William Optics RedCat 51 APO

[Craney]

Looks very cool and nicely designed.  

I would be interested to know how easy the focusing ring is to adjust and get absolutely spot-on with the mask.   Can it compete with the best Feathertouch, Moonlite etc....

 

[RayD]

6 minutes ago, Craney said:

Looks very cool and nicely designed.  

I would be interested to know how easy the focusing ring is to adjust and get absolutely spot-on with the mask.   Can it compete with the best Feathertouch, Moonlite etc....

 

It's 'firm' I would say, but the one I played with may not be a full production model possibly.  I think it will be smooth on the production models, and also seems to have a very good ratio, so fine adjustment should be easily possible. 

The focuser is actually one of the things I am most interested in as it is the bit that is most different, with most opting for Crayford or R&P, so it should be really interesting to test this out.

[Craney]

Thanks  @RayD   I will look forward with interest to your findings.

[RayD]

2 hours ago, Alien 13 said:

Looking at one of the videos it seems to suggest that the whole back end comes off including the rotator (not the focusser) which should give more back focus for a diagonal but looks like it needs to be special ...

Alan

I think the rotator drops off, Alan, and is where the filter slot is located. These are all the things I need to try I think.

I've got my pipe wrenches, burning gear, grinder and welder at the ready.............. Only kidding, Steve ?

[Chris]

26 minutes ago, RayD said:

It's 'firm' I would say, but the one I played with may not be a full production model possibly.  I think it will be smooth on the production models, and also seems to have a very good ratio, so fine adjustment should be easily possible. 

The focuser is actually one of the things I am most interested in as it is the bit that is most different, with most opting for Crayford or R&P, so it should be really interesting to test this out.

I'm sure I heard trever from backyard astro mention an adjuster ring for adjusting the tension on the helical focuser. I need to re-check the video, but it looked to adjust smoothly. 

[RayD]

1 minute ago, Lockie said:

I'm sure I heard trever from backyard astro mention an adjuster ring for adjusting the tension on the helical focuser. I need to re-check the video, but it looked to adjust smoothly. 

That would be absolutely ideal if it does have it, Chris.  

It wasn't unduly stiff, or anything that I would be concerned with, but it was definitely firm to rotate.  Certainly not as free as my Canon DSLR telephoto lenses, but not something that needed 2 hands.

Mind you, I was there early Friday so it could well be as floppy as a floppy thing now with hundreds of people having now used it.

[Chris]

3 minutes ago, RayD said:

That would be absolutely ideal if it does have it, Chris.  

It wasn't unduly stiff, or anything that I would be concerned with, but it was definitely firm to rotate.  Certainly not as free as my Canon DSLR telephoto lenses, but not something that needed 2 hands.

Mind you, I was there early Friday so it could well be as floppy as a floppy thing now with hundreds of people having now used it.

Yep, double checked Trevor's video. He shows the tensioner ring at the front at 3:21 minutes in. Happy days  

lol Yeah, I'm not sure I'd like to buy an Astrofest ex demo scope. 

[happy-kat]

Could you try it with a DSLR and barlow please such as a x2 or x1.6 shorty. Thinking of camera lens daytime angle.

[RayD]

4 minutes ago, happy-kat said:

Could you try it with a DSLR and barlow please such as a x2 or x1.6 shorty. Thinking of camera lens daytime angle.

Certainly can 

[souls33k3r]

Ray, matey can't wait for your review and please don't be gentle

Also I think you're missing a trick here. You need a handy assistant to model this scope and any other goodies in the future for your video... Look no further

[RayD]

2 minutes ago, souls33k3r said:

Ray, matey can't wait for your review and please don't be gentle

Also I think you're missing a trick here. You need a handy assistant to model this scope and any other goodies in the future for your video... Look no further

You are my first choice mate, you know that ?

I promise you my review will be honest, and wharts and all 

[souls33k3r]

9 minutes ago, RayD said:

You are my first choice mate, you know that ?

I promise you my review will be honest, and wharts and all 

I most definitely do brother

Knowing you, I expect nothing but the best possible review mate. 

What I'd be more interested in knowing how the focus holds in low and high temperature changes and how "sharp" are the images produced. 

[RayD]

1 minute ago, souls33k3r said:

how "sharp" are the images produced.

Sharpest in the world according to WO, so I am expecting something pretty good (aperture noted of course).

