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Author Topic: William Optics Flattener IV  (Read 7985 times)

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Offline NigelB

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William Optics Flattener IV
« on: 20:42:51, 14 April, 2009 »
I've been using the WO Flattener III with my Megrez 90 for a month or so and am very disappointed with the 'roundness' of the stars particularly at the field edges. So much so that I took some images without a Field Flatteenr to convince myself my scope wasnt faulty! See two images of Beehive Cluster without and with Field Flattener III.

 I am using a Canon 1000D for imaging.

Simon at the Widescreen Centre very kindly loaned me a Flattener IV to test last week. When it arrived I was surprised at the size. It is bigger than a coke can and weighs in at just over 600g!

Luckily the day it arrived there were clear ckies. Seeing was not brilliant and there was a full moon but I had a go at  M37 in Auriga. The results were superb, round stars corner to corner! See final full frame shot attached.

The Flattener IV has an adjustable distance setting to vary the lens to sensor distance. I set mine to that recommended for the Megrez 90. I did try varying the distance slightly and I could see any drop off in sharpness or roundness.

Using the Flattener IV has given me much lower FWHM figures with Nebulosity and the focussing seems to be sharper and more responsive.

All in all I think this is a superb piece of kit and thoroughly recommend it over the Flattener III.



[attachment deleted by admin]
Imaging scope: Takahashi FSQ106EDXII, Hasselblad 150mm lens
Imaging Camera: QSI583WSG, Astrodon LRGB and Ha, OIII and SII 3nm
Guide camera: Orion Starshoot
Mount: EQ6 Pro
Software: CCDStack, Maxim DL, Sky6, ,PixInsight, CS4, Noels Actions, EQDIR
http://www.nigelaball.com/

Offline Dangerous_Dave

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Re: William Optics Flattener IV
« Reply #1 on: 15:18:02, 22 April, 2009 »
Nice one Nigel. I use the Megrez 90 + FFIII and agree about star shapes. That said, the improvement over the un-flattened image is still good for such a cheap piece of kit and I am very happy with mine. Did you take a test image with the Flattener IV?

Any idea how much the FFIV retails for?
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

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Offline SteveL

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Re: William Optics Flattener IV
« Reply #2 on: 17:18:06, 22 April, 2009 »
The new and improved "second attempt" AFR-IV is somewhere in the region of £210-220 (!!). The first AFR got recalled, some say because the elements were put in the wrong way, some say it was recalled because it just didnt work. I`m also hearing from several sources that WO may have slightly messed it up againstead oin. The new AFR supposedly INCREASES your focal length, somewhere in the region of 1.15-1.2x, instead of the 0.8 reducer it was supposed to be. Sure, its a good flattener, but instead of taking my FLT98 down to f/5, it would now be up over f/7 if this is true...

I posted a message on the WO yahoo group requesting uncropped images with the AFR-IVm and the OTA/Camera details so I can work out what FoV it should give versus what it actually is. I will be taking some images on my FLT98 this weekend (weather permitting), and can compare them to the WO FFIII I used on it before. If the AFR-IV doesnt reduce, its going back!
http://www.steves-astro.com/
EQ6Pro/SW190mm MakNewt/Borg77@4.3/ED80Pro, QHY8, M25C, LodeStar, DSI, and 100% cloud cover :(

Offline SteveL

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Re: William Optics Flattener IV
« Reply #3 on: 17:30:17, 22 April, 2009 »
Nigel, is that M37 an uncropped image?
http://www.steves-astro.com/
EQ6Pro/SW190mm MakNewt/Borg77@4.3/ED80Pro, QHY8, M25C, LodeStar, DSI, and 100% cloud cover :(

Offline NigelB

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Re: William Optics Flattener IV
« Reply #4 on: 19:55:49, 22 April, 2009 »
Nigel, is that M37 an uncropped image?


Yes Steve that is an uncropped image
Imaging scope: Takahashi FSQ106EDXII, Hasselblad 150mm lens
Imaging Camera: QSI583WSG, Astrodon LRGB and Ha, OIII and SII 3nm
Guide camera: Orion Starshoot
Mount: EQ6 Pro
Software: CCDStack, Maxim DL, Sky6, ,PixInsight, CS4, Noels Actions, EQDIR
http://www.nigelaball.com/

Offline NigelB

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Re: William Optics Flattener IV
« Reply #5 on: 20:06:44, 22 April, 2009 »
The new AFR supposedly INCREASES your focal length, somewhere in the region of 1.15-1.2x, instead of the 0.8 reducer it was supposed to be. Sure, its a good flattener, f taking my FLT98 down to f/5, it would now be up over f/7 if this is true...


Now that would explain why I had problems framing Markarians Chain with the Flattener IV on the Megrez 90

The two images below should show this

First image is Megrez 90 + FF III + Canon 1000D

Second image is Megrez 90 + FF IV+ Canon 1000D




[attachment deleted by admin]
Imaging scope: Takahashi FSQ106EDXII, Hasselblad 150mm lens
Imaging Camera: QSI583WSG, Astrodon LRGB and Ha, OIII and SII 3nm
Guide camera: Orion Starshoot
Mount: EQ6 Pro
Software: CCDStack, Maxim DL, Sky6, ,PixInsight, CS4, Noels Actions, EQDIR
http://www.nigelaball.com/

Offline SteveL

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Re: William Optics Flattener IV
« Reply #6 on: 20:17:25, 22 April, 2009 »
Thanks Nigel... I submitted your image to Astrometry to get the FoV, and did some calculations on what it should be for a Megrez 90 + Canon 1000D

1000D + Megrez 90 @ native f/6.9 -> should give 122 arcmin x 81 arcmin

1000D + Megrez 90 @ 0.8x reduced f/5.5   -> should give 153 arcmin x 102 arcmin

Astrometry returned a FoV for your M37 image as 112 arcmin x 75 arcmin, so its actually a smaller FoV than using the Megrez natively. Using CCDCalc, I reckon the AFR-IV is turning your Megrez 90 into a ~680mm fl f/7.5

I do notice that WIlliam Optics have now removed any reference to the fact that the AFR is a reducer in the description, but one of the lines still states:

Quote
Takes FLT-98 to 490mm f/5.0 and the FLT-110 to 615mm f/5.6.

