was 50p, and came with a freebie ), but its got a lens mount which I dont have an adaptor for.

threaded mount, 51.8mm (2.040in) *ish*

I cant find any lens mount which corresponds - any ideas?


[1] canon 70-210mm FD in good nick

 

[voipio]

It's meant to screw onto the front of a standard lens with a 51.8mm thread for filters and suchlike. The canon 70-210mm FD has a 58mm thread on the front, so a suitable adapter might be this:

DragonFly Optical Kood - Anello adattatore per obiettivo tipo step down, da 58 a 52 mm: Amazon.co.uk: Electronics & Photo

Shop DragonFly Optical Kood - Anello adattatore per obiettivo tipo step down, da 58 a 52 mm. Free delivery and returns on eligible orders.

www.amazon.co.uk

 

[bigegg]

It's meant to screw onto the front of a standard lens with a 51.8mm thread for filters and suchlike.

D'oh.
That makes sense. :-D

 

[Kayos]

just bought a "opteka super wide fisheye lens 0.20x" at the car boot. (it was 50p, and came with a freebie ), but its got a lens mount which I dont have an adaptor for.

threaded mount, 51.8mm (2.040in) *ish*

I cant find any lens mount which corresponds - any ideas?


[1] canon 70-210mm FD in good nick

Is the FD lens F4?

 

[gt6s]

Had one Not wide angle fisheye at all. Just puts a vignete ring in picture. Needs to be on a WA lens

 

[bigegg]

Is the FD lens F4?

I believe so.
Not really had a look at it.

 

[Kayos]

I believe so.
Not really had a look at it.

2 versions, if its the F4 and not the F5.6 its a very good mid zoom, goes a bit soft at full distance but I used it as a walkabout on my A1 for a long time

The 5.6 is a bit soft

 

[bigegg]

2 versions, if its the F4 and not the F5.6 its a very good mid zoom, goes a bit soft at full distance but I used it as a walkabout on my A1 for a long time

The 5.6 is a bit soft

Reasonably certain it's not 5.6

 

[bigegg]

Reasonably certain it's not 5.6

I've had chance to have a look at it now:

It's marked "1:4". Does this equate to f4?
There's no "f" numbers marked on it.

 

[Seadog]

Does this help?

It means it's a zoom lens that can open as wide as f/4 when zoomed out to the widest angle of view. When zoomed in to the longest focal length it will only be able to open up to f/5.6. For some lenses minimum aperture will be something like f/22 for all focal lengths, for other lenses it might be around f/22 on the wide end and f/32 on the long end.

Remember that apertures are expressed as ratios or fractions, so f/4 means 1:4 (the aperture is 1/4 of the focal length) and f/5.6 means 1:5.6 (the aperture is 1/5.6 of the focal length).

So 1:4-5.6 could also be expressed as 1:4-1:5.6, f/4-f/5.6.

(By the courtesy of Google)

 

[droopsnoot]

It's marked "1:4". Does this equate to f4?
There's no "f" numbers marked on it.

Yes. The number of times I've thought I was in luck when I've seen a Pentax 50mm lens with 1:2 written on it at the car boot sale - they made an f1.2 version which is supposed to be a pretty good lens and it always catches me out.