# 2.0 Quantaray teleconverter - thoughts?



## ceejtank (Sep 11, 2012)

Quantaray Product Reviews and Ratings - Auxillary Lenses - 2x AF Tele-Converter for EOS from RitzCamera.com

I would be using this with my 70-300mm lens... anyone have any thoughts?  I havent heard much about quantaray ever.. but by the review / product description AF is still usable.. Someones selling a used one on craigslist near me.


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## Big Mike (Sep 11, 2012)

It may have the contacts for AF signals to pass through from the camera to the lens etc., but the problem is that most cameras need a maximum aperture of F5.6 (or larger) in order for AF to work.  That's why most lenses don't have anything smaller (for a maximum) than F5.6.  

The problem is that a teleconverter changes the effective max aperture...a 2X will likely eat up about two stops.  That means that if you put it behind your 70-300mm lens, the effective max aperture will be something like F8-F11, depending on the zoom.  That will not give the AF system enough light, and your AF likely won't work.

You could use it, and manually focus though.  

And there is still the issue of image quality to think about.  Image quality usually suffers a noticeable amount when using a TC...and I don't know what sort of quality you'd get with one from Quantaray.  But if more reach is more important that maximum image quality....then you'd get what you want.


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## ceejtank (Sep 11, 2012)

Yeah.. I've come to the understanding that with my current lenses I'll be losing AF.. however I want to extent my focal length for cheap right now, so some image quality loss is acceptable.  I'd be using it more for shots of the moon than anything really, so f8-11 is fine for me as I'll be on a tripod with a trigger release (possible locking the mirror too).  

It's more - is quantaray decent quality.  Probably should have phrased that better.

Thanks for the reply!


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## Tony S (Sep 11, 2012)

If the name on a lens or other item with glass in it starts with a Q don't get it.  You will have more than "some" image quality loss with the set up you are talking about.

Quantaray lenses are low end third party lenses made for certain camera companies, like Wolf/Ritz.  They are low quality unless you are looking for a good paper weight.  Most of the time they are made for them by Sigma and are their low end models.


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## ceejtank (Sep 11, 2012)

Tony S said:


> If the name on a lens or other item with glass in it starts with a Q don't get it. You will have more than "some" image quality loss with the set up you are talking about.
> 
> Quantaray lenses are low end third party lenses made for certain camera companies, like Wolf/Ritz. They are low quality unless you are looking for a good paper weight. Most of the time they are made for them by Sigma and are their low end models.




Thanks for the feedback.  I will take this into consideration.  I saw a add on craigslist for the 2.0 converter, looked on amazon, but no reviews, found the ritz reviews, but always want to check with places I trust more.

Thanks for the heads up.  I might look at it, and try it out.  But does not look like I'll be purchasing.


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## subscuck (Sep 11, 2012)

I've also read Tamron, Tokina, and Cosina make stuff under the Quantaray name. While Sigma, Tamron and Tokina all make some very nice to great glass, as Tony said, the Quantaray stuff isn't even close to those mfrs best glass. It seems to be very difficult finding out who makes what. Sigma, Tamron and Tokina don't have any mention of Quantaray on their web sites. That's not surprising, tho. I have also heard warranty issues can be difficult to get resolved. This may be due to trying to figure out who made it. Give it a pass.


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## Overread (Sep 11, 2012)

Even with a top end teleconverter I wouldn't pair a 2*TC with that lens - the softness at 600mm would be significant plus shooting at around f11 at the maximum aperture (widest aperture/smallest f number) you'll have a massive drop off of light - which means you'd further have to sacrifice image quality as you raise your ISO to get enough to have a decent shutter speed in all but the strongest of light. 

Honestly I know its a pain wanting longer lenses, but its just one area you can't go cheap and get good results with easily. There are many areas of photography where you can use cheaper gear to good effect - long range is simply not one of them. I'd say save the money and put it toward a longer lens in time - something like a Sigma 150-500mm or 50-500mm.


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## Big Mike (Sep 12, 2012)

> I'd be using it more for shots of the moon than anything really


I'd suggest that you may be better off with just your 70-300 (tripod etc) and just cropping the image, rather than using a cheap TC.


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## ceejtank (Sep 12, 2012)

Yeah, ive done that.. but cant get a crop thatll let me print the moon big enough for 3ft x 2ft.. i might just grab the 100-400 L and see if thatll work...


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## Big Mike (Sep 12, 2012)

You could always rent a lens if you only need it for the shot.  Or connect your camera to a telescope.


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## ceejtank (Sep 12, 2012)

That's true.  I might be trying to talk myself into buying the 100-400 though.. hahaha. 

I'm unsure as how I would connect it to a telescope... point me in the right direction?  I do have a pretty nice telescope.. if it's just an adapter or something...


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## Sw1tchFX (Sep 12, 2012)

GET IT!


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## Big Mike (Sep 12, 2012)

I've never looked into it, but 'T-ring' adapters for various camera mounts have been pretty standard for attaching to a telescope.  A 5 second google search brought this up, which they say, is better than the old T-mount option.
TELESCOPE CAMERA ADAPTERS |TelescopeAdapters.com


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## TheBiles (Sep 12, 2012)

Teleconverters degrade image quality so much that I couldn't even imagine going off-brand. Add that image degradation to an already lackluster 70-300, and you're just asking to throw money in the trash can. You will be SEVERELY disappointed in this case, and I suggest that you avoid it. Long telephoto lenses are just one of those times that cheaping out will come back to bite you in the ass and leave you wanting more. 

Sent from my Galaxy S III


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