Opteka lenses

I notice quite a few lenses by Opteka available through ebay at suprising (too good to be true?) prices. Does anyone have any experience of this make? Are they cheap and cheerful or hidden diamonds? (e.g. http://cgi.ebay.co.uk/650-1300mm-Tele-Lens-for-Pentax-AF-ist-ZX-L-ZX-60-ZX-7_W0QQitemZ7596083078QQcategoryZ4688QQcmdZViewItem

There's a comment here:
http://www.stevesforums.com/forums/view_topic.php?id=52778&forum_id=65

When it comes to lenses, you certainly don't get anything for nothing!
Matt

Hi,

I've never used one, and would hardly be qualified to comment on anything really..

but if you have a longish prime, say a 300, then that equates to a FOV of a 450 35mm lens. Stick either one or two 2x converters on it and you have either a 900 or 1800 lens. I think you lose two stops with each???? That would turn my 300 f5.6 into a 900 f11 or an 1800 f22.

As you can open up the aperture to focus and then close down manually once set, you don't get the initial dimness in the view finder; and for instance, even though not ideal, my Vivitar 2x is going to be probably far better optically when coupled with my 300 than a cheaply made 900.

Of course I'm probably wrong, but if you have a long prime to start with, you're only looking at a fiver each for the 2x converters. I did try this just after I got my DL, and somewhere on this machine is a shot of a roof top. I'll try and find it and post it up..

Cheers

Liam

Nope, I must have deleted it in camera.. oh well, I'll give it a go tomorrow and show you what I can get,

Cheers

Liam

Liam,

Good point. Earlier this week I was shooting some photos of the New Moon. I used both my Centon 500mm mirror lens and my Sigma 70-300mm lens with and without my 2x converter on the DS, and got some reasonable results, but part of the reason for the exercise was to try various ISO settings as well. Focussing was a bit difficult, partly due to frozen fingers at -2C ! I'm going to try and put a small gallery of the better ones together.

Post a link when you do, and I may even do the same.. depending on the results of course..

Cheers

Liam

Liam,

Well here they are http://www.ammonyte.plus.com/galleries/newmoon/index.html, taken with my 70-300mm Sigma lens (+ 2x converter for 600mm, 900mm 35mm film equivalent) and my 500mm Centon mirror lens (+ 2x converter for 1000mm, 1500mm 35mm film equivalent).

I'm not sure if the softness is due to focussing problems in an image with very little detail, a limitation of the lenses, a limitation of the photographer (I wear glasses and somethimes have problems with the viewfinder), or sheer ineptness on my part.

I used mirror lockup and a cable release to minimise movement of the camera. Shot in RAW and processed with RSP 2006.

Hi Ammonyte,

nice photos.. I like #12. The lack of sharpness could be due to using ISO 3200. I'm going to have to look it up, but I think that digitals must somehow use less pixels to increase the ISO rating and therefore decrease exposure time. In which case, you are using 1/32 of the available pixels in the sensor (my brain is hurting now, so correction/conformation is welcome) and therefore will sacrifice a lot of sharpness in the process, but eitherway, they're nice, especially the way you've managed to capture the invisible (to the naked eye) part of the moon, and getting the eclipse like halo effect with the visible.

Cheers

Liam

Thanks Liam. As the evening wore on and my fingers got colder and the Moon dropped closer to the horizon, my oldish eyes could start to see a little detail highlighted by "earthlight", but higher ISO settings (maybe avoiding 3200) do help.