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Bummed about my 2.5x powermate

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#1 rigel123

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Posted 09 February 2013 - 06:09 PM

Attaching an image that I overstretched to show what I am seeing when I shoot longer exposures of proms with my new 2.5X Powermate. I'm getting a "Ghost" image of the sun and it's driving me nuts. I don't get this when I use my cheapo orion 2X barlow! I like the clarity I get with the powermate but any ideas how to avoid getting this ghost?

Camera is a DMK31AU03. I can reduce the ghost somewhat when shooting at higher frame rates but it is still there and I hate trying clone it out or reduce it by playing with the background. I may just go back to my inexpensive barlow!

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#2 BYoesle

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Posted 09 February 2013 - 07:54 PM

I noticed this in your animation too. The Powermates use a telecentric lens arrangement, with both a negative lens and a positive lens - or lens groups. My guess is that one of the groups or lenses may involve a plano component. If these are not tilted, you may get a reflected image like this. I'd send the image with your description to TeleVue for a more informed opinion.

#3 sullij1

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Posted 09 February 2013 - 08:20 PM

WOW, Warren, I had similar issues with my Cak images. I never thought to peg the issue on the powermate. If you choose to follow Bob's advise, let us all know what Teleview says. Last time I saw this issue pop up it was an issue with the inside of the C to 1.25 adapters being not properly flocked.

When I saw your post it struck me to check my 2.5 Powermate for proper flocking on the objective side. Sure nuff, if you dis-assemble (unscrew the threaded elements) the inside elements are flocked. Unfortunately the chrome barrel on the objective side is not! Perhaps using flat black paint to flock the threaded chrome end on the powermate may make the reflectionm go away. If you have sun, it easy enough to do and post back (while you wait for teleview to respond).

Thanks for pegging the powermate as the possible culprit. I have been fighting the same reflection! :foreheadslap:

If it is the unflocked chrome end - that will be an easy fix for a lot of us.

Joe

#4 rigel123

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Posted 09 February 2013 - 10:05 PM

Thanks for the comments Bob/Joe, I'll definitely write to Televue and I'll report back what they say. The inexpensive barlow I have used in the past (it is a Meade, not an Orion) is a shorty 2X barlow. I took apart the Televue and it appears flat black all the way through. Glad to hear it's not just me!

#5 brianb11213

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Posted 10 February 2013 - 03:49 AM

The 2.5x Powermate works well with my Imaging Source cameras. I note that the filter thread on the front of the nosepiece is shiny metal and might be better blackened or flocked but it really doesn't seem to affect me. I suspect your reflection is between the front element of the powermate and the back element in the Ha diagonal ... the elements in the blocking filter are often slightly tilted to avoid internal reflections & perhaps yours isn't tilted enough.

I've always had issues with "ordinary" barlows for high resolution imaging ... some loss of contrast due to reflections similar to that shown in your image, some loss of resolution possibly caused by poor correction especially at short & long wavelengths (solar CaK & Ha) but mostly because the magnification varies so much with the magnification. Give me a Powermate any day. I just wish they made 1.5x, 2x and 3x in 1.25" fittings ... the 2" fitting Powermates are far too heavy & the 5x is way too powerful in a scope with anything like a sensible focal ratio.

#6 AstroPaolo

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Posted 10 February 2013 - 04:48 AM

the 2x and 4x powermate 2" gave me the same reflection and gost images, they cost a fortune, I expected no reflection in any conditions, my cheap 2x celestron barlow suffer alot less but it has a different lens system

televue probably didn't create them thinking also the solar imaging, i switched to the baader telecentric barlow, created for solar imaging; that also has an halpha range cleaner avoiding any reflection.

#7 marktownley

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Posted 10 February 2013 - 06:00 AM

I've read others having the same issue with the 2.5x powermate and Ha, I don't (luckily!) have this issue... Not sure what to suggest to fix...

#8 ASTROTRUCK

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Posted 10 February 2013 - 10:01 PM

same issue with my 2.5 powermate with my dmk41

so who do we send it back to - if we do our own paint job what are the chances of the paint flecking with constant summer heat.

they should be prepared to correct the flocking issue considering the cost for one up here in canada.