( http://www.williamoptics.com/accessories/flattener4_features.php#

Just seen your second reply... I am assuming your were looking at the AFR to both flatten AND reduce, but by all accounts, its not reducing. Its acting like a 1.1x barlow! I did not spend ~£220 for something that doesnt do 100% of what it was designed to do...

I just needed to see this for myself, with either my own images, or with someone else who could show an uncropped image. I think its time to rail at WO in the Yahoo group about this... considering the c_ckup with the first version, and now this, I despair!....The supplier who sold me the AFR knows about this potential issue now, and is willing to do a full refund if required. May I use your M37 image here as reference when I post on there? May I host the image on my website so I can link to it in that email?

http://www.steves-astro.com/
EQ6Pro/SW190mm MakNewt/Borg77@4.3/ED80Pro, QHY8, M25C, LodeStar, DSI, and 100% cloud cover :(

Offline SteveL

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Re: William Optics Flattener IV
« Reply #7 on: 20:37:21, 22 April, 2009 »
Here are the results

Flat3 -> 2.68 x 1.78 deg -> 160 x 106 -> f/5.3 (0.77x reduction)

Flat4 -> 1.87 x 1.25 deg -> 112 x 75 -> f/7.5 (1.09x increase)

I think that is all that needs to be said, really... quite damning for WO to screw it up.
http://www.steves-astro.com/
EQ6Pro/SW190mm MakNewt/Borg77@4.3/ED80Pro, QHY8, M25C, LodeStar, DSI, and 100% cloud cover :(

Offline steppenwolf

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Re: William Optics Flattener IV
« Reply #8 on: 22:00:16, 22 April, 2009 »
I have the FFIII and have noted 'spiky' stars at the edges of the FOV of my APS sized sensor (SXVF-M25C) when used with my Skywatcher ED 80 but this star shape is a huge improvement on the elongated stars that I got without it! The 0.8X reduction was an important part of my buying decision.
Regards,

Steve
http://www.skyatnightimages.co.uk
Night conceals the World but reveals the Universe

Offline chris.bailey

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Re: William Optics Flattener IV
« Reply #9 on: 07:37:25, 23 April, 2009 »
In my very limited tests with the FFIII it is very senstive to accurate spacing to the CCD.
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Offline NigelB

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Re: William Optics Flattener IV
« Reply #10 on: 21:22:21, 24 April, 2009 »
Here are the results

Flat3 -> 2.68 x 1.78 deg -> 160 x 106 -> f/5.3 (0.77x reduction)

Flat4 -> 1.87 x 1.25 deg -> 112 x 75 -> f/7.5 (1.09x increase)

I think that is all that needs to be said, really... quite damning for WO to screw it up.

Steve

Just done some analysis of more of my images on Astrometry

Results as follows

Megrez 90 + Canon 1000D                2.28° x 1.52°
Megrez 90 + FF III + Canon 1000D   2.84° x 1.89°
Megrez 90 + FF IV + Canon 1000D   1.87° x 1.25°

Therefore the FF III acts as a 0.8 reducer and the FF IV acts as a 1.2x barlow!

At least I know the correct figures to enter for FOVIs in Sky6 now!   :D
Imaging scope: Takahashi FSQ106EDXII, Hasselblad 150mm lens
Imaging Camera: QSI583WSG, Astrodon LRGB and Ha, OIII and SII 3nm
Guide camera: Orion Starshoot
Mount: EQ6 Pro
Software: CCDStack, Maxim DL, Sky6, ,PixInsight, CS4, Noels Actions, EQDIR
http://www.nigelaball.com/

Offline gsf1371

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Re: William Optics Flattener IV
« Reply #11 on: 15:09:17, 30 May, 2009 »
If its acting as a 1.2 x barlow, then there doesn't seem to be much point to it, as at 1.2 x I'd have thought the field edge misshapen stars would be 'zoomed' out of the image!? 220 quid is dear for a barlow!

i have the 0.8 v111 and have been trying to get it to work for quite a while. from what i gather, although it was marketed at dslr users the back focus distance, which i think they spec as 56mm from the back of the t ring ( who's t ring though, they're all different thicknesses!) is actually closer to 35-40mm, rendering it unusable for most combinations. I've improved things by getting the thinnest t ring i could find and I've been modding it today to give another 2 mil less back focus, I Hope to try this out tonight.

a pretty poor show on the ff/fr front from W O IMHO >:(
EQ6, RC8CF/featherlite, EQUINOX 80, Atic 16ic/modded 1000d etc

Offline Roger B

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Re: William Optics Flattener IV
« Reply #12 on: 17:18:39, 09 July, 2009 »
What does the spaceing affect ?   is it focus or colour correction ?

Roger
Scopes - TS65q, W/O 110 Triplet
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