[SteveNickolls]

On 06/02/2019 at 19:12, Lockie said:

Only some camera lenses are more expensive and don't have the colour correction and flat field, field rotator, or built in focus mask. 

+1 to all that. However it's 51mm objective and f/4.9 optics  light grasp pales against the Samyang 135mm f/2 lens. Apples and pears though.

Cheers,
Steve

[Chris]

30 minutes ago, SteveNickolls said:

+1 to all that. However it's 51mm objective and f/4.9 optics  light grasp pales against the Samyang 135mm f/2 lens. Apples and pears though.

Cheers,
Steve

How sharp are the corner stars at f/2 with the Samyang? Do you need to stop it down at all? If you don't I probably should get one. 

[SteveNickolls]

6 minutes ago, Lockie said:

Do you need to stop it down at all? If you don't I probably should get one. 

Thanks,

The Samyang lens is reviewed here-https://www.lenstip.com/index.html?test=obiektywu&test_ob=442 I can only add I have been extremely happy with mine which I always use at f/2 with a modified Canon 700D. I'm sure other SGL-ers with the lens will similarly vouch for it. The RedCat 51 has a lot of positive, desirable features but the speed of the optics (from my point of view) isn't one of them. If you bought the Samyang lens (it retails around £440 new) I don't think you would be disappointed. ? 

Cheers,

Steve

[Chris]

5 hours ago, SteveNickolls said:

Thanks,

The Samyang lens is reviewed here-https://www.lenstip.com/index.html?test=obiektywu&test_ob=442 I can only add I have been extremely happy with mine which I always use at f/2 with a modified Canon 700D. I'm sure other SGL-ers with the lens will similarly vouch for it. The RedCat 51 has a lot of positive, desirable features but the speed of the optics (from my point of view) isn't one of them. If you bought the Samyang lens (it retails around £440 new) I don't think you would be disappointed. ? 

Cheers,

Steve

Defo an option for me, thanks. 

 

[Chris]

I apologise if this vid has been linked already, but just in case it hasn't. 

p.s. This is at 500mm focal length, as it's shot with an M4/3 sensor with a crop factor of 2x.  

 

Edited February 10, 2019 by Lockie

[Astroscot2]

5 hours ago, SteveNickolls said:

+1 to all that. However it's 51mm objective and f/4.9 optics  light grasp pales against the Samyang 135mm f/2 lens. Apples and pears though.

Cheers,
Steve

The Samyang is fine if you want to image at 135mm, I'd be interested to know if there is a 250mm lens out there with the specs and comparison to the redcat?

[Chris]

5 minutes ago, Astroscot2 said:

The Samyang is fine if you want to image at 135mm, I'd be interested to know if there is a 250mm lens out there with the specs and comparison to the redcat?

This is a very good question. One way round it is if you shoot with a smaller sensor, but that relies on you having a bunch of cameras with different size sensors. 

Edited February 10, 2019 by Lockie

[Ags]

Canon 200/2.8L?

[happy-kat]

The focal length is the same, the crop sensor just gives the field of view of a 500 but not the magnification. Kingfishers are a super target.

With the redcat if you want the magnification use a barlow (to be tested by rayD) but you'll take a hit on focal ratio.

Edited February 10, 2019 by happy-kat

[Davey-T]

Got a few L lenses but not the 200 2.8L, the only " problem " with camera lenses, apart from the myriad bits of glass they deem necessary, is that they are in no way designed for astro' imaging so if they happen to work well for it that's just a bonus whereas a lens specifically designed for astro and also capable of good daylight performance must be good.

Dave

[Chris]

1 hour ago, happy-kat said:

The focal length is the same, the crop sensor just gives the field of view of a 500 but not the magnification. Kingfishers are a super target.

With the redcat if you want the magnification use a barlow (to be tested by rayD) but you'll take a hit on focal ratio.

I understand the resolution wouldn't be the same, but if you want to try and make a 135mm lens closer to a 250mm, it's the only way I can think of doing it whilst maintaining the 'speed' (as we are comparing it to an f2 lens)

effectively cropping down with a smaller sensor would be a waste of that lovely fat field though   

Edited February 10, 2019 by Lockie

[Davey-T]

8 minutes ago, Lockie said:

effectively cropping down with a smaller sensor would be a waste of that lovely fat field though

Guess you can say the same about all my Canon lenses used on a 60Da, does this mean if I buy a WO Redcat I'll have to buy a full frame DSLR 

Dave