Mirror lens

[Mr_P]

Id never seen one of these before but came across an 'Opteka 500-1000mm F8 Mirror Lens on t'internet earlier. Just wondered if anyone had used one before and if they were any good. I cant seem to be able to find any sample photographs.....

Its a fixed 500mm lens with a 2x converter in the box, so would this be 1000mm at F16???

[El_Sid]

Let's say that Opteka don't have the greatest of reputations round here...

I cant seem to be able to find any sample photographs.....

Now I wonder why should that be...

Its a fixed 500mm lens with a 2x converter in the box, so would this be 1000mm at F16???

Yep... with a viewfinder like a coalhole at midnight.

Honestly, don't waste yer cash...

[Malcolm_Stewart]

In an earlier life before going AF, I dabbled with mirror lenses, and they can have their uses, but the well known doughnut shaped out-of-focus highlights can not only enhance the right sort of subject (e.g. reflected sun speckles on waves at sea), but seriously spoil much ordinary photography, such as birds in front of a ground background.
The light passing is rarely equal to the quoted "aperture" because the secondary mirror blocks the light where it's at its most intense. So, think f9 instead of f8. On one of the independent brand 500 f8s that I tried, it didn't have a proper baffle tube to separate out-of-focus direct and in-focus reflected light, so it was very low on contrast for normal daytime use. (Perhaps OK for astro star photos.)

I've retained my Minolta 500 f8 RF, and it did give reasonably contrasty images but only fitted my manual Minolta bodies. I also had the Minolta 250 f5.6 RF and that did produce some reasonable slides, and was a very compact tele to carry around. I remember the Canon 500 f8 FD had a reasonable reputation.

[Mr_P]

Let's say that Opteka don't have the greatest of reputations round here...

I cant seem to be able to find any sample photographs.....

Now I wonder why should that be...

Its a fixed 500mm lens with a 2x converter in the box, so would this be 1000mm at F16???

Yep... with a viewfinder like a coalhole at midnight.

Honestly, don't waste yer cash...

Cheers, to be honest, I wasnt actually considering it at the moment anyway. I was just interested to see peoples opinions on such things. It said a lot to me that I couldnt find a user review either!! Didnt think it would be a lot of cop for £100

Thanks for letting me know though!! I know not to bother in the future. if I get to the point I think I need a 500mm lens, id probably go for a Sigma!!

[Dorset_Mike]

There are some useable mirror lenses they are manual focus, with one exception, Minolta/Sony 500/8; the Sigma 600/8 in Minolta/Sony mount does have a chip fitted so does give focus confirmation, (not sure about other mounts)

The aperture is fixed so exposure adjustment is by shutter speed or ND filters.

Mirror lenses are cheaper and lighter weight than conventional lenses of similar focal length, the bokeh is unique - donut shaped highlights - which puts a lot of people off.

[beejaybee]

Mirror lenses are cheaper and lighter weight than conventional lenses of similar focal length,

Much. There's the real difference - a 500mm f/8 mirror lens is practially pocketable, whereas a conventional 500mm lens is a bagful and a half in its own right. If it's a question of getting or missing a shot, having a cheap mirror lens in your bag is going to make all the difference. If it's a question of needing the very highest optical quality, forget it.

IMO the best mirror lens you're likely to come across is the Tamrom SP 500mm f/8 Adaptall-2 - manual focus but you can get adapters to fit just about any 35mm / digital camera with interchangeable lenses.

[swanseadave]

I seem to recall reading somewhere that mirror lenses in general have to be treated gently since a sharp knock is likely to move the mirror out of alignment,rendering the lens unusable.
I`ve never owned one but have used a borrowed one some years ago.The contrast was poor and I cannot remember the brand,just that it was 500mm f8 and was supplied witha range of slot in ND filters.

Cheers

[El_Sid]

It said a lot to me that I couldnt find a user review either!! Didnt think it would be a lot of cop for £100

While mirror lenses are generally cheaper than normal telephotos it's still a matter of you get what you pay for. I found a price for the now discontinued Sigma 600mm mirror that was a touch under £400 while Grays are flogging used 500m Nikkor mirror lenses for £375-675...

[Dorset_Mike]

I paid £159 from Ffordes for my Sigma 600/8, I've since seen another on their list for a similar price. (Minolta AF fit)

[beejaybee]

I seem to recall reading somewhere that mirror lenses in general have to be treated gently since a sharp knock is likely to move the mirror out of alignment,rendering the lens unusable.

Any precision optical device can be wrecked by knocking the elements off centre. I don't think there's any reason to suspect that mirror lenses are any more, or any less, susceptible in this respect.

[jeallen01]

Missed a real bargin in one of our local "Mr Exchanger"-type places about 10yrs ago: Sigma 600 in its original box, with some filters - £26 (Yes twenty six pounds) or thereabouts

Just did'nt know whether to buy it or not, but, when I decided to go ahead, it was gone

My Centon F8 500mm mirror is not bad - but the Panagor F5.6 300mm mirror is poor.

[beejaybee]

the Panagor F5.6 300mm mirror is poor.

