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WO RedCat 51: comments, observations, opinions and suggestions

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#1 weh

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Posted 29 April 2019 - 10:02 PM

My RedCat 51 arrived today. Much drama, but that's another story. This is just a few first impressions -- as a lens, not as a telescope -- it's cloudy here tonight so no stars.

 

This thing is sharp! I'm not trying to do any official testing -- not my bag and others more capable have promised something much more analytical -- but I did compare it side-by-side using the same Nikon D850 body attached to my 200mm f/2G AF-S VR Nikkor lens set at f/4.5 and to my two 300mm f/4 Nikkor lenses (f/4D AF-S and f/4E PF AF-S VR), both at f/4, wide open. It easily is sharper than either of the two 300mm lenses (I don't have a 300f/2.8 to run an informal comparison) and competition against the 200f/2 @ f/4.5, f/4 and f/2.8 is too close to call. Comparing the 200f/2 at f/2 against the RC51 250f/4.9 is bit unfair; however, the RC51 was the winner. I was really amazed as the 200f/2 is considered one of  Nikon's very sharpest lenses. I'm not bothering to post images -- they're boring -- a rusty hubcap leaning against a wooden fence about 200 yards from my camera with the lens firmly mounted using its base's A/S side to an FLM CB58 ball head on my PMG TR424L tripod with two cinder-blocks as ballast beneath the apex.

 

Now some suggestions: (1) A minor manufacturing improvement might be etching three marks on the RC tripod mount corresponding with vertical and horizontal at either side and four corresponding alignment marks on the lens, itself. I realize there is that whole rotating mount thing with all 360 degrees incorporated into the lens design; but sometimes, especially with the camera mounted and the len's tripod mount on a tripod, it's much easier to loosen the mount retaining screw and rotate the lens a quarter turn. Having those marks engraved/etched/painted would add a penny to production cost (maybe) and a great deal of convenience to the land-based end user.

 

And, (2) there are a lot of Allen wrenches needed for this thing. Not that I don't have quite a collection at hand, but having them at hand and having to guesstimate as I approach each screw is mildly annoying. Couldn't WO have specified the sizes used somewhere in the meager documentation?

 

Overall, I like it. Fit and finish are exemplary. It's very easy to use. And packaging is stellar (forgive the pun). I'm impressed. And I'm a jaded photographer with a history of 60 years of photographic equipment under my belt, including high-end gear from Contax, Hasselblad, Leica, Linhof, Rollei and Schneider as well as all the used and abused Japanese brands. I don't impress easily.

 

Just my two cents....


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#2 gregbradley

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Posted 30 April 2019 - 03:53 AM

Mine arrived today as well.

 

The fit and finish is superb. My focuser is a tad stiff but that may loosen over time.

 

I did some daytime testing and it looks like all 4 corners are pretty much in focus at the same time.

 

The focus lock will be handy once its focused.

 

The Canon EOS adapter though does not click tight it has about 15 degrees of movement once on with my EOS R.

 

I also got the Nikon and Sony E adapter. The Sony adapter is very well made and the same lovely reddish annodising. It fits very snugly.

 

I like the dual dovetail, one side Arca Swiss the other Vixen. Makes it much easier to mount as the Vixen dovetail is just a tad wide for an Arca Swiss mount.

 

Cloudy here as well but hopefully it may clear at some point tonight.

 

Greg.


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#3 GraySkies

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Posted 30 April 2019 - 03:47 PM

I'm doing a full youtube review on the RC51, but initial results are quite promising.

Single Light Sub [Linked to Jpeg as it came out of the camera]
https://drive.google...iew?usp=sharing

More info from my first light tests -> https://www.cloudyni...dcat/?p=9324900


Edited by GraySkies, 30 April 2019 - 03:47 PM.

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#4 Mike_Feldman

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Posted 30 April 2019 - 05:57 PM

I've got a Redcat on order, but I'm trying to figure out what adapter I need for my Sony a7Sii (E-mount).  The WO site lists E-mount adapter, but the distributors in the USA don't.

