View Full Version : Why so cheap?

13-07-2010, 1:22pm
Hi, I'm fairly new to photography and was just browsing ebay while on lunch and ended up at one stage looking at lens.

But why/what makes these lens so cheap?
Lens 1 (http://cgi.ebay.com.au/ODS-500mm-Zoom-Telephoto-Lens-Nikon-D3000-D5000-/360279601554?cmd=ViewItem&pt=AU_Cameras_Photographic_Accessories&hash=item53e2567192)

Lens 2 (http://cgi.ebay.com.au/ODS-800mm-Mirror-Telephoto-Lens-Nikon-D3000-D5000-/200482893516?cmd=ViewItem&pt=AU_Cameras_Photographic_Accessories&hash=item2eadb62ecc)

I have been looking at spending something around the $700-$88 range for 105mm macro lens and $1400 for a 500mm lens as I want to Macro shots and nature shots (birds etc).

As I said I'm fairly new to photography, like just over 4 weeks ago I got the camera :) So be gently when calling me a idiot please :p

Thanks in advance for the answers as well :D

13-07-2010, 1:45pm
I have had a few expensive hobbies in my time, and I am finding that Photography is the only one where cheap ebay buys are no good at all!

I can only speculate how poor the build quality and image quality would be, but you will see in the description the widest aperture you can reach is f8. If you don't know what that means, I'm sure it is explained in the new to photography forum but basically, it will be very hard to reach fast shutter speeds unless you are in very bright sunlight, meaning images you take will be blurry

But hey, if you have the money to burn... It could be some fun to play with, but you can buy much better accessories with the same money such as a flash, tripod or filters

13-07-2010, 1:51pm
Build quality is the biggest difference, with this hobby the more you pay the better quality you get.

There is more glass built into the lens's, better quality glass, glass coatings to improve image quality and the list goes on. Not to mention, the cheaper lens's dont have autofocus or even the ability to change aperture (the case with the 500mm), you are stuck at f/8 it seems. With such a long length, having a lower aperture in order to allow maximum light into the lens is essential...unless you are in perfect bright conditions it would be very difficult to take a clear and focused shot.

Since I'm not sure how much you know about camera's and settings being new to the hobby, check out these links which should help you understand it a bit better :th3::

Aperture info (http://www.ausphotography.net.au/forum/showthread.php?t=24050)

Shutter Speed info (http://www.ausphotography.net.au/forum/showthread.php?t=24051)

13-07-2010, 1:59pm
Don't buy these lenses - they are SOOOOO bad. Might as well shoot through a coke bottle.

13-07-2010, 2:16pm
probably inferior glass for starters. stacks of distortion and CA... thats a guess tho. someone here bought one and tried it but i cant remember who.

13-07-2010, 2:26pm
Paul of course :D

13-07-2010, 2:26pm
Loox like some of the old TELEPHOTO (NOT zoom) lenses from way back. The cheapness was from a very few lens elements requiring minimal correction. But the IQ on film wasn't too bad. They just didn't go wider than about f/8. I had two of the same "brand", one 400mm, f/5.6, the other 500mm, f/8 . Between "brands" they looked almost identical. I gave one away as a gift. And I can't find the other. The price then was typically about $99. Am.

13-07-2010, 2:29pm
paul of course :d
bazinga! :lol:

13-07-2010, 2:36pm
and, try sneaking that into the Australian Open.... Go on..!

13-07-2010, 2:43pm
Thanks for the replies...

I wasn't going to buy any of those lens I was more or less just wondering why so darn cheap...

I also like to buy local if I can for the fact of supporting local businesses and also warranty is easier most the time.

13-07-2010, 2:48pm
and, try sneaking that into the Australian Open.... Go on..!

