New Petzval sv555 54mm from SVBony

[DebinOz]

https://www.svbony.com/sv555-astrograph-lens/#F9395A

Has anyone ordered one of these or have any feedback as to the quality compared to a Redcat or Askar? These are on sale right now and half the price of the Redcat. Too good to be true? They are not saying what type of glass they use and the marketing is hilarious. The guy in the release livestream even dropped it while demonstrating. :rofl:

[OzEclipse]

Haven't ordered one. SV Bony are capable of producing excellent optics. I have a pair of SV Bony SV202 10x42ED's that are excellent.

For around that same price, you can get a Samyang/Rokinon 135mm f2, a fantastic tack sharp wide field astrographic lens. They are sharp wide open but with vignetting.

Add a quality 1.4X converter and you have a 200mm f2.8 and a 2X converter and you have a 270mm f4, not that different to the Redcat. Either of these will only have 45-55mm back focus depending which mount you buy so it depends what you want to hang behind it.
DSLR - no problems.
Dedicated Astrocam with filter wheel etc - you'll need to check back focus requirements.

[DebinOz]

I had a Samyang 135 and sold it to fund an upgrade to a longer focal length scope, being under the impression a telescope would yield better images at 250-400mm. I already have a 70-200 2.8L. To increase focal length I have been comparing a used 100-400 f4.5-5.6L, an f4 300mm, the Zenithstar 61 (F5.6, 360mm) and a refurbished redcat 51 (250mm, f4.9) I am using a full frame canon camera.

On paper, the 70-200 I already have looks like a winner at F2.8. Is the redcat or zenithstar going to yield better results?

[JohnA]

I ordered one today. At under $800 current promotion, thought it was worth a try.
Ill pair it with the 2600 camera, was thinking I could grab a 533, but I can crop the images from 2600 to what I need I suppose.

Ill report back once I get it and have had a play

[JohnA]

mine arrived today and for most part it looks like a decent build, but you can see quality control is not the best. The dovetail plate that came with mine is too narrow and wont secure onto my mount, will slide out. Its almost 2mm narrower then my other vixen bars.

So until i get a replacement from svbony i may have to use a shim in there to hold it in place, but i wonder if thats safe?

[JohnA]

so i emailed them about the issue and their reply was as follows

Okay. Thank you for your feedback. I helped you contact the technician.
The width of the dovetail plate is 42mm, which is normal. If you are worried about safety, you can clamp a piece of paper.
You can try it. I hope it helps you.
Have a good day.
Kind regards

I will replace it with a new plate, but i doubt id purchase another product from them.

Ill test mine tonight to see that it all works well, if it does i will keep it, but if there are issues ill be sending it straight back i think for a refund.

[Leo.G]

Is the plate actually narrower or is it machined at a different angle?
You'd need an original Vixen type or specs to check that.



That's unusual from my experience though I only bought a good quality microscope from them a few years back, every bit of the build is to the highest standard.
As for a piece of paper, not unless they are offering a free replacement scope if it slides out.
Vixen standards are 42mm are they not?
It may be like camera quick release plates, they all list as the standard compatible (Arca-Swiss) but there are many slightly narrower, I'm just grateful my 25Kg load capacity ball-head has an adjustable clamp or I'd have had some bad experiences and expensive Nikon repairs.

[JohnA]

Hey Leo, i measured it up against the vixen plate on me c925 and its narrower at the widest point.

I measured it at roughly 91.5 and it just wont mount securely.
Looking at all aftermarket ones i have noticed the following

geopix are 43.5
Asker are 44
Baadar are 44
PrimaLuce 43
Celestron 43.1
William optics is 41.7

[JohnA]

whilst setting up today to test everything out, i took a few 30sec shots of IC434

I have uploaded one of them here and noticed 3 large circles which i could not see in the moon video i took with the same camera and filter

Filter is a baader it/uv cut filter on asi678 camera


Would it be, filter, lens camera, and what would be the best thing to use to clean?

Thanks

[Leo.G]

John that looks like it could be the slightest bit of hair/dust but I'm not sure how to figure out exactly where it would be in the image train, I always start with cleaning my lenses with a good anti-static cloth (I buy them in packs of 500 from memory from AliExpress) and go right through.
I don't handle filters, I have a couple I don't really use much but they can be tricky depending on what they are made of.
Most of my gear I generally start with a blower bulb and good make up brush for stubborn dust, I still have an original Helena Rubinstein Make-up brush I was given by a company sales rep in the early 70s, it's camel hair and very fine and it has transferred through the years between camera bags. I also buy make up brush sets at Aldi when they are on special for my camera gear and my son has a set for his computer gear, soft brushes which don't scratch, used for removing hair and fluff (I have 5 cats, cat hair gets in places that would shock you, LOL). I DO NOT however use them on camera sensors, for that I spend the money on the foil sealed cleaners.
The little air bulb (blower) could resolve the issues, blow any dust off and see if it makes a difference. The general camera store things (and eBay) I find not great quality but my sons hearing aids came with a couple of amazing quality units that are great. Better quality units are worth the bit more cash if you want them to last.
NEVER use a compressor, there is always moisture even with a water trap. I also have an aldi inflation pump that's basically just a battery operated blower which sucks air in through a big fan on top and pressurises it out through a nozzle (mine uses the 20 Volt Aldi battery system same as a lot of my power tools from Aldi). I can use this to blow my telescope tubes out without introducing moisture but I put a fine mesh over the inlet to prevent it blowing dust out at my optics under pressure.


Canned air (refrigerant) is not good to use because it always introduces moisture content, maybe suitable for blowing out keyboards but even then I don't use it near computer or camera gear.
I do however drip the refrigerant out for varying projects and great on a burn (that's what canned compressed air is, refrigerant which gasses in above zero temperatures and pressurises as harmless gas (supposedly) in the can. Why didn't they ever do that with Freon?).

[JohnA]

Leo
Thank you so much for the detailed response. I have some of that stuff already at home and i'll order some anti static cloths.

I start with the little blower bulb and make up brush and see how that goes.

Again, thank you kindly for the advice

[Leo.G]

You're welcome and I hope it helps!
A good light source is usually your best bet for finding dust.
Camera stores also sell soft brushes but they are much dearer for a very similar brush with fine hair (now synthetic).

[JohnA]

i received my new vixen dovetail plate today, not from svbony, but an aftermarket one and this one fits on the mount perfectly. No fear of it sliding out.

From reading online seems it depends on the mounts saddle, some will clamp onto the svbony one just fine, where a select few are having issues like i did with mine.

So if you own a wave130i it wont secure the stock dovetail bar.

On the plus side, the newer one was longer, so i was also able to mount the asiair plus to the rear of it rather then the side of the telescope ring holder

First pic with the longer dovetail bar and asi mounted to the rear

Second pic show the asiair on the side and the original bar, was using a shim to hold it in the mount just for the pic.