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Astrophotography and Sketching >> DSLR & Digital Camera Astro Imaging & Processing

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Alnitak2009
member


Reged: 04/10/09
Posts: 22
Field Curvature Help
      #3417257 - 10/28/09 11:04 PM Attachment (12 downloads)

Hi all,

I took this image through my Meade 5000 Series APO 480mm f/l refractor and Canon 30D unmodded DSLR with IDA LSPF. There is noticable field curvature at the corners. I stacked about (6) images using DSS. Each image was taken at ISO 400 with noise reduction on. EXpoure times were around (5) minutes each.

I am amazed on how much information I managed to pull out on this target with the moon being at first quarter phase.

Does anyone have any suggestions on what field flattener works best with this short focal length refractor? I was looking at the Televue brand but its pricey. I came across a site a while back that illustrated various brands and compared images of each. Some brands tend to do a great job and others were fair but not perfect in there corrections. I can't find that site. I should have saved it.

If anyone had any good review sites or experience I would greatly appreciate it. I want to take images without this curvature.

Thanks,
Don


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Rankinstudio
sage
*****

Reged: 04/05/08
Posts: 412
Loc: Salt Lake City, UT, Lake Powel...
Re: Field Curvature Help new [Re: Alnitak2009]
      #3417269 - 10/28/09 11:08 PM

Its back ordered, but these work great for 80mm Short FL APO's

http://www.optcorp.com/product.aspx?pid=9180&kw=reducer&st=2

Cheers!

--------------------
David Rankin
http://www.rankinstudio.com
Astro Gallery
Orion 254mm F4.7 (imaging scope)
Baader MPCC
Quickcam pro 9000 (guider, imager)
Canon Rebel XSi (self modified)
Atlas EQ-G (EQ MOD)
Canon 50mm F1.8 II Lens
Canon 28-200 F3.2 Lens
DSLR peltier cooler





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UniversalMaster
super member


Reged: 11/20/08
Posts: 177
Re: Field Curvature Help new [Re: Rankinstudio]
      #3417761 - 10/29/09 08:23 AM

The best Field flattener I have found (*) for my 80mm f/6 Lomo triplet is by FAR the Takahshi FS60C 1.06x field flattener. Field is VERY flat to the corners of my 350D:
http://epsilon.flight.dk/Pictures/0006/Soeren_Madsen_Stellarvue_SV80_Canon350D_Tak_Center.htm

It may work for your scope too since the fl. and fr. are the same.
Here is an image without flattener from my scope:
http://epsilon.flight.dk/Pictures/0004/Soeren_Madsen_Stellarvue_SV80_Canon350D_Non.htm

Søren

(*) I have also tried the WO 0.8x III and the TV 0.8x TV85 reducer. The Tak is WAY superiour to these, but extends the focal length a little rather than reducing it. It also works much better than Stellarvues own flattener (my scope if from SV).

Edited by UniversalMaster (10/29/09 05:38 PM)


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David Rosenthal
Carpal Tunnel
*****

Reged: 06/23/06
Posts: 1645
Loc: NJ
Re: Field Curvature Help new [Re: UniversalMaster]
      #3418095 - 10/29/09 12:04 PM

I have had excellent success with the Astro-Tech Flattener. It is only a flattener, no reduction at all. It is priced real well and use it with my Borg 76ED, which is pretty close to yours. I did have to add 2 0.125 in spacers between the camera and the FF.

Here is a link to the product and there is a shot of one of my images there as well. Let me know if you need any additional images or a CCD Inspector shot.

PRODUCT LINK

--------------------
David Rosenthal | Midland Park, NJ


My Image Gallery
http://www.EastCoastAstro.com

Atlas EQ-G EQMOD USBDIR [Self-Hypertuned]
8" Meade SCT | Borg 76ED | Takahashi FS-60C
Self Modded 400D | SX MX716 | DSI Pro | SPC900NC
Series 5000 26mm, Hyperion 17mm, TV 11mm Plossl


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Spoonsize
Vendor/Clothing
*****

Reged: 08/27/04
Posts: 3293
Re: Field Curvature Help new [Re: David Rosenthal]
      #3418316 - 10/29/09 01:35 PM

The Baader MPCC works quite well with the Canon cameras and I just happen to have one listed in the classifieds. I went and left our Canon on the roof of our car and drove off. So, the MPCC and the DSLR T-ring are for sale.

--------------------
Steve Durham
www.margesmonograms.com
(Marge made me do it)

"Nobody get's in to see the WIZARD, Not Nobody, Not Nohow"


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