 

   https://williamoptic...at-51/focus.jpg

 

Shows M48 and M56 threads and the detail shows 48mmX0.75mm and 56mmX0.75mm threads.  That's the only place on the WO site I've found the thread pitch listed.  0.75mm is "T-mount" pitch.

 

I've got an M42 to Sony E-mount adapter already (2, actually), so an M48 to M42 seems the way for me to go.  I am concerned about thread pitch, though, since M42 (Pentax screw mount) is 42mmX1.0mm,

and is not to be confused with "T-mount".  I do have to worry about the distance to the focal-plane, so the WO adapter may be the safest bet, but how to order from the US.

 

Anyone got a Redcat adapted to a Sony alpha camera?  What are you using?

 

-- Mike



#5 GraySkies

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Posted 30 April 2019 - 06:27 PM

I've got a Redcat on order, but I'm trying to figure out what adapter I need for my Sony a7Sii (E-mount).  The WO site lists E-mount adapter, but the distributors in the USA don't.

 

   https://williamoptic...at-51/focus.jpg

 

Shows M48 and M56 threads and the detail shows 48mmX0.75mm and 56mmX0.75mm threads.  That's the only place on the WO site I've found the thread pitch listed.  0.75mm is "T-mount" pitch.

 

I've got an M42 to Sony E-mount adapter already (2, actually), so an M48 to M42 seems the way for me to go.  I am concerned about thread pitch, though, since M42 (Pentax screw mount) is 42mmX1.0mm,

and is not to be confused with "T-mount".  I do have to worry about the distance to the focal-plane, so the WO adapter may be the safest bet, but how to order from the US.

 

Anyone got a Redcat adapted to a Sony alpha camera?  What are you using?

 

-- Mike

Its a standard T2 Mount thread as far as I can see... so in theory any standard T2 adapter should work... I have another William Optic Scope Field Flattener and its T2 Mount, I don't think William Optics is about to do something drastically different...


Edited by GraySkies, 30 April 2019 - 06:33 PM.


#6 Mike_Feldman

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Posted 01 May 2019 - 10:44 AM

What's the old saw?  "The great thing about standards is that there are so many to choose from".

 

This seems to be the best easily found explanation: https://agenaastro.c...-explained.html

 

"T/T2/"42mm T" Thread  M42x0.75  Very common in photography and astronomy. The "T thread" is identical to the T2 thread from Baader. Not the same as Pentax/screw/M42 thread, which is M42x1.0."

 

So why can't the adapter makers actually specify the pitch as well as the diameter in their product descriptions?  I have yet to see that on-line.

 

And it goes on, but what does the "T" stand for?  Telescope?  Thread?  Terse?   Tacit?

 

-- Mike


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#7 gregbradley

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Posted 01 May 2019 - 11:39 PM

I got the Sony E mount 48mm long adapter for my Redcat 51. Its well made and works fine.

 

https://williamoptic...-for-sony-e-red

 

Greg.



#8 weh

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Posted 02 May 2019 - 11:11 AM

... And it goes on, but what does the "T" stand for?  Telescope?  Thread?  Terse?   Tacit?

Actually, it probably stood for "Taisei" -- the Japanese company that first produced lenses adaptable to a variety of camera mounting systems. That company is known as Tamron today. It comes in two varieties: 42mm and 48mm, both with a screw pitch of 0.75.


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#9 helgeras

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Posted 04 May 2019 - 10:43 AM

I received a RedCat 51 the other day, and the weather is lousy. However I was able to take a few 10 sec exposures at a hole in the clouds.

I would like to hear what others think of this, personally I am not too impressed, but then I am a newbie.

 

10 sec exposure iso 6400 heavy light pollution with sony a7s and a Redcat 51:

 

The link contains a fit, jpg, sony a7s raw and a cdinspector screenshot:

 

https://drive.google...B9IbPkhuAVKXO7q

 

I do not have the correct adapter for my camera yet, which probably is the cause for the heavy vignetting.

