
Good ultra widefield options?
#1
Posted 21 January 2025 - 01:42 PM
Basically I am looking for something to mount on top of my FF65. I have a 533 and a 2600, so my thinking is that I can swap cameras according to the desired field of view. Even use one or the other as a guiding set up, or run both together. Lots of options.
The Samyang 135 is an option, but then I am looking at probably 3d printed rings, occasional sample variation etc etc. That all starts to add up. Plus I am back with the mechanical issues of camera connection and tilt. Or is thatil focal speed worth it all. Hmm. That focal ratio cannot be ignored.
The minicat is far too much money and all this talk of poor stars rules it completely out.
The Askar FMA 180 pro matches the FL of my Nikkor and seems ideal. F4.5. slower FR means less issues that the fast samyang I expect. I guess that putting my modded 6DMKii on it would be a big ask, but with a bit of a crop and blurX I assume it is viable.
Is there anything else out there that I am missing? Any opinions on the FMA 180 pro?
Camera lenses are less appealing. I am tired of messing with rings and bits of tape to try and avoid things getting marked up by mounting rings and these useless delrin tips that vanish, and playing Lego for hours. I desire something that permanently sits on top of my FF65 without fuss and which I can swap cameras easily - with the Nikkor and rings, camera swaps are painful!
Price wise, a used or ex demo samyang, rings plus a m48 plate to swap out the EF bayonet mount is around the same ballpark as an Askar 180 pro. That is the sort of range I am looking at.
All mounted on an AM5 so I have no concerns about weight and have done it enough with various lenses anyway.
Thanks! When I say ultra wide, think along the lines of Rho, veil, all of Orion, m45 and lots of dust, vela SNR. Big beautiful targets in one frame.
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#2
Posted 21 January 2025 - 02:06 PM
You can set up an FOV with any equipment at https://telescopius.com/
Thanks. I use stellarium to determine my FoV with targets. It is not so much the FoV that I am interested in (for my use case anything between say 100 - 180mm FL works) but rather specific recommendations, or if I am missing something other than the Samyang and the Askar 180, or indeed pros and cons of either that I have missed. With an emphasis on options which are not lenses and are not Borg money...
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#3
Posted 21 January 2025 - 02:14 PM
Well, there's the Askar FMA135. I waffled between the Askar and a Samyang/Rokinon lens. In the end I didn't like the defraction spike like artifacts from the lens shutters on the camera lenses. I'm impressed by the Askar so far. https://app.astrobin...34/askar-fma135
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#4
Posted 21 January 2025 - 03:06 PM
I have the Rokinon 135mm and the Askar ACL200. I also find that using them at f/4 is best. I have the 3D printed rings for the 135mm and it seems solid. I use both with a 2600MC and a filter drawer. The 135mm with the ZWO/Canon filter drawer and the ACL200 with the ZWO M42/M48 filter drawer. Both setups once dialed in are set it and forget it except for focus.
I have an EvoGuide 50mm with the Starizona flattener but have not done much with it and prefer the ACL200. I'm also not really offended by the diffraction spikes from the camera lenses. Using a 2600 is best but a lager sensor gives you more options. I've used the ACL200 a few times with a 2400MC and the results were good.
I'm only doing EAA and here is an ACL200/2400 image. This is with no star shape correction.
Cygnus/Sadr area, 8 minutes total, FOV is 10.3° x 6.8°
Edited by MarMax, 21 January 2025 - 03:07 PM.
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#5
Posted 21 January 2025 - 03:24 PM
The ACL200 is FF but out of production so you have to buy used. The new SharpStar 50EDPH (V2 fixed some early issues) is 230mm F/L with the reducer but like the FMA180 it is only APSC. The SVBony SV555 is full frame but 243mm F/L.
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#6
Posted 21 January 2025 - 03:34 PM
A BORG 55FL F3.6 with the FeatherTouch focuser.
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#7
Posted 21 January 2025 - 03:35 PM
A BORG 55FL F3.6 with the FeatherTouch focuser.
I wish. Too pricey.
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#8
Posted 21 January 2025 - 03:52 PM
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#9
Posted 21 January 2025 - 03:52 PM
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#10
Posted 21 January 2025 - 03:55 PM
Agena has a customer return ACL200 for sale.
https://agenaastro.c...w-cln-1267.html
You can probably get one for less in the classifieds.
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#11
Posted 21 January 2025 - 05:45 PM
IMO a good copy (usable at f/2) of the Rokinon 135mm would probably be the best option, if only because of f/2. I've always found the images from the FMA180/FMA135 to be a bit soft, but I have heard they make great guide scopes, so that might be something to consider, too.
