Sit. Allow me to share with you a story about love and hate.
A curious thought invaded my mind: Are there any mirror/lenses available for DSLR’s? You see…I’m a fan of telescopes that utilize both a mirror and lens. These types of ‘scopes are known as catadioptrics.
What did I do? Well…I did what any sensible person would do—an internet search. Low and behold, I came across the Opteka 500mm. All the stats fueled an unjustified crush. The price also helped: $89.99.
Plus…the lens comes with a 2x converter, effectively doubling the focal length to a 1000mm. Impressive. I didn’t own the Opteka mirror lens, but my preconceived notions was all I needed to fall in love.
BIG mistake. The mechanical quality was impressive (for its price). All metal and a rubberized grip on the barrel. No plastic!
I came across unsuspecting geese, then aimed and fired…
The images on the back of the LCD screen were shitty beyond belief. My heart broke. Later that night, I decided to give this lens a chance to redeem itself. This time around, the Moon happened to be out.
Perfect. Can’t mess this up (or so I thought).
Heartbroken. Again. The images turned out blurry. What a shocker.
Exposure Times Needs To Be Fast
Many blurry images will be caused by a slow shutter speed, especially if the lens is handheld. Try not to expose slower than 1/500 seconds.
Did I forget to mention that the Opteka 500mm is a fixed f/8.0 lens? Well…it is. In order to shoot higher shutter speeds:
Don’t Be Afraid To Raise The ISO
These tactics can be applied to the Moon.
End of the Beginning
Due to the increased ISO (and other reasons) lunar images will not be katana sharp. However, they’re visually viable compared to the trash I was taking before.
All unprocessed images taken with this lens will look soft. Really soft. You can try to apply a unsharpening mask, but due it intelligently. Over processing the photograph will introduce artifacts and make noise more apparent.
Cropping the image brings to light imperfections due to the high ISO. But, nonetheless, the images are somewhat acceptable:
I don’t recommend this lens for astrophotography
The uncompromising aperture severely limits this lens as an everyday shooter. If you don’t have a guiding system, photographing stars/planets is not going to happen—it’s far too slow and the focal length is far too long.
As for the 2x tele-converter? I’m not going to pull any punches. The tele-converter is a waste of metal and glass. The vignetting is comical…might as well be imaging through a key-hole. Don’t waste your time with the accessory.
Does that mean this lens can’t be used for astrophotography? Kind of. There are a few situations where a lens like this can come in handy:
solar eclipses (with a proper filter) never look at the sun without a filter; you’ll burn your eyes out, kid!
Imaging Moon Phases
Sunspots (Again with proper filter)
For lunar photography; try these settings if you happen to own this lens and are currently heartbroken:
Day Moon photographic settings:
I’m still experimenting with this lens. Due to the low-contrast—the Opteka 500mm mirror/lens produces odd looking images. The lens is also capable of other strange optical defects (such as light donuts).
If you’re hoping that this lens will produce the same quality images as a catadioptric telescope, then you will be disappointed. You may as well purchase an actual telescope.