You couldnt even convince a security guy that it as pro gear though :rolleyes:

13-07-2010, 8:01pm
Yes they are dogs.
And they will mount on anything... camera bodies, I mean.:eek:
They are made of cheap plastic that warps under the Oz sun.
Have you ever had Tasco? You thought it was a great astronomical telescope only to be shocked to feel it was so light, the wind will blow it over from the tripod.
Same here.
The glass (is it? not sure) isn't even close to the cheapest kit lens of any major camera brand. Guaranteed disatisfaction, these gadgets.
Unless you are doing telephoto Lomo...:D:umm:

13-07-2010, 8:34pm
Like the other comments, I wouldn't be touching these lenses, I've been looking at them for years now on Ebay but decided a long time ago that they wouldn't be worth the problems:confused013

13-07-2010, 8:47pm
For some reason, they seem to be getting great feedback. :umm::scrtch::beer_mug:

08-08-2010, 3:32am
Hi All,
Must admit,Due to my love of really long distance Birding/wildlife shots, I also have been looking at the 500mm mirror lens from this seller.

Do agree,he has been getting good feedback from buyers...............Might just have to persevere with digiscoping,to get long telephoto Shots.


08-08-2010, 10:07pm
Are you guys taking about the ODS lenses ?

08-08-2010, 10:17pm
Are you guys taking about the ODS lenses ?

Yes, http://cgi.ebay.com.au/ODS-500mm-Zoom-Telephoto-Lens-Canon-550D-1000D-/190425146644?cmd=ViewItem&pt=AU_Cameras_Photographic_Accessories&hash=item2c56392514
Plastic craptastic :Doh:

08-08-2010, 10:22pm
An article on mirror lenses..


Bear Dale
08-08-2010, 10:28pm
If this doesn't look like a plastic POS I don't know what does -


08-08-2010, 10:46pm
If you want a birding lens go to the Nature > Birds forum in AP and see who posts there and ask them for advise about lens options. The birding togs in AP are very helpful and sincere.

13-08-2010, 9:44pm
Ok, to sort this out for myself, and to help others with all the questions, learn about the lens from my eyes. I bought a cheapie.

Check out post called "eBay - onlinedigitalshop (ods) - Anyone delt with them ?"

13-08-2010, 10:26pm
Hmmm. This thread got interesting. I now doubt whether these lenses are the same as the ones I mentioned above. Mine were metal housings. The consensus on these is that they're plastic.

But about the "mirror lenses".
I read the article about "mirror lenses" in the link posted by Joele
and found it to be disappointingly amateurish, relying on vagaries and generalisations. Just look at the first paragraph, "...strange...", "...there're..."
And in para 5 "...these lenses are mainly based on mirrors rather than glass elements...",
which means - anybody's guess!
Also in para 5 "...The lack of glass elements (apart from the correction element) is a significant design advantage compared to classic (refractive) lenses..."
So, what about the back glass element. In other words they are as much refractors as reflectors, hence correctly, "mirror-lens", or catadioptric.
And para 6 is supposed to be informative(!?!)
"...Unfortunately the design results also in some significant disadvantages like

* no aperture so it's not possible to control the depth-of-field.
* the mirror reflections eat contrast
* the overall sharpness is usually quite mediocre
* the secondary mirror produces an odd effect donut-like effect on the out-of-focus high-lights. The following picture illustrates this problem."

It is informative guff that the system went from fixed aperture to "no aperture".

And so on..., even to a purported "Conclusion".

After a whole page it doesn't prove anything. Like anything else, get a good mirror-lens and you'll get good results. I know of two instances, both f=500mm, f/8, catadiopric, and both of which I've had.

The first was a Sigma. It could not resolve anything at any distance. I think it suffered from dispersion (and perhaps circular aberration). When other people posted photos (in photo magazines) of shots with this lens you could see it in them too.

The second (still) is a Tamron SP (BBAR MC). It is pin sharp within its extremely narrow depth of focus, across the whole 5 degree field. It has very minor vignetting in corners of a frame.

Canon and Nikon also brand a range of mirror-lenses. I don't know what they're like, but they have the name.

The main disadvantages of these lenses, that I could say - and they are only comparative disadvantages - are:
1. fixed aperture
2. quite shallow depth of focus up to about 100+ m.

But that what they are, and that's about it. Am.