Doesn't surprise me. The "mirror lens" was invented by the gifted Russian optics designer Dmitri Maksutov as a telescope objective, the basic design is still widely used in small to medium sized telescopes, some of which are of very high quality indeed. But even f/8 is stretching the design, f/12 to f/15 is a normal focal ratio for a Mak scope to work at ... and there is no need for a scope to cover a 24x36 frame. f/5.6 is just way over the top; after all there are only four surfaces to work with (two reflecting surfaces and the two surfaces of the corrector plate).

[weasley]

I bought a Tamron 500mm f/8 Adaptall-2 with Nikon F mount to take on safari to Botswana and I'm damned glad I did. For the money it returned perfectly acceptable images of a wonderful experience without the need to take up too much of my limited baggage allowance (12 kg max, to include camera and clothes). It was mounted on an F801s which dealt with exposure in A mode fine since the mount coupled with the aperture ring on the body.

I have tried it on my D70s but it's all manual exposure and results are less impressive, and besides, I have the Sigma 100-300 f/4 with 1.4 converter that gets pretty close on magnification with a stop or so to spare.

I only ever used that lens for that 1 week, but I still have it and I'm glad I got it.

[SqueamishOssifrage]

An interesting thread. I have never owned a lens longer than 200mm, as I have never wanted or needed one. However, very occasionally I think the extra reach might be useful, and contemplate going up to around 500mm one way or t'other - but dead cheap.
The choices are:

1. Get a cheap and cheerful 500mm/f8 mirror job.
2. Stick 1.4x and 1.7x tele-converters behind a 200mm/f3.5, giving me 476mm/f8.33
3. Use the same lens with the 1.4x TC and add a 2x video type supplementary lens on the front end, giving 560mm/f4.9 but with AF.

So, which does everybody think would be the best/least worst approach?

[beejaybee]

which does everybody think would be the best/least worst approach?

Consider also a small (80mm aperture) astronomical refractor scope, OK it's more clunky in terms of its connection to the camera but the optical quality will probably surprise you - especially with a crop frame camera - & there's no nasty "donut" bokeh.

[El_Sid]

So, which does everybody think would be the best/least worst approach?

I'd say they're almost equally as bad...

I have a 'cheap and cheerful' 500mm/f8 mirror (a Sirius IRC) and it's pretty poor to say the least...

Stacking teleconverters is not really a recommended approach, even with those that are optically matched to the lens and each other, unless actually getting the picture is more important than image quality.

Unless the supplementary 2x supplementary video lens is of exceptional quality I don't think that's going to be that good either. Remember that most video uses a smaller sensor and operates at a lower resolution than stills cameras. I'd doubt that the image quality, especially at the edges, is going to be too well maintained.

[SqueamishOssifrage]

I reread your earlier post, viz.:

There's the real difference - a 500mm f/8 mirror lens is practially pocketable, whereas a conventional 500mm lens is a bagful and a half in its own right. If it's a question of getting or missing a shot, having a cheap mirror lens in your bag is going to make all the difference. If it's a question of needing the very highest optical quality, forget it.

IMO the best mirror lens you're likely to come across is the Tamrom SP 500mm f/8 Adaptall-2 - manual focus but you can get adapters to fit just about any 35mm / digital camera with interchangeable lenses.

Checking prices on eBay, I found one of the above at a sensible price, so I bought it, remembering that I already have the appropriate Adaptall II focus-confirm (chipped) mount. When it comes, I will set up my sophisticated optical bench (consisting of pointing the tripod mounted camera and lens at the outer dry stone wall of my house. ) and check it against the 1.4x -> 1.7x option. I don't think I'll bother with the third option, as I have never heard of anyone using one of these things on a still camera - and there must be a reason for that!

[SqueamishOssifrage]

Stacking teleconverters is not really a recommended approach, even with those that are optically matched to the lens and each other, unless actually getting the picture is more important than image quality.

Unless the supplementary 2x supplementary video lens is of exceptional quality I don't think that's going to be that good either. Remember that most video uses a smaller sensor and operates at a lower resolution than stills cameras. I'd doubt that the image quality, especially at the edges, is going to be too well maintained.

The 1.4x is matched to the lens, but the 1.7x is exceedingly generic. As for the 2x supplementary video, option, I had a look at the only one the right size for the lens, and noticed that although the thread was the correct size, there was an internal flange that would have caused severe vignetting.

On an impulse, bought a Tamron 500mm, as per my post above!

[daft_biker]

You found a need for something as long as 200mm?



Although I almost treated myself to a 400/5.6 recently....gave it a miss this time but will see what the future holds (but even if I do find the money for a longer lens I may well blow it on FF and tilt/shift lenses(24mm and 45mm)....tough choice! )

[El_Sid]

On an impulse, bought a Tamron 500mm, as per my post above!

I'd expect the Tamron to be rather better than my Sirius...

One thing I suspect they have in common is a potential for camera shake. These things don't weigh a lot and as a result don't dampen any little wobbles very much - which probably doesn't help the softness of the Siruius... Of course if you're one of those rock steady people or have sensor stabilisation you'll be rather better off...