#9 rigel123

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Posted 10 February 2013 - 10:02 PM

Hopefully will have a chance to talk to Televue once I'm back from my meeting. I'll be interested in their input.

#10 Aquarist

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Posted 11 February 2013 - 10:14 AM

Yes, please keep us posted.

#11 drksky

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Posted 11 February 2013 - 12:28 PM

Makes me curious to try out the 2.5X powermate that I bought a few weeks ago. Haven't had a clear day since then.

#12 Andy Devey

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Posted 11 February 2013 - 12:52 PM

Hi, just a thought, what about cutting a piece of matt black cardboard the same length of the inner circumference and putting it into the barrel of the the Powermate it would be very easy to do?

Regards

Andy

#13 ASTROTRUCK

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Posted 11 February 2013 - 03:14 PM

if it has to be opened then is there a critical alignment issue when reassembling

nagler i am sure may not be happy to receive back all our 2.5's

then are these isolated few not blackened not caught by them or all not blackened at all

#14 rigel123

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Posted 11 February 2013 - 09:50 PM

I did take mine apart and the only part that is shiny chrome is the very end of the tube, the entire inside is flat black. I may try some flat black on the very end and see if that takes care of it.

If anyone else notices this same reflection please let me know.

#15 sullij1

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Posted 11 February 2013 - 10:02 PM

I thought as Brianb, perhaps a reflection between the lens groups and the diagonal. It will be interesting to see how this pans out.

Warren, do you use a diagonal? If so, can you shoot one straight through without the diagonal and see what you get?

#16 Jim Lafferty

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Posted 14 February 2013 - 01:49 PM

Havent had that issue myself with my 2.5x powermate---Im assuming you arent doublestacked?

Jim

#17 marktownley

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Posted 14 February 2013 - 02:07 PM

What size blocker is being used in the scope?

#18 ASTROTRUCK

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Posted 01 March 2013 - 02:41 PM

question - i as stated using the 2.5 powerrmate have a very acute double image -using an etelon i place the powermate between the blocking filter & the dmk
IS IT SAFE TO PLACE THE POWERMATE BEFORE THE BLOCKING FILTER considering the etelon reduces the heat coming through , & still place the dmk after the blocking filter.
this somewhat changes the position of the various glass surfaces.

thanks


#19 rigel123

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Posted 01 March 2013 - 03:31 PM

Sorry, forgot about this as I have been busy with work and it has been cloudy. I did do some imaging with my Orion 2X and no problems.

Yes there is a diagonal it is the 1200 BF, and it is a single stack. I haven't had a chance to talk with Televue yet.

Just spoke to Televue, it's a spacing issue, will post more info later

#20 rigel123

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Posted 01 March 2013 - 08:21 PM

OK, this may make some sense. I spoke with Televue and it is the spacing that is causing the ghost. They suggest getting the PTR-1250 T Ring Adapter which replaces the eyepiece holder on the Powermate, as described by our sponsor here:

https://www.astronom...rmates_p3441...

Then I'll need another adapter to allow that to attach to the DMK31 camera.

When I look at the Orion Barlow I use that I don't have a problem with, it is a shorty model, and is about the length of the Powermate when you take the eyepiece holder off the Powermate. Of course it is not an inexpensive fix, I may just be using that CN discount!

#21 sullij1

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Posted 01 March 2013 - 10:10 PM

Thanks for the follow up Warren. Valuable information for anyone battling the issue.

#22 marktownley

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Posted 02 March 2013 - 04:21 AM

Yes, useful info there Warren, thanks :)

#23 ASTROTRUCK

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Posted 02 March 2013 - 11:25 AM

note that the advert states that removal of the nosepiece adapts to ccd's so maybe also to the dmk's

#24 rigel123

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Posted 02 March 2013 - 02:08 PM

note that the advert states that removal of the nosepiece adapts to ccd's so maybe also to the dmk's


Yep, need to read more closely before I order! The guy I spoke with at Televue was great, very helpful and asked a lot of questions about my setup before giving me the advice.

#25 rigel123

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Posted 11 March 2013 - 11:56 AM

Finally got all of the pieces and of course it is cloudy. For those of you interested, here is a look at the set up that I'll be testing out once I get to see the sun again!

First image is the Camera and Televue 2.5 X Powermate

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