Hi - I have the Canon EOS EF version of both the Samyang 135 F2 and the Rokinon 50 F1.4. The latter can capture the shoulders, waist and feet of Orion in one go.
I have used them with a ZWO camera, the ZWO filter drawer and the ZWO connector for Canon EF lenses. I think it may also have worked with the EFW directly attached to the camera (no tilt plate) and the ZWO adapter that is not a filter drawer. Details here: https://www.cloudyni...-lens-no-focus/
I also have an astro modded Canon EOS and am considering getting a Silence Corner Atoll DSLR rotator to mount this. It comes in different versions for different camera body sizes and lens diameters. It looks like version D would work for the Canon and the Rokinon / Samyang lenses.
https://silencecorne...ns/atoll-series is the manufacturer's site but they are also available on B&H and Amazon.
There are a couple of other brands as well - Fotopro, Benro and Smallrig.
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#12
Posted 21 January 2025 - 10:29 PM
I have a FMA180, Pentax 200 F2.8, and the MiniCat. I also have a FMA135 and a Rokinon 135 F2.
I bought the MiniCat to hopefully replace the FMA180. But have found the FMA is actually sharper, and weighs a lot less. The MiniCat needs BlurX, but the FMA is fine without it. The Pentax is sharp, but has some CA until F4. The FMA also has a touch of CA, but an L3 filter eliminates most of it.
Between the 135’s. They are similar in sharpness, but the Rokinon wins on lens speed. The Rokinon handles FF better. But the FMA is easier to focus due to its focuser. The Rokinon is very touchy to focus. The FMA makes a great guide scope too.
I’m heading out on a dark skies road trip late spring, RHO is my target. My main rig will be a 2600MC on the FMA180, but I’ll also be shooting with the Rokinon on my FF Pentax K1. I’ll have the FMA 135 along as a guide scope, and may try it too. Even though I bought the MiniCat with this trip in mind, I’m not taking it. In all the equipment I have, it has been my most disappointing purchase. I also considered the Borg 55. But it’s a lot more expensive, and not much sharper than the MiniCat.
Between 135mm and 180mm, the 180mm seems to frame most targets best for me with a 2600. These shots will give you a good idea of how sharp it is. They have pretty minimal cropping (just the dither) and processing. There was no PI, BXT, or star removal. But I did use an L3 filter. If you’re shooting with a smaller format, either of the 135’s may be a better choice.
Edited by Drothgeb, 21 January 2025 - 10:39 PM.
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#13
Posted 21 January 2025 - 11:03 PM
Many thanks for the suggestions all. The samyang/rok is less attractive if it has to be run at F4. If so (and adding up the prices of the rings) then I lean towards the Askar 180. The 135 Askar is another option to research - thanks.
It doesn't have to be. You already know it's pretty much a toss-up for the sample quality, but alot of us just image at f2 or f2.4 and toss those stars and then capture stars at f4. The sy 135 is close to equivalent to the fma135 at 6 clicks of the aperture dial - 31mm/f4.14. Obviously it's less plug-and play but I think there's a little more versatility to it.
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#14
Posted 22 January 2025 - 08:39 AM
If I was doing it again the FMA180 looks pretty good, but I have a Nikon 180mm f2.8 ED AI-s and like it a lot. I assume you have the ED version of the Nikon lens.
I'm using an ASI183MCPro that has a similar chip size to your 533, but smaller pixels, and I connect the lens with the ZWO Nikon filter drawer. My lens mounts pretty tight and with the small sensor size I use tilt doesn't seem to be a big issue. That might be different with something the size of your 2600. I don't use rings on the lens, just a pair of ZWO camera rings on the camera. At one point I used a Small Rigs Lens Support https://www.smallrig...rt-bsl2681.html on the dew shield but didn't see a big difference so stopped using it.
If you have the ED version you have 9 beautiful sunstar spikes (non-ED is 7 spikes)! Sometimes I do feel spiky, but when I don't I use filter step-down rings that thread in like normal lens filters.
For lens mounting options the film industry has lots of good parts, Small Rigs and CAMVATE being two manufactures.
This info might not be all that useful for you, but maybe someone later on.
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#15
Posted 22 January 2025 - 12:31 PM
Many thanks everyone, there is really helpful advice and feedback here.
After all the comments about the Samyang/Rok, plus looking at the huge user base out there I am going to look for one. looking at the amount of places on the lens that do not rotate (i.e. the actual barrel of the lens and not the aperture/focus rings) it is clear it will fit in rings better than the Nikkor. I will start with that and later down the road go for printed rings and an EAF mount. I will add a replacement M48 mount to eliminate the EF bayonet mount and hopefully any tilt issues.
The appeal of F2 under dark skies is just too great. As has been mentioned I can always shoot stars separately (which I usually do anyway).
Thanks all.
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