 

 

Helge

 

 



#10 GraySkies

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Posted 04 May 2019 - 11:21 AM

I received a RedCat 51 the other day, and the weather is lousy. However I was able to take a few 10 sec exposures at a hole in the clouds.
I would like to hear what others think of this, personally I am not too impressed, but then I am a newbie.

10 sec exposure iso 6400 heavy light pollution with sony a7s and a Redcat 51:

The link contains a fit, jpg, sony a7s raw and a cdinspector screenshot:

https://drive.google...B9IbPkhuAVKXO7q

I do not have the correct adapter for my camera yet, which probably is the cause for the heavy vignetting.


Helge


What do you mean by “I don’t have the correct adapter”?

Without the correct adapter, That’s likely also the reason you have to have a tilt, the collimation error, although I don’t know why you have such a high curvature but it could be that the sensor is so off that CCD inspector is blaming the lens rather than the poor camera placement.

#11 Mike_Feldman

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Posted 04 May 2019 - 11:21 AM

I do not have the correct adapter for my camera yet, which probably is the cause for the heavy vignetting.

So how did you connect your a7S?

 

I'm further back in the Highpoint line on my Redcat order.  I went ahead and ordered the WO Sony-E adaptor from the William Optics website.  Got a receipt from Paypal, but no further indication that the order's received or in process.  The item page said "In Stock", but who knows how long it's been since the page was updated.



#12 helgeras

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Posted 04 May 2019 - 12:30 PM

I used a T48 to Canon adapter connected to a Canon to Sony E adapter. My T 48 to Sony adapter is in the mail, I ordered it last weekend from wo.


Edited by helgeras, 04 May 2019 - 12:32 PM.


#13 weh

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Posted 04 May 2019 - 04:36 PM

I still haven't taken any pictures of stars. We've had some family things going on that have superseded my hobby activities so I haven't even picked up a camera in 3 days. Next week I should be able to play some more -- weather willing.



#14 AstroGabe

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Posted 05 May 2019 - 11:27 AM

Mine arrived a bit over a week ago.  I was on a trip for work, and only got to use it last night.  First impressions:

 

1.  The Bahtinov mask is a very handy accessory.  I'm used to autofocus with HSM motors on my focusers for my other scopes, so was worrying about moving back to manual focus.  I set up last night around 11pm and focused only twice throughout the imaging session.  After the first focus, the images were a bit soft, but I wonder if that was due to the scope cooling down.  After the second time with the Bahtinov, it kept pretty good focus throughout the session.

 

2.  The focus ring, while stiff, wasn't an issue w/ focusing.  I sensed no backlash, but I hope to get an autofocus solution in place so I can keep as many subs as possible.  I'm looking into Deepskydad's focus motor as an option.

 

3.  The vixen style shoe doesn't fit the saddle I have for the Mach 1.  This was a bit disappointing, but I rigged together a 7" ADM vixen style bar underneath the Redcat's dovetail.  The dovetail has 1/4-20 taps underneath, so attaching it was easy.

 

4.  The test was with a QSI690 - not great for testing edge of field performance - I mainly wanted to check star shapes since some pre-production versions had some really strange looking stars that might indicate internal reflection.  The images I got were sharp to the edge of the small 690 chip, which is no surprise there, and the star shapes looked fine.  A next test will be with my 16200 camera and a FOV with brighter field stars.  

 

get.jpg?insecure

 

IMG_2478.jpg


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#15 sparkyht

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Posted 06 May 2019 - 09:15 PM

I looked at the full res image and noticed that the stars have slight coma and diffraction spikes. Do you have this in all your subs? Over at SGL, there are a few owners who have coma-like stars from their RedCats. Curious. So far, I am not convinced that this lens will live up to the marketing hype. I hope to see more reports on this lens before mine ships so I can make a better informed decision.
 

