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  #41  
Old 06-09-2008, 09:55 PM
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Doug... How can you say that its unfortunately your imaging lens?? Gives better images than a lot of telescopes do (wider field too!)

Robin, with your 90-300 it is more likely that your going to be affected by chromatic abrasion than be annoyed by internal reflection..

EDIT: You wont find a flatter field than the 70-200 f/4 either... not in a telescope anyway..
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  #42  
Old 06-09-2008, 10:03 PM
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Quote:
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Doug... How can you say that its unfortunately your imaging lens?? Gives better images than a lot of telescopes do (wider field too!)

Robin, with your 90-300 it is more likely that your going to be affected by chromatic abrasion than be annoyed by internal reflection..

EDIT: You wont find a flatter field than the 70-200 f/4 either... not in a telescope anyway..
I've been misquoted, taken out of context - it's an outrage!!!!

"Chromatic abrasion"

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  #43  
Old 06-09-2008, 10:09 PM
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Oh... i see, i see... It is unfortunate that the reflection should happen with your main imaging lens.. (i guess i should think about things before jumping on a high horse and shooting my mouth off..)

And yes.. my spelling is average, especially with similar words...... abrasion aberration... Damnit!! you know what I ment
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  #44  
Old 06-09-2008, 10:43 PM
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Quote:
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Robin, with your 90-300 it is more likely that your going to be affected by chromatic abrasion than be annoyed by internal reflection..
The abrasions come into it trying to get all this crap back inside in the middle of night while on these stupid crutches

I got this lens at the right price though .. $0
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  #45  
Old 07-09-2008, 08:40 AM
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From Hutech Users Group...

> I don't think it is an internal reflection issue but vignetting. It may be an issue of faster f-ratios with such an interface filter; light farther off
> axis is getting clipped. Experiment by stopping it down to see if it
> dimmishes or goes away with something like f/6.
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  #46  
Old 07-09-2008, 08:43 AM
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but really... you dont want to stop down to F/6 if you dont HAVE to... although it would make focusing easier (if you're not auto focusing on a bright star..)
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  #47  
Old 07-09-2008, 08:50 AM
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Exactly Alex,
Forgot to add the final comment from the Hutech group...

> It may be better to mount a filter in front of the camera lens.

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  #48  
Old 07-09-2008, 08:54 AM
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Forgot to add the final comment from the Hutech group...

> It may be better to mount a filter in front of the camera lens.



Seriously though I've never really liked the idea of the internal clip filters.
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  #49  
Old 07-09-2008, 09:04 AM
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Seriously though I've never really liked the idea of the internal clip filters.
I think on paper they're a good idea if one uses a number of imaging systems with the one camera - saves buying multiple filters or a variety of step rings.
And, in theory they should protect your sensor from gathering dust too!

I've yet to try mine with my 50mm lens. I've concentrated on my L glass as that's my main system. If I can't sell mine I won't be too fussed - it can sit in my kit and wait to be coupled with that ED triplet that's got my name on it

The problems I have encountered are I believe specific to my particular imaging rig - but let's face it there are lots of imagers using similar types of rigs, so it's a wee bit of a disappointing outcome for such high end expensive gear. $350+ for a filter is a hefty price tag innit!!??

Doug

Last edited by dugnsuz; 07-09-2008 at 09:15 AM.
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  #50  
Old 08-09-2008, 11:53 PM
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Finally...

Tried testing the 70-200mm f4L at different focal lengths and with the nifty fifty 50mm f1.8 Mk1 lens.

From left to right...top row - 50mm f2.8, 70mm, 100mm,
bottom row - 135mm, 200mm all at f4.
(please excuse tracking errors and dubious framing)

As you can see internal reflection persists at all focal lengths.

All I can say is buyer beware if you're considering using a clip in front filter with camera lenses.

Hope this helps somebody...
All the best

Doug (Hutech Guinea Pig)
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  #51  
Old 08-09-2008, 11:57 PM
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yep.. not for lenses thats for sure...

(after seeing these pics, im doing the SMC in the next few days with the 1.4 extender!)

should fill the frame nicely!
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  #52  
Old 09-09-2008, 12:11 AM
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yep.. not for lenses thats for sure...

(after seeing these pics, im doing the SMC in the next few days with the 1.4 extender!)

should fill the frame nicely!
Yeah , Now to get my money back!!!!

Widefields of the SMC and LMCs with the 70-200 +/- extender and your QYH8 will be amazing.
SMC at 280, LMC at 100!
Sweet!
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  #53  
Old 09-09-2008, 01:00 AM
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Quote:
Originally Posted by dugnsuz View Post

As you can see internal reflection persists at all focal lengths.

All I can say is buyer beware if you're considering using a clip in front filter with camera lenses.

Hope this helps somebody...
All the best

Doug (Hutech Guinea Pig)
That's a shame Dougie.......
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  #54  
Old 09-09-2008, 04:26 PM
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That's a shame Dougie.......
All's good Andrew...
Dealer is going to swap (unless it sells of course!!) the front filter for a 72mm version.
Consider this fiasco a lesson learned!
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  #55  
Old 09-09-2008, 05:09 PM
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Excellent Doug !!!

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  #56  
Old 03-10-2008, 12:20 AM
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UPDATE 3.10.08

Dealer swapped Front Filter for 72mm screw in type - outside imaging with it right now...all subs look free of any vignetting/reflections and I'm pushing 10min exposures too!
Had to purchase a 67-72mm step up ring to get it to fit on my 70-200mm f4L lens ($10 from ebay) and another on the way to try out on my nifty fifty!
One downside - a 72mm filter collects dew quickly!!!

POSTED SOME IMAGES NOW, 72mm Filter First Light!!!

single subs, Cats Paw - 5mins, SMC - 10mins, both iso1600.
200mm f4
Not too bad - longer exp looks like some vignetting creeping in, fixed by flats hopefully - otherwise OK!
Off to bed now - knackered!
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Last edited by dugnsuz; 03-10-2008 at 01:38 AM.
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  #57  
Old 03-10-2008, 08:45 AM
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CLOSURE!
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  #58  
Old 03-10-2008, 09:11 AM
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nice pics doug, the cats paw stands out nicely against the background - smc good also. Looks like you have had a reasonable end to the filter problem
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  #59  
Old 04-10-2008, 02:48 AM
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I'm glad you managed to wangle your way out of that one Doug. Those Hutech filters ain't cheap regardless of size or source.
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  #60  
Old 12-10-2008, 08:01 AM
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CLOSURE!
Not Quite!!!!!!!!
Returned front filter to Hong Kong dealer, but have to make up the balance of $310HK for the 72mm filter.
Unfortunately, plummeting money markets means that 310 will cost me a bit more than it would have a month ago when this crap started!!!!

(That's me!)
Doug
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