 





 

Attached Thumbnails

  • aTLtjC5yWqoV_16536x16536_wmhqkGbg_mosaic.jpg


#16 AstroGabe

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Posted 06 May 2019 - 10:29 PM

Good eye Chad.  There does appear to be some coma, which appears to be opposite in orientation to the coma you'd experience with a reflector.  I think the diffraction spikes are the microlens array since it's aligned with the ccd pixels.  The diffraction spikes I was worried about are shown prominently in this image.

I did have an earlier image that was slightly out of focus, and it shows the coma more prominently.

 

 

Screen Shot 2019-05-06 at 10.22.27 PM.jpg



#17 Sarkikos

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Posted 09 May 2019 - 10:27 AM

For those who have recently received the WO RedCat 51, where did you order it from?  I see they are still on pre-order at Agena Astro.

 

Mike



#18 weh

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Posted 09 May 2019 - 02:10 PM

For those who have recently received the WO RedCat 51, where did you order it from? ....

I was #104 of 129 on WO's KickStarter campaign. I opted for the 55mm filter thread option which delayed delivery approximately 3 weeks and I've had it about 2 weeks now.



#19 AstroGabe

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Posted 09 May 2019 - 02:11 PM

I preordered mine from Agena in early March.  Got it late April.  



#20 helgeras

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Posted 10 May 2019 - 12:50 PM

I ordered mine in march from teleskop Express in Germany and got it late april.

Also I ordered the Sony E adapter from the wo website 2 weeks ago, and got it today. The vignetting is gone with that, now I just need clear skies to test it.


Edited by helgeras, 10 May 2019 - 12:51 PM.


#21 Mike_Feldman

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Posted 10 May 2019 - 03:46 PM

WO Redcat M48 Sony-E Adapter

 

Well, I chose to order the correct adapter directly from William Optics.  It arrived ahead of a ship notification for the Redcat itself.


Edited by Mike_Feldman, 10 May 2019 - 03:47 PM.


#22 Foc

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Posted 10 May 2019 - 06:25 PM

I have had my RedCat 51 from Agena for a week now, and obtained from William Optics directly the  diagonal and adapters for  Sony e-mount and  Olympus m4/3.  Of course as with any new arrival, the weather has not been good but a quick set of pics fixed to my old Vixen Porta Mount  suggests a Red dot finder or something similar might be handy for casual pics.  Has any one found a finder to fit nicely in the hole (do not know what the thread is) provided in the scope?



#23 timmbottoni

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Posted 10 May 2019 - 10:54 PM

Just a pic of the moon taken with the RedCat51 and my old Canon 60D taken tonight

 

Clear skies and peace to all tonight

Attached Thumbnails

  • IMG_9057-2.jpg


#24 helgeras

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Posted 13 May 2019 - 01:03 PM

I got a few hasty shots with the Redcat and the correct adapter, and CCD Inspector isn't that happy.

 

I am no expert in CCD inspector, so I would really appreciate if someone could look at the pictureand comment on it.

 

Can I fix that tilt? Is it as good as it can get or should I send it back to be fixed?

 

1 picture taken with a Sony A7s and Redcat. The directory contains the same picture as sony raw (ARW) as .fit and as .jpg. CCDInspector.png contains a screendump from CCD inspector:

 

 

https://drive.google...B9IbPkhuAVKXO7q



#25 ippiu

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Posted 14 May 2019 - 07:59 AM

Hi to everybody.

 

I have the beatiful gem RC51. And i'd like to investigate if it has the coma issues present in some previous models.

 

I took flat frame. I took a couple of quick images last week before the weather broke forever in .png (i forgot to change the file extension in .fit in Sharpcap).

i'm asking everyone a favor: could anybody take a look at my files and say if my RC51 is good? I would really appreciate if someone, more expert than me, could have a look at my pictures.

 

As soon as the weather will be fine (i hope soon...) i will have another test session taking .fit images...

 

https://drive.google...fcv9auwLiD48pRz

 

Thanks so much


Edited by ippiu, 14 May 2019 - 08:00 AM.



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